Improving cotton fiber quality can increase the economic income of cotton farmers, but achieving high fiber quality without decreasing cotton fiber yield remains a major challenge in saline-alkaline cotton fields. A f...Improving cotton fiber quality can increase the economic income of cotton farmers, but achieving high fiber quality without decreasing cotton fiber yield remains a major challenge in saline-alkaline cotton fields. A field experiment was conducted in 2020 and 2021 on saline-alkaline soil with cotton under drip irrigation to examine how amount and timing of leaching affected soils salinity, cotton fiber yield and quality. There were five leaching amounts(CK: 0 mm, W1: 75 mm, W2: 150 mm, W3: 225 mm and W4: 300 mm) and three leaching timings(T1: once at the seedling stage, T2: twice at the seedling and budding stages, and T3: thrice at the seedling, budding and pollen-setting stages). Soil salinity, soil nitrate nitrogen(NO_(3)-N), cotton nitrogen(N) uptake, irrigation water productivity(IWP), cotton fiber yield, fiber length, fiber uniformity, fiber strength, fiber elongation, micronaire and fiber quality index(FQI) were investigated. The results indicated that soil salinity and NO_(3)-N reduced with increasing leaching amount. The N uptake of cotton bolls was greater than in cotton leaves, stems and roots, and total N accumulation increased with increasing leaching amount. The optimal cotton fiber yield and IWP occurred in treatment W3T2, and were 3,199 and 2,771 kg ha^(-1), and 0.5482 and 0.4912 kg m-3in 2020 and 2021, respectively. Fiber length, strength, elongation, and uniformity increased with increasing leaching amount, while there was a negative relationship between fiber micronaire and leaching amount. Soil salinity, NO_(3)-N and fiber micronaire were negatively correlated with fiber quality(i.e., length, strength, elongation and uniformity) and yield, nitrogen uptake of various organs(i.e., root, stems and leaves) and whole plant nitrogen uptake. Pearson correlation analysis revealed that fiber elongation was most sensitive to soil salinity. The method of Entropy–Order Preference by Similarity to Ideal Solution(EM–TOPSIS) indicated that leaching of 300 mm of water applied equally at the seedling and budding periods was the optimal treatment to maintain soil salinity and nutrient levels and achieve high cotton fiber yield and quality. In conclusion, the optimal level of leaching treatment decreased soil salinity and improved nitrogen uptake and was beneficial to achieve high fiber yield and quality. Our results will be significant for guiding drip irrigation practice of leaching on saline-alkaline soils for sustainable cotton fiber production.展开更多
Using simulated soil column experiments, the effects of different dosages and ratios of KCI and MgCI2 mixture on salinization nutrient ions in the secondary salinization soil which had 3 years of planting were studied...Using simulated soil column experiments, the effects of different dosages and ratios of KCI and MgCI2 mixture on salinization nutrient ions in the secondary salinization soil which had 3 years of planting were studied, with the aim to provide the theory basis for the remediation of secondary salinization soil. Results showed that the content of soil K-, Mg2＋, CI- and the total salinity were increased, with the increasing concentrations of nutrient solution, while Na＋, Ca2＋ and HCO3- contents were reduced. Compared with originals oil, soil K＋, Na＋, Ca2＋, Mg2＋, CI- and total soil salinity were decreased, and HCO3- and SO42 were increased. In terms of the variation of soil total charge, the change ranges in 1：1 treatment varied small, but the residual of soil cationic decreased with increasing application of K＋ in the 2：1 treatment. It could be concluded that balanced and low application fertilizer could alleviate the soil saline, decrease the soil nutrition leaching and improve the balance among ions, while excess fertilization could accelerate the imbalance of zwitterions.展开更多
Various calibration methods have been propounded to determine profiles of apparent bulk soil electrical conductivity (ECa) and soil electrical conductivity of a saturated soil paste extract (ECe) or a 1:5 soil water e...Various calibration methods have been propounded to determine profiles of apparent bulk soil electrical conductivity (ECa) and soil electrical conductivity of a saturated soil paste extract (ECe) or a 1:5 soil water extract (EC1:5) using an electromagnetic induction instrument (EM38). The modeled coefficients, one of the successful and classical methods hitherto, were chosen to calibrate the EM38 measurements of the inverted salinity profiles of characteristic coastal saline soils at selected sites of Xincao Farm, Jiangsu Province, China. However, this method required three parameters for each depth layer. An integration approach, based on an exponential decay profile model, was proposed and the model was fitted to all the calibration sites. The obtained model can then be used to predict EC1:5 at a certain depth from electromagnetic measurements made using the EM38 device positioned in horizontal and vertical positions at the soil surface. This exponential decay model predicted the EC1:5 well according to the results of a one-way analysis of variance, and the further comparison indicated that the modeled coefficients appeared to be slightly superior to, but not statistically different from, this exponential decay model. Nevertheless, this exponential decay model was more significant and practical because it depended on less empirical parameters and could be used to perform point predictions of EC1:5 continuously with depth.展开更多
Modeling soil salinity in an arid salt-affected ecosystem is a difficult task when using remote sensing data because of the complicated soil context （vegetation cover, moisture, surface roughness, and organic matter...Modeling soil salinity in an arid salt-affected ecosystem is a difficult task when using remote sensing data because of the complicated soil context （vegetation cover, moisture, surface roughness, and organic matter） and the weak spectral features of salinized soil. Therefore, an index such as the salinity index （SI） that only uses soil spectra may not detect soil salinity effectively and quantitatively. The use of vegetation reflectance as an indirect indicator can avoid limitations associated with the direct use of soil reflectance. The normalized difference vegetation index （NDVI）, as the most common vegetation index, was found to be responsive to salinity but may not be available for retrieving sparse vegetation due to its sensitivity to background soil in arid areas. Therefore, the arid fraction integrated index （AFⅡ） was created as supported by the spectral mixture analysis （SMA）, which is more appropriate for analyzing variations in vegetation cover （particularly halophytes） than NDVI in the study area. Using soil and vegetation separately for detecting salinity perhaps is not feasible. Then, we developed a new and operational model, the soil salinity detecting model （SDM） that combines AFⅡ and SI to quantitatively estimate the salt content in the surface soil. SDMs, including SDM1 and SDM2, were constructed through analyzing the spatial characteristics of soils with different salinization degree by integrating AFⅡ and SI using a scatterplot. The SDMs were then compared to the combined spectral response index （COSRI） from field measurements with respect to the soil salt content. The results indicate that the SDM values are highly correlated with soil salinity, in contrast to the performance of COSRI. Strong exponential relationships were observed between soil salinity and SDMs （R2〉0.86, RMSE〈6.86） compared to COSRI （R2=0.71, RMSE=16.21）. These results suggest that the feature space related to biophysical properties combined with AFII and SI can effectively provide information on soil salinity.展开更多
A field experiment was carried out to investigate the effects of different emitter discharge rates under drip irrigation on soil salinity distribution and cotton yield in an extreme arid region of Tarim River catchmen...A field experiment was carried out to investigate the effects of different emitter discharge rates under drip irrigation on soil salinity distribution and cotton yield in an extreme arid region of Tarim River catchment in Northwest China. Four treatments of emitter discharge rates, i.e. 1.8, 2.2, 2.6 and 3.2 L/h, were designed under drip irrigation with plastic mulch in this paper. The salt distribution in the range of 70-cm horizontal distance and 100-cm vertical distance from the emitter was measured and analyzed during the cotton growing season. The soil salinity is expressed in terms of electrical conductivity （dS/m） of the saturated soil extract （ECe）, which was measured using Time Domain Reflector （TDR） 20 times a year, including 5 irrigation events and 4 measured times before/after an irrigation event. All the treatments were repeated 3 times. The groundwater depth was observed by SEBA MDS Dipper 3 automatically at three experimental sites. The results showed that the order of reduction in averaged soil salinity was 2.6 L/h 〉 2.2 L/h 〉 1.8 L/h 〉 3.2 L/h after the completion of irrigation for the 3-year cotton growing season. Therefore, the choice of emitter discharge rate is considerably important in arid silt loam. Usually, the ideal emitter discharge rate is 2.4-3.0 L/h for soil desalinization with plastic mulch, which is advisable mainly because of the favorable salt leaching of silt loam and the climatic conditions in the studied arid area. Maximum cotton yield was achieved at the emitter discharge rate of 2.6 L/h under drip irrigation with plastic mulch in silty soil at the study site. Hence, the emitter discharge rate of 2.6 L/h is recommended for drip irrigation with plastiic mulch applied in silty soil in arid regions.展开更多
Ecological restoration by Taman＇x plants on semi-arid saline lands affects the accumulation, distribution patterns and related mechanisms of soil water content and salinity. In this study, spatio-temporal variations ...Ecological restoration by Taman＇x plants on semi-arid saline lands affects the accumulation, distribution patterns and related mechanisms of soil water content and salinity. In this study, spatio-temporal variations of soil water content and salinity around natural individual Tamarix ramosissiraa Ledeb. were invetigated in a semi-arid saline region of the upper Yellow River, Northwest China. Specifically, soil water content, electrical conductivity （EC）, sodium adsorption ratio （SARa）, and salt ions （including Na＋, K＋, Ca2＋, Mg2＋ and 8042-） were measured at different soil depths and at different distances from the trunk of T. ramasissima in May, July, and September 2016. The soil water content at the 20-80 cm depth was significantly lower in July and September than in May, indicating that T. ramosissima plants absorb a large amount of water through the roots during the growing period, leading to the decreasing of soil water content in the deep soil layer. At the 0-20 cm depth, there was a salt island effect around individual T. ramosissima, and the ECe differed significantly inside and outside the canopy of T. ramosissima in May and July. Salt bioaccumulation and stemflow were two major contributing factors to this difference. The SAR at the 0-20 cm depth was significantly different inside and outside the canopy of T. ramosissima in the three sampling months. The values of SAR~ at the 60-80 cm depth in May and July were significantly higher than those at the 0-60 cm depth and higher than that at the corresponding depth in September. The distribution of Na＋ in the soil was similar to that of the SAI, while the concentrations of K＋, Ca2＋, and Mg2＋ showed significant differences among the sampling months and soil depths. Both season and soil depth had highly significant effects on soil water content, ECe and SARa, whereas distance from the trunk of T. ramosissima only significantly affected ECe. Based on these results, we recommend co-planting of shallow-rooted salt-tolerant species near the Tamarx plants and avoiding planting herbaceous plants inside the canopy of T. ramodssima for afforestation in this semi-arid saline region. The results of this study may provide a reference for appropriate restoration in the semi-arid saline regions of the upper Yellow River.展开更多
The aim of this paper was to research the spatio-temporal changes in total soluble salt content （TS） in a typical arid region of South Xinjiang, China, where the climate is arid and soil salinization happens easily....The aim of this paper was to research the spatio-temporal changes in total soluble salt content （TS） in a typical arid region of South Xinjiang, China, where the climate is arid and soil salinization happens easily. The total soluble salt content was interpreted by measurements made in the horizontal mode with EM38 and EM31. The electromagnetic induction （EM） surveys were made three times with the apparent soil electrical conductivity （ECa） measurements taken at 3 873 locations in Nov. 2008, 4 807 locations in Apr. 2009 and 6 324 locations in Nov. 2009, respectively. For interpreting the ECa measurements into total soluble salt content, calibtion sites were needed for EM survey of each time, e.g., 66 sites were selected in Nov. 2008 to measure ECa, and soils-core samples were taken by different depth layers of 0-10, 10-20 and 20-40 cm at the same time. On every time duplicate samples were taken at five sites to allevaite the local-scale variability, and soil temperatures in different layers through the profiles were also measured. Factors including TS, pH, water content, bulk density were analyzed by lab experiments. ECa calibration equations were obtained by linear regression analysis, which indicated that soil salinity was one primary concern to ECa with a determination coefficient of 0.792 in 0-10 cm layer, 0.711 in 10-20 cm layer and 0.544 in 20-40 cm layer, respectively. The maps of spatial distribution were predicted by Kriging interpolation, which showed that the high soil salinity was located near the drainage canal, which validated the trend effect caused by the irrigation canal and the drainage canal. And by comparing the soil salinity in different layers, the soluble salt accumulated to the top soil surface only in the area where the soil salinization was serious, and in the other areas, the soil salinity trended to increase from the top soil surface to 40 cm depth. Temporal changes showed that the soil salinity in November was higher than that in April, and the soil salinization trended to aggravate, especially in the top soil layer of 0-10 cm.展开更多
With increased cultivation of transgenic Bacillus thuringiensis （Bt） cotton in the saline alkaline soil of China, assessments of transgenic crop biosafety have focused on the effects of soil salinity on rhizosphere ...With increased cultivation of transgenic Bacillus thuringiensis （Bt） cotton in the saline alkaline soil of China, assessments of transgenic crop biosafety have focused on the effects of soil salinity on rhizosphere microbes and Bt protein residues. In 2013 and 2014, investigations were conducted on the rhizosphere microbial biomass, soil enzyme activities and Bt protein contents of the soil under transgenic Bt cotton （variety GK19） and its parental non-transgenic cotton （Simian 3） cultivated at various salinity levels （1.15, 6.00 and 11.46 dS m-1）. Under soil salinity stress, trace amounts of Bt proteins were ob- served in the Bt cotton GK19 rhizosphere soil, although the protein content increased with cotton growth and increased soil salinity levels. The populations of slight halophilic bacteria, phosphate solubilizing bacteria, ammonifying bacteria, nitrifying bacteria and denitrifying bacteria decreased with increased soil salinity in the Bt and non-Bt cotton rhizosphere soil, and the microbial biomass carbon, microbial respiration and soil catalase, urease and alkaline phosphatase activity also decreased. Correlation analyses showed that the increased Bt protein content in the Bt cotton rhizosphere soil may have been caused by the slower decomposition of soil microorganisms, which suggests that salinity was the main factor influencing the relevant activities of the soil microorganisms and indicates that Bt proteins had no clear adverse effects on the soil microorganisms. The results of this study may provide a theoretical basis for risk assessments of genetically modified cotton in saline alkaline soil.展开更多
The spatial estimation for soil properties was improved and sampling intensities also decreased in terms of incorporated auxiliary data. In this study, kriging and two interpolation methods were proven well to estimat...The spatial estimation for soil properties was improved and sampling intensities also decreased in terms of incorporated auxiliary data. In this study, kriging and two interpolation methods were proven well to estimate auxiliary variables： cokriging and regression-kriging, and using the salinity data from the first two stages as auxiliary variables, the methods both improved the interpolation of soil salinity in coastal saline land. The prediction accuracy of the three methods was observed under different sampling density of the target variable by comparison with another group of 80 validation sample points, from which the root-mean-square error （RMSE） and correlation coefficient （r） between the predicted and measured values were calculated. The results showed, with the help of auxiliary data, whatever the sample size of the target variable may be, cokriging and regression-kriging performed better than ordinary kriging. Moreover, regression-kriging produced on average more accurate predictions than cokriging. Compared with the kriging results, cokriging improved the estimations by reducing RMSE from 23.3 to 29% and increasing r from 16.6 to 25.5%, regression-kriging improved the estimations by reducing RMSE from 25 to 41.5% and increasing r from 16.8 to 27.2%. Therefore, regression-kriging shows promise for improved prediction for soil salinity and reduction of soil sampling intensity considerably while maintaining high prediction accuracy. Moreover, in regression-kriging, the regression model can have any form, such as generalized linear models, non-linear models or tree-based models, which provide a possibility to include more ancillary variables.展开更多
A pot experiment was carried out on a marine saline soil to study the effect of initial soluble Na/Ca ratio of saline soil on the salinity tolerance of barley plant.The results showed that (1) the Na/Ca ratio affected...A pot experiment was carried out on a marine saline soil to study the effect of initial soluble Na/Ca ratio of saline soil on the salinity tolerance of barley plant.The results showed that (1) the Na/Ca ratio affected significantly the dry weight of the plant at an earlier stage of growth,the critical values of initial Na/Ca ratio at which the plant could grow normally on soils containing salts of 2.5,3.5 and 4.5g kg^-1 were 30,20 and 15,respectively;(2)smaller Na/Ca ratio resulted in a considerable decrease in Na accumulation but a great increase in K accumulation in the barley plant;and (3) the plasmallema of barley leaf were badly injured when the Na/Ca ratio was more than 30 and the increase of Na content of plant caused an exudation of K from the leaf cells.Some critical indexes were suggested for the cultivation of barley plant on marine saline soils and could be used as reference in the biological reclamation of marine saline soils.展开更多
The integrated effect of irrigation and agricultural practices on soil salinity in the Jordan Valley （JV）, where over 60% of Jordan＇s agricultural produce is grown, was investigated in this study during 2009-2010. ...The integrated effect of irrigation and agricultural practices on soil salinity in the Jordan Valley （JV）, where over 60% of Jordan＇s agricultural produce is grown, was investigated in this study during 2009-2010. Due to the differences in agricultural operations, cropping patterns, irrigation management, and weather conditions, 206 top- and sub-soil samples were taken every 1 to 3 km from representative farms along a north-south （N-S） transect with 1 to 2 km lateral extents. Soil electrical conductivity of saturated extract （ECse）, Ca, Mg, K, Na, CI, and Na adsorption ratio （SAR） were determined in saturated paste extracts. Results indicated that about 63% of soils in the JV are indeed saline, out of which almost 46% are moderately to strongly saline. Along the N-S transect of the JV, ECse increased from 4.5 to 14.1 dS m-1 in top-soil samples. Similar increase was observed for the sub-soil samples. The major chemical components of soil salinity; i.e., Ca, Mg, and C1, also showed a similar increase along the N-S transect of the valley. Moreover, compared to previous field sampling, results showed that changes in soil salinity in the JV were dramatic. In addition, it was found that C1 imposed an existing and potential threat to sensitive crops in 60% of the soils in the JV, where C1 concentrations were greater than 710 mg L-1. Under the prevalent arid Mediterranean conditions, improving the management of .irrigation water, crops, and nutrient inputs and increasing water and fertilizer use efficiencies should be indispensable to conserve and sustain the already fragile agricultural soils in the JV.展开更多
Microbial adaptation to salinity can be achieved through synthesis of organic osmolytes,which requires high amounts of energy;however,a single addition of plant residues can only temporarily improve energy supply to s...Microbial adaptation to salinity can be achieved through synthesis of organic osmolytes,which requires high amounts of energy;however,a single addition of plant residues can only temporarily improve energy supply to soil microbes.Therefore,a laboratory incubation experiment was conducted to evaluate the responses of soil microbes to increasing salinity with repeated additions of plant residues using a loamy sand soil with an electrical conductivity in saturated paste extract(EC_e) of 0.6 dS m^(-1).The soil was kept non-saline or salinized by adding different amounts of NaCl to achieve EC_e of 12.5,25.0 and 50.0 dS m^(-1).The non-saline soil and the saline soils were amended with finely ground pea residues at two rates equivalent to 3.9 and 7.8 g C kg^(-1) soil on days 0,15 and29.The soils receiving no residues were included as a control.Cumulative respiration per g C added over 2 weeks after each residue addition was always greater at 3.9 than 7.8 g C kg^(-1) soil and higher in the non-saline soil than in the saline soils.In the saline soils,the cumulative respiration per g C added was higher after the second and third additions than after the first addition except with3.9 g C kg^(-1) at EC_e of 50 dS m^(_1).Though with the same amount of C added(7.8 g C kg^(-1)),salinity reduced soil respiration to a lesser extent when 3.9 g C kg^(-1) was added twice compared to a single addition of 7.8 g C kg^(-1).After the third residue addition,the microbial biomass C concentration was significantly lower in the soils with EC_e of 25 and 50 dS m^(_1) than in the non-saline soil at3.9 g C kg^(-1),but only in the soil with EC_e of 50 dS m^(-1) at 7.8 g C kg^(-1).We concluded that repeated residue additions increased the adaptation of soil microbial community to salinity,which was likely due to high C availability providing microbes with the energy needed for synthesis of organic osmolytes.展开更多
Spatial distribution of soil salinity can be estimated based on its environmental factors because soil salinity is strongly affected and indicated by environmental factors. Different with other properties such as soil...Spatial distribution of soil salinity can be estimated based on its environmental factors because soil salinity is strongly affected and indicated by environmental factors. Different with other properties such as soil texture, soil salinity varies with short-term time. Thus, how to choose powerful environmental predictors is especially important for soil salinity. This paper presents a similarity-based prediction approach to map soil salinity and detects powerful environmental predictors for the Huanghe(Yellow) River Delta area in China. The similarity-based approach predicts the soil salinities of unsampled locations based on the environmental similarity between unsampled and sampled locations. A dataset of 92 points with salt data at depth of 30–40 cm was divided into two subsets for prediction and validation. Topographical parameters, soil textures, distances to irrigation channels and to the coastline, land surface temperature from Moderate Resolution Imaging Spectroradiometer(MODIS), Normalized Difference Vegetation Indices(NDVIs) and land surface reflectance data from Landsat Thematic Mapper(TM) imagery were generated. The similarity-based prediction approach was applied on several combinations of different environmental factors. Based on three evaluation indices including the correlation coefficient(CC) between observed and predicted values, the mean absolute error and the root mean squared error we found that elevation, distance to irrigation channels, soil texture, night land surface temperature, NDVI, and land surface reflectance Band 5 are the optimal combination for mapping soil salinity at the 30–40 cm depth in the study area(with a CC value of 0.69 and a root mean squared error value of 0.38). Our results indicated that the similarity-based prediction approach could be a vital alternative to other methods for mapping soil salinity, especially for area with limited observation data and could be used to monitor soil salinity distributions in the future.展开更多
For engineering structures with saline soil as a filling material,such as channel slope,road subgrade,etc.,the rich soluble salt in the soil is an important potential factor affecting their safety performance.This stu...For engineering structures with saline soil as a filling material,such as channel slope,road subgrade,etc.,the rich soluble salt in the soil is an important potential factor affecting their safety performance.This study examines the Atterberg limits,shear strength,and compressibility of carbonate saline soil samples with different NaHCO3 contents in Northeast China.The mechanism underlying the influence of salt content on soil macroscopic properties was investigated based on a volumetric flask test,a mercury intrusion porosimetry(MIP)test,and a scanning electron microscopic(SEM)test.The results demonstrated that when NaHCO3 contents were lower than the threshold value of 1.5%,the bound water film adsorbed on the surface of clay particles thickened continuously,and correspondingly,the Atterberg limits and plasticity index increased rapidly as the increase of sodium ion content.Meanwhile,the bonding force between particles was weakened,the dispersion of large aggregates was enhanced,and the soil structure became looser.Macroscopically,the compressibility increased and the shear strength(mainly cohesion)decreased by 28.64%.However,when the NaHCO3 content exceeded the threshold value of 1.5%,the salt gradually approached solubility and filled the pores between particles in the form of crystals,resulting in a decrease in soil porosity.The cementation effect generated by salt crystals increased the bonding force between soil particles,leading to a decrease in plasticity index and an improvement in soil mechanical properties.Moreover,this work provides valuable suggestions and theoretical guidance for the scientific utilization of carbonate saline soil in backfill engineering projects.展开更多
Soil salinization is one of the most predominant environmental hazards responsible for agricultural land degradation,especially in the arid and semi-arid regions.An accurate spatial prediction and modeling of soil sal...Soil salinization is one of the most predominant environmental hazards responsible for agricultural land degradation,especially in the arid and semi-arid regions.An accurate spatial prediction and modeling of soil salinity in agricultural land are so important for farmers and decision-makers to develop the appropriate mechanisms to prevent the loss of fertile soil and increase crop production.El Outaya plain is marked by soil salinity increases due to the excessive use of poor groundwater quality for irrigation.This study aims to compare the performance of simple kriging,cokriging(SCOK),multilayer perceptron neural networks(MLP-NN),and support vector machines(SVM)in the prediction of topsoil and subsoil salinity.The field covariates including geochemical properties of irrigation groundwater and physical properties of soil and environmental covariates including digital elevation model and remote sensing derivatives were used as input candidates to SCOK,MLP-NN,and SVM.The optimal input combination was determined using multiple linear stepwise regression(MLSR).The results revealed that the SCOK using field covariates including water electrical conductivity(ECw)and sand percentage(sand%),and environmental covariates including land surface temperature(LST),topographic wetness index(TWI),and elevation could significantly increase the accuracy of soil salinity spatial prediction.The comparison of the prediction accuracy of the different modeling techniques using the Taylor diagram indicated that MLP-NN using LST,TWI,and elevation as inputs were more accurate in predicting the topsoil salinity[ECs(TS)]with a mean absolute error(MAE)of 0.43,root mean square error(RMSE)of 0.6 and correlation coefficient of 0.946.MLP-NN using ECw and sand%as inputs were more accurate in predicting the subsoil salinity[ECs(SS)]with MAE of 0.38,RMSE of0.6,and R of 0.968.展开更多
Soil is the essential part for agricultural and environmental sciences,and soil salinity and soil water content are both the important influence factors for sustainable development of agriculture and ecological enviro...Soil is the essential part for agricultural and environmental sciences,and soil salinity and soil water content are both the important influence factors for sustainable development of agriculture and ecological environment.Digital camera,as one of the most popular and convenient proximal sensing instruments,has its irreplaceable position for soil properties assessment.In this study,we collected 52 soil samples and photographs at the same time along the coast in Yancheng City of Jiangsu Province.We carefully analyzed the relationship between soil properties and image brightness,and found that soil salt content had higher correlation with average image brightness value than soil water content.From the brightness levels,the high correlation coefficients between soil salt content and brightness levels concentrated on the high brightness values,and the high correlation coefficients between soil water content and brightness levels focused on the low brightness values.Different significance levels(P)determined different brightness levels related to soil properties,hence P value setting can be an optional way to select brightness levels as the input variables for modeling soil properties.Given these information,random forest algorithm was applied to develop soil salt content and soil water content inversion models using randomly 70%of the dataset,and the rest data for testing models.The results showed that soil salt content model had high accuracy(R_(v)^(2)=0.79,RMSE_(v)=12 g/kg,and RPD_(v)=2.18),and soil water content inversion model was barely satisfied(R_(v)^(2)=0.47,RMSE_(v)=3.04%,and RPD_(v)=1.38).This study proposes a method of modeling soil properties with a digital camera.Combining unmanned aerial vehicle(UAV),it has potential popularization and application value for precise agriculture and land management.展开更多
[Objective] The paper was to analyze the soil salinity characteristics in Xinjiang region, and develop salinization characteristic research, so as to provide reference for salinization research in arid region. [Method...[Objective] The paper was to analyze the soil salinity characteristics in Xinjiang region, and develop salinization characteristic research, so as to provide reference for salinization research in arid region. [Method] With different land types of soil vertical profiles in Karamay absorbing carbon forest as research object, soil salinity and water soluble ions were determined and analyzed using statistical characteristic value and trend surface, and the distribution characteristic of soil salinity in the region was explored.[Result] The salinity in survey area of absorbing carbon forest mainly were sulfate-chloride type and chloride type, of which cations were mainly Na＋, K＋ and Ca2＋, anions were CO32-, Cl- and SO42-, the variation coefficient of CO32 - was as high as 292.91, while the variation coefficient of Cl- was 265.56. The variation of soil total soluble salts in the soil layer of 0-100 cm was not significant, indicating that the content in each soil layer was relatively stable. [Conclusion] The study provided basis for speeding up dynamic monitoring for soil salinization and finding the effective control approach against salinization展开更多
Soil salinity affects the growth and yield of crops.The stress of soil salinity on plants can be mitigated by inoculation of plant growth promoting bacteria(PGPR).The influence of PGPR inoculation on wheat(Triticum ae...Soil salinity affects the growth and yield of crops.The stress of soil salinity on plants can be mitigated by inoculation of plant growth promoting bacteria(PGPR).The influence of PGPR inoculation on wheat(Triticum aestivum L.)crop productivity under salinity stress has not been properly addressed so far.Therefore,the present study was conducted to investigate the effects of various PGPR strains(W14,W10 and 6K;alone and combined)at several growth attributes of wheat plant under different soil salinity gradients(3,6 and 9 dS m-1).The growth attributes of wheat(height,roots,shoots,spikes,grains quality,biological and economical yield,nutrients nitrogen,phosphorus and potassium in grains)were highly affected by salinity and decreased with increasing salinity level.The PGPR inoculation substantially promoted growth attributes of wheat and prominent results were observed in W14×W10×6K treatment at all salinity levels.The results suggest that inoculation of PGPR is a potential strategy to mitigate salinity stress for improving wheat growth and yield.展开更多
In order to assess the effects of chemical properties of soil salinity on electrical conductivity of 1：5 soil/water extract （EC1：5）, the study focused on revealing the main chemical factors contributing to EC of s...In order to assess the effects of chemical properties of soil salinity on electrical conductivity of 1：5 soil/water extract （EC1：5）, the study focused on revealing the main chemical factors contributing to EC of soil extracts and their relative importance. The relationship between EC1：5 and the chemical properties of soil salinity in the delta oasis of Weigan and Kuqa rivers, China, were studied using path coefficient analysis, a path analysis method. We studied each key element affecting EC1：5 either directly or indirectly. The results obtained show that the salt content, total dissolved solids （TDS）, and the sum of the sodium ion concentration and the kalium ion concentration are the most influential factors on 1：5 soil/ water extract （EC1：5） in the 0-10 cm and the 30-50 cm soil layer. The results show that the sequence of direct path coefficients in the 0-10 cm and the 30-50 cm soil layers on soil conductivity is TDS→Na^＋ ＋ K^＋→Salt content→Ca^2＋→Cl-→the sodium dianion ratio （SDR）→pH→ SO4^2-→HCO3^-→Mg^2＋→the soluble sodium percentage （SSP） sodium absorption ratio （SAR） and TDS→Salt content→Na^＋ ＋ K^＋→Ca^2＋→SDR→Mg^2＋→HCO3^-→SSP→pH→SO4^2-→SAR→Cl^-. The salt content, chlorine ion, and SAR are the main factors affecting 1：5 soil/water extract （EC1：5） in the 10-30 centimeter soil layer. The order of direct path coefficients result is as follows： Salt content→Cl^-→SAR→SSP→TDS→Ca^2＋→Mg^2＋= SO4^2-→HCO3^-→pH→SDR→Na^- ＋ K^＋. Moreover, the effects of HCO3^-, pH were very weak. Though the direct path coefficients between EC1：5 and SAR, SO4^2- and Ca^2＋ were not high, influence of other chemical factors caused the coefficients to increase, making the summation of their direct and indirect path coefficients relatively high. The models of the different soil layers were structured separately. Evidences showed that multiple regression relations between EC1：5 and most of the primary factors had sound reliability and very good accuracy. The research results can serve as a reference to the scientific management amelioration and utilization of saline in the Delta Oasis of Weigan and Kuqa rivers.展开更多
To achieve the greatest leaching efficiency,water movement must occur under unsaturated flow conditions.Accordingly,the water application intensity of irrigation must be chosen carefully.The aim of this study was to e...To achieve the greatest leaching efficiency,water movement must occur under unsaturated flow conditions.Accordingly,the water application intensity of irrigation must be chosen carefully.The aim of this study was to evaluate the impact of the water application intensity of micro-sprinkler irrigation on coastal saline soil with different salt contents.To achieve this objective,a laboratory experiment was conducted with three soil salinity treatments(2.26,10.13,and 22.29 dS/m)and three water application intensity treatments(3.05,5.19,and 7.23 mm/h).The results showed that the effect of soil salinity on soil water content,electrical conductivity,and pH was significant,and the effect of the water application intensity was insignificant.High soil water content was present in the 40e60 cm profile in all soil salinity treatments,and the content was higher in the medium and high water application intensity treatments than in the low-intensity treatment.Significant salt leaching occurred in all treatments,and the effect was stronger in the high soil salinity treatment and medium water application intensity treatment.In the medium and high soil salinity treatments,pH exhibited a decreasing trend,with no trend change in the low soil salinity treatment,and the pH value was higher in the medium water application intensity treatment than in the other two treatments.These results indicated that the three intensities evaluated had no statistically different effect on the electrical conductivity of saturated soil-paste extracts(EC)in the upper 20 cm of the soil profile,and it would be better to maintain a lower value of the water application intensity.展开更多
基金financially supported by the National Key Research and Development Program of China (2022YFD1900401)the Science and Technology Project of Agriculture, Xinjiang Production and Construction Corps, China (2021AB037)。
文摘Improving cotton fiber quality can increase the economic income of cotton farmers, but achieving high fiber quality without decreasing cotton fiber yield remains a major challenge in saline-alkaline cotton fields. A field experiment was conducted in 2020 and 2021 on saline-alkaline soil with cotton under drip irrigation to examine how amount and timing of leaching affected soils salinity, cotton fiber yield and quality. There were five leaching amounts(CK: 0 mm, W1: 75 mm, W2: 150 mm, W3: 225 mm and W4: 300 mm) and three leaching timings(T1: once at the seedling stage, T2: twice at the seedling and budding stages, and T3: thrice at the seedling, budding and pollen-setting stages). Soil salinity, soil nitrate nitrogen(NO_(3)-N), cotton nitrogen(N) uptake, irrigation water productivity(IWP), cotton fiber yield, fiber length, fiber uniformity, fiber strength, fiber elongation, micronaire and fiber quality index(FQI) were investigated. The results indicated that soil salinity and NO_(3)-N reduced with increasing leaching amount. The N uptake of cotton bolls was greater than in cotton leaves, stems and roots, and total N accumulation increased with increasing leaching amount. The optimal cotton fiber yield and IWP occurred in treatment W3T2, and were 3,199 and 2,771 kg ha^(-1), and 0.5482 and 0.4912 kg m-3in 2020 and 2021, respectively. Fiber length, strength, elongation, and uniformity increased with increasing leaching amount, while there was a negative relationship between fiber micronaire and leaching amount. Soil salinity, NO_(3)-N and fiber micronaire were negatively correlated with fiber quality(i.e., length, strength, elongation and uniformity) and yield, nitrogen uptake of various organs(i.e., root, stems and leaves) and whole plant nitrogen uptake. Pearson correlation analysis revealed that fiber elongation was most sensitive to soil salinity. The method of Entropy–Order Preference by Similarity to Ideal Solution(EM–TOPSIS) indicated that leaching of 300 mm of water applied equally at the seedling and budding periods was the optimal treatment to maintain soil salinity and nutrient levels and achieve high cotton fiber yield and quality. In conclusion, the optimal level of leaching treatment decreased soil salinity and improved nitrogen uptake and was beneficial to achieve high fiber yield and quality. Our results will be significant for guiding drip irrigation practice of leaching on saline-alkaline soils for sustainable cotton fiber production.
基金Supported by the Science and Technology Development Project in Weifang(2015GX078 and 2013YD182)~~
文摘Using simulated soil column experiments, the effects of different dosages and ratios of KCI and MgCI2 mixture on salinization nutrient ions in the secondary salinization soil which had 3 years of planting were studied, with the aim to provide the theory basis for the remediation of secondary salinization soil. Results showed that the content of soil K-, Mg2＋, CI- and the total salinity were increased, with the increasing concentrations of nutrient solution, while Na＋, Ca2＋ and HCO3- contents were reduced. Compared with originals oil, soil K＋, Na＋, Ca2＋, Mg2＋, CI- and total soil salinity were decreased, and HCO3- and SO42 were increased. In terms of the variation of soil total charge, the change ranges in 1：1 treatment varied small, but the residual of soil cationic decreased with increasing application of K＋ in the 2：1 treatment. It could be concluded that balanced and low application fertilizer could alleviate the soil saline, decrease the soil nutrition leaching and improve the balance among ions, while excess fertilization could accelerate the imbalance of zwitterions.
基金Project supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZCX2-YW-406-3)the National Key Basic Research Support Foundation (NKBRSF) of China (No. 2005CB121108).
文摘Various calibration methods have been propounded to determine profiles of apparent bulk soil electrical conductivity (ECa) and soil electrical conductivity of a saturated soil paste extract (ECe) or a 1:5 soil water extract (EC1:5) using an electromagnetic induction instrument (EM38). The modeled coefficients, one of the successful and classical methods hitherto, were chosen to calibrate the EM38 measurements of the inverted salinity profiles of characteristic coastal saline soils at selected sites of Xincao Farm, Jiangsu Province, China. However, this method required three parameters for each depth layer. An integration approach, based on an exponential decay profile model, was proposed and the model was fitted to all the calibration sites. The obtained model can then be used to predict EC1:5 at a certain depth from electromagnetic measurements made using the EM38 device positioned in horizontal and vertical positions at the soil surface. This exponential decay model predicted the EC1:5 well according to the results of a one-way analysis of variance, and the further comparison indicated that the modeled coefficients appeared to be slightly superior to, but not statistically different from, this exponential decay model. Nevertheless, this exponential decay model was more significant and practical because it depended on less empirical parameters and could be used to perform point predictions of EC1:5 continuously with depth.
基金financially supported by the National Basic Research Program of China (2009CB825105)the National Natural Science Foundation of China (41261090)
文摘Modeling soil salinity in an arid salt-affected ecosystem is a difficult task when using remote sensing data because of the complicated soil context （vegetation cover, moisture, surface roughness, and organic matter） and the weak spectral features of salinized soil. Therefore, an index such as the salinity index （SI） that only uses soil spectra may not detect soil salinity effectively and quantitatively. The use of vegetation reflectance as an indirect indicator can avoid limitations associated with the direct use of soil reflectance. The normalized difference vegetation index （NDVI）, as the most common vegetation index, was found to be responsive to salinity but may not be available for retrieving sparse vegetation due to its sensitivity to background soil in arid areas. Therefore, the arid fraction integrated index （AFⅡ） was created as supported by the spectral mixture analysis （SMA）, which is more appropriate for analyzing variations in vegetation cover （particularly halophytes） than NDVI in the study area. Using soil and vegetation separately for detecting salinity perhaps is not feasible. Then, we developed a new and operational model, the soil salinity detecting model （SDM） that combines AFⅡ and SI to quantitatively estimate the salt content in the surface soil. SDMs, including SDM1 and SDM2, were constructed through analyzing the spatial characteristics of soils with different salinization degree by integrating AFⅡ and SI using a scatterplot. The SDMs were then compared to the combined spectral response index （COSRI） from field measurements with respect to the soil salt content. The results indicate that the SDM values are highly correlated with soil salinity, in contrast to the performance of COSRI. Strong exponential relationships were observed between soil salinity and SDMs （R2〉0.86, RMSE〈6.86） compared to COSRI （R2=0.71, RMSE=16.21）. These results suggest that the feature space related to biophysical properties combined with AFII and SI can effectively provide information on soil salinity.
基金supported by the National Basic Research Program of China (2009CB421302)the National Natural Science Foundation of China (41071026,51069017)
文摘A field experiment was carried out to investigate the effects of different emitter discharge rates under drip irrigation on soil salinity distribution and cotton yield in an extreme arid region of Tarim River catchment in Northwest China. Four treatments of emitter discharge rates, i.e. 1.8, 2.2, 2.6 and 3.2 L/h, were designed under drip irrigation with plastic mulch in this paper. The salt distribution in the range of 70-cm horizontal distance and 100-cm vertical distance from the emitter was measured and analyzed during the cotton growing season. The soil salinity is expressed in terms of electrical conductivity （dS/m） of the saturated soil extract （ECe）, which was measured using Time Domain Reflector （TDR） 20 times a year, including 5 irrigation events and 4 measured times before/after an irrigation event. All the treatments were repeated 3 times. The groundwater depth was observed by SEBA MDS Dipper 3 automatically at three experimental sites. The results showed that the order of reduction in averaged soil salinity was 2.6 L/h 〉 2.2 L/h 〉 1.8 L/h 〉 3.2 L/h after the completion of irrigation for the 3-year cotton growing season. Therefore, the choice of emitter discharge rate is considerably important in arid silt loam. Usually, the ideal emitter discharge rate is 2.4-3.0 L/h for soil desalinization with plastic mulch, which is advisable mainly because of the favorable salt leaching of silt loam and the climatic conditions in the studied arid area. Maximum cotton yield was achieved at the emitter discharge rate of 2.6 L/h under drip irrigation with plastic mulch in silty soil at the study site. Hence, the emitter discharge rate of 2.6 L/h is recommended for drip irrigation with plastiic mulch applied in silty soil in arid regions.
基金funded by the Fundamental Research Funds for the Central Universities (2016ZCQ06)the Forestry Industry Research Special Funds for Public Welfare Projects (201504402)the Application Technology of Seaweed Fertilizer Based on Desertification Control and Saline-alkili Soil Improvement (2016HXFWSBXY002)
文摘Ecological restoration by Taman＇x plants on semi-arid saline lands affects the accumulation, distribution patterns and related mechanisms of soil water content and salinity. In this study, spatio-temporal variations of soil water content and salinity around natural individual Tamarix ramosissiraa Ledeb. were invetigated in a semi-arid saline region of the upper Yellow River, Northwest China. Specifically, soil water content, electrical conductivity （EC）, sodium adsorption ratio （SARa）, and salt ions （including Na＋, K＋, Ca2＋, Mg2＋ and 8042-） were measured at different soil depths and at different distances from the trunk of T. ramasissima in May, July, and September 2016. The soil water content at the 20-80 cm depth was significantly lower in July and September than in May, indicating that T. ramosissima plants absorb a large amount of water through the roots during the growing period, leading to the decreasing of soil water content in the deep soil layer. At the 0-20 cm depth, there was a salt island effect around individual T. ramosissima, and the ECe differed significantly inside and outside the canopy of T. ramosissima in May and July. Salt bioaccumulation and stemflow were two major contributing factors to this difference. The SAR at the 0-20 cm depth was significantly different inside and outside the canopy of T. ramosissima in the three sampling months. The values of SAR~ at the 60-80 cm depth in May and July were significantly higher than those at the 0-60 cm depth and higher than that at the corresponding depth in September. The distribution of Na＋ in the soil was similar to that of the SAI, while the concentrations of K＋, Ca2＋, and Mg2＋ showed significant differences among the sampling months and soil depths. Both season and soil depth had highly significant effects on soil water content, ECe and SARa, whereas distance from the trunk of T. ramosissima only significantly affected ECe. Based on these results, we recommend co-planting of shallow-rooted salt-tolerant species near the Tamarx plants and avoiding planting herbaceous plants inside the canopy of T. ramodssima for afforestation in this semi-arid saline region. The results of this study may provide a reference for appropriate restoration in the semi-arid saline regions of the upper Yellow River.
基金supported by the Special Fund of Industrial (Agriculture) Research for Public Welfare of China(200903001)the Special Fund of Industrial (Marine) Research for Public Welfare of China (201105020-3 and 201105020-4)+2 种基金the Science and Technology Support Program of Jiangsu Province, China (BE2010313)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-359)the National Natural Science Foundation of China (41171181)
文摘The aim of this paper was to research the spatio-temporal changes in total soluble salt content （TS） in a typical arid region of South Xinjiang, China, where the climate is arid and soil salinization happens easily. The total soluble salt content was interpreted by measurements made in the horizontal mode with EM38 and EM31. The electromagnetic induction （EM） surveys were made three times with the apparent soil electrical conductivity （ECa） measurements taken at 3 873 locations in Nov. 2008, 4 807 locations in Apr. 2009 and 6 324 locations in Nov. 2009, respectively. For interpreting the ECa measurements into total soluble salt content, calibtion sites were needed for EM survey of each time, e.g., 66 sites were selected in Nov. 2008 to measure ECa, and soils-core samples were taken by different depth layers of 0-10, 10-20 and 20-40 cm at the same time. On every time duplicate samples were taken at five sites to allevaite the local-scale variability, and soil temperatures in different layers through the profiles were also measured. Factors including TS, pH, water content, bulk density were analyzed by lab experiments. ECa calibration equations were obtained by linear regression analysis, which indicated that soil salinity was one primary concern to ECa with a determination coefficient of 0.792 in 0-10 cm layer, 0.711 in 10-20 cm layer and 0.544 in 20-40 cm layer, respectively. The maps of spatial distribution were predicted by Kriging interpolation, which showed that the high soil salinity was located near the drainage canal, which validated the trend effect caused by the irrigation canal and the drainage canal. And by comparing the soil salinity in different layers, the soluble salt accumulated to the top soil surface only in the area where the soil salinization was serious, and in the other areas, the soil salinity trended to increase from the top soil surface to 40 cm depth. Temporal changes showed that the soil salinity in November was higher than that in April, and the soil salinization trended to aggravate, especially in the top soil layer of 0-10 cm.
基金supported by the National Natural Science Foundation of China (31501253)the Project for the Development of Genetically Modified Crops, Ministry of Agriculture, China (2016ZX08011-002)
文摘With increased cultivation of transgenic Bacillus thuringiensis （Bt） cotton in the saline alkaline soil of China, assessments of transgenic crop biosafety have focused on the effects of soil salinity on rhizosphere microbes and Bt protein residues. In 2013 and 2014, investigations were conducted on the rhizosphere microbial biomass, soil enzyme activities and Bt protein contents of the soil under transgenic Bt cotton （variety GK19） and its parental non-transgenic cotton （Simian 3） cultivated at various salinity levels （1.15, 6.00 and 11.46 dS m-1）. Under soil salinity stress, trace amounts of Bt proteins were ob- served in the Bt cotton GK19 rhizosphere soil, although the protein content increased with cotton growth and increased soil salinity levels. The populations of slight halophilic bacteria, phosphate solubilizing bacteria, ammonifying bacteria, nitrifying bacteria and denitrifying bacteria decreased with increased soil salinity in the Bt and non-Bt cotton rhizosphere soil, and the microbial biomass carbon, microbial respiration and soil catalase, urease and alkaline phosphatase activity also decreased. Correlation analyses showed that the increased Bt protein content in the Bt cotton rhizosphere soil may have been caused by the slower decomposition of soil microorganisms, which suggests that salinity was the main factor influencing the relevant activities of the soil microorganisms and indicates that Bt proteins had no clear adverse effects on the soil microorganisms. The results of this study may provide a theoretical basis for risk assessments of genetically modified cotton in saline alkaline soil.
基金the National Natural Science Foundation of China （40571066, 40001008）the Postdoctoral Science Foundation of China （20060401048） the Key Program of Science and Technology Bureau of Zhejiang Province, China 030523）.
文摘The spatial estimation for soil properties was improved and sampling intensities also decreased in terms of incorporated auxiliary data. In this study, kriging and two interpolation methods were proven well to estimate auxiliary variables： cokriging and regression-kriging, and using the salinity data from the first two stages as auxiliary variables, the methods both improved the interpolation of soil salinity in coastal saline land. The prediction accuracy of the three methods was observed under different sampling density of the target variable by comparison with another group of 80 validation sample points, from which the root-mean-square error （RMSE） and correlation coefficient （r） between the predicted and measured values were calculated. The results showed, with the help of auxiliary data, whatever the sample size of the target variable may be, cokriging and regression-kriging performed better than ordinary kriging. Moreover, regression-kriging produced on average more accurate predictions than cokriging. Compared with the kriging results, cokriging improved the estimations by reducing RMSE from 23.3 to 29% and increasing r from 16.6 to 25.5%, regression-kriging improved the estimations by reducing RMSE from 25 to 41.5% and increasing r from 16.8 to 27.2%. Therefore, regression-kriging shows promise for improved prediction for soil salinity and reduction of soil sampling intensity considerably while maintaining high prediction accuracy. Moreover, in regression-kriging, the regression model can have any form, such as generalized linear models, non-linear models or tree-based models, which provide a possibility to include more ancillary variables.
文摘A pot experiment was carried out on a marine saline soil to study the effect of initial soluble Na/Ca ratio of saline soil on the salinity tolerance of barley plant.The results showed that (1) the Na/Ca ratio affected significantly the dry weight of the plant at an earlier stage of growth,the critical values of initial Na/Ca ratio at which the plant could grow normally on soils containing salts of 2.5,3.5 and 4.5g kg^-1 were 30,20 and 15,respectively;(2)smaller Na/Ca ratio resulted in a considerable decrease in Na accumulation but a great increase in K accumulation in the barley plant;and (3) the plasmallema of barley leaf were badly injured when the Na/Ca ratio was more than 30 and the increase of Na content of plant caused an exudation of K from the leaf cells.Some critical indexes were suggested for the cultivation of barley plant on marine saline soils and could be used as reference in the biological reclamation of marine saline soils.
文摘The integrated effect of irrigation and agricultural practices on soil salinity in the Jordan Valley （JV）, where over 60% of Jordan＇s agricultural produce is grown, was investigated in this study during 2009-2010. Due to the differences in agricultural operations, cropping patterns, irrigation management, and weather conditions, 206 top- and sub-soil samples were taken every 1 to 3 km from representative farms along a north-south （N-S） transect with 1 to 2 km lateral extents. Soil electrical conductivity of saturated extract （ECse）, Ca, Mg, K, Na, CI, and Na adsorption ratio （SAR） were determined in saturated paste extracts. Results indicated that about 63% of soils in the JV are indeed saline, out of which almost 46% are moderately to strongly saline. Along the N-S transect of the JV, ECse increased from 4.5 to 14.1 dS m-1 in top-soil samples. Similar increase was observed for the sub-soil samples. The major chemical components of soil salinity; i.e., Ca, Mg, and C1, also showed a similar increase along the N-S transect of the valley. Moreover, compared to previous field sampling, results showed that changes in soil salinity in the JV were dramatic. In addition, it was found that C1 imposed an existing and potential threat to sensitive crops in 60% of the soils in the JV, where C1 concentrations were greater than 710 mg L-1. Under the prevalent arid Mediterranean conditions, improving the management of .irrigation water, crops, and nutrient inputs and increasing water and fertilizer use efficiencies should be indispensable to conserve and sustain the already fragile agricultural soils in the JV.
文摘Microbial adaptation to salinity can be achieved through synthesis of organic osmolytes,which requires high amounts of energy;however,a single addition of plant residues can only temporarily improve energy supply to soil microbes.Therefore,a laboratory incubation experiment was conducted to evaluate the responses of soil microbes to increasing salinity with repeated additions of plant residues using a loamy sand soil with an electrical conductivity in saturated paste extract(EC_e) of 0.6 dS m^(-1).The soil was kept non-saline or salinized by adding different amounts of NaCl to achieve EC_e of 12.5,25.0 and 50.0 dS m^(-1).The non-saline soil and the saline soils were amended with finely ground pea residues at two rates equivalent to 3.9 and 7.8 g C kg^(-1) soil on days 0,15 and29.The soils receiving no residues were included as a control.Cumulative respiration per g C added over 2 weeks after each residue addition was always greater at 3.9 than 7.8 g C kg^(-1) soil and higher in the non-saline soil than in the saline soils.In the saline soils,the cumulative respiration per g C added was higher after the second and third additions than after the first addition except with3.9 g C kg^(-1) at EC_e of 50 dS m^(_1).Though with the same amount of C added(7.8 g C kg^(-1)),salinity reduced soil respiration to a lesser extent when 3.9 g C kg^(-1) was added twice compared to a single addition of 7.8 g C kg^(-1).After the third residue addition,the microbial biomass C concentration was significantly lower in the soils with EC_e of 25 and 50 dS m^(_1) than in the non-saline soil at3.9 g C kg^(-1),but only in the soil with EC_e of 50 dS m^(-1) at 7.8 g C kg^(-1).We concluded that repeated residue additions increased the adaptation of soil microbial community to salinity,which was likely due to high C availability providing microbes with the energy needed for synthesis of organic osmolytes.
基金Under the auspices of Special Fund for Ocean Public Welfare Profession Scientific Research(No.201105020)National Natural Science Foundation of China(No.41471178,41023010,41431177)National Key Technology Innovation Project for Water Pollution Control and Remediation(No.2013ZX07103006)
文摘Spatial distribution of soil salinity can be estimated based on its environmental factors because soil salinity is strongly affected and indicated by environmental factors. Different with other properties such as soil texture, soil salinity varies with short-term time. Thus, how to choose powerful environmental predictors is especially important for soil salinity. This paper presents a similarity-based prediction approach to map soil salinity and detects powerful environmental predictors for the Huanghe(Yellow) River Delta area in China. The similarity-based approach predicts the soil salinities of unsampled locations based on the environmental similarity between unsampled and sampled locations. A dataset of 92 points with salt data at depth of 30–40 cm was divided into two subsets for prediction and validation. Topographical parameters, soil textures, distances to irrigation channels and to the coastline, land surface temperature from Moderate Resolution Imaging Spectroradiometer(MODIS), Normalized Difference Vegetation Indices(NDVIs) and land surface reflectance data from Landsat Thematic Mapper(TM) imagery were generated. The similarity-based prediction approach was applied on several combinations of different environmental factors. Based on three evaluation indices including the correlation coefficient(CC) between observed and predicted values, the mean absolute error and the root mean squared error we found that elevation, distance to irrigation channels, soil texture, night land surface temperature, NDVI, and land surface reflectance Band 5 are the optimal combination for mapping soil salinity at the 30–40 cm depth in the study area(with a CC value of 0.69 and a root mean squared error value of 0.38). Our results indicated that the similarity-based prediction approach could be a vital alternative to other methods for mapping soil salinity, especially for area with limited observation data and could be used to monitor soil salinity distributions in the future.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.42330708 and 41820104001)。
文摘For engineering structures with saline soil as a filling material,such as channel slope,road subgrade,etc.,the rich soluble salt in the soil is an important potential factor affecting their safety performance.This study examines the Atterberg limits,shear strength,and compressibility of carbonate saline soil samples with different NaHCO3 contents in Northeast China.The mechanism underlying the influence of salt content on soil macroscopic properties was investigated based on a volumetric flask test,a mercury intrusion porosimetry(MIP)test,and a scanning electron microscopic(SEM)test.The results demonstrated that when NaHCO3 contents were lower than the threshold value of 1.5%,the bound water film adsorbed on the surface of clay particles thickened continuously,and correspondingly,the Atterberg limits and plasticity index increased rapidly as the increase of sodium ion content.Meanwhile,the bonding force between particles was weakened,the dispersion of large aggregates was enhanced,and the soil structure became looser.Macroscopically,the compressibility increased and the shear strength(mainly cohesion)decreased by 28.64%.However,when the NaHCO3 content exceeded the threshold value of 1.5%,the salt gradually approached solubility and filled the pores between particles in the form of crystals,resulting in a decrease in soil porosity.The cementation effect generated by salt crystals increased the bonding force between soil particles,leading to a decrease in plasticity index and an improvement in soil mechanical properties.Moreover,this work provides valuable suggestions and theoretical guidance for the scientific utilization of carbonate saline soil in backfill engineering projects.
文摘Soil salinization is one of the most predominant environmental hazards responsible for agricultural land degradation,especially in the arid and semi-arid regions.An accurate spatial prediction and modeling of soil salinity in agricultural land are so important for farmers and decision-makers to develop the appropriate mechanisms to prevent the loss of fertile soil and increase crop production.El Outaya plain is marked by soil salinity increases due to the excessive use of poor groundwater quality for irrigation.This study aims to compare the performance of simple kriging,cokriging(SCOK),multilayer perceptron neural networks(MLP-NN),and support vector machines(SVM)in the prediction of topsoil and subsoil salinity.The field covariates including geochemical properties of irrigation groundwater and physical properties of soil and environmental covariates including digital elevation model and remote sensing derivatives were used as input candidates to SCOK,MLP-NN,and SVM.The optimal input combination was determined using multiple linear stepwise regression(MLSR).The results revealed that the SCOK using field covariates including water electrical conductivity(ECw)and sand percentage(sand%),and environmental covariates including land surface temperature(LST),topographic wetness index(TWI),and elevation could significantly increase the accuracy of soil salinity spatial prediction.The comparison of the prediction accuracy of the different modeling techniques using the Taylor diagram indicated that MLP-NN using LST,TWI,and elevation as inputs were more accurate in predicting the topsoil salinity[ECs(TS)]with a mean absolute error(MAE)of 0.43,root mean square error(RMSE)of 0.6 and correlation coefficient of 0.946.MLP-NN using ECw and sand%as inputs were more accurate in predicting the subsoil salinity[ECs(SS)]with MAE of 0.38,RMSE of0.6,and R of 0.968.
基金Under the auspices of the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA28110301,XDA2306040303)National Natural Science Foundation of China(No.41807001,41977424)Natural Science Foundation of Jilin Province(No.20200201026JC)。
文摘Soil is the essential part for agricultural and environmental sciences,and soil salinity and soil water content are both the important influence factors for sustainable development of agriculture and ecological environment.Digital camera,as one of the most popular and convenient proximal sensing instruments,has its irreplaceable position for soil properties assessment.In this study,we collected 52 soil samples and photographs at the same time along the coast in Yancheng City of Jiangsu Province.We carefully analyzed the relationship between soil properties and image brightness,and found that soil salt content had higher correlation with average image brightness value than soil water content.From the brightness levels,the high correlation coefficients between soil salt content and brightness levels concentrated on the high brightness values,and the high correlation coefficients between soil water content and brightness levels focused on the low brightness values.Different significance levels(P)determined different brightness levels related to soil properties,hence P value setting can be an optional way to select brightness levels as the input variables for modeling soil properties.Given these information,random forest algorithm was applied to develop soil salt content and soil water content inversion models using randomly 70%of the dataset,and the rest data for testing models.The results showed that soil salt content model had high accuracy(R_(v)^(2)=0.79,RMSE_(v)=12 g/kg,and RPD_(v)=2.18),and soil water content inversion model was barely satisfied(R_(v)^(2)=0.47,RMSE_(v)=3.04%,and RPD_(v)=1.38).This study proposes a method of modeling soil properties with a digital camera.Combining unmanned aerial vehicle(UAV),it has potential popularization and application value for precise agriculture and land management.
基金Supported by Arid Meteorological Science Research Foundation of China Meteorological Bureau(IAM201001)National 973 Project(2006CB705809)Key Project of Knowledge Innovation of CAS(KSCX-YW-09)~~
文摘[Objective] The paper was to analyze the soil salinity characteristics in Xinjiang region, and develop salinization characteristic research, so as to provide reference for salinization research in arid region. [Method] With different land types of soil vertical profiles in Karamay absorbing carbon forest as research object, soil salinity and water soluble ions were determined and analyzed using statistical characteristic value and trend surface, and the distribution characteristic of soil salinity in the region was explored.[Result] The salinity in survey area of absorbing carbon forest mainly were sulfate-chloride type and chloride type, of which cations were mainly Na＋, K＋ and Ca2＋, anions were CO32-, Cl- and SO42-, the variation coefficient of CO32 - was as high as 292.91, while the variation coefficient of Cl- was 265.56. The variation of soil total soluble salts in the soil layer of 0-100 cm was not significant, indicating that the content in each soil layer was relatively stable. [Conclusion] The study provided basis for speeding up dynamic monitoring for soil salinization and finding the effective control approach against salinization
文摘Soil salinity affects the growth and yield of crops.The stress of soil salinity on plants can be mitigated by inoculation of plant growth promoting bacteria(PGPR).The influence of PGPR inoculation on wheat(Triticum aestivum L.)crop productivity under salinity stress has not been properly addressed so far.Therefore,the present study was conducted to investigate the effects of various PGPR strains(W14,W10 and 6K;alone and combined)at several growth attributes of wheat plant under different soil salinity gradients(3,6 and 9 dS m-1).The growth attributes of wheat(height,roots,shoots,spikes,grains quality,biological and economical yield,nutrients nitrogen,phosphorus and potassium in grains)were highly affected by salinity and decreased with increasing salinity level.The PGPR inoculation substantially promoted growth attributes of wheat and prominent results were observed in W14×W10×6K treatment at all salinity levels.The results suggest that inoculation of PGPR is a potential strategy to mitigate salinity stress for improving wheat growth and yield.
基金supported by the National Natural Science Foundation of China(40861020)the Natural Science Foundation of Xinjiang(200821128)+1 种基金the Key Laboratory of Oasis Ecology in Xinjiang University(XJDX0201-2008-03)the Fund of Young Teachers Scientific Research in Xinjiang University(QN070122),China
文摘In order to assess the effects of chemical properties of soil salinity on electrical conductivity of 1：5 soil/water extract （EC1：5）, the study focused on revealing the main chemical factors contributing to EC of soil extracts and their relative importance. The relationship between EC1：5 and the chemical properties of soil salinity in the delta oasis of Weigan and Kuqa rivers, China, were studied using path coefficient analysis, a path analysis method. We studied each key element affecting EC1：5 either directly or indirectly. The results obtained show that the salt content, total dissolved solids （TDS）, and the sum of the sodium ion concentration and the kalium ion concentration are the most influential factors on 1：5 soil/ water extract （EC1：5） in the 0-10 cm and the 30-50 cm soil layer. The results show that the sequence of direct path coefficients in the 0-10 cm and the 30-50 cm soil layers on soil conductivity is TDS→Na^＋ ＋ K^＋→Salt content→Ca^2＋→Cl-→the sodium dianion ratio （SDR）→pH→ SO4^2-→HCO3^-→Mg^2＋→the soluble sodium percentage （SSP） sodium absorption ratio （SAR） and TDS→Salt content→Na^＋ ＋ K^＋→Ca^2＋→SDR→Mg^2＋→HCO3^-→SSP→pH→SO4^2-→SAR→Cl^-. The salt content, chlorine ion, and SAR are the main factors affecting 1：5 soil/water extract （EC1：5） in the 10-30 centimeter soil layer. The order of direct path coefficients result is as follows： Salt content→Cl^-→SAR→SSP→TDS→Ca^2＋→Mg^2＋= SO4^2-→HCO3^-→pH→SDR→Na^- ＋ K^＋. Moreover, the effects of HCO3^-, pH were very weak. Though the direct path coefficients between EC1：5 and SAR, SO4^2- and Ca^2＋ were not high, influence of other chemical factors caused the coefficients to increase, making the summation of their direct and indirect path coefficients relatively high. The models of the different soil layers were structured separately. Evidences showed that multiple regression relations between EC1：5 and most of the primary factors had sound reliability and very good accuracy. The research results can serve as a reference to the scientific management amelioration and utilization of saline in the Delta Oasis of Weigan and Kuqa rivers.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.2016B14614)the Program of China Scholarship Council(Grant No.201906715015)+1 种基金the National Key Research and Development Program of China(Grant No.2017YFC040320502)a project funded by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘To achieve the greatest leaching efficiency,water movement must occur under unsaturated flow conditions.Accordingly,the water application intensity of irrigation must be chosen carefully.The aim of this study was to evaluate the impact of the water application intensity of micro-sprinkler irrigation on coastal saline soil with different salt contents.To achieve this objective,a laboratory experiment was conducted with three soil salinity treatments(2.26,10.13,and 22.29 dS/m)and three water application intensity treatments(3.05,5.19,and 7.23 mm/h).The results showed that the effect of soil salinity on soil water content,electrical conductivity,and pH was significant,and the effect of the water application intensity was insignificant.High soil water content was present in the 40e60 cm profile in all soil salinity treatments,and the content was higher in the medium and high water application intensity treatments than in the low-intensity treatment.Significant salt leaching occurred in all treatments,and the effect was stronger in the high soil salinity treatment and medium water application intensity treatment.In the medium and high soil salinity treatments,pH exhibited a decreasing trend,with no trend change in the low soil salinity treatment,and the pH value was higher in the medium water application intensity treatment than in the other two treatments.These results indicated that the three intensities evaluated had no statistically different effect on the electrical conductivity of saturated soil-paste extracts(EC)in the upper 20 cm of the soil profile,and it would be better to maintain a lower value of the water application intensity.
