By applying bromide ion as tracer, the channeling flow has been quantitatively described in saline rice soil and alkaline soil of Da＇an City, Jilin Province of China. Breakthrough curves of bromide ion in the saline ...By applying bromide ion as tracer, the channeling flow has been quantitatively described in saline rice soil and alkaline soil of Da＇an City, Jilin Province of China. Breakthrough curves of bromide ion in the saline rice soils after 1-year cultivation and 5-year cultivation and alkaline soil have been attained. Results show that the rice cultivation practice can improve the alkaline soil structure, however, it can accelerate the development of channeling flow pathway. Therefore, the channeling flow pathway has been developed widely in saline rice soil, but rarely in the alkaline soil. Three models of convection-dispersion equation （CDE）, transfer functional model （TFM） and Back-Progation Network （BP Network） were used to simulate the transportation process of bromide ion. The peaks of probability density function of saline rice soil are higher with left skewed feature compared with that of the alkaline soil. It shows that the TIM and CDE can simulate the transportation process of the bromide ion in saline rice soil after 5-year cultivation, however, some deviation exists when it was used to simulate transportation process of bromide ion in saline rice soil after 1-year cultivation and alkaline soil; BP network can effectively simulate transportation process of bromide ion in both saline rice soil and alkaline soil.展开更多
Of the factors affecting migration and bioavailability of toxic metals in heavy metal contaminated soil, DOC （dissolved organic carbon） provides binding sites for metal cations and reduces the fixation and adsorptio...Of the factors affecting migration and bioavailability of toxic metals in heavy metal contaminated soil, DOC （dissolved organic carbon） provides binding sites for metal cations and reduces the fixation and adsorption of heavy metals by soil solid phase. Elevation of DOC level due to the direct incorporation of crop residues may lead to enhanced accumulation of toxic metals in crop body grown in polluted farmland. In this study, an incubation experiment and a pot experiment were conducted respectively to investigate the effects of wheat straw incorporation on DOC level, cadmium availability, and Cd accumulation in rice plant, and to establish the relation between Cd solubility and DOC level. A Cd-contaminated rice soil was used and incorporated with different rates （0%, 0.5% and 1%） of wheat straw in both experiments. Results showed that the change pattern of Cd in soil solution was very similar to that of DOC level. Wheat straw addition significantly elevated Cd and DOC level in soil solution while NH4NO3-extrated Cd was not affected. There existed a close linear correlation between soluble Cd and DOC level. Enhanced Cd accumulation in rice plant, grown in a Cd contaminated soil, induced by wheat straw incorporation was observed in this study.展开更多
There are about 1 million ha of Si-deficiency paddy soils in Hubei Province. Practically, it is essential to study the Si nutrient status in those Si-deficiency rice soil and its regional distribution before the appli...There are about 1 million ha of Si-deficiency paddy soils in Hubei Province. Practically, it is essential to study the Si nutrient status in those Si-deficiency rice soil and its regional distribution before the application of Si-fertilizer. According to the analysis of 50 rice soil samples which collected from 20 counties/cities in Hubei Province, the available Si content in rice soils derived from different parent materials varied greatly. The Si content from high to low was in sequence of limestone, redpurplish sandy shale with carbonate, alluvium and lacustrine deposits, quaternary period red clay, granitic gneiss, and sandy shale. In addition, the Si content in rice soil was remarkably related with its pH. It seems that the pH 6.5 might be a demarcation line that divided the supplying Si ability of rice soils into the low and high categories (Table 1). Integrating the results with a critical soil Si-deficiency as 100 mg/kg, the evaluation index of soil Si supplying capability of a rice soil展开更多
With the aim of finding the geochemical differences and helping to build alleviating strategies against iron toxicity, two hematite dominant valley bottoms irrigating rice soils were investigated in the Tropical Savan...With the aim of finding the geochemical differences and helping to build alleviating strategies against iron toxicity, two hematite dominant valley bottoms irrigating rice soils were investigated in the Tropical Savannah region of Burkina Faso. The first site was Tiefora, a 15-ha modern double-season irrigated rice system and moderately affected by iron toxicity (10% of the area with a toxicity score of 4). The second site was Moussodougou, a 35-ha traditional singleseason irrigated rice valley-bottom, with 50% facing more severe iron toxicity (score 7). Nine soil extracts were taken from three depths—30, 50 and 100 cm—i.e. 27 at Tiefora and 27 at Moussodogou. Five techniques were used to measure the data: 1) the ferrous iron concentration was determined using a reflectometer, 2) a pH-meter yielded the pH, 3) clay-proportions were obtained by United States Department of Agriculture (USDA) grain size analysis and densitometry, 4) the organic matter was determined by oven drying (900℃) and v) the dry bulk density was determined by using undisturbed soil samples. Statistical hypothesis testing of One-way ANOVA and Welch t-test was applied to the data to isolate the similarities and the differences between the two sites. A geochemical analysis followed to find the causes of these differences. The results showed that while oxidation of pyrite leads to a simultaneous increase in Fe2+ concentrations and acidity in the soils of coastal floodplains and mangroves, the oxidation of hematite in Tropical savannah valley bottoms decreases Fe2+ but also increases acidity during the dry season. As a consequence, it was found that the single-season irrigation scheme Moussodougou is significantly (p-value 0.4%) more acidic (pH 5.7) than the double-season system of Tiefora (6.4) with also 750 - 1800 mg/l higher ferrous Fe2+. The ferrous iron reached 3000 mg/l in some layers in Moussodougou. This result is a justification to modernize a traditional single-season spate irrigation schemes into a double-season irrigated rice scheme.展开更多
Chemical fertilizers are a source of soil degradation. In order to mitigate soil degradation and to face the negative impacts of climate change, the use of organic fertilizers, accessible to small farmers can maintain...Chemical fertilizers are a source of soil degradation. In order to mitigate soil degradation and to face the negative impacts of climate change, the use of organic fertilizers, accessible to small farmers can maintain the productivity of cereals including rice. The objective of this experiment is to study the effect of organo-mineral fertilizers on soil chemical properties, growth and physiology parameters and yield of rice. For this purpose, a completely randomized block design with three replications was adopted. Different organic (Fertinova, Organova and Fertinova + Organova) and mineral (NPK + Urea) fertilizers were applied to cultivate the NERICA L19 variety of rice. The soil chemical properties (pH), germination rate, growth, yield and physiological (chlorophyll content) parameters were assessed. The results revealed a germination rate of the grains varying between 87.5 and 100%. Fertinova and Fertinova + Organova had the highest germination rates. Soil pH decreased significantly from initial (6.71 ± 0.01) to final (5.73 ± 0.04) with the development cycle of the rice. Organo-mineral fertilizers influenced significantly (p = 5.36e−09) soil chemical properties by increasing pH (4%) compared to Control. Analysis of variance on growth and yield parameters, yield and chlorophyll content revealed a significant difference (p < 0.05) between fertilizers. Growth and yield parameters and yield were significantly higher in NPK and Fertinova + Organova than in Fertinova, Organova and Control. For the biomass the NPK + Urea recorded significantly highest biomass (488.28 ± 60.83 g). Leaves chlorophyll content varied significantly according to the daytime and the status of leaf development. The higher chlorophyll content was recorded at noon (27.96 ± 0.32 SPAD value) and with young leaves (30.21 ± 0.35 SPAD value). NPK + Urea (29.36 ± 0.45 SPAD value) and Fertinova (27.78 ± 0.40 SPAD value) favored more chlorophyll content in the rice leaves. Rice performed better in NPK + Urea and Fertinova + Organova fertilizers.展开更多
This study investigated if super rice could better cope with soil water deficit and if it could have better yield performance and water use efficiency （WUE） under alternate wetting and drying （AWD） irrigation than...This study investigated if super rice could better cope with soil water deficit and if it could have better yield performance and water use efficiency （WUE） under alternate wetting and drying （AWD） irrigation than check rice. Two super rice cultivars and two elite check rice cultivars were grown in pots with three soil moisture levels, well watered （WW）, moderate water deficit （MWD） and severe water deficit （SWD）. Two cultivars, each for super rice and check rice, were grown in field with three irrigation regimes, alternate wetting and moderate drying （AWMD）, alternate wetting and severe drying （AWSD） and conventional irrigation （CI）. Compared with that under WW, grain yield was significantly decreased under MWD and SWD treatments, with less reduction for super rice than for check rice. Super rice had higher percentage of productive tillers, deeper root distribution, higher root oxidation activity, and greater aboveground biomass production at mid and late growth stages than check rice, especially under WMD and WSD. Compared with CI,AWMD increased, whereasAWSD decreased grain yield, with more increase or less decrease for super rice than for check rice. Both MWD and SWD treatments and eitherAWMD orAWSD regime significantly increased WUE compared with WW treatment or CI regime, with more increase for super rice than for check rice. The results suggest that super rice has a stronger ability to cope with soil water deficit and holds greater promising to increase both grain yield and WUE by adoption of moderate AWD irrigation.展开更多
A simulation model developed by the authors (Huang et al., 1999) was validated against independent field measurements of methane emission from rice paddy soils in Texas of USA, Tuzu Of China and Vercelli of Italy.A si...A simulation model developed by the authors (Huang et al., 1999) was validated against independent field measurements of methane emission from rice paddy soils in Texas of USA, Tuzu Of China and Vercelli of Italy.A simplified version of the simulation model was further validated against methane emission measurements from various regions of the world, including italy, China, Indonesia, Philippines and the United States. Model validation suggested that the seasonal variation of methane emission was mainly regulated by rice growth and development and that methane emission could be predicted from rice net productivity, cultivar character, soil texture and temperature, and organic matter amendments. Model simulations in general agreed with the observations. The comparison between computed and measured methane emission resulted in correlation coefficients r2 values from 0.450 to 0.952, significant at 0.01-0.001 probability level.On the basis of available information on rice cultivated area, growth duration, grain yield, soil texture and temperature, methane emission from rice paddy soils of China's Mainland was estimated for 28 rice cultivated provinces/municipal cities by employing the validated model. The calculated daily methane emission rates, on a provincial scale, ranged from 0.12 to 0.71 g m-2 with an average of 0.26 g m-2. A total amount of 7.92 Tg CH4 per year, ranging from 5.89 to 11.17 Tg year-1, was estimated to be released from Chinese rice paddy soils. Of the total, 45% was emitted from the single-rice growing season, and 19% and 36% were from the early-rice and the late-rice growing seasons, respectively. Approximately 70% of the total was emitted in the region located at latitude between 25°and 32°N. The emissions from rice fields in Sichuan and Hunan provinces were calculated to be 2.34 Tg year-1, accounting for approximately 30% of the total.展开更多
Biochar may affect the root morphology and nitrogen(N)use efficiency(NUE)of rice at seedling stage,which has not been clearly verified until now.To clarify it,we conducted a pot experiment regarding to two soil types(...Biochar may affect the root morphology and nitrogen(N)use efficiency(NUE)of rice at seedling stage,which has not been clearly verified until now.To clarify it,we conducted a pot experiment regarding to two soil types(Hydragric Anthrosol and Haplic Acrisol),two biochar application rates(0.5 wt%and 1.5 wt%)and two rice varieties(common rice var.Xiushui134 and hybrid super rice var.Zhongkejiayou12-6)meanwhile.Seedling NUE of common rice Xiuhui134 was significantly increased(p<0.05)by 78.2%in Hydragric Anthrosol and by 91.4%in Haplic Acrisol following biochar addition with 1.5 wt%.However,biochar addition exerted no influence on seedling NUE of super rice Zhongkejiayou12-6 in both soils.Overall,0.09–0.10 units higher soil pH and 105–116%higher soil NH_(4)^(+)-N were observed in Xiushui134 growing two soils with 1.5 wt%biochar.In addition,improved root morphology(including longer root length,larger root surface area,bigger root volume,and more root tips)contributed to the higher seedling NUE of Xiushui134 in two soils.The soil pH and NH_(4)^(+)-N content,also the root morphology were influenced by biochar,which though could not thoroughly explained the NUE of Zhongkejiayou12-6.In conclusion,biochar application to paddy soil changed soil pH and NH_(4)^(+)-N content,root growth,and the consequent seedling NUE of rice,which effects are relative with rice cultivar,biochar addition rate,and soil type.展开更多
The double-rice cropping system is a very important intensive cropping system for food security in China. There have been few studies of the sustainability of yield and accumulation of soil organic carbon (SOC) in the...The double-rice cropping system is a very important intensive cropping system for food security in China. There have been few studies of the sustainability of yield and accumulation of soil organic carbon (SOC) in the double-rice cropping system following a partial substitution of chemical fertilizer by Chinese milk vetch (Mv). We conducted a 10-year (2008–2017) field experiment in Nan County, South-Central China, to examine the double-rice productivity and SOC accumulation in a paddy soil in response to different fertilization levels and Mv application (22.5 Mg ha^–1). Fertilizer and Mv were applied both individually and in combination (sole chemical fertilizers, Mv plus 100, 80, 60, 40, and 0% of the recommended dose of chemical fertilizers, labeled as F100, MF100, MF80, MF60, MF40, and MF0, respectively). It was found that the grain yields of double-rice crop in treatments receiving Mv were reduced when the dose of chemical fertilizer was reduced, while the change in SOC stock displayed a double peak curve. The MF100 produced the highest double-rice yield and SOC stock, with the value higher by 13.5 and 26.8% than that in the F100. However, the grain yields increased in the MF80 (by 8.4% compared to the F100), while the SOC stock only increased by 8.4%. Analogous to the change of grain yield, the sustainable yield index (SYI) of double rice were improved significantly in the MF100 and MF80 compared to the F100, while there was a slight increase in the MF60 and MF40. After a certain amount of Mv input (22.5 Mg ha^–1), the carbon sequestration rate was affected by the nutrient input due to the stimulation of microbial biomass. Compared with the MF0, the MF100 and MF40 resulted in a dramatically higher carbon sequestration rate (with the value higher by 71.6 and 70.1%), whereas the MF80 induced a lower carbon sequestration rate with the value lower by 70.1% compared to the MF0. Based on the above results we suggested that Mv could partially replace chemical fertilizers (e.g., 40–60%) to improve or maintain the productivity and sustainability of the double-rice cropping system in South-Central China.展开更多
With an understanding of the processes of methane production, oxidation and emission, a semi-empirical model, focused on the contributions of rice plants to the processes and also the influence of environmental factor...With an understanding of the processes of methane production, oxidation and emission, a semi-empirical model, focused on the contributions of rice plants to the processes and also the influence of environmental factors, was developed to predict methane emission from rice paddy soils. In the present model, the amount of methane transported from the soil to the atmosphere was determined by the rates of CH4 production and an emitted fraction. The rates of CH4 production in irrigated rice soils were computed from the availability of methanogenic substrates that are primarily derived from rice plaaes and added organic matter and the influence of soil texture, soil redox potential and temperature. The fraction of methane emitted was assumed to be modulated by the rice plants and declines with rice growth and development. TO make it applicable to a wider area with limited data sets, a simplified version of the model was also derived to predict methane emission in a more practical manner.展开更多
Cadmium （Cd） entering the human body via the food chain is of increasing concern. This study investigates the effects of soil type and genotype on variations in the Cd concentrations of different organs of nine rice...Cadmium （Cd） entering the human body via the food chain is of increasing concern. This study investigates the effects of soil type and genotype on variations in the Cd concentrations of different organs of nine rice plants grown on two types of soils with two Cd levels. Cd concentrations in nine rice cultivars varied significantly with genotype and soil type （P 〈 0.01）. The Cd concentration was higher in red paddy soil （RP） than in yellow clayey paddy soil （YP）. The average Cd concentrations of different organs in three rice types were indica 〉 hybrid 〉 japonica for the Cd treatments and controls. The polished grain concentration in YP and RP soils had a range of 0.055--0.23 mg/kg and 0.13-0.36 mg/kg in the Cd treatment, respectively. Two rice cultivars in YP soil and five rice cultivars in RP soil exceeded the concentration limits in the Chinese Food Hygiene Standard （0.2 mg/kg）. The Cd concentrations in roots, stems, and leaves were all significantly and positively correlated to that in polished grain in a single test. The Cd concentrations in polished grain were positively and significantly （P 〈 0.01） correlated with the calculated transfer factors of stem to grain and leaf to grain Cd transfer. The results indicated that the variations of Cd concentration in grain were related to Cd uptake and the remobilization of Cd from stem and leaf to grain. Also, the cultivars with a strong tendency for Cd-accumulation should be avoided in paddy soil with low soil pH and low organic matter content to reduce the risks to human health from high Cd levels in rice.展开更多
The canopy temperature of rice at the flowering stage and the soil water content were investigated under different soil water treatments （the soil water contents were 24%, 55%, 90% and 175% at the flowering stage）. ...The canopy temperature of rice at the flowering stage and the soil water content were investigated under different soil water treatments （the soil water contents were 24%, 55%, 90% and 175% at the flowering stage）. The canopy temperature was lower than air temperature, and the soil water content significantly influenced the canopy temperature. The lower the soil water content, the higher the canopy temperature, the less the accumulative absolute value of canopy-air temperature difference. Moreover, the maximum difference between treatments and CK in the accumulative absolute value of canopy-air temperature difference appeared at 13：00 μm. in a day, thus, it could be considered as a suitable measuring time. Under the lowest water content treatment, the peak flowering occurred in the first three days （about 70% of panicles flowered）, resulting in shortened and lightened panicle of rice. As to the CK and the high water content treatments, the peak flowering appeared in the middle of flowering duration, with longer panicle length and higher panicle weight. Results indicated the lower the soil water content, the less the filled grain number and grain yield.展开更多
Pot experiments were conducted in 2002 and 2003 to investigate the effects of soil copper（Cu） concentration on growth, development and yield formation of rice by using the japonica cultivar Wuxiangjing 14 and hybrid...Pot experiments were conducted in 2002 and 2003 to investigate the effects of soil copper（Cu） concentration on growth, development and yield formation of rice by using the japonica cultivar Wuxiangjing 14 and hybrid rice combination Shanyou 63. The plant height, leaf number, elongated internode number and heading date of rice plants were not affected at soil Cu levels below 200 mg/kg, but affected significantly at above 400 mg/kg. The inhibitory effects on rice growth and development were increased with the increment of soil Cu levels. The grain yields decreased significantly with raising soil Cu levels. The main reasons for the grain yield reductions under lower soil Cu levels （100, 200 mg/kg） were mainly due to the decrease of number of spikelets per panicle, however, under higher soil Cu levels （more than 400 mg/kg）, both panicle number and number of spikelets per panicle contributed to the yield loss. The decreases of panicle number by Cu stress were mainly attributed to slow recovery from transplanting, delayed tillering and reduced maximum tiller numbers. The reduction of number of spikelets per panicle under soil Cu stress resulted from the decreases of both shoot dry weight （SDW） at the heading date and the ratio of spikelets to SDW. Total biomass at maturity decreased significantly with the increase of soil Cu levels, while economic coefficient showed non-significant decrease except under soil Cu levels above 800 mg/kg.展开更多
Hexachlorobenzene （HCB）, a persistent organic pollutant （POP）, has been found in paddy soils. To improve the understanding of HCB contamination in paddy soils, a laboratory simulative study was carried out to inve...Hexachlorobenzene （HCB）, a persistent organic pollutant （POP）, has been found in paddy soils. To improve the understanding of HCB contamination in paddy soils, a laboratory simulative study was carried out to investigate the behavior of HCB in a paddy soil and rice plants. This study was divided into three experiments. First, an experiment aimed to examine the evaporation of HCB in paddy soil. In the second experiment, rice was planted in 10 mg/kg HCB contaminated soil and after pot culture at 3, 6, 9, and 27 weeks （at maturity）, both soil and plant samplings were scheduled to be sampled. The soil samples comprised rhizosphere soil, nortrhizosphere soil, and unplanted contaminated soil, whereas plant samples included shoots, roots, and rice grains （dehusked）. Lastly, in this part, HCB in xylem saps was designed to be examined. The results showed that （1） the HCB translocation from paddy soil to rice by vaporization; （2） the HCB concentration in rice grains was surprisingly high; （3） the observed HCB decrease in rice rhizosphere offers a potential means for in situ HCB degradation; （4） HCB might not be transported along transpiration in rice.展开更多
Rice is very sensitive to low zinc(Zn) supply in submerged paddy soils and Zn deficiency is one of the major limiting factors in determining rice production in India. A field experiment was conducted during the summer...Rice is very sensitive to low zinc(Zn) supply in submerged paddy soils and Zn deficiency is one of the major limiting factors in determining rice production in India. A field experiment was conducted during the summer-rainy seasons of 2009 and 2010 at the research farm of the Indian Agricultural Research Institute, New Delhi, to determine the effects of summer green manure crops and Zn fertilizers on diethylenetriaminepentaacetic acid(DTPA)-extractable(available) Zn concentration in soil and total Zn content in Basmati rice cultivar Pusa Basmati 1 at periodic intervals. Summer green manure crops included Sesbania aculeata(Dhaincha),Crotalaria juncea(Sunhemp), and Vigna unguiculata(Cowpea) and the Zn fertilizers used were ethylenediaminetetraacetic acid(EDTA)-chelated Zn, ZnSO4·7H2O, ZnSO4·H2O, ZnO, and ZnSO4·7H2O + ZnO. Beneficial effects of summer green manure crops and Zn fertilizers on DTPA-extractable Zn concentration in soil and total Zn content in dry matter of Basmati rice at periodic intervals were observed, with significant increases in all the determined parameters, in comparison with those in the control(no Zn application or summer fallow). The rate of increase varied among summer green manure crops and Zn fertilizers during both years. Among the summer green manures, incorporation of S. aculeata led to a significant increase in mean Zn content in Basmati rice grain and straw when compared with C. juncea, V. unguiculata, and summer fallow treatments. Among the Zn fertilizers, significant increases in Zn content in Basmati rice dry matter and DTPA-extractable Zn concentration in soil during various growth stages of the plant were recorded with EDTA-chelated Zn application, followed by the application of ZnSO4·7H2O, ZnSO4·H2O, ZnSO4·7H2O + ZnO, ZnO,and no Zn. The highest mean Zn content in Basmati rice grain and straw was recorded with EDTA-chelated Zn application in 2009 and 2010, respectively. The application of ZnSO4·7H2O was the second best treatment after EDTA-chelated Zn;however, it was statistically inferior to EDTA-chelated Zn. The lowest values were recorded with the control(no Zn application) during both years of study. The amount of Zn concentration in soil was found to be significantly positively correlated with the Zn content in Basmati rice dry matter during both years. Significantly higher levels of residual fertility in soil after the harvest of Basmati rice were observed with application of EDTA-chelated Zn and incorporation of S. aculeata when compared with those of other Zn sources and summer green manures.展开更多
High grain-Cd-accumulating rice variety Yongyou 9 was planted in Cd-contaminated farmland in Taizhou City, Zhejiang Province, China to study the effects of 5-aminolevulinic acid(ALA) and24-epibrassinolide(EBR) on Cd a...High grain-Cd-accumulating rice variety Yongyou 9 was planted in Cd-contaminated farmland in Taizhou City, Zhejiang Province, China to study the effects of 5-aminolevulinic acid(ALA) and24-epibrassinolide(EBR) on Cd accumulation in brown rice. Results showed that the exogenous ALA and EBR had no significant effects on agronomic traits, soil pH and total Cd content in soil, but had some effects on the available Cd content in soil, and significantly influenced the Cd accumulation in the different parts of rice. Results also showed that 100 mg/L exogenous ALA significantly reduced the Cd accumulation in brown rice to blow the food safety standard(0.2 mg/kg), and also significantly reduced the Cd contents in the roots and culm of rice. However, 200 mg/L exogenous ALA treatment increased the Cd content in brown rice remarkably. In addition, 0.15 mg/L EBR treatment increased Cd accumulation in roots, culm, leaves and brown rice notably, whereas 0.30 mg/L exogenous EBR treatment reduced the Cd accumulation in brown rice properly, but it was not significant. Therefore,proper concentration of ALA can effectively reduce the Cd accumulation in brown rice, which can be used as an effective technical method for the safe production of rice in Cd polluted farmland.展开更多
To determine the sufficiency and deficiency indices of soil available Zn by the Agro Services International （ASI） method （ASI-Zn） for Zn fertilizer recommendation in rice production in the alluvial soil of the coa...To determine the sufficiency and deficiency indices of soil available Zn by the Agro Services International （ASI） method （ASI-Zn） for Zn fertilizer recommendation in rice production in the alluvial soil of the coastal Yellow Sea, the relationship between relative rice yield and soil available ASI-Zn concentration was analyzed from a ten-field experiment with various soil test classes ranging from low to high fertility in 2005 and 2006, and nine Zn fertilizer application rates （0, 7.5 15, 22.5, 30, 37.5, 45, 52.5 and 60 kg Zn/ha） arranged at random with three replications in each field. There was a significant quadratic relationship between soil available ASI-Zn and rice yield, and a significant linear relationship between soil available ASI-Zn concentration and Zn fertilization rate. For rice variety Wuyujing 3, soil available ASI-Zn was deficient when the value was at lower than 1 mg Zn/L, low at 1 to 2 mg Zn/L, sufficient at 1 to 2 mg Zn/L, excessive at higher than 7.5 mg Zn/L. Thus, Zn fertilizer recommendation could be done according to the sufficiency and deficiency indices of soil ASI-Zn. For most of alluvial soils of the coastal Yellow Sea in the study, the available ASI-Zn was lower than 1 mg Zn/L, and then the optimum application rate of Zn fertilizer was about 20 kg Zn/ha.展开更多
How to improve the water use efficiency of rice in black soil regions was studied. The black soil region in paddy fields was chosen as the research object. The research showed the fertilizer coupling mathematical mode...How to improve the water use efficiency of rice in black soil regions was studied. The black soil region in paddy fields was chosen as the research object. The research showed the fertilizer coupling mathematical model with N,P,K,irrigation water( W) and water use efficiency( WUE),which was set up under the condition of controlled irrigation with quadratic D- 416 optimized saturation design. The results show that the decending order of single factor' s influence on the WUE was N,K,P and W. All the interactions between N&P,N&K,N&W,K&P,P&W and K&W on the WUE were raised initially,and when reached a certain value,they began to decline. The decending order of each interaction on the WUE was K&P,K&W,N&K,N&P,P&W and N&W. When the WUE was targeted within 1. 8- 2. 5 kg / km^3,an optimized proportion plan was obtained in the 95% confidence interval,i. e. N 87. 76- 103. 32 kg / hm^2,K_2 O 52. 37- 66. 53 kg / hm^2 and P_2O_536. 80- 46. 71 kg / hm^2. Furthermore,the late tillering of the soil moisture content was 70. 07%- 72. 57% of the saturated moisture content.展开更多
Using hybrid rice Yixiang1577 as the material, the mid-season and ratooning hybrid rice yield variation was studied in Southem Sichuan at different levels of nitrogen fertilizer. The results showed that rice yield by ...Using hybrid rice Yixiang1577 as the material, the mid-season and ratooning hybrid rice yield variation was studied in Southem Sichuan at different levels of nitrogen fertilizer. The results showed that rice yield by using N fertilizer increased to the most significant level than no fertilizer ones, and the mid-season rice and rice yield by using more N fertilizer increased to the significant level than less fertilizer ones. The rice yield by using no fertilizer ones increased to the most significant level than some used fertilizer, and the ratooning rice and rice yield by using more N fertilizer decreased to the most significant level than less fertilizer ones. The rice yield by using some fertilizer increased to the most significant level than no fertilizer ones for mid-season＋rationing rice and rice yield by using some fertilizer had no obvious differences at different nitrogen levels. Therefore, application of fertilizer can improve yield of mid-season rice and mid-season＋rationing rice. Soil test results showed that nutrient contents in rice field in South Sichuan were very rich in nitrogen, which could provide more adequate crop growth potential soil nitrogen nutrition. The crops with a deep root system had stronger ability of utilization on soil nitrogen. Therefore, the ratooning rice used no or little N fertilizer had a high yield performance because they made full use of soil nitrogen with deep root system.展开更多
The importance of soil organic carbon（SOC） sequestration in agricultural soils as climate-change-mitigating strategy has become an area of focus by the scientific community in relation to soil management.This study ...The importance of soil organic carbon（SOC） sequestration in agricultural soils as climate-change-mitigating strategy has become an area of focus by the scientific community in relation to soil management.This study was conducted to determine the temporal effect of different tillage systems and residue management on distribution, storage and stratification of SOC, and the yield of rice under double rice（Oryza sativa L.） cropping system in the southern China.A tillage experiment was conducted in the southern China during 2005–2011, including plow tillage with residue removed（PT0）, plow tillage with residue retention（PT）, rotary tillage with residue retention（RT）, and no-till with residue retention on the surface（NT）.The soil samples were obtained at the harvesting of late rice in October of 2005, 2007 and 2011.Multiple-year residue return application significantly increased rice yields for the two rice-cropping systems; yields of early and late rice were higher under RT than those under other tillage systems in both years in 2011.Compared with PT0, SOC stocks were increased in soil under NT at 0–5, 5–10, 10–20, and 20–30 cm depths by 33.8, 4.1, 6.6, and 53.3%, respectively, in 2011.SOC stocks under RT were higher than these under other tillage treatments at 0–30 cm depth.SOC stocks in soil under PT were higher than those under PT0 in the 0–5 and 20–30 cm soil layers.Therefore, crop residues played an important role in SOC management, and improvement of soil quality.In the 0–20 cm layer, the stratification ratio（SR） of SOC followed the order NT〉RT〉PT〉PT0; when the 0–30 cm layer was considered, NT also had the highest SR of SOC, but the SR of SOC under PT was higher than that under RT with a multiple-year tillage practice.Therefore, the notion that conservation tillage lead to higher SOC stocks and soil quality than plowed systems requires cautious scrutiny.Nevertheless, some benefits associated with RT system present a greater potential for its adoption in view of the multiple-year environmental sustainability under double rice cropping system in the southern China.展开更多
基金Under the auspices of the Key Innovation Project of Chinese Academy of Sciences (No. KZCX1-SW-19-02)
文摘By applying bromide ion as tracer, the channeling flow has been quantitatively described in saline rice soil and alkaline soil of Da＇an City, Jilin Province of China. Breakthrough curves of bromide ion in the saline rice soils after 1-year cultivation and 5-year cultivation and alkaline soil have been attained. Results show that the rice cultivation practice can improve the alkaline soil structure, however, it can accelerate the development of channeling flow pathway. Therefore, the channeling flow pathway has been developed widely in saline rice soil, but rarely in the alkaline soil. Three models of convection-dispersion equation （CDE）, transfer functional model （TFM） and Back-Progation Network （BP Network） were used to simulate the transportation process of bromide ion. The peaks of probability density function of saline rice soil are higher with left skewed feature compared with that of the alkaline soil. It shows that the TIM and CDE can simulate the transportation process of the bromide ion in saline rice soil after 5-year cultivation, however, some deviation exists when it was used to simulate transportation process of bromide ion in saline rice soil after 1-year cultivation and alkaline soil; BP network can effectively simulate transportation process of bromide ion in both saline rice soil and alkaline soil.
文摘Of the factors affecting migration and bioavailability of toxic metals in heavy metal contaminated soil, DOC （dissolved organic carbon） provides binding sites for metal cations and reduces the fixation and adsorption of heavy metals by soil solid phase. Elevation of DOC level due to the direct incorporation of crop residues may lead to enhanced accumulation of toxic metals in crop body grown in polluted farmland. In this study, an incubation experiment and a pot experiment were conducted respectively to investigate the effects of wheat straw incorporation on DOC level, cadmium availability, and Cd accumulation in rice plant, and to establish the relation between Cd solubility and DOC level. A Cd-contaminated rice soil was used and incorporated with different rates （0%, 0.5% and 1%） of wheat straw in both experiments. Results showed that the change pattern of Cd in soil solution was very similar to that of DOC level. Wheat straw addition significantly elevated Cd and DOC level in soil solution while NH4NO3-extrated Cd was not affected. There existed a close linear correlation between soluble Cd and DOC level. Enhanced Cd accumulation in rice plant, grown in a Cd contaminated soil, induced by wheat straw incorporation was observed in this study.
文摘There are about 1 million ha of Si-deficiency paddy soils in Hubei Province. Practically, it is essential to study the Si nutrient status in those Si-deficiency rice soil and its regional distribution before the application of Si-fertilizer. According to the analysis of 50 rice soil samples which collected from 20 counties/cities in Hubei Province, the available Si content in rice soils derived from different parent materials varied greatly. The Si content from high to low was in sequence of limestone, redpurplish sandy shale with carbonate, alluvium and lacustrine deposits, quaternary period red clay, granitic gneiss, and sandy shale. In addition, the Si content in rice soil was remarkably related with its pH. It seems that the pH 6.5 might be a demarcation line that divided the supplying Si ability of rice soils into the low and high categories (Table 1). Integrating the results with a critical soil Si-deficiency as 100 mg/kg, the evaluation index of soil Si supplying capability of a rice soil
文摘With the aim of finding the geochemical differences and helping to build alleviating strategies against iron toxicity, two hematite dominant valley bottoms irrigating rice soils were investigated in the Tropical Savannah region of Burkina Faso. The first site was Tiefora, a 15-ha modern double-season irrigated rice system and moderately affected by iron toxicity (10% of the area with a toxicity score of 4). The second site was Moussodougou, a 35-ha traditional singleseason irrigated rice valley-bottom, with 50% facing more severe iron toxicity (score 7). Nine soil extracts were taken from three depths—30, 50 and 100 cm—i.e. 27 at Tiefora and 27 at Moussodogou. Five techniques were used to measure the data: 1) the ferrous iron concentration was determined using a reflectometer, 2) a pH-meter yielded the pH, 3) clay-proportions were obtained by United States Department of Agriculture (USDA) grain size analysis and densitometry, 4) the organic matter was determined by oven drying (900℃) and v) the dry bulk density was determined by using undisturbed soil samples. Statistical hypothesis testing of One-way ANOVA and Welch t-test was applied to the data to isolate the similarities and the differences between the two sites. A geochemical analysis followed to find the causes of these differences. The results showed that while oxidation of pyrite leads to a simultaneous increase in Fe2+ concentrations and acidity in the soils of coastal floodplains and mangroves, the oxidation of hematite in Tropical savannah valley bottoms decreases Fe2+ but also increases acidity during the dry season. As a consequence, it was found that the single-season irrigation scheme Moussodougou is significantly (p-value 0.4%) more acidic (pH 5.7) than the double-season system of Tiefora (6.4) with also 750 - 1800 mg/l higher ferrous Fe2+. The ferrous iron reached 3000 mg/l in some layers in Moussodougou. This result is a justification to modernize a traditional single-season spate irrigation schemes into a double-season irrigated rice scheme.
文摘Chemical fertilizers are a source of soil degradation. In order to mitigate soil degradation and to face the negative impacts of climate change, the use of organic fertilizers, accessible to small farmers can maintain the productivity of cereals including rice. The objective of this experiment is to study the effect of organo-mineral fertilizers on soil chemical properties, growth and physiology parameters and yield of rice. For this purpose, a completely randomized block design with three replications was adopted. Different organic (Fertinova, Organova and Fertinova + Organova) and mineral (NPK + Urea) fertilizers were applied to cultivate the NERICA L19 variety of rice. The soil chemical properties (pH), germination rate, growth, yield and physiological (chlorophyll content) parameters were assessed. The results revealed a germination rate of the grains varying between 87.5 and 100%. Fertinova and Fertinova + Organova had the highest germination rates. Soil pH decreased significantly from initial (6.71 ± 0.01) to final (5.73 ± 0.04) with the development cycle of the rice. Organo-mineral fertilizers influenced significantly (p = 5.36e−09) soil chemical properties by increasing pH (4%) compared to Control. Analysis of variance on growth and yield parameters, yield and chlorophyll content revealed a significant difference (p < 0.05) between fertilizers. Growth and yield parameters and yield were significantly higher in NPK and Fertinova + Organova than in Fertinova, Organova and Control. For the biomass the NPK + Urea recorded significantly highest biomass (488.28 ± 60.83 g). Leaves chlorophyll content varied significantly according to the daytime and the status of leaf development. The higher chlorophyll content was recorded at noon (27.96 ± 0.32 SPAD value) and with young leaves (30.21 ± 0.35 SPAD value). NPK + Urea (29.36 ± 0.45 SPAD value) and Fertinova (27.78 ± 0.40 SPAD value) favored more chlorophyll content in the rice leaves. Rice performed better in NPK + Urea and Fertinova + Organova fertilizers.
基金sponsored by the National Natural Science Foundation of China(31461143015,31271641,31471438)the National Key Technology Support Program of China(2014AA10A605,216YFD0300206-4)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),Chinathe Jiangsu Creation Program for Post-graduation Students,China(KYZZ15_0364)
文摘This study investigated if super rice could better cope with soil water deficit and if it could have better yield performance and water use efficiency （WUE） under alternate wetting and drying （AWD） irrigation than check rice. Two super rice cultivars and two elite check rice cultivars were grown in pots with three soil moisture levels, well watered （WW）, moderate water deficit （MWD） and severe water deficit （SWD）. Two cultivars, each for super rice and check rice, were grown in field with three irrigation regimes, alternate wetting and moderate drying （AWMD）, alternate wetting and severe drying （AWSD） and conventional irrigation （CI）. Compared with that under WW, grain yield was significantly decreased under MWD and SWD treatments, with less reduction for super rice than for check rice. Super rice had higher percentage of productive tillers, deeper root distribution, higher root oxidation activity, and greater aboveground biomass production at mid and late growth stages than check rice, especially under WMD and WSD. Compared with CI,AWMD increased, whereasAWSD decreased grain yield, with more increase or less decrease for super rice than for check rice. Both MWD and SWD treatments and eitherAWMD orAWSD regime significantly increased WUE compared with WW treatment or CI regime, with more increase for super rice than for check rice. The results suggest that super rice has a stronger ability to cope with soil water deficit and holds greater promising to increase both grain yield and WUE by adoption of moderate AWD irrigation.
文摘A simulation model developed by the authors (Huang et al., 1999) was validated against independent field measurements of methane emission from rice paddy soils in Texas of USA, Tuzu Of China and Vercelli of Italy.A simplified version of the simulation model was further validated against methane emission measurements from various regions of the world, including italy, China, Indonesia, Philippines and the United States. Model validation suggested that the seasonal variation of methane emission was mainly regulated by rice growth and development and that methane emission could be predicted from rice net productivity, cultivar character, soil texture and temperature, and organic matter amendments. Model simulations in general agreed with the observations. The comparison between computed and measured methane emission resulted in correlation coefficients r2 values from 0.450 to 0.952, significant at 0.01-0.001 probability level.On the basis of available information on rice cultivated area, growth duration, grain yield, soil texture and temperature, methane emission from rice paddy soils of China's Mainland was estimated for 28 rice cultivated provinces/municipal cities by employing the validated model. The calculated daily methane emission rates, on a provincial scale, ranged from 0.12 to 0.71 g m-2 with an average of 0.26 g m-2. A total amount of 7.92 Tg CH4 per year, ranging from 5.89 to 11.17 Tg year-1, was estimated to be released from Chinese rice paddy soils. Of the total, 45% was emitted from the single-rice growing season, and 19% and 36% were from the early-rice and the late-rice growing seasons, respectively. Approximately 70% of the total was emitted in the region located at latitude between 25°and 32°N. The emissions from rice fields in Sichuan and Hunan provinces were calculated to be 2.34 Tg year-1, accounting for approximately 30% of the total.
基金This research is funded by the National Natural Science Foundation of China(31972518)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Biochar may affect the root morphology and nitrogen(N)use efficiency(NUE)of rice at seedling stage,which has not been clearly verified until now.To clarify it,we conducted a pot experiment regarding to two soil types(Hydragric Anthrosol and Haplic Acrisol),two biochar application rates(0.5 wt%and 1.5 wt%)and two rice varieties(common rice var.Xiushui134 and hybrid super rice var.Zhongkejiayou12-6)meanwhile.Seedling NUE of common rice Xiuhui134 was significantly increased(p<0.05)by 78.2%in Hydragric Anthrosol and by 91.4%in Haplic Acrisol following biochar addition with 1.5 wt%.However,biochar addition exerted no influence on seedling NUE of super rice Zhongkejiayou12-6 in both soils.Overall,0.09–0.10 units higher soil pH and 105–116%higher soil NH_(4)^(+)-N were observed in Xiushui134 growing two soils with 1.5 wt%biochar.In addition,improved root morphology(including longer root length,larger root surface area,bigger root volume,and more root tips)contributed to the higher seedling NUE of Xiushui134 in two soils.The soil pH and NH_(4)^(+)-N content,also the root morphology were influenced by biochar,which though could not thoroughly explained the NUE of Zhongkejiayou12-6.In conclusion,biochar application to paddy soil changed soil pH and NH_(4)^(+)-N content,root growth,and the consequent seedling NUE of rice,which effects are relative with rice cultivar,biochar addition rate,and soil type.
基金supported by the earmarked fund for China Agriculture Research System (CARS-22)the Key Special Projects in National Key Research and Development Plan of China (2017YFD0301504 and 2016YFD0300900)+1 种基金the Scientific and Technological Innovation Project in Hunan Academy of Agricultural Sciences, China (2017JC47)the International Plant Nutrition Institute, Canada (IPNI China Program: Hunan-18)
文摘The double-rice cropping system is a very important intensive cropping system for food security in China. There have been few studies of the sustainability of yield and accumulation of soil organic carbon (SOC) in the double-rice cropping system following a partial substitution of chemical fertilizer by Chinese milk vetch (Mv). We conducted a 10-year (2008–2017) field experiment in Nan County, South-Central China, to examine the double-rice productivity and SOC accumulation in a paddy soil in response to different fertilization levels and Mv application (22.5 Mg ha^–1). Fertilizer and Mv were applied both individually and in combination (sole chemical fertilizers, Mv plus 100, 80, 60, 40, and 0% of the recommended dose of chemical fertilizers, labeled as F100, MF100, MF80, MF60, MF40, and MF0, respectively). It was found that the grain yields of double-rice crop in treatments receiving Mv were reduced when the dose of chemical fertilizer was reduced, while the change in SOC stock displayed a double peak curve. The MF100 produced the highest double-rice yield and SOC stock, with the value higher by 13.5 and 26.8% than that in the F100. However, the grain yields increased in the MF80 (by 8.4% compared to the F100), while the SOC stock only increased by 8.4%. Analogous to the change of grain yield, the sustainable yield index (SYI) of double rice were improved significantly in the MF100 and MF80 compared to the F100, while there was a slight increase in the MF60 and MF40. After a certain amount of Mv input (22.5 Mg ha^–1), the carbon sequestration rate was affected by the nutrient input due to the stimulation of microbial biomass. Compared with the MF0, the MF100 and MF40 resulted in a dramatically higher carbon sequestration rate (with the value higher by 71.6 and 70.1%), whereas the MF80 induced a lower carbon sequestration rate with the value lower by 70.1% compared to the MF0. Based on the above results we suggested that Mv could partially replace chemical fertilizers (e.g., 40–60%) to improve or maintain the productivity and sustainability of the double-rice cropping system in South-Central China.
文摘With an understanding of the processes of methane production, oxidation and emission, a semi-empirical model, focused on the contributions of rice plants to the processes and also the influence of environmental factors, was developed to predict methane emission from rice paddy soils. In the present model, the amount of methane transported from the soil to the atmosphere was determined by the rates of CH4 production and an emitted fraction. The rates of CH4 production in irrigated rice soils were computed from the availability of methanogenic substrates that are primarily derived from rice plaaes and added organic matter and the influence of soil texture, soil redox potential and temperature. The fraction of methane emitted was assumed to be modulated by the rice plants and declines with rice growth and development. TO make it applicable to a wider area with limited data sets, a simplified version of the model was also derived to predict methane emission in a more practical manner.
基金supported by the Special Funds for Agroscientific Research (No. 200903015)the Quality Supervision Scientific Research (No. 200910201) in the public interest
文摘Cadmium （Cd） entering the human body via the food chain is of increasing concern. This study investigates the effects of soil type and genotype on variations in the Cd concentrations of different organs of nine rice plants grown on two types of soils with two Cd levels. Cd concentrations in nine rice cultivars varied significantly with genotype and soil type （P 〈 0.01）. The Cd concentration was higher in red paddy soil （RP） than in yellow clayey paddy soil （YP）. The average Cd concentrations of different organs in three rice types were indica 〉 hybrid 〉 japonica for the Cd treatments and controls. The polished grain concentration in YP and RP soils had a range of 0.055--0.23 mg/kg and 0.13-0.36 mg/kg in the Cd treatment, respectively. Two rice cultivars in YP soil and five rice cultivars in RP soil exceeded the concentration limits in the Chinese Food Hygiene Standard （0.2 mg/kg）. The Cd concentrations in roots, stems, and leaves were all significantly and positively correlated to that in polished grain in a single test. The Cd concentrations in polished grain were positively and significantly （P 〈 0.01） correlated with the calculated transfer factors of stem to grain and leaf to grain Cd transfer. The results indicated that the variations of Cd concentration in grain were related to Cd uptake and the remobilization of Cd from stem and leaf to grain. Also, the cultivars with a strong tendency for Cd-accumulation should be avoided in paddy soil with low soil pH and low organic matter content to reduce the risks to human health from high Cd levels in rice.
基金This paper was translated from its Chinese version in Chinese Journal of Rice Science.
文摘The canopy temperature of rice at the flowering stage and the soil water content were investigated under different soil water treatments （the soil water contents were 24%, 55%, 90% and 175% at the flowering stage）. The canopy temperature was lower than air temperature, and the soil water content significantly influenced the canopy temperature. The lower the soil water content, the higher the canopy temperature, the less the accumulative absolute value of canopy-air temperature difference. Moreover, the maximum difference between treatments and CK in the accumulative absolute value of canopy-air temperature difference appeared at 13：00 μm. in a day, thus, it could be considered as a suitable measuring time. Under the lowest water content treatment, the peak flowering occurred in the first three days （about 70% of panicles flowered）, resulting in shortened and lightened panicle of rice. As to the CK and the high water content treatments, the peak flowering appeared in the middle of flowering duration, with longer panicle length and higher panicle weight. Results indicated the lower the soil water content, the less the filled grain number and grain yield.
文摘Pot experiments were conducted in 2002 and 2003 to investigate the effects of soil copper（Cu） concentration on growth, development and yield formation of rice by using the japonica cultivar Wuxiangjing 14 and hybrid rice combination Shanyou 63. The plant height, leaf number, elongated internode number and heading date of rice plants were not affected at soil Cu levels below 200 mg/kg, but affected significantly at above 400 mg/kg. The inhibitory effects on rice growth and development were increased with the increment of soil Cu levels. The grain yields decreased significantly with raising soil Cu levels. The main reasons for the grain yield reductions under lower soil Cu levels （100, 200 mg/kg） were mainly due to the decrease of number of spikelets per panicle, however, under higher soil Cu levels （more than 400 mg/kg）, both panicle number and number of spikelets per panicle contributed to the yield loss. The decreases of panicle number by Cu stress were mainly attributed to slow recovery from transplanting, delayed tillering and reduced maximum tiller numbers. The reduction of number of spikelets per panicle under soil Cu stress resulted from the decreases of both shoot dry weight （SDW） at the heading date and the ratio of spikelets to SDW. Total biomass at maturity decreased significantly with the increase of soil Cu levels, while economic coefficient showed non-significant decrease except under soil Cu levels above 800 mg/kg.
文摘Hexachlorobenzene （HCB）, a persistent organic pollutant （POP）, has been found in paddy soils. To improve the understanding of HCB contamination in paddy soils, a laboratory simulative study was carried out to investigate the behavior of HCB in a paddy soil and rice plants. This study was divided into three experiments. First, an experiment aimed to examine the evaporation of HCB in paddy soil. In the second experiment, rice was planted in 10 mg/kg HCB contaminated soil and after pot culture at 3, 6, 9, and 27 weeks （at maturity）, both soil and plant samplings were scheduled to be sampled. The soil samples comprised rhizosphere soil, nortrhizosphere soil, and unplanted contaminated soil, whereas plant samples included shoots, roots, and rice grains （dehusked）. Lastly, in this part, HCB in xylem saps was designed to be examined. The results showed that （1） the HCB translocation from paddy soil to rice by vaporization; （2） the HCB concentration in rice grains was surprisingly high; （3） the observed HCB decrease in rice rhizosphere offers a potential means for in situ HCB degradation; （4） HCB might not be transported along transpiration in rice.
文摘Rice is very sensitive to low zinc(Zn) supply in submerged paddy soils and Zn deficiency is one of the major limiting factors in determining rice production in India. A field experiment was conducted during the summer-rainy seasons of 2009 and 2010 at the research farm of the Indian Agricultural Research Institute, New Delhi, to determine the effects of summer green manure crops and Zn fertilizers on diethylenetriaminepentaacetic acid(DTPA)-extractable(available) Zn concentration in soil and total Zn content in Basmati rice cultivar Pusa Basmati 1 at periodic intervals. Summer green manure crops included Sesbania aculeata(Dhaincha),Crotalaria juncea(Sunhemp), and Vigna unguiculata(Cowpea) and the Zn fertilizers used were ethylenediaminetetraacetic acid(EDTA)-chelated Zn, ZnSO4·7H2O, ZnSO4·H2O, ZnO, and ZnSO4·7H2O + ZnO. Beneficial effects of summer green manure crops and Zn fertilizers on DTPA-extractable Zn concentration in soil and total Zn content in dry matter of Basmati rice at periodic intervals were observed, with significant increases in all the determined parameters, in comparison with those in the control(no Zn application or summer fallow). The rate of increase varied among summer green manure crops and Zn fertilizers during both years. Among the summer green manures, incorporation of S. aculeata led to a significant increase in mean Zn content in Basmati rice grain and straw when compared with C. juncea, V. unguiculata, and summer fallow treatments. Among the Zn fertilizers, significant increases in Zn content in Basmati rice dry matter and DTPA-extractable Zn concentration in soil during various growth stages of the plant were recorded with EDTA-chelated Zn application, followed by the application of ZnSO4·7H2O, ZnSO4·H2O, ZnSO4·7H2O + ZnO, ZnO,and no Zn. The highest mean Zn content in Basmati rice grain and straw was recorded with EDTA-chelated Zn application in 2009 and 2010, respectively. The application of ZnSO4·7H2O was the second best treatment after EDTA-chelated Zn;however, it was statistically inferior to EDTA-chelated Zn. The lowest values were recorded with the control(no Zn application) during both years of study. The amount of Zn concentration in soil was found to be significantly positively correlated with the Zn content in Basmati rice dry matter during both years. Significantly higher levels of residual fertility in soil after the harvest of Basmati rice were observed with application of EDTA-chelated Zn and incorporation of S. aculeata when compared with those of other Zn sources and summer green manures.
基金supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LY17C020005)the Key Research and Development Project of Zhejiang Province,China(Grant No.2015C03020-4)+2 种基金the National Nature Science Foundation of China(Grant No.31401356)Jinhua Science and Technology Project(Grant No.2015-2-012)the National Training Program for College Students to Innovate and Start Enterprise(Grant No.201710356013)
文摘High grain-Cd-accumulating rice variety Yongyou 9 was planted in Cd-contaminated farmland in Taizhou City, Zhejiang Province, China to study the effects of 5-aminolevulinic acid(ALA) and24-epibrassinolide(EBR) on Cd accumulation in brown rice. Results showed that the exogenous ALA and EBR had no significant effects on agronomic traits, soil pH and total Cd content in soil, but had some effects on the available Cd content in soil, and significantly influenced the Cd accumulation in the different parts of rice. Results also showed that 100 mg/L exogenous ALA significantly reduced the Cd accumulation in brown rice to blow the food safety standard(0.2 mg/kg), and also significantly reduced the Cd contents in the roots and culm of rice. However, 200 mg/L exogenous ALA treatment increased the Cd content in brown rice remarkably. In addition, 0.15 mg/L EBR treatment increased Cd accumulation in roots, culm, leaves and brown rice notably, whereas 0.30 mg/L exogenous EBR treatment reduced the Cd accumulation in brown rice properly, but it was not significant. Therefore,proper concentration of ALA can effectively reduce the Cd accumulation in brown rice, which can be used as an effective technical method for the safe production of rice in Cd polluted farmland.
文摘To determine the sufficiency and deficiency indices of soil available Zn by the Agro Services International （ASI） method （ASI-Zn） for Zn fertilizer recommendation in rice production in the alluvial soil of the coastal Yellow Sea, the relationship between relative rice yield and soil available ASI-Zn concentration was analyzed from a ten-field experiment with various soil test classes ranging from low to high fertility in 2005 and 2006, and nine Zn fertilizer application rates （0, 7.5 15, 22.5, 30, 37.5, 45, 52.5 and 60 kg Zn/ha） arranged at random with three replications in each field. There was a significant quadratic relationship between soil available ASI-Zn and rice yield, and a significant linear relationship between soil available ASI-Zn concentration and Zn fertilization rate. For rice variety Wuyujing 3, soil available ASI-Zn was deficient when the value was at lower than 1 mg Zn/L, low at 1 to 2 mg Zn/L, sufficient at 1 to 2 mg Zn/L, excessive at higher than 7.5 mg Zn/L. Thus, Zn fertilizer recommendation could be done according to the sufficiency and deficiency indices of soil ASI-Zn. For most of alluvial soils of the coastal Yellow Sea in the study, the available ASI-Zn was lower than 1 mg Zn/L, and then the optimum application rate of Zn fertilizer was about 20 kg Zn/ha.
文摘How to improve the water use efficiency of rice in black soil regions was studied. The black soil region in paddy fields was chosen as the research object. The research showed the fertilizer coupling mathematical model with N,P,K,irrigation water( W) and water use efficiency( WUE),which was set up under the condition of controlled irrigation with quadratic D- 416 optimized saturation design. The results show that the decending order of single factor' s influence on the WUE was N,K,P and W. All the interactions between N&P,N&K,N&W,K&P,P&W and K&W on the WUE were raised initially,and when reached a certain value,they began to decline. The decending order of each interaction on the WUE was K&P,K&W,N&K,N&P,P&W and N&W. When the WUE was targeted within 1. 8- 2. 5 kg / km^3,an optimized proportion plan was obtained in the 95% confidence interval,i. e. N 87. 76- 103. 32 kg / hm^2,K_2 O 52. 37- 66. 53 kg / hm^2 and P_2O_536. 80- 46. 71 kg / hm^2. Furthermore,the late tillering of the soil moisture content was 70. 07%- 72. 57% of the saturated moisture content.
基金Supported by Rice Industry Technical System Construction Project from the Ministry of Agriculture
文摘Using hybrid rice Yixiang1577 as the material, the mid-season and ratooning hybrid rice yield variation was studied in Southem Sichuan at different levels of nitrogen fertilizer. The results showed that rice yield by using N fertilizer increased to the most significant level than no fertilizer ones, and the mid-season rice and rice yield by using more N fertilizer increased to the significant level than less fertilizer ones. The rice yield by using no fertilizer ones increased to the most significant level than some used fertilizer, and the ratooning rice and rice yield by using more N fertilizer decreased to the most significant level than less fertilizer ones. The rice yield by using some fertilizer increased to the most significant level than no fertilizer ones for mid-season＋rationing rice and rice yield by using some fertilizer had no obvious differences at different nitrogen levels. Therefore, application of fertilizer can improve yield of mid-season rice and mid-season＋rationing rice. Soil test results showed that nutrient contents in rice field in South Sichuan were very rich in nitrogen, which could provide more adequate crop growth potential soil nitrogen nutrition. The crops with a deep root system had stronger ability of utilization on soil nitrogen. Therefore, the ratooning rice used no or little N fertilizer had a high yield performance because they made full use of soil nitrogen with deep root system.
基金funded by the Special Fund for Agro-Scientific Research in the Public Interest in China(201103001)
文摘The importance of soil organic carbon（SOC） sequestration in agricultural soils as climate-change-mitigating strategy has become an area of focus by the scientific community in relation to soil management.This study was conducted to determine the temporal effect of different tillage systems and residue management on distribution, storage and stratification of SOC, and the yield of rice under double rice（Oryza sativa L.） cropping system in the southern China.A tillage experiment was conducted in the southern China during 2005–2011, including plow tillage with residue removed（PT0）, plow tillage with residue retention（PT）, rotary tillage with residue retention（RT）, and no-till with residue retention on the surface（NT）.The soil samples were obtained at the harvesting of late rice in October of 2005, 2007 and 2011.Multiple-year residue return application significantly increased rice yields for the two rice-cropping systems; yields of early and late rice were higher under RT than those under other tillage systems in both years in 2011.Compared with PT0, SOC stocks were increased in soil under NT at 0–5, 5–10, 10–20, and 20–30 cm depths by 33.8, 4.1, 6.6, and 53.3%, respectively, in 2011.SOC stocks under RT were higher than these under other tillage treatments at 0–30 cm depth.SOC stocks in soil under PT were higher than those under PT0 in the 0–5 and 20–30 cm soil layers.Therefore, crop residues played an important role in SOC management, and improvement of soil quality.In the 0–20 cm layer, the stratification ratio（SR） of SOC followed the order NT〉RT〉PT〉PT0; when the 0–30 cm layer was considered, NT also had the highest SR of SOC, but the SR of SOC under PT was higher than that under RT with a multiple-year tillage practice.Therefore, the notion that conservation tillage lead to higher SOC stocks and soil quality than plowed systems requires cautious scrutiny.Nevertheless, some benefits associated with RT system present a greater potential for its adoption in view of the multiple-year environmental sustainability under double rice cropping system in the southern China.
