In this work, 23 black soil profiles were surveyed and 113 soil samples were collected to determine the field capacity (FC) of the black soil in Northeast China. The effectiveness of three methods measuring FC, the Wi...In this work, 23 black soil profiles were surveyed and 113 soil samples were collected to determine the field capacity (FC) of the black soil in Northeast China. The effectiveness of three methods measuring FC, the Wilcox method (WM), the undisturbed soil pressure plate method (PUM) and the air-dried sieved soil pressure plate method (PDM) were compared to select a suitable laboratory measurement method. Results show that the FC values measured by PDM are greater than those measured by PUM, and the values measured by PUM are greater than those measured by WM. PUM is more suitable for the determination of FC in the study area. One regression equation between PUM and PDM has been established through which undisturbed soil can be replaced by air-dried sieved soil, which is easier to get, to measure FC. FCs vary from 23.50% to 37.00%, with an average of 31.65%, which differ greatly among the 23 black soil profiles. FC is found to be significantly positively correlated with the silt content, clay content and bulk density of the soil, but significantly negatively correlated with the sand content. An empirical pedotransfer function is established to estimate the FC using available soil physical and chemical properties.展开更多
This paper presents a simplified dynamic method based on the definition of field capacity. Two soil hydraulic characteristics models, the Brooks-Corey （BC） model and the van Genuchten （vG） model, and four soil dat...This paper presents a simplified dynamic method based on the definition of field capacity. Two soil hydraulic characteristics models, the Brooks-Corey （BC） model and the van Genuchten （vG） model, and four soil data groups were used in this study. The relative drainage rate, which is a unique parameter and independent of the soil type in the simplified dynamic method, was analyzed using the pressure-based method with a matric potential of -1/3 bar and the flux-based method with a drainage flux of 0.005 cm/d. As a result, the relative drainage rate of the simplified dynamic method was determined to be 3% per day. This was verified by the similar field capacity results estimated with the three methods for most soils suitable for cultivating plants. In addition, the drainage time calculated with the simplified dynamic method was two to three days, which agrees with the classical definition of field capacity. We recommend the simplified dynamic method with a relative drainage rate of 3% per day due to its simple application and clearly physically-based concept.展开更多
Farmers have to finish their harvesting with high efficiency,because of time and cost.However,farmers are lacking knowledge and information required for selecting suitable combine harvesters and giving the conditions ...Farmers have to finish their harvesting with high efficiency,because of time and cost.However,farmers are lacking knowledge and information required for selecting suitable combine harvesters and giving the conditions of their rice fields,because both information factors(combine harvester and field condition)impact the field capacity.The field capacity model was generated from combine harvesters with the Thai Hom Mali rice variety(KDML-105).Therefore,this study aimed to determine the prediction model for effective field capacity to combine harvesters when harvesting the Thai Hom Mali rice variety(KDML-105).The methods began by collecting data of 15 combine harvesters,such as field,crop,and machine conditions and operating times;to generate the prediction model for the KDML-105 variety.The prediction model was then validated using 12 combine harvesters that were collected similarly to the model creation.The results showed a root mean square error(RMSE)of 0.24 m^(2)/s for the model.The prediction model can be applied for farmers to select the proper combine harvesters and give their field conditions.展开更多
Biological soil crusts are widely distributed in arid and semiarid regions. They have an important eco- logical role, especially by modifying physical and chemical properties of soils. Biological crusts may also modif...Biological soil crusts are widely distributed in arid and semiarid regions. They have an important eco- logical role, especially by modifying physical and chemical properties of soils. Biological crusts may also modify seed germination and seedling establishment. The effects vary widely according to the type of crust and the vas- cular plant species. The objective of this study was to determine the effect of moss-dominated biological soil crusts on the emergence, biomass and survival of Poa ligularis Nees ex Steud. under different irrigation regimes. We col- lected seeds of P. ligularis and biological soil crusts composed of two species of mosses： Syntrichia princeps （De Not.） Mitt and Ceratodon purpureus （Hedw.） Brid. from an area in the Monte of Argentina. The result showed that seedling emergence of P. ligularis was higher in treatments with bare soil than in soil covered by crusts, and also in those with watering to field capacity. Mean emergence time was higher in treatments with bare soil and watering to field capacity. Seedling biomass also showed significant differences between treatments. These results suggest that biological soil crusts dominated by mosses do not promote P. ligularis emergence, although they would not affect its survival.展开更多
Grain to Green program on arable land has been conducted for decades in semi-arid regions of North China.However,it remains uncertain how afforestation practices affect soil hydraulic properties(SHP).Two afforestation...Grain to Green program on arable land has been conducted for decades in semi-arid regions of North China.However,it remains uncertain how afforestation practices affect soil hydraulic properties(SHP).Two afforestation types,i.e.shrubland(SL)and woodland(WL),and the adjacent cropland(CL)were investigated to determine afforestation effects on SHP in this area.Disturbed and undisturbed soil cores were collected in three experimental sites.Soil field capacity(FC),wilting point(WP),and available water capacity(AWC)increased in SL compared to the CL.Soil saturated water content,however,decreased significantly in both SL and WL.Correlation and redundancy analysis identified that bulk density(BD)and soil organic carbon(SOC)were the main factors regulating SHP across different land uses.Lower saturated water contents in afforestation sites were likely driven by the higher BD,compared to the adjacent cropland.FC,WP,and AWC were positively correlated to SOC content.While afforestation may not increase the saturated water content of a landscape,our results indicate that it can improve soil water retention and could be an effective practice for soil and water conservation.展开更多
Chickpea （Cicer arietinum L.） is a crop cultivated in semi-arid and rainfed areas of Pakistan and it experiences terminal drought stress. In this paper, the morpho-anatomical study regarding roots of chickpea was ca...Chickpea （Cicer arietinum L.） is a crop cultivated in semi-arid and rainfed areas of Pakistan and it experiences terminal drought stress. In this paper, the morpho-anatomical study regarding roots of chickpea was carried out to investigate the drought adaptation strategies. Twelve cultivars of chickpea were grown in pots under drought stress of 70% and 35% field capacity in addition to control （100%）. Root segments of mature chickpea plants were sectioned in 2 cm from root-shoot junction and used for making transverse sections. The development of sleeve and stele tissues and their proportion were markedly influenced by moisture availability to the root system. Roots length, flesh and dry weight, and number of secondary roots were decreased under field capacity of 70% and 35% as compared to control in 12 cultivars of chickpea. Root epidermis and cortex of CH47/04 consisted of cells with thickened walls and with 2-3 cell layers of sclerenchymatous cells below the epidermis. Increased number of medullary rays and high vascular region was observed in cultivars CH120/04, CH47/04, CH587/05 and CH87/02. Anatomical studies showed that CH47/04 was highly tolerant among 12 cultivars of chickpea, while CH587/05 and CH87/02 behaved moderately under both levels of drought stress （70% and 35% field capacity）.展开更多
[Objective] The paper was to study and modify non-limiting water range （NLWR） of soil. [Method] The water content when total soil water potential was -0.3 MPa or soil mechanical resistance was 0.85 MPa was selected ...[Objective] The paper was to study and modify non-limiting water range （NLWR） of soil. [Method] The water content when total soil water potential was -0.3 MPa or soil mechanical resistance was 0.85 MPa was selected as the lower limit of NLWR to replace the original water content of permanent wilting point or the water content under soil mechanical resistance of 2.0 MPa. NLWR could be calculated us-ing the minimum value of upper limit minus the maximum value of lower limit. [Re-sult] Compared with original NLWR or least limiting water range （LLWR）, the modi-fied NLWR had more practical significance. When Db〉Db-thr, soil physical properties hindered the growth of crops, so the soil should be improved; when Db〉Db-thr, soil physical properties hindered the growth of crops, so-the soil should be improved; wtlen Db〈Db-thr, as long as the soil water content is within NLWR, soil physical properties had no effect on crop growth. NLWR at this time could be used as the basis for irrigation man- agement in farmland. [Conclusion] The study provides theoretical support and scientific basis for relevant researches about evolution rule and regulatory mechanisms of soil physical quality, relationship between soil physical quality and crop growth and yield, water-fertilizer-salt management of soil.展开更多
<em>Haor</em> represents the food basket of Bangladesh and rice is the only crop grown once a year. Harvesting of rice is labor-intensive works and required migrated labor to complete the harvesting works....<em>Haor</em> represents the food basket of Bangladesh and rice is the only crop grown once a year. Harvesting of rice is labor-intensive works and required migrated labor to complete the harvesting works. Mechanical intervention of rice harvesting is urgently needed to increase the productivity. The proper knowledge of economic valuation and operational necessities needs to use of combine harvesters. Research objective was selected to test the technical and economic analysis of Zoomlion rice combine harvester (which is originally developed in China) in Maisherkandi, Mithamain Upazila under Kishoregonj district. The above-mentioned areas are representing <em>haor</em> areas of Bangladesh. Based on the straight-line method, fixed cost items which are machine purchase price, shelter, tax, and insurance were calculated. During the operation of the combine harvester variable cost items such as maintenance and repair, fuel, oil, drivers and guidance were collected. The breakeven point was calculated in terms of the hectares that must be harvested yearly to cover fixed annual costs;and the payback period. Harvesting speed ranged from 1.23 - 3.20 km<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>hr<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span></span>1</sup>. The field capacity of harvester was obtained 0.15 ha<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>hr<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> and consumed fuel of up to 32 L<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span></span>1</sup>. Field sizes of less than 800 m<sup>2</sup> should be avoided for the Zoomlion combine harvester to operate the harvester machine in an efficient manner. The combine produced grains loss ranging from 1.60% - 1.91%. At an initial cost of Tk 2,000,000, owning the combine harvester becomes profitable after 20 ha of paddy field harvested at a harvesting capacity of 0.15 ha<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>hr<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span></span>1</sup>. Vibration and noise were observed in tolerable limit of the operator. The operator felt comfort to operate the machine. This machine is capable to operate in the muddy field having a water height of 4 - 8 cm. Workability of the combine harvesters depended on soil, weather, crop condition, land size and shape. The combine harvester was able to develop sufficient traction in soft soil during harvesting period in <em>haor</em> area. Zoomlion harvester is a cost-effective and time-saving machine but the initial costs are higher.展开更多
In Bangladesh, the use of machinery in agriculture production is fast rising. Researchers are developing technology to replace traditional hand weeding to manage weeds in rice fields. The present study has been taken ...In Bangladesh, the use of machinery in agriculture production is fast rising. Researchers are developing technology to replace traditional hand weeding to manage weeds in rice fields. The present study has been taken to increase weeding efficiency and reduce the drudgery in weeding and mulching. A line-to-line distance of 20 cm, the operation is push-pull, and field operating condition at 2 - 4 cm standing water (for softening the field) was the designed hypothesis. The weeder consists of a skid/float, float holder, float adjuster, main body frame, rotor, axel, bush, rotor holder, rotor holder adjuster, handle, handle griper, handle holder, handle height adjuster, nut, bolt, etc. The designed weeder was fabricated using MS sheet, MS pipe, MS flat bar, MS nut-bolt, etc. When the rotors perform back and forth, the weeder’s two conical rotors with six plain blades and six serrated blades work together to uproot and bury the weeds. It also contains a 2 mm thick float assembly with a precise angle of 22 degrees. Weeds are uprooted by the weeder’s blades and buried in the muddy soil. It causes topsoil disturbance and enhances aeration. The weeding efficiency and capacity of the conical weeder were 81.92% and 0.0203 ha/h respectively. With a push-pull operation, the weeder can uproot and bury the weeds in a single row at a time. The pushing force and weight of weeder were 43.42 N and 5.6 kg respectively. Farmers can use this weeder to increase their comfort and reduce the drudgery associated with weeding and mulching in their fields.展开更多
Generally,nanotechnology plays an very important role in various applied scientific fields.Iron and magnesium nanoparticles(NPs)can cause positive or negative changes in soil physical and mechanical properties,especia...Generally,nanotechnology plays an very important role in various applied scientific fields.Iron and magnesium nanoparticles(NPs)can cause positive or negative changes in soil physical and mechanical properties,especially in long periods.The aim of this study was to investigate the multi-year effects of NPs on soil water retention and aggregate tensile strength.A wheat farm loamy soil was amended with 1%,3%,and 5%(weight/weight)of magnesium oxide(Mg O)and iron oxide(Fe_(3)O_(4))NPs in three replications and incubated for three years.Water contents were measured at different matric suctions of 0,10,20,40,60,100,300,1000,and 15000 cm.The van Genuchten model was fitted to the moisture data.Tensile strength was measured on the 2–4 mm aggregates at matric suctions of 300(i.e.,field capacity)and 15000(i.e.,permanent wilting point)cm.The results showed that the levels of 1%and 3%Fe_(3)O_(4)NPs significantly increased water retention,compared to the no NP application control and 5%Mg O NPs,which is probably due to the increase of adsorption surfaces in the treated soils.Water contents at field capacity and permanent wilting point in the 5%Mg O NP treatment decreased compared to those of the other treatments,due to the increased soil vulnerability and reduced soil fine pores.The application of Fe_(3)O_(4)NPs did not have any significant effect on soil tensile strength.Based on the results of this study,soil physical and mechanical properties could be affected by NP application.展开更多
In the present study,self-propelled cabbage/cauliflower harvester was designed,developed and evaluated.The machine consisted of different components like engine,frame,shearing(cutting)unit and power transmission unit....In the present study,self-propelled cabbage/cauliflower harvester was designed,developed and evaluated.The machine consisted of different components like engine,frame,shearing(cutting)unit and power transmission unit.The power transmission unit consisted of main clutch,shearing blade operating clutch,belt drive unit,chain and sprocket drive,universal joint and cutter blade assembly.The main working principle of harvester is based on shearing of crop stem against high-speed rotating blade.The power from the engine is transmitted by belt-pulley drive unit to transmission shaft on which chain and sprocket is mounted on one side and then power is transmitted to shearing blade coupling with the help of a stationary pulley and fixed socket.Average mean head diameter of the selected cabbage and cauliflower was 89.5±15.24 mm and 107.5±15.24 mm,respectively.Average mean stem(plant)diameter of the selected cabbage and cauliflower was 18±4.85 mm and 21.5±3.08 mm,respectively.The shearing force increased with increase in diameter of stem.The optimum performance of the machine was achieved when it was operated at 1.5 km/h forward speed and the shearing blade moving at speed of 147 rpm.The mean field capacity for developed prototype was observed as 0.063 ha/h and 0.053 in case of cabbage and cauliflower,respectively with field efficiency of 91.97 and 90.48%.The average head damage was negligible(0.15%)for both the crops.The average untrimmed percentage with developed harvester was 3.2 and 3.0%in case of cabbage and cauliflower crop,respectively.The developed machine helps to increase the field capacity in cabbage/cauliflower harvesting due to 7-times more capacity and 50%cheaper compared to traditional method of cabbage/cauliflower harvesting.At the operating condition of forward speed(1.5 km/h)and shearing blade speed(147 rpm),the machine could harvest 0.5 ha of cabbage and 0.42 ha of cauliflower farm per day of 8-h.This same task would have required between 15 labour per day if entirely done manually.展开更多
The use of the power tillers （walking tractors） are increasingly popular in Nigeria among farmers adopting Sawah rice production technology. This study compares the effects of two types of power tillers on physical ...The use of the power tillers （walking tractors） are increasingly popular in Nigeria among farmers adopting Sawah rice production technology. This study compares the effects of two types of power tillers on physical properties of soil and rice yield. because soil properties determine to a large extents rice yield. Data on soil properties and rice yield were collected and subjected to t-test statistics. The results show that, significant differences exit for all the physical properties of soils rice yields from fields where the two power tiller were used with yields from rice field where SHAKTI was used was higher than KUBOTA. It is important that farmers using these models of power tillers for rice production should not only focus on the purchase cost of these power tillers but their overall efficiency in order to achieve the desired high level of yield.展开更多
Salt and sodicity of saline-alkali soil adversely affect the construction of ecological landscapes and negatively impact crop production.The reclamation potential of biochar(BC,wheat straw biochar applied at\%by weigh...Salt and sodicity of saline-alkali soil adversely affect the construction of ecological landscapes and negatively impact crop production.The reclamation potential of biochar(BC,wheat straw biochar applied at\%by weight),gypsum(G,0.4%by weight),and gypsum coupled with biochar(GBC)was examined in this laboratory-based study by evaluating their effects on a saline-alkali soil(silt loam)with no amendment as a control(CK).Saline ice and fresh water(simulated rainfall)were leached through soil columns to investigate changes in salt content,sodium adsorption ratio(SAR),alkalinity,and pH of the leachate and the soil.Results showed that saturated water content and field water capacity(FWC)significantly increased by 4.4%and 5.6%,respectively,in the BC treatment after a short incubation time.Co-application of biochar and gypsum(GBC)increased soil saturated hydraulic conductivity(Ks)by 58.4%,which was also significantly higher than the sole addition.Electrical conductivity(EC)of the leachate decreased sharply after saline ice leaching;subsequent freshwater leaching accelerated the removal of the rest of the salts,irrespective of the amendment application.However,the application of gypsum(G and GB)significantly enhanced the removal of exchangeable Na^+and reduced leachate SAR.After leaching,the soil salt content decreased significantly for all treatments.The application of gypsum resulted in a significantly lower soil pH,exchangeable sodium percentage(ESP),SAR,and alkalinity values than those recorded for the CK and BC treatments.These results demonstrated that the co-application of gypsum and biochar could improve saline-alkali soil hydraulic conductivity and decrease leaching-induced sodicity over a short period.展开更多
Composts are considered to be one of the best soil amendments.However,the effects of composts with added polymeric materials on soil physical,hydraulic,and micromorphological properties have not been widely discussed....Composts are considered to be one of the best soil amendments.However,the effects of composts with added polymeric materials on soil physical,hydraulic,and micromorphological properties have not been widely discussed.Changes in soil physical properties influence the numerous services that soils provide.We studied the impacts of composts with the addition of three different polymers(F1–F3)produced from polyethylene and thermoplastic corn starch on the physical,hydraulic,and micromorphological properties of two soils,a Cambic Phaeozem and a Luvic Phaeozem.Applying composts with polymers had limited or no significant effect on soil bulk density and porosity,but increased the field water capacity by 18%–82%and 3%–6%and the plant-available water content by 15%–23%and 4%–17%for the Cambic Phaeozem and Luvic Phaeozem,respectively.The application of composts with polymers had a greater effect on the Cambic Phaeozem than on the Luvic Phaeozem.It was suggested that the use of modified composts led to changes in soil physical properties and micromorphological features and this effect was dependent on the compost application rate.Composts made with the addition of composite synthetic and natural material-derived polymers during composting were found to be a composite mixture that can be successfully used in agriculture.展开更多
In this work,we tuned the magnetostructural transformation and the coupled magnetocaloric properties of Mn_(48-x)V_(x)Ni_(42)Sn_(10)(x=0,1,2,and 3)ferromagnetic shape memory alloys prepared by means of partial replace...In this work,we tuned the magnetostructural transformation and the coupled magnetocaloric properties of Mn_(48-x)V_(x)Ni_(42)Sn_(10)(x=0,1,2,and 3)ferromagnetic shape memory alloys prepared by means of partial replacement of Mn by V.It is observed that the martensitic transformation temperatures decrease with the increase of V content.The shift of the transition temperatures to lower temperatures driven by the applied field,the metamagnetic behavior,and the thermal hysteresis indicates the first-order nature for the magnetostructural transformation.The entropy changes with a magnetic field variation of 0-5 T are 15.2,18.8,and 24.3 J.kg^(-1).K^(-1)for the x=0,1,and 2 samples,respectively.The tunable martensitic transformation temperature,enhanced field driving capacity,and large entropy change suggest that Mn_(48-x)V_(x)Ni_(42)Sn_(10)alloys have a potential for applications in magnetic cooling refrigeration.展开更多
This paper is devoted to a study of L^q-tracing of the fractional temperature field u(t, x)—the weak solution of the fractional heat equation(?_t +(-?_x)~α)u(t, x) = g(t, x) in L^p(R_+^(1+n)) subject to the initial ...This paper is devoted to a study of L^q-tracing of the fractional temperature field u(t, x)—the weak solution of the fractional heat equation(?_t +(-?_x)~α)u(t, x) = g(t, x) in L^p(R_+^(1+n)) subject to the initial temperature u(0, x) = f(x) in L^p(R^n).展开更多
Standard Disk Plough(SDP)is the integral element of traditional farming system in Middle and Northern Sudan.In SDP,the tilt angle between the planes of the cutting edge of the disk which is inclined to a vertical line...Standard Disk Plough(SDP)is the integral element of traditional farming system in Middle and Northern Sudan.In SDP,the tilt angle between the planes of the cutting edge of the disk which is inclined to a vertical line may be altered according to the field conditions.Tractor drivers usually use an angle close to maximum in order to decrease the tillage depth,consequently decreasing power requirements,without considering the tillage quality and the impact on the soil properties.This experiment was conducted at the College of Agricultural Studies farm of Sudan University of Science and Technology to study the effects of three tilt angles(15°,20°and 25°)on soil bulk density,mean weight diameter,wheel slippage,work rate(or effective field capacity)and soil volume disturbed using mounted disk plough.The nature of soil on the farm found to be light clay.The theoretical forward speed was maintained at 6 km/h.The results showed that increasing tilt angle of the plough significantly(p<0.05)increased the bulk density,mean weight diameter and field capacity while significantly decreasing the tractor wheel slippage and soil volume disturbance.展开更多
Background and aims:Since few studies have existed in the literature about the effect of zinc(Zn)on cadmium(Cd)chemical forms in soils.Therefore,this study has been performed to determine the impact of Zn on cadmium C...Background and aims:Since few studies have existed in the literature about the effect of zinc(Zn)on cadmium(Cd)chemical forms in soils.Therefore,this study has been performed to determine the impact of Zn on cadmium Cd chemical forms in two soil textural classes in Fars province-Iran at two soil water content(SWC)(flooded soil water content(FSWC)and field capacity soil water content(FCSWC))and study the kinetic modeling of Cd.Methods and materials:Variables were three levels of Cd(0,30 and 60 mg kg-1 of soil as CdSO4·8H2O),three levels of Zn(0,5 and 10 mg kg-1 of soil as Zn-EDTA)three level Incubation times(2,4 and eight weeks),two soil textural classes(clay and sandy clay loam)and two SWC.The randomized completed block design(RCBD)was used for this experiment.The Tessier sequential extraction method was used to determine the Cd concentration in(WsEx),(Fe-MnOx),(Car),(Om)and(Res)chemical forms.Results:In the FSWC,Zn reduced the Cd concentration in Fe-MnOx,Car and Om forms and increased the WsEx but had no significant effect on the Res form.Changes in the Cd chemical forms under the in-fluence of Zn in both soils followed a similar trend.In the FCSWC,Zn reduced the Cd concentration Car and Om forms and increased the Cd concentration in the Fe-MnOx and WsEx forms while had no sig-nificant effect on Res form in the sandy clay loam soil.In the clay soil adding Zn reduced the Cd con-centration in Car and Om fractions and increased the Fe-MnOx and Res forms while has no significant effect on WsEx form.The competitive transport and adsorption Interactions between these two ions caused the changing in the Cd concentration in its chemical forms.Zn reduces the Cd concentration in the forms which are easily released into the soil solution from where they can be absorbed by plants.The power function kinetic mode is the best fitted model which can describe the Cd adsorption in our soil samples.The clay and organic compounds control the Cd adsorption in soils.The higher rate of Cd adsorption in almost all shaking times shows that Cd has more ability to occupy the adsorption sites in soils.展开更多
Estimation of soil water content(SWC)in deep soil profiles is of crucial importance for strategic management of water resource for sustainable land use in arid and semi-arid zones,as well as for soil and water conserv...Estimation of soil water content(SWC)in deep soil profiles is of crucial importance for strategic management of water resource for sustainable land use in arid and semi-arid zones,as well as for soil and water conservation.Soil properties have a very important effect on SWC.This study aimed to analyze the influence of soil particle size on SWC,for the first time using soil particle size to estimate SWC in deep soil profiles.SWC was measured mainly in farmland,natural grasslands and plantations of Caragana from the surface to more than 20 m depth.The same soil samples were also tested for particle size.The results show that the soil desiccation is formed in the caragana forest in 3–18 m soil layers,but almost no formation in 18–24 m layers;water content of farmland and grassland is different in all soil profiles although they are both shallow rooted plants.Correlation analysis indicated that SWC could be well predicted by clay content and the close correlation between SWC and clay content yielded a coefficient of determination(R^(2))of 0.82 and 0.72,respectively,for farmland and grassland.After multiple regression analysis,a regression model was built using SWC,clay content and sand content data,giving R^(2)=0.66.The model provided reliable estimates of SWC profile based on textural class.This can assist in estimating water depletion by vegetation,by comparing moisture of farmland and grassland soils with that of plantation forests,and in selecting sustainable land use of arid land.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.40671111)Major State Basic Research Development Program of China(No.2007CB407203)
文摘In this work, 23 black soil profiles were surveyed and 113 soil samples were collected to determine the field capacity (FC) of the black soil in Northeast China. The effectiveness of three methods measuring FC, the Wilcox method (WM), the undisturbed soil pressure plate method (PUM) and the air-dried sieved soil pressure plate method (PDM) were compared to select a suitable laboratory measurement method. Results show that the FC values measured by PDM are greater than those measured by PUM, and the values measured by PUM are greater than those measured by WM. PUM is more suitable for the determination of FC in the study area. One regression equation between PUM and PDM has been established through which undisturbed soil can be replaced by air-dried sieved soil, which is easier to get, to measure FC. FCs vary from 23.50% to 37.00%, with an average of 31.65%, which differ greatly among the 23 black soil profiles. FC is found to be significantly positively correlated with the silt content, clay content and bulk density of the soil, but significantly negatively correlated with the sand content. An empirical pedotransfer function is established to estimate the FC using available soil physical and chemical properties.
基金supported by the National Natural Science Foundation of China(Grants No.51179083 and 91225302)
文摘This paper presents a simplified dynamic method based on the definition of field capacity. Two soil hydraulic characteristics models, the Brooks-Corey （BC） model and the van Genuchten （vG） model, and four soil data groups were used in this study. The relative drainage rate, which is a unique parameter and independent of the soil type in the simplified dynamic method, was analyzed using the pressure-based method with a matric potential of -1/3 bar and the flux-based method with a drainage flux of 0.005 cm/d. As a result, the relative drainage rate of the simplified dynamic method was determined to be 3% per day. This was verified by the similar field capacity results estimated with the three methods for most soils suitable for cultivating plants. In addition, the drainage time calculated with the simplified dynamic method was two to three days, which agrees with the classical definition of field capacity. We recommend the simplified dynamic method with a relative drainage rate of 3% per day due to its simple application and clearly physically-based concept.
文摘Farmers have to finish their harvesting with high efficiency,because of time and cost.However,farmers are lacking knowledge and information required for selecting suitable combine harvesters and giving the conditions of their rice fields,because both information factors(combine harvester and field condition)impact the field capacity.The field capacity model was generated from combine harvesters with the Thai Hom Mali rice variety(KDML-105).Therefore,this study aimed to determine the prediction model for effective field capacity to combine harvesters when harvesting the Thai Hom Mali rice variety(KDML-105).The methods began by collecting data of 15 combine harvesters,such as field,crop,and machine conditions and operating times;to generate the prediction model for the KDML-105 variety.The prediction model was then validated using 12 combine harvesters that were collected similarly to the model creation.The results showed a root mean square error(RMSE)of 0.24 m^(2)/s for the model.The prediction model can be applied for farmers to select the proper combine harvesters and give their field conditions.
基金supported by the National Scientific and Technical Research Council (PIP 112-200801-01046)
文摘Biological soil crusts are widely distributed in arid and semiarid regions. They have an important eco- logical role, especially by modifying physical and chemical properties of soils. Biological crusts may also modify seed germination and seedling establishment. The effects vary widely according to the type of crust and the vas- cular plant species. The objective of this study was to determine the effect of moss-dominated biological soil crusts on the emergence, biomass and survival of Poa ligularis Nees ex Steud. under different irrigation regimes. We col- lected seeds of P. ligularis and biological soil crusts composed of two species of mosses： Syntrichia princeps （De Not.） Mitt and Ceratodon purpureus （Hedw.） Brid. from an area in the Monte of Argentina. The result showed that seedling emergence of P. ligularis was higher in treatments with bare soil than in soil covered by crusts, and also in those with watering to field capacity. Mean emergence time was higher in treatments with bare soil and watering to field capacity. Seedling biomass also showed significant differences between treatments. These results suggest that biological soil crusts dominated by mosses do not promote P. ligularis emergence, although they would not affect its survival.
基金financially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA23090403)the National Key Research and Development Program of China(Grant No.2019YFD1100503)the National Major Science and Technology Program for Water Pollution Control and Treatment(Grant No.2017ZX07101001)。
文摘Grain to Green program on arable land has been conducted for decades in semi-arid regions of North China.However,it remains uncertain how afforestation practices affect soil hydraulic properties(SHP).Two afforestation types,i.e.shrubland(SL)and woodland(WL),and the adjacent cropland(CL)were investigated to determine afforestation effects on SHP in this area.Disturbed and undisturbed soil cores were collected in three experimental sites.Soil field capacity(FC),wilting point(WP),and available water capacity(AWC)increased in SL compared to the CL.Soil saturated water content,however,decreased significantly in both SL and WL.Correlation and redundancy analysis identified that bulk density(BD)and soil organic carbon(SOC)were the main factors regulating SHP across different land uses.Lower saturated water contents in afforestation sites were likely driven by the higher BD,compared to the adjacent cropland.FC,WP,and AWC were positively correlated to SOC content.While afforestation may not increase the saturated water content of a landscape,our results indicate that it can improve soil water retention and could be an effective practice for soil and water conservation.
文摘Chickpea （Cicer arietinum L.） is a crop cultivated in semi-arid and rainfed areas of Pakistan and it experiences terminal drought stress. In this paper, the morpho-anatomical study regarding roots of chickpea was carried out to investigate the drought adaptation strategies. Twelve cultivars of chickpea were grown in pots under drought stress of 70% and 35% field capacity in addition to control （100%）. Root segments of mature chickpea plants were sectioned in 2 cm from root-shoot junction and used for making transverse sections. The development of sleeve and stele tissues and their proportion were markedly influenced by moisture availability to the root system. Roots length, flesh and dry weight, and number of secondary roots were decreased under field capacity of 70% and 35% as compared to control in 12 cultivars of chickpea. Root epidermis and cortex of CH47/04 consisted of cells with thickened walls and with 2-3 cell layers of sclerenchymatous cells below the epidermis. Increased number of medullary rays and high vascular region was observed in cultivars CH120/04, CH47/04, CH587/05 and CH87/02. Anatomical studies showed that CH47/04 was highly tolerant among 12 cultivars of chickpea, while CH587/05 and CH87/02 behaved moderately under both levels of drought stress （70% and 35% field capacity）.
基金Supported by National Natural Science Foundation of China(41161037,31371582)~~
文摘[Objective] The paper was to study and modify non-limiting water range （NLWR） of soil. [Method] The water content when total soil water potential was -0.3 MPa or soil mechanical resistance was 0.85 MPa was selected as the lower limit of NLWR to replace the original water content of permanent wilting point or the water content under soil mechanical resistance of 2.0 MPa. NLWR could be calculated us-ing the minimum value of upper limit minus the maximum value of lower limit. [Re-sult] Compared with original NLWR or least limiting water range （LLWR）, the modi-fied NLWR had more practical significance. When Db〉Db-thr, soil physical properties hindered the growth of crops, so the soil should be improved; when Db〉Db-thr, soil physical properties hindered the growth of crops, so-the soil should be improved; wtlen Db〈Db-thr, as long as the soil water content is within NLWR, soil physical properties had no effect on crop growth. NLWR at this time could be used as the basis for irrigation man- agement in farmland. [Conclusion] The study provides theoretical support and scientific basis for relevant researches about evolution rule and regulatory mechanisms of soil physical quality, relationship between soil physical quality and crop growth and yield, water-fertilizer-salt management of soil.
文摘<em>Haor</em> represents the food basket of Bangladesh and rice is the only crop grown once a year. Harvesting of rice is labor-intensive works and required migrated labor to complete the harvesting works. Mechanical intervention of rice harvesting is urgently needed to increase the productivity. The proper knowledge of economic valuation and operational necessities needs to use of combine harvesters. Research objective was selected to test the technical and economic analysis of Zoomlion rice combine harvester (which is originally developed in China) in Maisherkandi, Mithamain Upazila under Kishoregonj district. The above-mentioned areas are representing <em>haor</em> areas of Bangladesh. Based on the straight-line method, fixed cost items which are machine purchase price, shelter, tax, and insurance were calculated. During the operation of the combine harvester variable cost items such as maintenance and repair, fuel, oil, drivers and guidance were collected. The breakeven point was calculated in terms of the hectares that must be harvested yearly to cover fixed annual costs;and the payback period. Harvesting speed ranged from 1.23 - 3.20 km<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>hr<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span></span>1</sup>. The field capacity of harvester was obtained 0.15 ha<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>hr<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> and consumed fuel of up to 32 L<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span></span>1</sup>. Field sizes of less than 800 m<sup>2</sup> should be avoided for the Zoomlion combine harvester to operate the harvester machine in an efficient manner. The combine produced grains loss ranging from 1.60% - 1.91%. At an initial cost of Tk 2,000,000, owning the combine harvester becomes profitable after 20 ha of paddy field harvested at a harvesting capacity of 0.15 ha<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>hr<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span></span>1</sup>. Vibration and noise were observed in tolerable limit of the operator. The operator felt comfort to operate the machine. This machine is capable to operate in the muddy field having a water height of 4 - 8 cm. Workability of the combine harvesters depended on soil, weather, crop condition, land size and shape. The combine harvester was able to develop sufficient traction in soft soil during harvesting period in <em>haor</em> area. Zoomlion harvester is a cost-effective and time-saving machine but the initial costs are higher.
文摘In Bangladesh, the use of machinery in agriculture production is fast rising. Researchers are developing technology to replace traditional hand weeding to manage weeds in rice fields. The present study has been taken to increase weeding efficiency and reduce the drudgery in weeding and mulching. A line-to-line distance of 20 cm, the operation is push-pull, and field operating condition at 2 - 4 cm standing water (for softening the field) was the designed hypothesis. The weeder consists of a skid/float, float holder, float adjuster, main body frame, rotor, axel, bush, rotor holder, rotor holder adjuster, handle, handle griper, handle holder, handle height adjuster, nut, bolt, etc. The designed weeder was fabricated using MS sheet, MS pipe, MS flat bar, MS nut-bolt, etc. When the rotors perform back and forth, the weeder’s two conical rotors with six plain blades and six serrated blades work together to uproot and bury the weeds. It also contains a 2 mm thick float assembly with a precise angle of 22 degrees. Weeds are uprooted by the weeder’s blades and buried in the muddy soil. It causes topsoil disturbance and enhances aeration. The weeding efficiency and capacity of the conical weeder were 81.92% and 0.0203 ha/h respectively. With a push-pull operation, the weeder can uproot and bury the weeds in a single row at a time. The pushing force and weight of weeder were 43.42 N and 5.6 kg respectively. Farmers can use this weeder to increase their comfort and reduce the drudgery associated with weeding and mulching in their fields.
文摘Generally,nanotechnology plays an very important role in various applied scientific fields.Iron and magnesium nanoparticles(NPs)can cause positive or negative changes in soil physical and mechanical properties,especially in long periods.The aim of this study was to investigate the multi-year effects of NPs on soil water retention and aggregate tensile strength.A wheat farm loamy soil was amended with 1%,3%,and 5%(weight/weight)of magnesium oxide(Mg O)and iron oxide(Fe_(3)O_(4))NPs in three replications and incubated for three years.Water contents were measured at different matric suctions of 0,10,20,40,60,100,300,1000,and 15000 cm.The van Genuchten model was fitted to the moisture data.Tensile strength was measured on the 2–4 mm aggregates at matric suctions of 300(i.e.,field capacity)and 15000(i.e.,permanent wilting point)cm.The results showed that the levels of 1%and 3%Fe_(3)O_(4)NPs significantly increased water retention,compared to the no NP application control and 5%Mg O NPs,which is probably due to the increase of adsorption surfaces in the treated soils.Water contents at field capacity and permanent wilting point in the 5%Mg O NP treatment decreased compared to those of the other treatments,due to the increased soil vulnerability and reduced soil fine pores.The application of Fe_(3)O_(4)NPs did not have any significant effect on soil tensile strength.Based on the results of this study,soil physical and mechanical properties could be affected by NP application.
文摘In the present study,self-propelled cabbage/cauliflower harvester was designed,developed and evaluated.The machine consisted of different components like engine,frame,shearing(cutting)unit and power transmission unit.The power transmission unit consisted of main clutch,shearing blade operating clutch,belt drive unit,chain and sprocket drive,universal joint and cutter blade assembly.The main working principle of harvester is based on shearing of crop stem against high-speed rotating blade.The power from the engine is transmitted by belt-pulley drive unit to transmission shaft on which chain and sprocket is mounted on one side and then power is transmitted to shearing blade coupling with the help of a stationary pulley and fixed socket.Average mean head diameter of the selected cabbage and cauliflower was 89.5±15.24 mm and 107.5±15.24 mm,respectively.Average mean stem(plant)diameter of the selected cabbage and cauliflower was 18±4.85 mm and 21.5±3.08 mm,respectively.The shearing force increased with increase in diameter of stem.The optimum performance of the machine was achieved when it was operated at 1.5 km/h forward speed and the shearing blade moving at speed of 147 rpm.The mean field capacity for developed prototype was observed as 0.063 ha/h and 0.053 in case of cabbage and cauliflower,respectively with field efficiency of 91.97 and 90.48%.The average head damage was negligible(0.15%)for both the crops.The average untrimmed percentage with developed harvester was 3.2 and 3.0%in case of cabbage and cauliflower crop,respectively.The developed machine helps to increase the field capacity in cabbage/cauliflower harvesting due to 7-times more capacity and 50%cheaper compared to traditional method of cabbage/cauliflower harvesting.At the operating condition of forward speed(1.5 km/h)and shearing blade speed(147 rpm),the machine could harvest 0.5 ha of cabbage and 0.42 ha of cauliflower farm per day of 8-h.This same task would have required between 15 labour per day if entirely done manually.
文摘The use of the power tillers （walking tractors） are increasingly popular in Nigeria among farmers adopting Sawah rice production technology. This study compares the effects of two types of power tillers on physical properties of soil and rice yield. because soil properties determine to a large extents rice yield. Data on soil properties and rice yield were collected and subjected to t-test statistics. The results show that, significant differences exit for all the physical properties of soils rice yields from fields where the two power tiller were used with yields from rice field where SHAKTI was used was higher than KUBOTA. It is important that farmers using these models of power tillers for rice production should not only focus on the purchase cost of these power tillers but their overall efficiency in order to achieve the desired high level of yield.
基金This study was jointly supported by the National Key Research and Development Project of China(No.2016YFD0200303)the Natural Science Foundation of China-Shandong Joint Key Project(Nos.U 1806215 and U1906221)+1 种基金the Key Project of Chinese Academy of Sciences(No.KFZD-SW-112-03-02)the National Natural Science Foundation of China(No.41977015).
文摘Salt and sodicity of saline-alkali soil adversely affect the construction of ecological landscapes and negatively impact crop production.The reclamation potential of biochar(BC,wheat straw biochar applied at\%by weight),gypsum(G,0.4%by weight),and gypsum coupled with biochar(GBC)was examined in this laboratory-based study by evaluating their effects on a saline-alkali soil(silt loam)with no amendment as a control(CK).Saline ice and fresh water(simulated rainfall)were leached through soil columns to investigate changes in salt content,sodium adsorption ratio(SAR),alkalinity,and pH of the leachate and the soil.Results showed that saturated water content and field water capacity(FWC)significantly increased by 4.4%and 5.6%,respectively,in the BC treatment after a short incubation time.Co-application of biochar and gypsum(GBC)increased soil saturated hydraulic conductivity(Ks)by 58.4%,which was also significantly higher than the sole addition.Electrical conductivity(EC)of the leachate decreased sharply after saline ice leaching;subsequent freshwater leaching accelerated the removal of the rest of the salts,irrespective of the amendment application.However,the application of gypsum(G and GB)significantly enhanced the removal of exchangeable Na^+and reduced leachate SAR.After leaching,the soil salt content decreased significantly for all treatments.The application of gypsum resulted in a significantly lower soil pH,exchangeable sodium percentage(ESP),SAR,and alkalinity values than those recorded for the CK and BC treatments.These results demonstrated that the co-application of gypsum and biochar could improve saline-alkali soil hydraulic conductivity and decrease leaching-induced sodicity over a short period.
基金financed by the Ministry of Science and Higher Education of the Republic of Polandwithin the framework of the project“Utilization of Biomass for the Preparation of Environmentally Friendly Polymer Materials”(BIOMASA)(No.POIG 01.01.02-10123/09),partially financed by the European Union within the European Regional Development Fund。
文摘Composts are considered to be one of the best soil amendments.However,the effects of composts with added polymeric materials on soil physical,hydraulic,and micromorphological properties have not been widely discussed.Changes in soil physical properties influence the numerous services that soils provide.We studied the impacts of composts with the addition of three different polymers(F1–F3)produced from polyethylene and thermoplastic corn starch on the physical,hydraulic,and micromorphological properties of two soils,a Cambic Phaeozem and a Luvic Phaeozem.Applying composts with polymers had limited or no significant effect on soil bulk density and porosity,but increased the field water capacity by 18%–82%and 3%–6%and the plant-available water content by 15%–23%and 4%–17%for the Cambic Phaeozem and Luvic Phaeozem,respectively.The application of composts with polymers had a greater effect on the Cambic Phaeozem than on the Luvic Phaeozem.It was suggested that the use of modified composts led to changes in soil physical properties and micromorphological features and this effect was dependent on the compost application rate.Composts made with the addition of composite synthetic and natural material-derived polymers during composting were found to be a composite mixture that can be successfully used in agriculture.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51601092,51571121,and 11604148)the Fundamental Research Funds for the Central Universities,China(Grant Nos.30916011344 and 30916011345)+5 种基金the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province,Chinathe Postdoctoral Science Foundation Funded Project(Grant No.2016M591851)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20160833,20160829,and 20140035)the Qing Lan Project of Jiangsu Provincethe Priority Academic Program Development of Jiangsu Higher Education InstitutionsShanxi Scholarship Council of China(Grant No.2016-092)
文摘In this work,we tuned the magnetostructural transformation and the coupled magnetocaloric properties of Mn_(48-x)V_(x)Ni_(42)Sn_(10)(x=0,1,2,and 3)ferromagnetic shape memory alloys prepared by means of partial replacement of Mn by V.It is observed that the martensitic transformation temperatures decrease with the increase of V content.The shift of the transition temperatures to lower temperatures driven by the applied field,the metamagnetic behavior,and the thermal hysteresis indicates the first-order nature for the magnetostructural transformation.The entropy changes with a magnetic field variation of 0-5 T are 15.2,18.8,and 24.3 J.kg^(-1).K^(-1)for the x=0,1,and 2 samples,respectively.The tunable martensitic transformation temperature,enhanced field driving capacity,and large entropy change suggest that Mn_(48-x)V_(x)Ni_(42)Sn_(10)alloys have a potential for applications in magnetic cooling refrigeration.
基金supported by National Natural Science Foundation of China (Grant Nos. 11301249 and 11271175)the Applied Mathematics Enhancement Program of Linyi University (Grant No. LYDX2013BS059)Natural Sciences and Engineering Research Council of Canada (FOAPAL) (Grant No. 202979463102000)
文摘This paper is devoted to a study of L^q-tracing of the fractional temperature field u(t, x)—the weak solution of the fractional heat equation(?_t +(-?_x)~α)u(t, x) = g(t, x) in L^p(R_+^(1+n)) subject to the initial temperature u(0, x) = f(x) in L^p(R^n).
基金Thanks for the financial support from The National Maize Industry Technology R&D CenterMechanized corn(CARS-02)production system optimization technology and equipment research demonstration projects(200903059).
文摘Standard Disk Plough(SDP)is the integral element of traditional farming system in Middle and Northern Sudan.In SDP,the tilt angle between the planes of the cutting edge of the disk which is inclined to a vertical line may be altered according to the field conditions.Tractor drivers usually use an angle close to maximum in order to decrease the tillage depth,consequently decreasing power requirements,without considering the tillage quality and the impact on the soil properties.This experiment was conducted at the College of Agricultural Studies farm of Sudan University of Science and Technology to study the effects of three tilt angles(15°,20°and 25°)on soil bulk density,mean weight diameter,wheel slippage,work rate(or effective field capacity)and soil volume disturbed using mounted disk plough.The nature of soil on the farm found to be light clay.The theoretical forward speed was maintained at 6 km/h.The results showed that increasing tilt angle of the plough significantly(p<0.05)increased the bulk density,mean weight diameter and field capacity while significantly decreasing the tractor wheel slippage and soil volume disturbance.
文摘Background and aims:Since few studies have existed in the literature about the effect of zinc(Zn)on cadmium(Cd)chemical forms in soils.Therefore,this study has been performed to determine the impact of Zn on cadmium Cd chemical forms in two soil textural classes in Fars province-Iran at two soil water content(SWC)(flooded soil water content(FSWC)and field capacity soil water content(FCSWC))and study the kinetic modeling of Cd.Methods and materials:Variables were three levels of Cd(0,30 and 60 mg kg-1 of soil as CdSO4·8H2O),three levels of Zn(0,5 and 10 mg kg-1 of soil as Zn-EDTA)three level Incubation times(2,4 and eight weeks),two soil textural classes(clay and sandy clay loam)and two SWC.The randomized completed block design(RCBD)was used for this experiment.The Tessier sequential extraction method was used to determine the Cd concentration in(WsEx),(Fe-MnOx),(Car),(Om)and(Res)chemical forms.Results:In the FSWC,Zn reduced the Cd concentration in Fe-MnOx,Car and Om forms and increased the WsEx but had no significant effect on the Res form.Changes in the Cd chemical forms under the in-fluence of Zn in both soils followed a similar trend.In the FCSWC,Zn reduced the Cd concentration Car and Om forms and increased the Cd concentration in the Fe-MnOx and WsEx forms while had no sig-nificant effect on Res form in the sandy clay loam soil.In the clay soil adding Zn reduced the Cd con-centration in Car and Om fractions and increased the Fe-MnOx and Res forms while has no significant effect on WsEx form.The competitive transport and adsorption Interactions between these two ions caused the changing in the Cd concentration in its chemical forms.Zn reduces the Cd concentration in the forms which are easily released into the soil solution from where they can be absorbed by plants.The power function kinetic mode is the best fitted model which can describe the Cd adsorption in our soil samples.The clay and organic compounds control the Cd adsorption in soils.The higher rate of Cd adsorption in almost all shaking times shows that Cd has more ability to occupy the adsorption sites in soils.
基金This study was financed by the National Basic Program of China(Grant no.2007CB407204)the National Natural Science Foundation of China(Grant no.40471082)Thanks are given to the members of project team for field assistance,and also to Dr.David Cushley for language revision.
文摘Estimation of soil water content(SWC)in deep soil profiles is of crucial importance for strategic management of water resource for sustainable land use in arid and semi-arid zones,as well as for soil and water conservation.Soil properties have a very important effect on SWC.This study aimed to analyze the influence of soil particle size on SWC,for the first time using soil particle size to estimate SWC in deep soil profiles.SWC was measured mainly in farmland,natural grasslands and plantations of Caragana from the surface to more than 20 m depth.The same soil samples were also tested for particle size.The results show that the soil desiccation is formed in the caragana forest in 3–18 m soil layers,but almost no formation in 18–24 m layers;water content of farmland and grassland is different in all soil profiles although they are both shallow rooted plants.Correlation analysis indicated that SWC could be well predicted by clay content and the close correlation between SWC and clay content yielded a coefficient of determination(R^(2))of 0.82 and 0.72,respectively,for farmland and grassland.After multiple regression analysis,a regression model was built using SWC,clay content and sand content data,giving R^(2)=0.66.The model provided reliable estimates of SWC profile based on textural class.This can assist in estimating water depletion by vegetation,by comparing moisture of farmland and grassland soils with that of plantation forests,and in selecting sustainable land use of arid land.
