| Effects of soil physical quality(S)on cotton yield and nutrient economic utilization were studied in this work.Results showed that soil physical quality is closely related to cotton yield and its components.The cotton yield,the harvest density,the number of effective bolls per plant and the weight of the single boll increase with the increase of S.The linear equation between seed cotton yield(Y)and S is as follows:Y=72980S+2996.8(R2=0.8991,P<0.01).he classification standard of soil physical quality based on S is as follows:S≥ 0.05,very good;0.035≤S<0.05,good;0.020≤S<0.035,poor;S<0.020,very poor.According to relationship between cotton yield and S,the yield of seed cotton increases 1094.7kg hm-2for every 0.015 increase of S.Therefore,soil physical quality(S)is one of the important factors affecting cotton yield.The effect of soil physical quality(S)on cotton yield was further reflected in its effect on cotton yield components.The results of this work showed that the harvest density,effective boll number per plant and boll weight per plant increased by 8600 hm-2,0.72 and 0.16 g for each grade of soil physical quality(S increased by 0.015).Therefore,improving soil physical quality is helpful to improve cotton yield.The reason why the improvement of soil physical quality(S)can improve cotton yield and its constituent elements is that the increase of S can improve the absorption of nutrients and the efficiency of economic utilization.The relationship equations between nitrogen(N),phosphorus(P2O5)and potassium(K2O)in cotton and soil physical quality(S)was N=2747.3S+167.39(R2=0.8892,P<0.01),P2O5=1042.25+61.644(R2=0.8991,P<0.01)and K2O=3067.8S+165.8(R2=0.8994,P<0.01),respectively.Relationship between Economic Utilization ratio of nitrogen(N),phosphorus(P2O5),potassium(K2O)in Cotton and S was Y=59.239S+18.917(R2=0.8986,P<0.01),Y=148.435+51.19I(R2=0.8727.P<0.01),and r=40.637S+18.844(R2=0.8727,P<0.01),respectively.The relationship between soil physical quality parameter(S)and no-limiting water range(NLWR)was analyzed.The results showed that there was a significant correlation between S and NLWR.The relationship is NLWR=0.05581n(S)+0.2766(R2=0.9761,P<0.01)The NLWR represents the water range that does not produce mechanical resistance,water stress and ventilation stress to the growth and yield of the crop.Therefor,it can affect the yield of the cotton and its constituent elements,and affect the nutrient uptake and the economic efficiency of the nutrient.The results of this study showed that with the rising of NLWR,the yield of cotton,the harvest density,the number of effective bolls per plant,the weight of single boll,the nutrient absorption of nitrogen and phosphorus,and the economic utilization rate are increasing.If the soil physical property of is increase by 1 grade,the cotton yield will be increased by 876.15 kg hm-2,harvest density increased by 7000 plant hm-2,effective bolls per plant increased by 0.6,boll weight increased by 0.1 g,nitrogen,phosphorus and potassium uptake increased by 33.0 kg hm-2,12.5 kg hm-2,36.8 kg hm-2,.Economic utilization rate of nitrogen,phosphorus and potassium increased by 0.72 kg kg-1,1.8 kg kg-1,0.53 kg kg-1,respectivelyThe influence mechanism of soil physical quality(S)on cotton yield was different.S<0.020,the production reduction factor is the mechanical resistance,the water stress and the ventilation are insufficient;0.020<S<0.0350,the production reduction factor is the mechanical resistance and the water stress;when the 0.035<S<0.050,the yield restriction factor is the mechanical resistance;and S>0.05,the physical property has no effect on the yield of the cottonFurther analysis of the relationship between S and NLWR can explain the physical meaning of each classification standard of S.Results showed that:soil water content(w)of capillary rupture(wRC)at S=0.050 is equal to w of field capacity(wFC)at S=0.035;volumetric soil water content(0)at air-filled porosity equal 10%(θAFP)is equal to 0 at field capacity(θFC)at S=0.035 These results showed that classification of S:0.05≥S>0.035,soil physical quality is very good;0.05≥S>0.035,soil physical quality is good;0.035≥S>0.02,soil physical quality is poor;0.02≥S,soil physical quality is very poor;has special physical propertiesAccording to the analysis of the relationship between S and soil bulk density,the problem of deterioration of soil physical quality may exist in drip irrigation cotton field under mulch film,especially in the practice of production in southern Xinjiang,after the cotton field began to irrigate,it is often irrigated once in 6-7 days.Combined with the local transpiration and evaporation,when S<0.035,there may be insufficient water supply in soil about 3-4 days after irrigation,and the cotton is subjected to water stress and mechanical resistance stress,which leads to the reduction of cotton yieldIn practice,according to irrigation cycle,climate,law of farmland water consumption and physical properties of soil,when the water supply provided by no-limiting water range in plough layer soil is less than that in irrigation cycle,the water consumption of farmland in irrigation cycle is lower than that in irrigation cycle.Soil physical properties have a negative impact on crop growth,so it is necessary to improve soil physical properties,in order to reduce soil bulk density and increase soil S.Finally,water from NLWR of the plough layer soil is greater than or equal to the farmland water consumption in irrigation period. |
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