Effects Of Consecutive Straw Returned To Soil On Soil Fertility And Wheat Yield Formation From Wheat-cotton Rotation System

Wheat-cotton rotation system is an important planting systems in China’s Yangtze River and Yellow River Basin.Potassium fertilizer is of great significance to wheat yield,high yield and quality improvement.China is the lack of potassium resources,potash mainly rely on imports,farmers use potassium potency is low.The potash reserves of China are penurious.Subsequently,China imports a large quantity of K fertilizers every year.Farmers are not active to adding potassium fertilizer with high price.As an important renewable resource,straw contains abundant potassium which can replenish soil potassium.In production,the yield of wheat straw and cotton residue is 9000 and 7500 kg ha-1 in Yangtze River Valley,respectively.Therefore,application rates of wheat straw in cotton season were designated as 0,4500 and 9000 kg·hm-2(W0,W4500,W9000),and those of cotton residue in wheat season were designated as 0,3750 and 7500 kg·hm-2(CO,C3750,C7500).Finally,there were nine crop residue incorporation treatments without organic K fertilizer applied in the wheat-cotton rotation system,by the processes of independent assortment of wheat straw and cotton residue.Additionally,two independent K fertilizer treatments without crop residue incorporation were designated as 150 and 300 kg K2O hm-2(K150 and K300).The experimental study 2014-2015 and In the two growing seasons,the effects of single season,two season,half and total amount of continuous straw on the yield and quality of wheat were compared under the normal application of nitrogen and phosphorus fertilizer,and compared with the treatment of potassium fertilizer.The main results were as follows:1 Effects of Consecutive Straw Returned to Soil on Yield and Quality of Wheat from Wheat-Cotton Rotation SystemThe results showed that compared with the control without straw and potassium fertilizer,the two successive straws increased significantly the number of grains per hectare and the yield was increased.The effect of total straw growth was more than half the amount of field,and the two seasons were more than one season but also lower than potassium treatment.The effect of straw production in Nanjing is greater than that of Dafeng,and the year of straw returning interaction between with the straw significantly influence the formation of wheat yield and spike number.The results showed that wheat yield of total amount of straw returned to soil and K150 and K300 increased by 40.1%,36.0%,55.2%and 56.7%,55.6%and 61.2%respectively in 2015 and 2016 at Nanjing,respectively.The wheat yield of total amount of straw returned to soil and K150 and K300 increased by 30.5%,27.3%,25.4%and 30.8%,31.7%and 37.7%respectively in 2015 and 2016,Straw returned to soil also affected the quality of wheat flour,and the content of flour protein and sedimentation increased significantly with the increase of straw returning rate,while the effect of straw returning and potassium treatment had no significant effect on flour yield and wet gluten content.2 Effects of Consecutive Straw Returned to Soil on Accumulation and Distribution of Wheat Biomass from Wheat-Cotton Rotation SystemThe results showed that the biomass and biomass accumulation of wheat were significantly increased with the increase of straw returning rate,and the results were the same.The difference between treatments is less than that of Nanjing.Compared with no straw,straw returning to soil and potassium significantly increased the contribution rate of biomass to the grain after anthesis,and the contribution rate of Dafeng pilot was slightly lower than that of Nanjing.There was no significant effect of straw returning and potassium on the distribution of biomass in wheat at maturity.3 Effects of Consecutive Straw Returned to Soil on Soil fertility and wheat nutrient uptake from Wheat-Cotton Rotation SystemThe results showed that the soil bulk density and soil water content were significantly decreased by straw returning and applying potassium to the control without straw and potash fertilizer,and the difference was more obvious with the increase of the years.In the aspect of soil nutrient content,the content of available potassium in the soil was significantly lower than that in the case of no straw and potash fertilizer.However,the content of soil available potassium in the whole field of straw was close to that of potassium fertilizer,and the soil.The effect of straw returning to potash on soil total nitrogen and available potassium was not significant.Compared with the control without straw and potassium fertilizer,straw returning significantly increased the uptake of nitrogen,phosphorus and potassium by wheat straw and grain.Therefore,based on the yield of wheat,consecutive straw returned to soil in the wheat-cotton rotation system to replace inorganic K fertilizer could be substituted or partially replaced in two soil types.In addition,soil fertility were improved by changing the soil physical properties and soil nitrogen,phosphorus and potassium content.