Effects Of Straw Returning On Crop Yield Formation And Synergistic Utilization Of Straw And Soil Nutrients In Multi-cropping System

The efficient use of straw and nutrients is an important factor in achieving sustainable development under the multi-planting model.Elucidation the characteristics of crop nutrition and straw nutrition release,detection synergistic utilization of straw and soil nutrition would have great significance in keep soil nutrition balance,increase crop grain yield and improve rice quality.In this study,field and pot experiences was used to investigate the effects of tillage mode?tillage with straw incorporation T1;tillage with straw mulchT2;no-tillage with straw mulch T3?and straw returning methods on crop yield formation and synergistic utilization of straw and soil nutrient.The main results are as follows:1.Effects of straw returning on crop growthThe result indicated that straw returning was obviously inhibited the dry matter accumulation and root growth around 20 to 30 days after transplanting,but significantly increased in following growth periods.However,the level and the duration were determined by the tillage mode and straw incorporation method and straw type.Under T1,Wheat and rapeseed straw would inhibit the growth of rice root and shoot,but significantly promote root growth and dry matter accumulation in heading stage to maturity stage,as severe soil solidification and the harmful substance aggression in the early growth period.Nevertheless,wheat straw had longer and more intense inhibition duration,and the promotion of growth in later stage cannot offset the previous inhibition,so performed as great decreasing in final dry matter accumulation,while rapeseed straw treatment was slight increase.However,wheat and rapeseed straw mulch under T1 and T2 had less inhibitory effect on rice dry matter accumulation and root growth,thus shows significantly increase dry matter accumulation.Therefore,straw incorporation under T1 shown higher improve on non-rice crop dry matter accumulation.2.Effects of straw returning on grain yield and componentsThe result shown that wheat straw under T1 was significantly reduce the number effective panicles of rice,thus decrease grain yield.However,the inhibition of effective panicle number was significantly reduce or contrary performed as promoting in the following years with straw incorporation.With pot experimental condition,wheat straw under T1 was obviously improve number of effective panicle and increase grain yield,and significantly decrease the gap with field experimental condition in second year.Nevertheless,rapeseed straw under T1 would promote the effective panicles of rice,thereby increasing rice yield.Straw mulch under tillage and no-tillage significantly promoted the effective panicle number and grain number,thereby increased grain yield.Furthermore,wheat straw mulch was higher than rapeseed straw under T2 on rice grain yield,while rapeseed straw mulch was much higher under T3.However,with decrease in rice season,the increase in non-rice season.Correlation analysis showed that there was a significant correlation between rice root morphology and distribution and rice yield and its components.There is a good quadratic fitting equation for straw nutrents release and rice yield and its components factors.3.Effects of straw returning on rice qualityThe results shown that straw mulch significantly promoted the percentage of chalky and chalkiness degree,decreased the amylose and gel.consistency contain on high-nitrogen efficiency variety rice.However,significantly decrease he percentage of chalky and chalkiness degree on low-nitrogen efficiency variety.Wheat and rapeseed straw mulch obviously improved brown and heading rice,increased gle.consistency and protein content,and decrease the percentage of chalky and chalkiness degree in each tillage mode.However,wheat straw incorporation under T1 was obviously promoted the percentage of chalky and chalkiness degree in first year,thereby significantly decreased in the second year,on the contrary,rapeseed straw incorporation under T1 was obviously decreased the percentage of chalky and chalkiness degree in first year,but significantly promoted in the second year.Nevertheless,wheat and rapeseed straw incorporation were significantly improved brown and heading rice,increased gle.consistency and protein content.Furthermore,with comprehensive comparison,rapeseed straw incorporation under T1 and straw mulch under T3 shown great advance on rice quality.Correlation analysis showed that there was a significant correlation between rice root morphology and rice quality.4.Effects of straw mulch on crop nutrition accumulationThe results shown that wheat and rapeseed straw had significant effects on the total nitrogen,phosphorus and potassium accumulation in rice and non-rice crops.However,the straw returning had significant effects on the nutrient uptake of rice in different periods under various tillage patterns and incorporation methods.On nitrogen uptakes aspect,straw mulch as if performed great inhibition in 0-20days after transplanting,then so as in 30days after transplanting to heading stage,and in other growth stage performed obviously promoting at the first and second rice season.However,it just performed inhibition in 20-30days after transplanting,the other growth stage shown great promoting at the third rice season.On phosphorus and potassium absorption,the straw returning treatments all performed significantly inhibited the absorption of phosphorus and potassium in 0-20 days after rice transplanting at the first year,and all performed significantly inhibited the absorption of phosphorus and potassium in 20-30days after rice transplanting at the second year.Then shown great promoting or slightly inhibition on early rice growth periods in the following rice season,but in the subsequent growth period,it showed obvious promotion.Under the rice season,the nitrogen accumulation of wheat incorporation treatments were significantly higher than that of rapeseed incorporation treatments,while the accumulation of phosphorus and potassium of rapeseed was the highest.5.Effects of straw returning on soil nutrition balanceThe results shown that compare to no straw incorporation,wheat and rapeseed straw mulch were generally and significantly improved soil available nitrogen,available phosphorus and available potassium in each period.Rapeseed straw under T1 was significantly reduced the available nitrogen stratification rate of soil,while the wheat straw was significantly increased.Wheat and rapeseed straw incorporation under T1were significantly increased the stratification rate of available phosphorus after non-rice harvest,but significantly decreased in rice season,wheat and rapeseed straw incorporation treatments were increased the stratification ratio of potassium in each crop growth stage.However,wheat and rapeseed straw mulch T1and T2 were generally increased the stratification of available nitrogen,available phosphorus and available potassium.Furthermore,under our fertilization conditions,the rice-wheat/oil planting model caused losses to soil of available nitrogen and potassium,and showed a significant surplus for soil potassium.The soil nutrient loss mainly produced in non-rice season.However,with the continued of straw returning,the soil nutrition of straw returning treatments has gradually reduced the loss in each quarter.At the same time,no straw returning treatments in the non-rice season,the soil of available phosphorus,available potassium and available nitrogen would run off due to the leaching of rainwater.The quadratic equation fitting of soil nutrient and crop nutrient accumulation showed that the soil nutrient in non-rice season and the nutrient uptake of rice in the early growth stage,and the nutrient uptake of soil nutrients and non-rice crops at maturity stage had a good fit,while straw Returning nutrient release has a good quadratic equation for non-rice soil nutrient content.6.Effects of straw returning on straw decomposition and nutrition releasethe result shown that the rice varieties had no obvious effects on the total amount of decomposition,nitrogen,phosphorus and potassium released and the release of potassium in each period,but significantly reduced the amount of straw decomposition and nitrogen and phosphorus release in each growth period.Straw mulching can significantly accelerate the decomposition of wheat straw and the release of nitrogen and phosphorus.However,wheat straw under T1 the decomposition of wheat straw and the release rate of nitrogen and phosphorus had obviously slowed down in first year of straw incorporation,but had increase in the years.While rapeseed straw incorporation under T1,the decomposition and nitrogen and phosphorus release was generally accelerated.However,the tillage mode and incorporation method had no significant difference in potassium release.At the same time,with the continuous of straw returning,the gap of straw decomposing and nutrient release under the tillage mode and straw incorporation method gradually reduced.7.Effects of straw returning on nitrogen fate of non-rice season appliedThe ¹⁵N tracer study results showed that straw incorporation under T1 promoted nitrogen uptake in non-rice crops and reduce nitrogen residues in the soil,but straw mulching could keep the nitrogen of non-rice season applied and increase the absorption of rice in the next crop season.Meanwhile,the returning of straw in rice seasonal can interception the residual nitrogen of non-rice season applied,and promote the adsorption of rice,thus promoting the absorption and utilization of nitrogen by crops.Straw mulching treatments could significantly increase the straw nitrogen release and promote the nitrogen uptake and utilization of rice.Furthermore,rapeseed straw treatments was higher than that of wheat straw on nitrogen uptake and utilization ratio of straw release in each tillage mode and incorporation method.Nevertheless,31.23%-77.22%nitrogen of straw releases had remaining in the soil.The stratification rate of straw nitrogen in soil at the heading stage little gap among each treatments,but at the maturity stage,the stratification rate of straw mulching was significantly reduced,while the stratification rate of straw mulching treatment was significantly increased.8.effects of straw returning on nitrogen fate of rice season appliedThe ¹⁵N tracer study results showed that straw incorporation under T1 had a slight inhibitory effect on nitrogen uptakes of base and tiller fertilizer applied at 20 days after transplanting,and showed significant inhibition at 30 days after transplanting.However,it performed significantly promotion in following growth periods.While straw mulch under T2 significantly inhibited the nitrogen absorption of rice in 20-30d after transplanting period.Moreover,wheat straw mulch under T3 showed significant inhibition of nitrogen uptake before 30 days after transplanting,but significantly promoted in the subsequent growth stages.While rapeseed straw under T3 had significant promotion in all periods.At the same time,the straw also intercepted some nitrogen of application,about 31.48%-45.68%applied nitrogen was absorbed by the rice,and 23.58%-38.02%was left in the soil,and 1.15%-2.56%of the applied nitrogen was intercepted by the returning straw.Straw incorporation under T1 and T2 had significantly increased the nitrogen stratification rate in soil of base and tiller stage applied.While straw mulch under T3 significantly reduced the nitrogen stratification rate of basal and tiller stage applied.However,straw incorporation under T1significantly improved the nitrogen stratification rate in sol of panicle fertilizer,while straw mulch under T2 and T3 significantly reduced,especially the wheat straw mulch.It indicated that under the straw incorporation,the straw could intercept the nitrogen of applied fertilizer in non-rice and rice seasons,as a medium to improve crop absorb and utilize.Nevertheless,the straw decomposition and nutrition runs through the whole crop growth season.Otherwise,most of the straw nitrogen was remained in the soil,and intercepted by the next returning straw and absorbed by next crop season.Therefore,the straw returning performed that the nutrient uptake of the crop and the soil profit and loss tend to balance with the continuation of straw incorporation.