| The application of crop straw improves the physical structure of soil and increases the soil nutrient,obviously,has positive yield effect on agricultural production.It remains unclear,however,if the application of crop straw has a common effect of yield among different agricultural systems in China.Meta-analysis is a scientific method of quantitative review,which could quantitatively analyze the comprehensive effect of straw return on crop yield nationwide.Therefore,basing on the scientific theory of meta-analysis,we collected and sorted out the Chinese published literatures in the past 30 years(a total pf 274 piece of literature and 1930 pairs data until December 31,2019),quantifying the effect of crop yield,especially of wheat,maize and rice yield,under the straw return;furthermore,determining effect of straw return by the influence of different area,soil,tillage and fertilizer and so on.It is of great significance to the popularization and application of straw returning technology in the whole country and provides theoretical basis for the popularization of straw returning in accordance with local conditions.The main findings are as follows:1.The application of crop straw significantly increased crop yield,average increasing rate was 8.06%,with a 95% confidence interval [7.52%~8.60%].As for wheat,maize and rice,the yield increased 5.72%(95% confidence interval: 4.96% to 6.49%),9.22%(95% confidence interval: 8.30% to 10.15%)and 7.51%(95% confidence interval: 6.80% to 8.21%),respectively,under straw returning conditions.According to funnel plot test and calculation of fail-safe number,these results have no publication bias.2.Above all,the positive yield effect of straw return was significantly affected by soil type,soil pH,plant system,tillage method,fertilization,experiment years,return duration and other factors(the heterogeneity test results reached an extremely significant level).The average annual precipitation,soil types,tillage method,fertilization and expriment years significantly influenced the positive yield effect of straw return on wheat.Soil type,fertilization,returnduration and return method significantly influenced the positive yield effect of straw return on maize.The average annual temperature,soil types,soil pH,plant systems,straw type and fertilization significantly influenced the positive yield effect of straw return on rice.3.In the different tillage method,the increasing rate of yield on crop was the highest about11.05% and 8.98%,under tillage and no-till method,respectively.No-till was the best method for wheat,which improved 11.93% of yield.And for maize and rice,tillage produced the best yield effect of straw return.In the different management of fertilizer,the increasing rate of straw return with no fertilization was 25.66% for the total crops,25.70% for wheat,23.04%for maize and 30.90% for rice,which was significantly higher than the other modes.It indicated that the crop straw has a huge potential on the replacement of nitrogen.In the other agricultural management,feces return method improved the increasing rate of yield on wheat and maize;by mulching film and adding straw inoculant,the yield effect of straw return on maize and rice was further enhanced.In addition,the most suitable amount of straw return was 50~100% of ex-crop straw,long term application of crop straw has the better effect.The long-time application of crop straw,combining with no-till or deep tillage,normally fertilization,suitable amount of crop straw,could maintain a continuous positive effect of crop yield in different agricultural regions. |
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