Effect Of Straw Incorporation On The Yield Of Rice And Wheat And The Greenhouse Gas Emission In Field

Straw residue of rice,wheat or maize is a by-product,but it contains organic carbon,nitrogen(N),phosphorus(P),potassium(K)and other mineral nutrients.The straw residue is usually burn,which not only wastes resources,but also pollutes the environment.At present,straw incorporation into field is being widely used.Although there are studies on the effect of straw incorporation on crop yields and greenhouse gas emissions in the field,little information is available about the effect of maize straw incorporation on rice yield and the effect of annual incorporation of wheat and rice straw residues on the crop yields and greenhouse gas emissions.In this study,two experiments,maize straw incorporation and annual incorporation of wheat and rice straws,were conducted.In the experiment of maize straw incorporation,a japonica hybrid rice cultivar Yongyou 2640 was field-grown with maize straw incorporation(JG),taking no maize straw incorporation as control(CK),and two N levels,either no N(ON)or 300 kg N/ha(300N)was applied.In the experiment of annual incorporation of wheat and rice straws,two wheat cultivars,Yangmai 16 and Yandmai 20,and two rice cultivars,Yongyou 2640 and Huaidao 5,were used with four treatments:(1)neither wheat straw nor rice straw was incorporated(CK);(2)only wheat straw was incorporated before rice transplanting;(3)only rice straw was incorporated before wheat sowing;and(4)both wheat and rice straws were incorporated into field.The effect of maize straw incorporation on rice yield and greenhouse gas emissions and the effect of annual incorporation of wheat and rice straws on yields of rice and wheat,plant physiological traits,nutrient absorption and utilization,greenhouse gas emissions,and soil properties were investigated.The main results are as follows:1.At the ON or 300N condition,maize straw incorporation significantly increased the grain yield of Yongyou 2640 by 11.45%to 13.79%when compared with control(CK).Annual incorporation of wheat and rice straws significantly increased the yields of both rice and wheat,with the increase of 9.26%to 11.64%.Both maize straw incorporation and annual incorporation of wheat and rice straws increased leaf chlorophyll content(SPAD value)and photosynthetic rate,root oxidation activity,root bleeding,and root total absorption area and active absorption area.2.Both maize straw incorporation and annual incorporation of wheat and rice straws increased dry matter production and the absorption,accumulation and partial productivity of N,P and K of rice and wheat.3.Compared with control,both maize straw incorporation and annual incorporation of wheat and rice straws increased greenhouse gas emissions and global warm potential(GWP).These increases were more for straw incorporation in two seasons than that in one season.4.Straw incorporation increased soil respiration,soil redox potential and the content of N,P and K in soil,and increased the content of amino acids in wheat kernels when compared with the control.