Effect Of Utilization Patterns Of Multiple Cropping Green Manure After Wheat Harvest On Nitrogen Use Characteristics Of Rotation Maize

The great issues facing are long-term continuous cropping of wheat and maize and lower N fertilizer use efficiency.Investigation on the effects of different green manure retention practices on nitrogen use characteristics of rotation maize is of significant importance.In the Shiyang river basin,a field experiment was conducted to determine the effects of different green manure retention practices on nitrogen use characteristics of subsequent maize in a wheat-green manure-maize rotation system.Green manure retention practices consisted of i)Tillage with full quantity of green manure incorporated in the soil,ii)No-tillage with full quantity of green manure mulched on soil surface,iii)Tillage with root incorporated in the soil and with above ground green manure removed;iv)No-tillage with above ground green manure removed,and vi)Conventional tillage without green manure.Through the field experiment,investigate the response of soil nitrogen utilization during the growth period of maize to different green manure retention practices,Clarify the effect and mechanism of soil nitrogen loss under different green manure retention practices,in order to reveal the effect of green manure retention practices to maize nitrogen utilization characteristics and maize yield formation;Explore effective ways to further achieve high yield of maize and efficient use of nitrogen under the wheat-maize rotation system.The main results of this study are as follows:1.Full quantity of green manure mulched on soil surface and employing no-till and full quantity of green manure incorporated in the soil achieves high yield of maize.The average maize grain yield reached 14274.9 kg·hm^-2 and 15002.2 kg·hm^-2,which was 18.2%and 20.4%higher than that conventional tillage without green manure.This is mainly due to the fact that the number of ears,seed number of per ear and seed weight of maize of no-tillage with full quantity of green manure mulched on soil surface were higher than that of conventional tillage without green manure treament of root utilization patterns.Meanwhile,tillage with full quantity of green manure incorporated in the soil and no-tillage full quantity of green manure mulched on soil surface can significantly increase maize leaf area index.It guarantees the function of photosynthetic in the later growing stage of maize and lays the foundation for high yield of maize.2.Full quantity of green manure incorporated in the soil and full quantity of green manure mulched on soil surface with no-tillage facilitated nitrogen high and efficient use of maize,the N use efficiency and N partial productivity were increased by 17.3%,22.2%,This is mainly due to the fact that the full quantity of green manure incorporated to the field can effectively prevent nitrogen gas loss,and provide a nutrient basis for maize growth and development.The two treatment also significantly increased above-ground nitrogen accumulation both in plants and in grains and were significantly higher than that of the treatment with green manure roots retuned only,And effectively promote nitrogen transfer to vegetative organs.3.Green manure incorporated to soil has an blocking effect on the loss of soil nitrogen,which laid a good foundation for the improvement of farmland nutrients and the efficient use of maize nitrogen.Compared with the green manure root retention practices and conventional tillage without green manure,full quantity of green manure incorporated in the soil increased the volatilization rate and amount of soil ammonia after maize base fertilizer and top dressing.During the period of basic fertilizer,Full quantity of green manure mulched on soil surface and employing no-till and full quantity of green manure incorporated in the soil were 24.2%and24.1%higher than that of the conventional tillage without green manure treatment,after top dressing at the big trumpet stage,it was 60.7%and 69.4%higher than that of the non-multi-planting green manure,and it was 46.1%and 55.9%higher than that of the conventional tillage without green manure treatment.This is because after the green manure is put into the farmland,on the one hand,it increases the inorganic nitrogen content of the soil and increases the ammonia volatilization potential;On the other hand,full quantity of green manure incorporated in the soil increased the soil urease activity and soil water content associated with nitrogen conversion.Compared with the green manure stubble retention practices and conventional tillage without green manure,full quantity of green manure incorporated in the soil can effectively reduce the N₂O emissions during the whole growth period of maize.Full quantity of green manure mulched on soil surface and employing no-till and full quantity of green manure incorporated in the soil were 16.8%and 17.4%higher than that of the conventional tillage without green manure treatment.Correlation analysis shows that N₂O emissions are significantly positively correlated with the activities of nitrate reductase and nitrite reductase related to denitrification,Studies have shown that the full quantity of green manure incorporated in the soil reduces the activity of nitrate reductase and nitrite reductase.4.Full quantity of green manure incorporated in the soil effectively increased the nitrogen content of different forms of soil during the growth period of the rotation maize.Compared with the green manure root retention practices and conventional tillage without green manure,full quantity of green manure mulched on soil surface and employing no-till and full quantity of green manure incorporated in the soil increased the total nitrogen content during the whole growth period by 8.0%and 6.7%,the nitrate nitrogen content was increased by 3.8%and 5.9%,and the ammonium nitrogen content increases by 18.3%?15.9%,the microbial biomass nitrogen content increases by 21.2%?19.6%,and a large amount of nitrogen is concentrated in the 0-30 cm tillage layer,which can ensure the effective supply of maize nutrients.This study explored the effects of utilization patterns of multiple cropping green manure after wheat harvest on nitrogen use characteristics of later-cropping maize.The response of nitrogen absorption and utilization of main crops to the introduction of legume green manure into wheat-maize rotation system was revealed.Under the condition of full quantity of green manure incorporated in the farmland in full bloom period,full quantity of green manure mulched on soil surface and employing no-till and full quantity of green manure incorporated in the soil achieves high yield of maize while increasing soil nitrogen content,Inhibitting nitrogen loss,and facilitate high nitrogen efficient use of maize.Therefore,it can be used as one of the high yield and efficient planting models for optimizing the wheat-maize rotation system in the oasis irrigation area.