Effect Of Straw-return Coupled With Different Nitrogen Fertilizers On Crop And Soil Properties

In China, straw-return is a main and popular way for dealing with straw under the concept of circular economy. With the popularization and development of straw-return techniques, straw-return with nitrogen (N) fertilization became the new trend of such practices. In this study, field experiments were conducted to investigate the influence of different treatments of straw-return coupled with N fertilization on grain yield, typical factors of crop yield components, nutrient uptake processes, soil available nutrients and biological characteristics in the Huang-Huai-Hai Plain. Main conclusions were drawn as follows:1. Straw-return greatly increased wheat yield under the same condition of N fertilization, but the difference between treatments with or without straw-return was not significant. Compared with no N fertilization, the increase in wheat yield with chemical fertilization mainly due to the increase in wheat panicles per unit area, but there was no significant difference between these grain yields. Overall, straw-return could enhance the yield by a rate of 6.34%-12.17%. In addition, straw-return obviously improved the crop uptake of N, phosphorus (P) and potassium (K) during the growth of winter wheat.2. Straw-return with N fertilization increased the content of soil alkali-hydro N and available K, and increased the soil urease activity and the soil nitrate content, especially in the depth of 0-80cm, and reduced nitrate concentration in the depth of 80-180cm, which provides the fertility basis for crop nutrient uptake. In addition, straw-return reduced soil available P content, and also demonstrated the trend of reducing the soil microbial biomass N.3. In no fertilization conditions, straw-return significantly increased summer corn yield. In straw-return conditions, the summer corn grain yield increased under the the application of organic-inorganic fertilizer, in comparison with the application of chemical fertilizers, but the difference did not achieve a significant level. Organic fertilizer application improved corn grain numbers, but it did not impact 100 kernel weight of summer corn. The crop N use efficiency in organic fertilizer treatments was significantly higher than that in the chemical fertilizer treatments by a rate of 12.6-21.7%. Meanwhile, N fertilization increased the crop uptake of N, P and K, especially at the late period of crop growth.4. In the straw-return conditions, the organic-inorganic fertilizer, comparing with the chemical fertilizer obviously increased the content of soil available nutrients as N, P, K, during the period of the middle and late summer maize growth. Meanwhile, the organic-inorganic fertilizer obviously increased the soil microbial biomass N and urease activity in the milk stage of summer corn, and improved the transformation of inorganic N to its organic species, which provided ample fertility basis for the key period of summer corn yield formation. Besides, in the straw-return conditions, the organic-inorganic fertilizer can promote the crop absorption of soil NO3-N and reduce its translocation and accumulation in the deeper soil layers, which reduced the nitrate leaching and thus lessen environmental pollution.