Effect Of Optimized Nutrient Management On Effective Nitrogen Use In Maize Cropping System

Excessive and unreasonable fertilization resulted in low nitrogen (N) use efficiency and negativeenvironmental effect in the intensive maize cropping system. The synchronization of soil N supplyand crop N demand with the optimum N rate and N application methods was important to increaseyield, reduce N loss and maintain agricultural sustainablity. This study employed an ecologicalintensification nutrient management system (EI) combined with optimized N rate based onNutrient-Expert recommended systems and optimized field management practices. A field experimentwas carried out to study the effect of ecological intensification nutrient management system onnitrogen agronomic effect, soil physical and chemical characteristics and soil nutrients balance incomparison with farmer practices (FP). The aim of the study was to provide scientific basis for theintensive maize cropping system with optimized nutrient management practices. The main resultswere shown as follows with spring maize system in Jilin province for three years and doublemaize-wheat cropping system in Hebei province for two years:1Compared with FP treatment, the EI treatment decreased nitrogen, phosphorus and potassiumfertilizer rates by28.3%,48.3%and10.0%in spring maize cropping system, respectively; anddecreased40.0%-46.7%for nitrogen fertilizer and47.1%-56.5%for phosphorus fertilizer andincreased2.6times potassium fertilizer in maize-wheat rotation system. In both cropping systemsmentioned above, with the significantly reuced fertilizer rate, especially for N and P fertilizers, andthe integrated optimized management, the EI treatment maintained the similar high yield level, butincreased remarkably the average net annual profit for farmer by558-1385Yuan/hm~2.2In spring maize cropping system, the FP treatment had higher soil available phosphorus andexchangeable potassium contents in comparison with EI treatment, but the difference wasn’tsignificant. In summer maize-wheat rotation system, in the first year, the two treatments, EI and FP,didn’t show significant difference in soil available phosphorus and exchangeable potassium, but thetwo parameters significantly increased in FP treatment in the second year compared with EI treatment.3Soil nutrients content significantly decreased with soil depth in two maize cropping systems in bothEI and FP treatments.4Soil pH in EI treament was higher than that in FP treatment, but the difference wasn’t significant,the result showed that the potencial of soil acidification in FP treatments increased with excessive Nfertilizer application in two maize cropping systems. In the0-20cm soil layer, soil bulk density andpH increased with soil depth.5In the two maize cropping systems. the EI treatment decreased residual nitrogen after harvest in therange of38.2%-57.0%, and reduced the apparent nitrogen losses in the range of23.9%-47.0%,compared with the FP treatment.The results obtained through this study clearly indicate that the ecological intensification nutrientmanagement system can maintain crop yield, increase farmer’s profit, decrease nutrient loss and protect environment in the two maize cropping systems.