Agronomic And Environmental Response To Ecological Intensification Management In Maize Cropping System

Optimum field management practices need to be developed and improved to solve the challenge of increasing food production while retaining the ecological integrity of cropping system underlying the goal of sustainable agriculture.In our study,the concept of ecological intensification?EI?was introduced and applied to the spring maize and summer maize-winter wheat cropping system in Jilin and Hebei province,China,respectively.The aims of this study was to reveal the advantages and functions of El practices on increasing crop yield potential and decreasing the environmental risky when compared to farmers'practices?FP?.The main results are showed as below:1)The average grain yield of spring maize was 11.8 t ha^-1 in EI treatment,while the FP treatment had an average of 11.2 t ha^-1 grain yield across six seasons.The Hybrid Maize Model was used to simulate the potential yield under water-limited condition,and the results showed that grain yield with 76%of the average potential yield(15.5 t ha^-1)in EI treatment was closer to the yield potential than FP treatment.Adjusted nitrogen?N?fertilizer rate,split-application of N at the right time and proper recommended hybrid maize planting density were used to improve N use efficiency and decreasing the negative effects to the environment.Consequently,a total of 180 kg N ha^-1 was enough for maize growth and resulted in equal plant N uptake as the 251 kg N ha^-1 applied in FP.Higher agronomic efficiency of N?AE?,recovery efficiency of N?RE?and partial factor productivity of N?PFP?in El treatment(39.7 kg kg^-1 66.1%and 66.2 kg kg^-1)were observed relative to those in FP treatment(26.9 kg kg^-1,42.5%and 50.4 kg kg^-1).Improved N use efficiency contributed significantly less N loss to the environment.Our results showed that calculated soil Nmin,the apparent N loss and total GHG emission was 37.5%,34.3%and 29.8%lower in EI treatment when compared to FP treatment;2)The summer maize in EI treatment achieved a mean grain yield of 8.7 t ha^-1,while the corresponding value was 8.2 t ha^-1 in the FP treatment.Meanwhile,the averaged grain yield of winter wheat was 7.1 t ha^-1 in El treatment;while the FP treatment achieved equivalent average grain yield of 7.2 t ha^-1 across six-year of cropping-seasons.Through constantly adjusting N supply,the split-application of N at right time and proper recommended planting density for hybrid maize improved N use efficiency and reduced the negative environmental effects in either summer maize or winter wheat.Therefore,an increase of AE,RE and PFP of N in EI treatment(9.8 kg kg^-1,35.7%,49.8 kg kg^-1,respectively)were observed when compared to FP treatment(6.3 kg kg^-1,17.2%,32.6 kg kg^-1,respectively)in summer maize;while higher AE,RE and PFP of N(11.8 kg kg^-1,48.7%,43.3 kg kg^-1,respectively)were obtained in EI treatment versus those in FP treatment(9.8 kg kg^-1,40.7%,33.3 kg kg^-1,respectively)in winter wheat.The parameters of soil N loss and GHG emission were taken into account to evaluate the environmental risky of excessive N supply.Results showed that El treatment decreased by 93.1 kg ha^-1 residual N per year as compared to FP treatment in the summer maize-winter wheat rotation system.Likewise,decreased GHG emission by 23%and 37%was observed in summer maize and winter wheat of EI treatment as compared to FP treatment,respectively.Ecological intensification?El?nutrient management have been focused on the concept of 4R nutrient management stewardship?right rate,right time,right placement and right sources?and combined with optimal planting density and new hybrid maize variety,the results indicated that the El nutrient management could efficiently improve crop yield,nitrogen uptake and nitrogen use efficiency and significantly decrease the soil nitrogen loss and greenhouse gas emission to the environment.