Fertigation Management In Silage Corn Based On Root Layer Regulation

Currently,irrational utilization of water and fertilizer resources in silage corn production is a common problem in central Inner Mongolia.The waste of water and fertilizer resources reduces the income of farmers and causes serious environmental risks.In the current study,field experiments with different fertilization patterns and N rate were conducted from 2017 to 2018 to investigate plant nutrient content,yield,nutrient use efficiency and soil nitrogen supply and spatial distribution of silage corn.Based on the results,the optimum fertilization patterns were demonstrated.The economic benefits and environmental problems were compared and analyzed to form a high-yield and high-efficiency nutrient resource management model for silage corn in central Inner Mongolia.The results are as follows:(1)Under the traditional mode of nitrogen fertilizer application,the accumulation of soil nitrogen in the early stage greatly increased,and the nitrate was leached with excessive irrigation.The soil unable to meet the nitrogen demand of crops in the later stage,resulting in the aging of plants.The optimum N application significantly increased crop yield and nitrogen use efficiency.According to the absorption law of nitrogen,phosphorus and potassium nutrients in silage corn,N,P2O5 and K2O demand per 1000 kg of fresh silage corn is 2.3-2.5 kg,1.5-1.7 kg and 1.9-2.1 kg.(2)Compared with farmers' practice,soil testing based N application and the multi-frequency top dressing without base fertilizer increased yield by 12500 kg/ha and 23500 kg/hm2,respectively,with an increase of 25.3%and 47.4%.The average income of the traditional model was about 5400 yuan/hm2 while two optimization modes increased the net gain 103%and 119%,respectively.Fertilization optimum application of silage corn greatly achieves the goal of increasing resources use efficiency and farmers'income.(3)The traditional silage corn nutrient resource management model has great drawbacks.The NPK combination is unreasonable which caused a large loss of nutrients and environmental pollution.The N use efficiency(NUE)of farmers' practice was only 20.7%,while the NUE for two optimum patterns were 51.8%and 62.1%.respectively.According to the study of nitrogen balance in silage corn field,the apparent loss of nitrogen is up to 111.5 kg/hm2.The apparent loss of nitrogen in two optimized mode is 25.5 kg/hm2 and 12 kg/hm2,respectively.The optimization of the fertilization structure not only reduces the amount of fertilizer but also increases crop yield and reduces environmental risks.