Selection Of Silage Maize Variety,Planting Density And Combined Application Of Nitrogen Fertilizer In Northwest Hebei Province

In order to solve the problem of animal husbandry feed shortage in Bashang area of Northwest Hebei province and to seek the key technology of silage maize production process with high yield and high efficiency,the field experiment was conducted in Zhangjiakou comprehensive test station of national forage system.This study was carried out in two parts:（1）Silage maize variety and planting density screening test was carried out from May to October,2018;（2）Nitrogen fertilizer combination test of silage maize was carried out from May to October,2019 on the basis of screening test.The planting variety and planting density were two factors in the screening test.The planting varieties were Xuntian 3171,Xuntian 16,Xunqing 858,Fengtian 12,with 3 planting densities of 67,500 plants·hm^-2,79,500plants·hm^-2 and 90,000 plants·hm^-2.There were 8 treatments in the N application experiment,namely no N application,conventional N application,optimal N application,slow-release N application,the ratios of slow-release fertilizer and fast-release fertilizer respectively is 9:1,8:2,7:3and 6:4 were respectively.Each treatment was repeated for 3 times.The results showed that:（1）With the increase of planting density,the plant height,stem diameter and maximum leaf area of silage maize gradually decreased,and the yield first increased and then decreased with the increase of planting density.The yield was the highest when the planting density was79,500 plants·hm^-2.Among all the varieties,the yield of Xunqing 858 was the highest,with 73.5 t·hm^-2 for fresh grass and 18.3 t·hm^-2 for hay.The contents of crude protein,soluble carbohydrate and crude fat of silage corn decreased with the increase of planting density.The contents of acid and neutral washing fiber increased with the increase of planting density.The starch content showed a trend of increasing first and then decreasing,and reached the highest at 79,500 plants·hm^-2.（2）Compared with farmer traditional nitrogen application,optimized nitrogen application could increase plant height,stem diameter,maximum leaf area,leaf chlorophyll content and yield of silage corn.When the ratio of slow-release nitrogen fertilizer and fast-release nitrogen fertilizer was 7:3,the yield of fresh grass and hay was 73.1 t·hm^-2 and 14.1 t·hm^-2,respectively.Compared with the treatment without nitrogen fertilizer,the yield of fresh grass and hay increased by 58.06%and 44.83%,respectively.At the same time,the content of crude protein and starch was the highest,the content of acid washing fiber and neutral washing fiber was lower,and the quality was the best.（3）When the ratio of slow-release nitrogen fertilizer and fast-release nitrogen fertilizer was 7:3,the apparent balance surplus of soil nitrogen could be significantly reduced,the nitrogen utilization efficiency of silage maize could be improved,and the leaching loss of soil nitrate nitrogen could be reduced.A comprehensive analysis of the effects of silage maize varieties,planting density and nitrogen fertilizer combination on yield,quality and soil properties under the test conditions showed that the most suitable silage maize varieties for planting in northwest Hebei province was Xunqing 858,the appropriate planting density was 79,500 plants·hm^-2,and the optimal combination ratio of slow-release nitrogen fertilizer and fast-release nitrogen fertilizer was 7:3.