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黄土区人工牧草地 18年苜蓿连作对土壤耕层水解总氮、氨态氮、氨基酸氮及氨基糖氮含量有很大影响 ,不施肥条件下苜蓿连作能明显增加土壤耕层水解总氮、氨基酸氮和氨基糖氮含量。连续施 P处理根层水解总氮、氨态氮、氨基酸氮和氨基糖氮含量分别比对照增加 4 13.5 5 m g/ kg、5 8.39mg/ kg、16 9.83m g/ kg和 10 7.0 1mg/ kg;NPM处理土壤耕层水解总氮与对照相比增加 192 .5 8mg/ kg、氨基酸氮增加 2 2 3.4 4 mg/ kg、氨基糖氮增加 2 5 .6 6 m g/kg,而氨态氮含量则大幅度降低 ;在 6 0～ 10 0 cm不同处理的各形态氮含量接近且随土层加深逐渐减少。粮草轮作系统中不同苜蓿生长年限对土壤的水解总氮、氨态氮和氨基酸氮含量有增加的作用
The continuous cropping of alfalfa with artificial pasture for 18 years in loess area had a significant effect on the contents of total nitrogen, ammonia nitrogen, amino acid nitrogen and amino sugar and nitrogen in hydrolyzed soil. Under the condition of no fertilization, continuous cropping of alfalfa significantly increased total nitrogen and amino acid Nitrogen and amino sugars Nitrogen content. The content of total nitrogen, ammonia nitrogen, amino acid nitrogen and amino sugar - nitrogen of roots hydrolyzed by continuous application of P increased 4 13.5 5 mg / kg, 5 8.39 mg / kg, 16 9.83 mg / kg and 10 7.0 1 mg / kg respectively compared with the control. Compared with the control, NPM treatment increased total nitrogen in the topsoil by 192.58 mg / kg, amino acid nitrogen increased by 22.4 4 mg / kg, aminoglycoside nitrogen increased by 25.66 mg / kg, while ammonia nitrogen content increased Significantly decreased. The contents of nitrogen in different treatments at 600 ~ 100 cm were close to each other and decreased with the deepening of soil depth. The effects of different alfalfa growing years on soil hydrolyzable total nitrogen, ammonia nitrogen and amino acid nitrogen in forage grass rotation system have an increasing role