套作小麦/玉米不同施氮水平对土壤养分与微生物数量的影响

Effects of Different Nitrogen Application Levels on Soil Nutrient Content and Soil Edaphon Population in Wheat/Corn Intercropping Field

通过田间试验,研究了河套灌区套作小麦/玉米不同施氮水平下土壤微生物数量及土壤养分的动态变化规律。结果表明:小麦带土壤有机质含量随着生育期的推进逐渐下降,在灌浆期降到最低值,土壤碱解氮、速效磷含量从苗期到拔节期呈上升趋势,拔节期至灌浆期迅速下降,在灌浆期降到最低;玉米带土壤有机质、碱解氮、速效磷含量均呈降-升-降的趋势。小麦带细菌、真菌数量随着生育期的推进先增加后降低,抽穗期数量最多,放线菌数量呈现降-升-降的变化趋势;玉米带细菌、真菌、放线菌数量随着生育期的推进呈先减少后增加再减少的趋势,在灌浆期达到最高。与不施氮相比,施氮明显增加了土壤养分含量和土壤微生物数量,各施氮处理均达5%显著差异水平,且随着施氮水平的提高,土壤养分含量和土壤微生物数量也随之先增加后降低,N2水平时土壤养分含量达到最高,土壤微生物数量出现峰值,当施氮水平过高(N3)时,土壤养分和土壤微生物数量不再增加反而减少,说明适宜的施氮量(N2)更能促进土壤中养分和微生物数量的增加。

With the field experiment,in this paper the dynamic change of soil edaphon populations and soil nutrient content in wheat/corn intercropping field were studied under different nitrogen application levels in the Hetao irrigated area. The results indicated that the soil organic matter content in wheat belt was gradually decreased with the development of growth period and down to the lowest at filling stage,the contents of soil alkali-hydrolyzable nitrogen and available phosphorus were in an increase trend,but they were sharply decreased from jointing stage to filling stage and down to the lowest at filling stage. The contents of soil organic matter,alkali-hydrolyzable nitrogen and available phosphorus in corn belt were all in a decrease-increase-decrease trend. The populations of bacteria and fungi in wheat belt were increased at first and then decreased with the development of growth period,and they were the highest at heading stage. The actinomycetes population in corn belt was in a decrease-increase-decrease trend,and it was the highest at filling stage. Compared with the situation without applying nitrogen,the soil nutrient content and soil edaphon populations were significantly increased by applying nitrogen fertilizer,and the difference between the different nitrogen treatment levels was higher than 5%. With the increase of applying nitrogen,the soil nutrient content and soil edaphon populations were increased at first and then decreased. Both the soil nutrient content and soil edaphon populations reached the highest at high nitrogen application level（ N2）,but they were decreased at very high nitrogen application level（ N3）. These explained that the oil nutrient content and soil edaphon population could be increased by an appropriate application amount of nitrogen（ N2）.