施氮对苜蓿根际土壤微生物数量、酶活性及干草产量的影响

Effects of Nitrogen Addition on Microbial Quantity,Enzyme Activity in Rhizosphere Soil and Alfalfa Hay Yield

为探究不同施氮量对紫花苜蓿根际土壤微生物数量、酶活性、干草产量的影响,设置4个施氮梯度,施氮量分别为:0kg/hm^(2)(N _(0))、60kg/hm^(2)(N_(1))、120kg/hm^(2)(N_(2))和180kg/hm^(2)(N _(3)),测定紫花苜蓿根际土壤微生物数量、酶活性及干草产量,并进行综合分析。结果表明:紫花苜蓿根际土壤细菌、真菌、放线菌数量及根际土壤碱性磷酸酶、过氧化氢酶活性均随施氮量的增加呈先升高后降低的趋势。当施氮量达120kg/hm^(2)(N_(2))时,紫花苜蓿根际土壤细菌、真菌、放线菌数量均达到最大值,分别为7.56、6.11和6.35lg cfu/g;土壤碱性磷酸酶、过氧化氢酶活性均达到最高,分别为21944.44和944.04U/(g·d),且显著高于其他处理(P<0.05)。苜蓿干草产量在N 2处理下达到最大值,为22.46t/hm^(2)。通过综合评定,当施氮量为120kg/hm^(2)(N_(2))时,有利于增加苜蓿根际土壤微生物数量及促进根际土壤酶活性,进而提高苜蓿干草产量。

This study explored the effect of different rates of nitrogen addition on the number of microorganisms,the enzyme activity of rhizosphere soil,and alfalfa hay yield by setting four nitrogen gradients,and the nitrogen addition amounts were:0kg/hm^(2)(N _(0)),60kg/hm^(2)(N_(1)),120kg/hm^(2)(N_(2)),and 180kg/hm^(2)(N_(3)),respectively.The results showed that the number of bacterium,fungi,actinomyces,and the alkaline phosphatase and catalase activities in rhizosphere soil increased and decreased afterward with the increase of nitrogen addition.The number of bacterium(7.56 lg cfu/g),fungi(6.11 lg cfu/g),and actinomyces(6.35 lg cfu/g)in rhizosphere soil and alfalfa hay yield(22.46 t/hm^(2))reached the maximum in the N_(2)treatment.Meanwhile,the soil alkaline phosphatase and catalase activities were also the highest in the N 2 treatment,with 21944.44 U/(g·d)and 944.04 U/(g·d),respectively,which were significantly higher than other treatments(P<0.05).In conclusion,when the nitrogen addition rate was 120 kg/hm^(2),it was beneficial to increase the number of microorganisms and promote the enzyme activity of rhizosphere soil,which improved the hay yield of alfalfa.