化肥减量对玉米田土壤酶活性及微生物量的影响

【目的】在小麦-玉米轮作模式下，探讨有机培肥时化肥减量对玉米田土壤酶活性及微生物量的影响。【方法】于2010-10-2011-07在陕西杨凌进行大田试验，试验共设置化肥不减量+高有机肥（NPK+HM）、化肥不减量+中有机肥（NPK+MM）、化肥不减量+低有机肥（NPK+LM）、化肥减量70%+高有机肥（30%NPK+HM）、化肥减量50%+中有机肥（50%NPK+MM）、化肥减量30%+低有机肥（70%NPK+LM）和对照（NPK）7个处理,分别于玉米苗期、拔节期、大喇叭口期、抽雄期、灌浆期及成熟期采集玉米田0～20 cm土层土样，测定土壤蔗糖酶、过氧化氢酶、多酚氧化酶、脲酶活性及土壤微生物量碳、氮含量，分析不同施肥处理土壤酶活性及土壤微生物量碳、氮含量的变化规律。【结果】无论在化肥减量还是不减量条件下，增施有机肥均可以明显提高土壤蔗糖酶、过氧化氢酶和脲酶的活性及微生物量碳、氮含量，但土壤多酚氧化酶活性却显著下降；有机培肥条件下，不同的化肥减量处理对土壤蔗糖酶、脲酶、过氧化氢酶、多酚氧化酶活性以及土壤微生物量碳、氮含量的影响不同，其中化肥减量50%+中量有机肥（50%NPK+MM）处理的土壤酶活性及微生物量碳、氮含量均最高，且与化肥不减量+高量有机培肥（NPK+HM）处理对土壤酶活性以及微生物量碳、氮含量的作用几乎一致。另外，各有机培肥处理玉米不同生育阶段的土壤呼吸强度均较对照（NPK）处理高，但差异并不明显。【结论】在小麦-玉米轮作模式下，化肥减量50%+中量有机肥（50%NPK+MM）是比较合理的施肥方式，化肥适度减量在土壤培肥过程中是合理可行的。

Effects on maize field soil enzyme activities and microbial biomass of chemical fertilizer reduction

【Objective】 The purpose of this research was to determine the effects on the soil enzymes activities and microbial biomass in the maize field with different treatments of organic fertilizer addition with chemical fertilizer reduction in the wheat-maize cropping pattern.【Method】 From Oct 2010 to Jul 2011,field test in Yangling Shaanxi was done.There were 7 treaments:fertilizer fixed match high manure(NPK+HM);fertilizer fixed match medium manure(NPK+MM);fertilizer fixed match low manure(NPK+LM);fertilizer decrement 30% match low manure(70%NPK+LM);fertilizer decrement 50% match medium manure(50% NPK+MM);fertilizer decrement 70% match high manure(30%NPK+HM);CK.And 0-20 cm soilduring was collected in maize seeding,shooting,large belling tasseling,filling and autumn.The activity of soil invertase,catalase,polyphnol,urease and the soil microbial biomass carbon(SMBC),the microbil biomass nitrogen(SMBN) were determined.Then analysis was made on the different fertilization on soil enzyme activities and the soil microbial biomass carbon(SMBC),the microbil biomass nitrogen(SMBN).【Result】 The results show that organic fertilizer addition has the greatest impact on the soil invertase activity,urease activity,catalase activity,the soil microbial biomass carbon(SMBC) and the microbil biomass nitrogen(SMBN).But organic fertilizer addition decreases significantly the activity of soil polyphenol oxidase.On the contrary,under the situation of the treatments of organic fertilizer addition with chemical fertilizer reduction,the results of the soil invertase activity,the soil urease polyphenol oxidase activity,SMBC and SMBN are different,and the soil enzymes activities and microbial biomass are all top in the 50%NPK+MM treatment.The studies show that the effects on the soil enzymes activities and microbial biomass are the same between the 50% NPK+MM treatment and NPK+HM treatment.Also the soil respiration intensity of different treatments at the maize growth stages is higher than that of contrast treatment,but there is no difference among all the treatment.【Conclusion】 50%NPK+MM is the proper fertility in the mode of wheat and maize cultivation.The research indicates that reducing the chemical fertilizers moderately is reasonable in the technique of improving the fertility of soil.