冬季种养结合对稻田土壤微生物量及有效碳氮库的影响

以双季稻冬闲田种植绿肥与养鸡结合的新型种养制度为平台,通过冬季绿肥和鸡粪还田,减少水稻生育期化肥用量,探讨"冬季绿肥-双季稻"轮作种植制度和"冬季种养结合-双季稻"种养制度下对稻田土壤微生物碳、氮和可溶性有机碳、氮的影响。试验包括5个处理,分别为冬闲(F)、冬季种植黑麦草(R)、冬季种植紫云英(M)、冬季种植黑麦草与养鸡结合(RC)以及冬季种植紫云英与养鸡结合(MC)。结果表明,在整个试验的动态过程中,微生物量碳、氮及可溶性有机碳、氮含量高低总体趋势表现为绿肥养鸡绿肥冬闲,各处理间差异显著(P0.05);"冬季种养结合-双季稻"种养制度能显著提高土壤微生物量碳、氮和可溶性有机碳、氮。各处理微生物量碳、氮和可溶性有机氮在3月24日达到最大值,RC、MC、R和M处理微生物量碳最大值分别为492.22,464.91,432.34和435.48mg/kg;微生物量氮的最大值分别为118.20,101.03,70.13和85.46mg/kg;可溶性有机氮的最大值分别为1001.47,926.21,832.80和870.75mg/kg;可溶性有机碳在早稻苗期达到最大值,RC、MC、R和M最大值分别为278.95,266.40,246.13和249.84mg/kg。微生物量碳含量的高峰在早稻移栽初期、晚稻孕穗期和灌浆期,微生物量氮的高峰出现在早稻分蘖期、齐穗灌浆期和晚稻孕穗期,可溶性有机碳在稻田养鸡及成鸡出栏后较高。与冬闲田种植绿肥和休闲相比,冬闲稻田种植绿肥结合养鸡对增加微生物生物量的贡献更大,并显著提高土壤的可溶性有机碳氮,间接反映了种养制度能提高土壤有机碳、氮的矿化速率和土壤的活性有机碳氮以及满足水稻生长期间自身养分需求。

Effects of winter green manure crops with and without chicken rearing on microbial biomass and effective carbon and nitrogen pools in a double-crop rice paddy soil

This study examined the short term effects of the crop rotation systems known as “winter green ma-nure with double cropped rice”and “winter planting and chicken raising with double cropped rice”on paddy soil microbial biomass and dissolved organic C and N.The goal of a winter planting and chicken raising in rice double cropping systems is to return green manure and chicken manure to soils and reduce the amount of fertil-izer during the rice growing period.Five winter treatments were included:fallow (F),planting ryegrass (R), planting milk vetch (M),planting ryegrass and rearing chickens (RC),planting milk vetch and rearing chick-ens (MC).In general soil microbial biomass and dissolved organic C and N were increased significantly,com-pared to a winter fallow,by a green manure crop and further increased when chickens were also reared,al-though values were subject to dynamic seasonal fluctuation.Specifically,the maximum values for soil microbi-al biomass C were 492.22,464.91,432.34,435.48 and 378.02 mg/kg for the treatments RC,MC,R,M and F,respectively;while the corresponding maxima for microbial biomass N were 118.20,101.03,70.13,85.46 and 61.12 mg/kg,respectively.The maxima for dissolved organic N were 1001.47,926.21,832.80,870.75 and 719.86 mg/kg;and the maxima for dissolved organic C were 278.95,266.40,246.13,249.84 and 201.58 mg/kg,for RC,MC,R,M and F,respectively.The dynamics of microbial biomass C,N and dissolved organ-ic C were different at different growth stages.Microbial biomass C peaked at the transplanting,booting and filling stage of late rice.Microbial biomass N peaked at the tillering and heading stage of early rice,and the booting stage of late rice.While the dissolved organic C peaked at seedling stage of early rice and it was higher during the period of raising chickens and after chicken removal from the paddy field.In summary,compared to a winter fallow paddy field,planting green manure and raising chickens significantly increased microbial bio-mass and soil dissolved organic carbon and nitrogen,which indirectly indicates that winter manure and chicken rearing systems can improve the soil organic carbon,and soil labile organic carbon contents,as well as nitrogen levels and nitrogen mineralization rate.Plant nutrients needed by the rice crop during the rice growing season can thus be provided by a winter planting and chicken raising.