养猪场处理尾水灌溉对太湖地区水稻土硝酸根异化还原为铵的影响

POTENTIAL OF DISSIMILATORY NITRATE REDUCTION TO AMMONIUM IN PADDY SOILS IN THE TAIHU LAKE REGION AS AFFECTED BY IRRIGATION WITH TAIL WATER FROM PIG REARING

以太湖地区的普通简育水耕人为土(湖白土)和底潜简育水耕人为土(乌栅土)为研究对象,通过室内15N示踪实验研究了养猪场处理尾水灌溉对土壤硝酸根异化还原为铵(DNRA)的影响。底潜简育水耕人为土(乌栅土)DNRA速率和相对潜势分别为N 0.68～0.79 mg kg-1d-1(以干土计)和34.61%～44.45%;普通简育水耕人为土(湖白土)DNRA速率和相对潜势分别为N 1.14～1.41 mg kg-1d-1(以干土计)和54.24%～106.70%。养猪场处理尾水对2种土壤的DNRA速率均影响不大;养猪场处理尾水对普通简育水耕人为土(湖白土)DNRA相对潜势影响不大而明显降低了底潜简育水耕人为土(乌栅土)DNRA相对潜势。相关分析表明,土壤DNRA相对潜势与培养开始(r=0.836,p<0.05,n=6)和结束(r=0.936,p<0.01,n=6)时的土壤溶解有机碳/硝态氮(DOC/NO3--N)均显著正相关,而与培养始末土壤Eh和DOC含量的相关性不显著。以上研究结果表明,太湖地区底潜简育水耕人为土(乌栅土)具有较高的DNRA潜势,实践上有可能通过调控DN-RA过程实现保持土壤氮素而减少农田氮损失的目的;尾水灌溉主要通过改变土壤DOC/NO3--N而影响DN-RA对NO3-异化还原的贡献,且其影响因土壤类型而异。

Using the 15-nitrogen （15N） tracing method, potential of dissimilatory nitrate reduction to ammonium （DNRA） in Typic Hapli-Stagnic Anthrosols and Endogleyic Hapli-Stagnic Anthrosols of the Taihu Lake region as affected by tail water from pig rearing was studied. DNRA rates and relative potentials varied in the range of N 0. 68 0.79 mg. kg-1 dry soil d-1 and 34.61%-44.45% , respectively, in Typic Hapli-Stagnic Anthrosols, and in the range of N 1. 14 - 1.41 mg kg -1 dry soil d -1 and 54.24%- 106.70% , respectively in Endogleyic Hapli-Stagnic Anthrosols. Irrigation with tail water from pig rearing had little effect on DNRA rates in both soils and DNRA relative potential in Typic Hapli- Stagnic Anthrosols, while it obviously reduced DNRA relative potential in Endogleyic Hapli-Stagnic Anthrosols. Correlation analysis indicates that soil DNRA relative potential was significantly positively correlated with the ratio of soil dissolved organic carbon to nitrate nitrogen （DOC/NO3--N） at the start （r =0. 836, p 〈0.05, n =6） and the end （r =0. 936, p 〈 0.01, n =6） of the incubation, but not significantly correlated with soil Eh or DOC at the start and the end of the incubation. The results indicate that Endogleyic Hapli-Stagnic Anthrosols is of much higher DRNA potential, therefore, in prac- tice, it might be possible to enhance N retention through regulation of DNRA and hence to minimize N loss from paddy fields; and irrigation of the soils with tail water affects the contribution of DNRA to dissimilatory NO3- reduction mainly by changing soil DOC/NO3-N and its effect varies with the soil types.