施用控释氮肥对稻田土壤微生物生物量碳、氮的影响

Effect of controlled release nitrogen fertilizer on soil microbial biomass carbon and nitrogen contents

借助农业部望城红壤水稻土生态环境野外观测试验站的控释氮肥试验,研究了施用控释氮肥对水稻不同生育期间稻田土壤微生物生物量碳、氮动态变化的影响。试验共设5个处理:①CK,(不施氮肥);②Urea(施用尿素);③CRNF(施用与处理②等氮量的控释氮肥);④70%CRNF(施用控释氮肥,用氮量为处理②的70%);⑤50%CRNF+M(施用控释氮肥和猪粪,总氮量为处理②的70%,其中控释氮肥用量为处理②的50%,猪粪含氮量为处理②的20%)。结果表明,施肥后10 d,施氮处理土壤微生物生物量碳和氮均达最高,随生育进程推进逐渐下降,成熟期有一定的回升;施肥初期,施用等氮量的控释氮肥处理(CRNF)土壤微生物量碳、氮含量较尿素处理(Urea)分别增加5.4%和22.5%,而水稻生育中后期,控释氮肥处理(CRNF)土壤微生物量碳、氮含量较尿素处理(Urea)下降幅度大,该处理向地上部提供氮素营养较尿素处理高;施氮量较高的CRNF处理,土壤微生物生物量碳低于控释氮肥节氮处理(70%CRNF),但在大多数取样时期,土壤微生物量氮高于控释氮肥节氮处理(70%CRNF);控释氮肥配施有机肥的节氮处理较其他单施化肥处理显著增加土壤微生物生物量碳、氮含量。控释氮肥与有机肥配施,不仅能节约氮肥用量,而且能明显地提高土壤微生物生物量碳、氮的含量。

A field experiment was conducted at Key monitoring Experimental Station for Reddish Paddy Soil Eco-Environment in Wangcheng,Hunan to study the effect of applying controlled release nitrogen fertilizer（CRNF） on soil microbial biomass carbon（SMBC） and nitrogen（SMBN） contents.There were five treatments in this experiment： ① CK,non-N application;② Urea,（N-source is urea）;③ CRNF,（N-source is CRNF,the same N rate as treatment ②）;④ 70% CRNF,（N-source is CRNF,70% N rate of treatment ②）;⑤ 50% CRNF ＋ M,（N-source are CRNF and pig manure,the same N rate as treatment ④,the nitrogen ratio of CRNF to pig manure is 5： 2）.Results showed that the highest contents of SMBC and SMBN in soil were detected in all treatments supplied with exogenous N at 10 d after fertilizers application,after that significantly decreased as growth stage progressed,finally a marked increase was observed at the late stage of rice growth.Results also revealed that the content of SMBN from CRNF treatment was 5.4% and 22.5% higher than those from Urea treatment;The contents of SMBC and SMBN in the CRNF treatment were decreased much more than those in the Urea treatment during rice middle and late growh satges,implying that,more nitrogen fertilizer was transferred to rice by using CRNF;In the treatments with CRNF application,the content of SMBN was positively related to the rate of N supply in most of sampling times,on contrary the content of SMBC decreased with an increase of the N rate;Compared to 70% CRNF,additional organic N had a remarkable impact on the contents of SMBN and SMBC.These findings suggest that a combination of CRNF and organic fertilizer can not only save the N usage but also increase the contents of SMBN and SMBC in soils.