氯甲基吡啶对滴灌棉田土壤微生物群落功能多样性的影响

已知硝化抑制剂氯甲基吡啶能有效抑制土壤硝化,减少氮的淋洗和硝化-反硝化损失,促进作物对氮素的吸收,但是其对干旱区滴灌条件下土壤微生物群落功能多样性的影响尚不明确。本试验研究了尿素添加氯甲基吡啶(Nitrapyrin)分次随水滴施对干旱区滴灌棉田土壤微生物碳代谢和群落功能多样性的影响。试验采用随机区组设计,设置不施氮肥[CK,0 kg(N)·hm~(-2)]、单施尿素[Urea,225 kg(N)·hm~(-2)]和尿素添加氯甲基吡啶[Urea+nitrapyrin,225 kg(N)·hm~(-2)+2.25 kg(nitrapyrin)·hm~(-2)]3个处理,重复4次,采用Biolog-ECO法进行土壤微生物碳代谢和功能多样性研究。结果表明:与不施氮肥(CK)相比,施用尿素和尿素添加氯甲基吡啶均能显著提高土壤微生物对31种碳源的代谢能力(AWCD)和代谢强度(S)(P0.05),增加土壤微生物多样性和丰富度(Shannon指数、Simpson指数、Mc Intosh指数和Richness指数)以及对各类碳源的利用能力。尿素添加氯甲基吡啶随水滴施后,土壤微生物AWCD值、碳代谢强度、Shannon指数、Simpson指数、Mc Intosh指数以及Richness指数均大于单施尿素处理,且较单施尿素处理分别提高13.83%、9.33%、1.29%、1.34%、11.26%、11.79%(P0.05),均匀度指数则低于单施尿素处理(P0.05)。PCA和聚类分析结果表明,施用尿素和尿素添加氯甲基吡啶对土壤微生物群落功能多样性均产生了显著影响,但尿素添加氯甲基吡啶与单施尿素处理差异不显著;氯甲基吡啶的添加提高了土壤微生物对聚合物、酚酸、羧酸、氨基酸以及胺类的利用,降低了对碳水化合物的利用(P0.05)。上述研究结果得出,在干旱区滴灌棉田,尿素添加氯甲基吡啶分次随水滴施可调控土壤的微生态环境,在一定程度上提高土壤微生物的代谢能力,增加微生物群落功能多样性,缓解因长期施用无机氮肥导致的土壤微生物活性的降低。

Effect of nitrapyrin on functional diversity of soil microbial community in drip-fertigated cotton field

As one of the nitrification inhibitors (NIs),nitrapyrin (2-chloro-6-(trichloromethyl)-pyridine) exhibits some effective influences on controlling nitrification,reducing nitrogen leaching and nitrification-denitrification losses,increasing crop nitrogen uptake.However,information is still scant regarding the effect of nitrapyrin on the functional diversity of soil microbial community under drip irrigation condition in arid area.In view of this,a field trial (of randomized block design) was conducted to evaluate the impact of repeated supply of nitrapyrin with urea via fertigation on the functional diversity of soil microbial community in a drip-fertigated cotton field.Three treatments were established:CK[0 kg (N)·hm^-2],Urea[225 kg (N)·hm^-2]and Urea+nitrapyrin[225 kg (N)·hm^-2+2.25 kg (nitrapyrin)·hm^-2],each treatment was replicated three times.Biolog-ECO technology was used to explore carbon metabolism and community functional diversity of soil microbial.The results showed that the application of urea and urea plus nitrapyrin significantly increased metabolic capacity of 31 carbon sources (AWCD) and intensity of carbon metabolism (S) of soil microbial community compared with CK (P<0.05),it also increased the diversity and richness of soil microbial community[Shannon index (H''),Simpson index (D),McIntosh index (U) and Richness index (R)]and improved the utilization of six types of carbon sources used by soil microbial community to some extent.Urea+nitrapyrin treatment increased AWCD,S,H'',D,U and R of soil microbial community respectively by 13.83%,9.33%,1.29%,1.34%,11.26% and 11.79%(P>0.05),it decreased Pielou evenness index (J)(P>0.05) compared with Urea treatment.Principal component analysis and cluster analysis indicated that the application of urea and urea plus nitrapyrin significantly influenced the functional diversity of soil microbial community.However,there was no significant difference between Urea and Urea+nitrapyrin treatments.Furthermore,the addition of nitrapyrin increased the utilization of polymers,phenolic acids,carboxylic acids,amino acids and amines by soil microbial community,but decreased the utilization of carbohydrates compare with Urea treatment (P>0.05).The results demonstrated that the repeated supply of nitrapyrin with urea via fertigation regulated soil micro-ecological environment,increased soil microbial metabolism and functional diversity of community.It inhibited the reduction of soil microbial activity due to long-term application of inorganic nitrogen fertilizers in drip-fertigated cotton fields in arid areas.