有机肥替代部分化肥对长期连作棉田产量、土壤微生物 数量及酶活性的影响

Abstract

施用有机物是作物增产、增加土壤有机质和改善土壤生物学性状的有效措施.在大田滴灌条件下,采用土壤酶学和微生物平板培养方法,研究了常规施肥(CF)减量20%-40%,配施3000、6000 kg/hm²有机类肥料对棉花产量、土壤微生物数量及土壤酶活性的影响.结果表明:降低CF用量20%-40%情况下,滴灌棉田配施3000、6000 kg/hm²的有机类肥料可获得与CF处理相持平的产量(4945-4978 kg/hm²),有机肥和生物有机肥配施处理间的棉花产量差异不显著(<em>P</em> < 0.05).细菌、放线菌和假单胞杆菌数量均随有机肥用量的增加而升高,不同类有机肥配施间表现为OF+BF > BF > OF;真菌数量则随有机肥施量升高而降低,其中OF+BF配施处理最为显著.有机无机肥配施显著提高了土壤酶活性,80% CF和60% CF与有机肥配施处理土壤碱性磷酸酶、荧光素二乙酸酯酶(FDA)、β-葡萄糖苷酶和脱氢酶的活性比CF处理分别升高了3.8%、17%、18%、55%和10.1%、19%、20%、60%,不同类型有机肥对土壤酶活性影响差异不显著.土壤细菌/真菌比、土壤放线菌/真菌和假单胞杆菌/真菌比均随有机肥施量的增加而升高,施用化肥或有机肥均显著降低了假单胞杆菌/细菌比.细菌、放线菌和假单胞杆菌数量与土壤脱氢酶、β-葡萄糖苷酶、碱性磷酸酯酶和荧光素二乙酸酯酶活性均呈显著或极显著正相关,真菌数量与4种酶活性呈负相关.CF减量20%-40%配施以3000、6000 kg/hm²有机肥不仅不会导致棉花减产,而且对提高土壤酶活性、调节土壤细菌、真菌、放线菌群落组成结构,改善北疆绿洲滴灌棉田土壤生物学性状有显著作用.;Organic fertilizer application is an effective approach to enhancing soil organic matter, soil biological activity as well as crop yield in agriculture. In the present research, a two-year field experiment was established to study the impacts of combined use of organic fertilizer with chemical fertilizer (CF) on cotton yield, soil microbial biomass, soil enzyme activities and soil microbial community structural composition in drip-irrigation condition in northern Xinjiang. Compared with CK, 100% chemical fertilizer treatment (300 kg N/hm², 90 kg P₂O₅/hm², 60 kg K₂O/hm²) or treatments of organic manure at different rates combined with chemical fertilizer significantly increased (<em>P</em> < 0.05) cotton yield. With chemical fertilizer or organic manure supply, cotton yield could be reached up to 4945-4978 kg/hm², however, there was no statistical difference (<em>P</em> < 0.05) among 100% CF fertilization and treatments with 20% to 40% chemical fertilizer substituted by 3000-6000 kg/hm²organic fertilizer. The number of soil bacteria, actinomycetes as well as pseudomonas significantly increased with increasing amendment rate of organic manure, but the number of soil fungi decreased with organic fertilizer rates increasing. For instance, the number of soil bacteria increased by 13%-41% in the treatments of organic manure at different rates combined with CF than in the treatment with 100% CF, whereas, the number of soil fungi in the treatment with 100% CF fertilizer is 1.4-1.6 times higher than that in the treatment with organic manure combined with CF at budding stage of cotton. Organic fertilizer application significantly enhanced (<em>P</em> < 0.05) soil enzyme activities. Compared with the treatment with 100% CF supply, soil enzyme activities of alkaline phosphatase, fluorescein acetate esterase, β-glucosidase and dehydrogenase increased by 3.8%, 17%, 18% and 55% in the treatments with 80% CF combined with 3000 kg/hm² organic manure, and increased by 10.1%, 19%, 20%, and 60% in the treatments with 60% CF fertilizer combined with 6000 kg/hm² organic manure (BF-organic), respectively. The ratios of soil bacteria/fungi, soil actinomycetes/fungi and pseudomonas/fungi increased with increasing application rate of organic manure, but pseudomonas/bacteria ratio markedly reduced in the treatment with 100 CF or organic fertilizer supply. A significant positive correlation (<em>P</em> < 0.05) was observed between the number of soil bacteria, actinomycetes and pseudomonas was significantly positively correlated with the activity of soil enzymes including dehydrogenase, β-glucosidase, alkaline phosphatase and fluorescein acetate esterase, respectively. However, an obvious negative correlation was observed between soil fungi number and the activity of soil enzymes such as dehydrogenase, β-glucosidase, alkaline phosphatase and fluorescein acetate esterase. Our conclusion is that 20%-40% of total chemical fertilizer application rate can be substituted by 3000-6000 kg/hm² organic fertilizer with no cotton yield decrease. Moreover, organic fertilizer addition addition plays a significant role in increasing soil enzyme activities, regulating soil microbial community structural composition as well as improving soil biological properties in cotton mono-cropping system under drip-irrigation condition in northern Xinjiang.