[Effects of long-term different fertilization patterns on soil nutrients and microbial community structure of tomato in a solar greenhouse.]

The phospholipid fatty acid (PLFA) technique was used to investigate the effects of fertilization on soil characteristics and microbial community of tomato in a solar greenhouse in Shouguang, Shandong Province, China, based on a long-term (12-year) fertilization experiment. The experiment involved a control (CK) and five fertilization treatments, namely, traditional nitrogen application (CN), traditional nitrogen application+straw return (CNS), optimized nitrogen application (SN), optimized nitrogen application+straw return (SNS), and organic manure nitrogen application+straw return (MNS). Results showed that the contents of soil organic matter and avai-lable P and K under all fertilization treatments were significantly higher than that of CK, but no significant difference among fertilization treatments. The traditional nitrogen application (i.e., CN and CNS) significantly decreased soil pH. The reduction of nitrogen fertilizer (i.e., SN, SNS and MNS) did not affect soil pH. Compared with CK, no straw treatment (i.e., CN and SN) and MNS did not affect the content of soil available N, but nitrogen combined with straw returned (i.e., CNS and SNS) significantly increased soil available N content. The optimized N with straw return (i.e., SNS) treatment resulted in the highest soil available N. Compared with CK and treatments without straw (i.e., CN, SN), treatments with straw (i.e., MNS, CNS and SNS) substantially changed soil microbial community structure and increased the biomass of soil bacteria, fungi, actinomycetes, mycorrhizal fungi, and the total amount of PLFA. SNS treatment had the highest soil microbial diversity, the highest biomass of soil bacteria, fungi, and actinomycetes, the highest total amount of PLFA, the highest ratios of fungi/bacteria and monounsaturated fatty acids/saturated fatty acids (MONO/SAT), the two indicators for soil ecosystem stability. Further, it had the lowest ratios of iso/anteiso fatty acids (i/a) and gram-positive/gram-negative bacteria (G+/G-), the indicators for nutritional stress. Redundancy and correlation analysis revealed that soil organic matter was the main factor affecting soil microbial community structure, with a significant positive correlation with actinomycetes and gram-positive bacteria. In conclusion, straw returning combined with optimized nitrogen application (i.e., SNS, 8 t·hm-2 of wheat straw with N fertilizer reduced by 58.3%) could improve soil nutrient status, soil microbial biomass, soil microbial community structure, and soil ecological environment. It would be an effective measure for reducing fertilizer application and improving efficiency.为了阐明长期不同施肥方式对日光温室番茄土壤养分和微生物群落结构的影响,以山东寿光12年番茄定位施肥试验土壤为对象,采用磷脂脂肪酸(PLFA)分析方法,研究了传统施氮(CN)、传统施氮+秸秆(CNS)、优化施氮(SN)、优化施氮+秸秆(SNS)、有机肥+秸秆(MNS)5种施肥方式对土壤主要理化性质和微生物群落结构的影响,以不施肥处理(CK)为对照。结果表明: 与CK相比,所有施肥处理均显著提高了土壤有机质、速效磷和速效钾含量,但各施肥处理间无显著差异;传统氮肥施用量的CN、CNS处理土壤pH值显著降低,而减氮施肥的SN、SNS和MNS处理对土壤pH值没有显著影响。与CK相比,不添加秸秆的处理(CN、SN)和MNS对土壤碱解氮含量没有显著影响,但施氮的同时添加秸秆的CNS和SNS处理显著提高了土壤碱解氮含量,其中SNS的碱解氮含量最高。与CK和不添加秸秆的处理(CN、SN)相比,所有添加秸秆的处理(MNS、CNS、SNS)均能显著改变土壤微生物群落结构,增加土壤中细菌、真菌、放线菌、菌根真菌含量和PLFA总量,其中,SNS处理的土壤微生物多样性、土壤细菌、真菌、放线菌和PLFA总量均达到最大值,真菌/细菌和单不饱和脂肪酸/饱和脂肪酸(MONO/SAT)两个表征土壤生态系统稳定性的指标在SNS中最高,而表征土壤养分胁迫的异构脂肪酸/反异构脂肪酸(i/a)和革兰氏阳性菌/革兰氏阴性菌(G+/G-)在SNS中最低。冗余分析和相关分析表明,土壤有机质是影响土壤微生物群落最主要的环境因子,有机质与放线菌和革兰氏阳性菌呈显著正相关。秸秆还田优化施氮(SNS,添加麦秸秆8 t·hm-2,减氮58.3%)可显著提升土壤养分状况,增加土壤微生物生物量,改善微生物群落结构和土壤生态环境,是一种有效的减肥增效施肥措施。.