With increasing demand for organic rice (Oryza sativa L.), there is a pressing need for more research on the effects of management practices on soil nutrient cycling and health in organic production. Soil microbial community could be used as an indicator of soil nutrient status and health; however, in drill‐seeded, delay‐flooded organic rice systems, how a soil microbial community responds to changes in soil properties under different nitrogen (N) management practices is not yet well understood. A greenhouse trial with four replications was conducted to study the effects of a cropping system (organic system receiving an organic certified soil amendment, Nature Safe [N–P–K, 13–0–0]; conventional system receiving a urea [46–0–0] fertilizer), N rate (0, 50, 100, 150, 200, and 250 kg N ha⁻¹), and rice cultivation (RiceTec XP753 and no plant [control]) on phospholipid‐derived fatty acids profiling of soil microbial community structure at four growth stages of rice. Soil total microbial biomass (TMB) was significantly affected by the interaction of N rate × rice cultivation and the main effect of growth stage. Total microbial biomass was higher in soils with rice cultivation and soils with high N rates but lower at the growth stages after dry–wet alternations. Cropping system did not affect TMB, but its interaction with rice cultivation or growth stage significantly affected microbial community structure. The fungi/bacteria ratio linearly increased with increasing N rate and was significantly lower at heading than the other stages. Variations in microbial community structure strongly correlated to changes in soil pH, electrical conductivity, and total dissolved N induced by different management practices. This work clearly shows the responses of soil parameters, TMB, and community structure to N rate at different growth stages of organic and conventional rice, which is crucial for refining the criteria and making improved management decisions in organic rice production.

中文翻译：

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土壤微生物群落对有机和常规水稻生产中氮素施用的响应

随着对有机稻（Oryza sativa L.）的需求增加，迫切需要对管理实践对有机生产中土壤养分循环和健康的影响进行更多研究。土壤微生物群落可作为土壤养分状况和健康的指标；然而，在播种，延迟注水的有机水稻系统中，土壤微生物群落如何在不同的氮（N）管理实践下对土壤性质的变化作出反应尚不清楚。进行了四次重复的温室试验，以研究种植系统的效果（有机系统接受有机认证的土壤改良剂，Nature Safe [N–P–K，13-0-0]；常规系统使用尿素[46– [0–0]肥料），氮素含量（0、50、100、150、200和250千克N ha ^-1）和水稻种植（RiceTec XP753，无植物[对照]），在水稻的四个生长阶段对土壤微生物群落结构的磷脂衍生脂肪酸进行分析。施氮量×水稻的相互作用和生育期的主要影响显着影响土壤微生物总生物量（TMB）。在水稻种植和高氮含量的土壤中，微生物总生物量较高，但在干湿交替后的生长期，微生物总生物量较低。种植系统没有影响TMB，但它与水稻的栽培或生长期的相互作用显着影响了微生物群落结构。真菌/细菌比率随着氮素含量的增加而线性增加，抽穗期显着低于其他阶段。微生物群落结构的变化与土壤pH的变化密切相关，电导率，以及不同管理方法引起的总溶解氮。这项工作清楚地显示了有机稻和常规稻不同生育阶段土壤参数，TMB和群落结构对氮素含量的响应，这对于完善有机稻米的生产标准和制定管理决策至关重要。