The application of biosolids to cropping soils may improve soil health, supply nitrogen and other nutrients for crops. There are specific guidelines on the quantity of biosolids that can be applied to a soil to grow selected crops. However, some recommendations overlook environmental factors such as soil organic N and N supplied by irrigation water. We conducted a three-year field monitoring programme to study the effect of biosolid application on sodicity, soil nitrogen and organic carbon status to a depth of 1.8 m in a vertisol with a history of sewage effluent water irrigation. Biosolid application had no effect on soil sodicity. Improvements in soil organic carbon (SOC) were short-lived and occurred only during the first year. N accumulation and leaching below the root zone (1.2 m) occurred after two years and suggest a possible off-farm environmental risk. The higher residual mineral N in biosolid treatment 2 years after application implies an opportunity to reduce N inputs in vertisols treated with biosolids and effluent water. The biosolid application rate of 35 Mg ha⁻¹ was well below the nitrogen-limited biosolid application rate (NLBAR) (100 Mg ha⁻¹) under the current guidelines. This warrants further refinement of NLBAR to suit specific circumstances such as effluent-enriched water irrigation and additional in-crop fertilizer application.

中文翻译：

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具有经过处理的污水富集水灌溉历史的生物固体修正的钠化 Vertisol 中土壤氮和碳的变化

将生物固体应用于耕作土壤可以改善土壤健康，为作物提供氮和其他养分。对于可用于土壤以种植选定作物的生物固体的数量，有特定的指导方针。然而，一些建议忽略了环境因素，例如土壤有机氮和灌溉水提供的氮。我们开展了一项为期三年的现场监测计划，以研究生物固体应用对具有污水排放水灌溉历史的 1.8 m 深度的土壤中的碱度、土壤氮和有机碳状态的影响。生物固体施用对土壤碱度没有影响。土壤有机碳 (SOC) 的改善是短暂的，仅在第一年发生。根区以下氮的积累和淋溶（1. 2 m) 发生在两年后，表明可能存在非农场环境风险。应用后 2 年，生物固体处理中较高的残留矿物 N 意味着有机会减少用生物固体和污水处理的 vertisol 中的 N 输入。35 Mg ha的生物固体施用率^-1远低于现行指南下的限氮生物固体施用率 (NLBAR) (100 Mg ha ^{-1 )。}这需要进一步完善 NLBAR 以适应特定情况，例如富水灌溉和额外的作物施肥。