Abstract On-farm adoption of minimum soil disturbance and increased residue retention will alter nitrogen (N) dynamics in soils and N fertiliser management in the intensive rice–based triple cropping systems of the Eastern Gangetic Plains. However, the consequences of changes in N forms, N mineralisation and its availability for crops have not been determined. Field experiments were conducted at two locations (Alipur and Digram) of north–west Bangladesh (NWB) to examine N cycling under three planting practices (conventional tillage (CT), strip planting (SP) and bed planting (BP)) with increased (HR) or low residue retention (LR– the current practice) on Calcareous Brown Flood Plain and Grey Terrace soils. Total N and available N were measured on soil samples as was N uptake by crops at different growth stages in the 13–14th (Alipur) and 12–13th (Digram) crops since treatments commenced. At each location (0–10 cm soil depth), SP, including non–puddled transplanting of rice seedlings (NP), together with HR increased total N by 9 and 32 % relative to BPHR, and CTHR and by 62 % relative to the current farm practice (CTLR). In general, the cumulative available N in soils during mustard and rice cropping under CT with HR was higher than other crop establishment and residue retention practices while under wheat and jute, total availability of N did not vary among crop establishment types with increased residue retention. Nitrogen availability in the initial phase of crop growth (0–60 DAS) was generally higher with CT than SP and BP. By contrast, for all crops, the estimated potentially mineralisable N was higher and its decay rate was lower under SPHR than other crop establishment and residue retention practices. Conservation Agriculture practices (SP, and NP of rice, together with HR) have altered the N cycling by reducing the level of mineral N available to plants in the early growing season when crop demand is low, but by increasing soil total N (0−10 cm) and plant N uptake which enhanced the synchrony between crop demand and available N supply.

中文翻译：

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恒河东部平原以水稻为基础的种植系统的保护性农业实践增加了土壤氮的储存量和作物的可用性

摘要 农场采用最小土壤扰动和增加残留物保留将改变东部恒河平原以水稻为基础的集约化三重作物系统中土壤中的氮（N）动态和氮肥管理。然而，氮形式、氮矿化及其对作物的可用性变化的后果尚未确定。在孟加拉国西北部 (NWB) 的两个地点 (Alipur 和 Digram) 进行了田间试验，以检查三种种植方式（常规耕作（CT）、条带种植（SP）和床铺（BP））下的氮循环，随着（ HR) 或低残留保留率（LR – 目前的做法）在钙质棕色洪泛平原和灰色阶地土壤上。自处理开始以来，在第 13-14 届（Alipur）和第 12-13 届（Digram）作物的不同生长阶段测量土壤样品的总氮和有效氮。在每个位置（0-10 厘米土壤深度），SP，包括水稻幼苗的非水坑移栽 (NP) 和 HR 使总氮相对于 BPHR 增加了 9 % 和 32 %，而 CTHR 相对于 BPHR 增加了 62 %当前农场实践（CTLR）。一般来说，在芥菜和水稻种植期间土壤中累积有效氮在 HR 下高于其他作物种植和残留物保持措施，而在小麦和黄麻下，氮的总可用性在作物种植类型之间没有变化，残留物保持率增加。在作物生长的初始阶段（0-60 DAS），CT 的氮可用性通常高于 SP 和 BP。相比之下，对于所有作物，在 SPHR 下，估计的潜在可矿化 N 比其他作物建立和残留物保留实践更高，其衰减率更低。保护性农业实践（水稻的 SP 和 NP，连同 HR）通过在作物需求低的早期生长季节降低植物可利用的矿物质氮水平，但通过增加土壤总氮（0- 10 cm) 和植物吸收氮，这增强了作物需求和可用氮供应之间的同步性。