Optimum soil physical conditions for crop establishment are more likely to occur with mechanised row‐sowing using metered seeding and controlled depth placement of seeds than with broadcast sowing, that is common in many traditional South Asian cropping practices. Establishment success is a limitation for post‐rice crops in medium to heavy textured soils in the Eastern Gangetic Plain because sowing coincides with rapid topsoil drying and increases in soil strength. In addition, due to lack of rainfall in the post‐rice season the crop relies on access to stored soil water during vegetative and reproductive growth to achieve adequate yields. Our aim was to determine whether decreased soil disturbance (from full tillage to zero tillage (ZT) to undisturbed soil (Fallow)) and direct seeding (using small‐scale seeders) could 1) enhance chickpea crop establishment by conserving seedbed soil water and 2) alter crop water use of the water stored in the soil profile. The silt loam soil has an estimated volumetric soil water content (θv) of 34% at field capacity. At sowing, θv in the seedbed was between 25% to 29%. This was adequate for successful chickpea crop establishment, but slightly wetter than optimum for tillage. In the wet soil at sowing, there was evidence of smeared furrow walls and poor soil covering of the seed in the seedbed in strip planting (SP; rotating blades in front of tine) and ZT. Uncovered furrows (in ZT; using a tine opener) and the fallow soil lost more surface soil water (9%, 23 days after sowing) than the seedbeds created with greater levels of soil disturbance. In 2008, grain yield of single‐pass shallow tillage (SPST) was greater than SP but in 2009, grain yields of all one‐pass tillage techniques (ZT, SP, SPST) were greater than in the broadcast seeding in fully tilled soils. The improvement in chickpea yields was attributed to greater plant numbers, early plant vigour and root growth. Chickpea roots were found to 60 cm depth in the soil profile, and soil water content was less than the θv of wilting point to this depth at podding. There is evidence that root growth and plant water uptake occur deeper in these soil profiles to achieve the grain yields > 1,000 kg/ha recorded in this study. Mechanised sowing in rows with small‐scale seeders has the capability to overcome establishment and yield limitations for chickpea on medium to heavy soils in the post‐rice season.

中文翻译：

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土壤扰动水平、土壤含水量和雨养鹰嘴豆的建立：孟加拉国西北部小农农场的机械化播种选择

与在许多传统南亚种植实践中常见的广播播种相比，使用计量播种和受控深度播种的机械化行播更有可能实现作物生长的最佳土壤物理条件。在恒河平原东部的中等至重质地土壤中，种植成功是水稻后作物的一个限制，因为播种与表土快速干燥和土壤强度增加同时发生。此外，由于后稻季降雨不足，作物在营养和生殖生长期间依赖于储存的土壤水来获得足够的产量。我们的目的是确定减少土壤扰动（从全耕到零耕 (ZT) 到未扰动的土壤（休耕））和直播（使用小规模播种机）是否可以 1）通过保护苗床土壤水分和 2 ) 改变储存在土壤剖面中的水的作物用水。在田间持水量下，粉砂壤土的估计体积土壤含水量 (θv) 为 34%。播种时，苗床中的 θv 在 25% 到 29% 之间。这对于成功建立鹰嘴豆作物来说是足够的，但比最佳耕作略湿。在播种时潮湿的土壤中，有证据表明在条播（SP；尖齿前的旋转叶片）和 ZT 中，苗床中的犁沟壁被涂抹并且土壤覆盖不良。未覆盖的犁沟（在 ZT 中；使用开沟器），休耕土壤比土壤扰动程度更高的苗床失去更多的表层土壤水分（9%，播种后 23 天）。2008 年，单程浅耕（SPST）的粮食产量大于 SP，但 2009 年，所有单程耕作技术（ZT、SP、SPST）的粮食产量均高于全耕土壤的广播播种。鹰嘴豆产量的提高归因于更多的植物数量、早期植物活力和根系生长。在土壤剖面中发现鹰嘴豆根部深度为 60 cm，并且在结荚时土壤含水量小于该深度的萎蔫点 θv。有证据表明，根系生长和植物吸水在这些土壤剖面中发生得更深，以实现本研究中记录的 > 1,000 kg/ha 的谷物产量。