Laser land levelling is expanding rapidly in the rice-wheat (RW) and maize-wheat (MW) systems of the Indo-Gangetic Plains of India and Pakistan. Current practice is to level to zero (0%) gradient, whereas a small gradient (e.g. 0.1%) is typically used in developed countries. Therefore, experiments were conducted in farmers’ plots (~15 m x 40 m) in the Eastern Gangetic Plains to evaluate laser levelling with a 0.1% gradient in comparison with 0% and farmer levelling practice (FL). The study was conducted over two years in RW and MW systems. In the MW system, raised beds in plots lasered with 0% and 0.1% gradients were also evaluated. Laser levelling with 0% gradient significantly reduced irrigation amount and/or increased irrigation water productivity (WPi) in all crops/systems grown on the flat compared to FL except for wheat in the MW system. While there was a consistent trend for higher yield with a 0% gradient compared with FL, the differences were not significant in any crop/system. For the RW system, the results suggest no to marginal benefits in irrigation amount and WPi from levelling with a 0.1% gradient in comparison with 0% gradient. In that system, by far the bigger gains were from changing from FL to laser levelling with 0% gradient. This resulted in substantial reductions in irrigation amount, which greatly increased WPi in both crops (by ~40%), while yield was not affected. Rice grown with FL was not profitable, but lasering with 0% gradient significantly increased gross margin for rice, wheat and the total RW system. As for the RW system, levelling to 0% with a flat configuration significantly increased WPi of both crops in the MW system compared to FL, but by a lesser proportion. Raised beds significantly increased yield of maize by 8% (0.5 t ha⁻¹), reduced irrigation amount by 20% (40 mm) and increased WPi by 34% (1.0 kg m⁻³) in comparison with the laser levelled flat plots. Gross margin of the MW system on beds was 17–20% higher than FL, and gross margin with beds on a 0.1% gradient was significantly higher than either gradient on the flat. The results suggest that the gains from levelling with a 0.1% gradient compared to 0% are marginal; however, this may change if the goal of consolidation of small farmer plots into larger fields becomes a reality provided there is a proportionate increase in irrigation flow rates, and ability to drain.

在印度和巴基斯坦的印度恒河平原的水稻-小麦 (RW) 和玉米-小麦 (MW) 系统中，激光土地平整正在迅速扩大。目前的做法是将梯度调平到零 (0%)，而发达国家通常使用小梯度（例如 0.1%）。因此，我们在恒河东部平原的农民地块 (~15 m x 40 m) 中进行了实验，以评估 0.1% 梯度的激光平整度与 0% 和农民平整实践 (FL) 的比较。该研究在 RW 和 MW 系统中进行了两年多的时间。在 MW 系统中，还评估了用 0% 和 0.1% 梯度激光照射的地块中的凸起床。与 FL 相比，除 MW 系统中的小麦外，0% 梯度的激光整平显着减少了灌溉量和/或增加了种植在平地上的所有作物/系统的灌溉水生产率 (WPi)。虽然与 FL 相比，0% 梯度具有更高产量的一致趋势，但在任何作物/系统中差异都不显着。对于 RW 系统，结果表明，与 0% 梯度相比，0.1% 梯度平整在灌溉量和 WPi 方面没有到边际效益。在该系统中，到目前为止，更大的收益来自从 FL 更改为 0% 梯度的激光整平。这导致灌溉量大幅减少，这大大增加了两种作物的 WPi（约 40%），而产量并未受到影响。用 FL 种植的水稻没有盈利，但 0% 梯度的激光显着增加了水稻、小麦和整个 RW 系统的毛利率。对于 RW 系统，与 FL 相比，将 MW 系统中两种作物的 WPi 以平坦配置调平至 0%，但比例较小。高架床使玉米产量显着提高了 8%（0.5 吨公顷^-1 )，与激光平整的平地相比，灌溉量减少了 20% (40 mm)，WPi 增加了 34% (1.0 kg m ^-3 )。MW 系统在床上的毛利率比 FL 高 17-20%，在 0.1% 梯度上的床的毛利率显着高于平板上的任一梯度。结果表明，与 0% 相比，0.1% 梯度调平的收益是微不足道的；然而，如果灌溉流量和排水能力成比例增加，将小农田合并为大田的目标成为现实，这种情况可能会改变。