Devkota Krishna Prasad, Yadav Sudhir, Humphreys E, Kumar Akhilesh, Kumar Pankaj, Kumar Virender, Malik R K, Srivastava Amit K
International Rice Research Institute (IRRI), Los Baños, Laguna, The Philippines.
African Sustainable Agriculture Research Institute (ASARI), Mohammed VI Polytechnic University (UM6P), Laayoune, Morocco.
Agric Water Manag. 2021 Sep 1;255:107036. doi: 10.1016/j.agwat.2021.107036.
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), reduced irrigation amount by 20% (40 mm) and increased WPi by 34% (1.0 kg m) 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.
激光平地技术在印度和巴基斯坦印度河—恒河平原的稻麦（RW）和玉米—小麦（MW）种植系统中迅速推广。目前的做法是将土地平整为零坡度（0%），而在发达国家通常采用小坡度（如0.1%）。因此，在恒河平原东部的农民地块（约15米×40米）上进行了试验，以评估0.1%坡度的激光平地与0%坡度平地以及农民传统平地做法（FL）相比的效果。该研究在RW和MW种植系统中进行了两年时间。在MW种植系统中，还评估了坡度为0%和0.1%的激光平地地块上的高畦。与FL相比，坡度为0%的激光平地显著减少了所有在平地上种植的作物/系统的灌溉量和/或提高了灌溉水生产率（WPi），MW种植系统中的小麦除外。虽然与FL相比，0%坡度的产量有持续增加的趋势，但在任何作物/系统中差异均不显著。对于RW种植系统，结果表明与0%坡度平地相比，0.1%坡度平地在灌溉量和WPi方面的收益不显著或仅有少量收益。在该系统中，到目前为止，最大的收益来自从FL转变为0%坡度的激光平地。这使得灌溉量大幅减少，两种作物的WPi都大幅提高（约40%），而产量不受影响。采用FL种植水稻无利可图，但0%坡度的激光平地显著提高了水稻、小麦以及整个RW种植系统的毛利润。对于RW种植系统，与FL相比，平整为0%坡度的平地显著提高了MW种植系统中两种作物的WPi，但提高幅度较小。与激光平地的平坦地块相比，高畦使玉米产量显著提高8%（0.5吨/公顷），灌溉量减少20%（40毫米），WPi提高34%（1.0千克/立方米）。MW种植系统中高畦的毛利润比FL高17 - 20%，0.1%坡度高畦的毛利润显著高于平坦地块上任何一种坡度的毛利润。结果表明，与0%坡度相比，0.1%坡度平地的收益微不足道；然而，如果将小农户地块合并为更大农田的目标成为现实，且灌溉流量和排水能力相应增加，这种情况可能会改变。
