Matin Md A, Hossain Md I, Gathala Mahesh K, Timsina Jagadish, Krupnik Timothy J
International Maize and Wheat Improvement Center (CIMMYT), Gulshan 2, Dhaka, 1212, Bangladesh.
Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur 1701, Bangladesh.
Soil Tillage Res. 2021 Mar;207:104854. doi: 10.1016/j.still.2020.104854.
Fine-textured clayey soils dominate Asian rice fields that are kept either fallow or cultivated with non-rice crops after harvest of monsoon rice. Use of seeding machinery compatible with the principles of conservation agriculture on such soils, however, has not been promising. Under these conditions - which predominate the population and poverty dense areas of coastal South Asia - such machinery fails to open a furrow or throws excessive soil out of the tilled furrow during strip-till seeding. This results in a poor seed coverage at planting jeopardizing crop establishment. In response, this soil bin study investigated strip-tillage blade designs and settings to optimize rotary strip-till system for wet clay soil conditions common in South Asian rice fields. Three designs of C type rotary blade (conventional, medium and straight) and two blade settings (four and six blades per row; 50 and 100 mm cutting widths) were tested at three blade operating depths (50, 75, and 100 mm) using a tillage test rig and a soil bin, and a high-speed camera to understand the processes of soil cutting, throwing, backfilling, and creation of furrow seedbed. The soil bin soil consisted of a wet sandy-clay-loam soil with a moisture content of 28.2% (85% of field capacity) and was compacted to the bulk density of 1440 kg m. Using the test rig, rotary speed of the blades was maintained at 480 rpm and forward speed at 0.4 m s. At four blades per row setting, all blades created high amounts of optimum clods (1-20 mm size). The conventional and medium blades threw too much soil out of the strip-tilled furrow while the straight blade created adequate backfill at 75 and 100 mm operating depths. At 6 blades per row setting, all blades produced high amounts of backfill at any depths, but the straight blade also produced the highest amounts of optimum clods and a uniform furrow. Considering machine and energy costs, blade performance, and the necessity of minimizing soil disturbance in strip-tillage, our study indicates that the use of straight blades (four blades per row) operated at a depth of 75 or 100 mm are more ideal. These specifications are likely to enhance strip-tillage stand establishment in fine-textured soils with high moisture contents, though further work is needed under actual field conditions to confirm suitability of the proposed strip-till system for crop establishment in currently fallowed as well as the intensively cropped lands of Asia.
质地细腻的黏质土壤在亚洲稻田中占主导地位，这些稻田在季风稻收获后要么休耕，要么种植非水稻作物。然而，在这类土壤上使用符合保护性农业原则的播种机械，效果并不理想。在南亚沿海人口密集且贫困的地区，这种情况很常见，在带状免耕播种过程中，此类机械无法开出犁沟，或者将过多土壤抛出已耕作的犁沟。这导致播种时种子覆盖效果不佳，危及作物定植。作为应对措施，这项土槽试验研究了带状耕作刀片的设计和设置，以优化适用于南亚稻田常见湿黏土条件的旋转带状耕作系统。使用耕作试验台、土槽以及高速摄像机，在三个刀片作业深度（50毫米、75毫米和100毫米）下，对三种C型旋转刀片设计（常规型、中型和直型）以及两种刀片设置（每行四个和六个刀片；切割宽度50毫米和100毫米）进行了测试，以了解土壤切割、抛掷、回填以及犁沟苗床形成的过程。土槽中的土壤为湿砂质黏壤土，含水量为28.2%（田间持水量的85%），压实后的容重为1440千克/立方米。使用试验台时，刀片的转速保持在480转/分钟，前进速度为0.4米/秒。在每行四个刀片的设置下，所有刀片都产生了大量尺寸适宜的土块（1 - 20毫米）。常规刀片和中型刀片将过多土壤抛出带状耕作的犁沟，而直型刀片在75毫米和100毫米的作业深度下产生了足够的回填土。在每行六个刀片的设置下，所有刀片在任何深度都产生了大量的回填土，但直型刀片还产生了数量最多的尺寸适宜的土块，并形成了均匀的犁沟。考虑到机械和能源成本、刀片性能以及在带状耕作中尽量减少土壤扰动的必要性，我们的研究表明，使用每行四个刀片的直型刀片，在75毫米或100毫米的深度下作业更为理想。这些规格可能会提高在高含水量的质地细腻土壤中的带状耕作定植效果，不过还需要在实际田间条件下做进一步研究，以确认所提议的带状耕作系统对亚洲目前休耕以及集约种植土地上作物定植的适用性。
