Study On Precision Depth-control Mechanism Of Corn No-till Planter In Double-cropping Area

Corn planting has been usually carried out in field covered with stubble on the North China Plain where the main cropping system is annual wheat-corn double cropping. As the existence of wheat straw and stubble, it was difficult to maintain good sowing performance, especially the planting depth uniformity. Conventional corn no-till planters were usually lack of depth-control mechanism, and their planting depth were adjusted by tractor driver, while some no-till planter with rear gauge wheel resulted in profiling lag. The existing planter with side gauge wheels cannot apply to this area directly due to its structure and size. Based on the situations above, this paper presented a depth-control method with single-side gauge wheel, and then developed depth-control mechanism with single-side gauge wheel as well as V-shape closing wheel, followed with field experiment.The main results of this paper are as follows:(1) Relationship between emergence time and planting depth as well as seed direction was studied, and the significance of planting depth-control research was defined. Planting depth range for conformance requirements of emergence time were obtained through the study. The influence of gauge wheel pressure and closing wheel pressure for planting depth uniformity and seeding growth were experimented, as a result, optional pressure of closing wheel was 200N, while the pressure of gauge wheel should be more than 750N. This study provided a basis for planting depth-control mechanism.(2) Depth-control method of single-side gauge wheel were put forward applying planting depth stability theory and kinetic analysis, based on the existing depth-control mechanism of no-till planter. Depth-control mechanism of single-side gauge wheel was developed to achieve uniform planting depth by the manner that making running track of single-side gauge wheel and fertilizer opener’s ditch get together.(3)The movement and ditching cross-section of soil particles on different ditching depth were analyzed compared with actual field experiment performance. The influence of parallel four-bar linkage length, radius of gauge wheel as well as down fore on planting depth uniformity were studied by ADAMS. The result was that optional length of four-bar linkage was 350-400mm; the suitable radius of gauge wheel was 380mm, while the down force should be more than 600N.(4) A field experiment was conducted to compare the performances of depth-control mechanism of single-side gauge wheel with two conventional depth-control mechanism (depth-control mechanism of a double-side gauge wheel and a rear gauge wheel) by testing in fields with two different amounts of stubble (0.78 kg/m2 and 0.64 kg/m2). The results showed that with depth-control mechanism of single-side gauge wheel, the quality of seeding depth index, coefficient of variation of depth, the quality of emergence time index and the quality of feed index was 95.45%,13.91%,87.87% and 91.90% respectively, which was better than the other two kind of depth-control mechanism. The depth-control mechanism of single-side gauge wheel had good passing ability with simple structure and working reliability in field covered with stubble, which can be applied to corn no-till planting in double cropping area.