油菜直播机分层定量施肥装置设计与试验

针对长江中下游地区现有油菜直播同步肥料混施作业,肥料施用方式粗放的问题,结合油菜厢面条播种植模式及油菜根系生长规律,该研究提出了一种基于肥料流均匀分布的上下层肥量按比例分配、上层肥料左右分施技术,设计了一种分层定量施肥装置,通过构建肥料在均布器中均匀分散的状态转移矩阵验证该装置的肥料均布效果,并确定了装置的基本参数。以挡杆直径、挡杆组数、挡杆组间距为试验因素,实际施肥比例与目标施肥比例最小误差为目标,利用二次回归正交旋转组合仿真试验确定肥料均布装置的最优结构参数为挡杆直径3 mm、挡杆组数5、挡杆组间距8.9 mm。为进一步验证肥料比例调节分配机构性能,以目标施肥比例与实际施肥比例的误差、上下层落肥管排肥量稳定性变异系数和上层落肥管左右两侧排肥量稳定性变异系数为评价指标,开展最优参数组合下的排肥性能试验。试验结果表明,上下层实际施肥比例与目标施肥比例的最大误差为4.1个百分点,排肥量稳定性变异系数低于3.9%,说明肥料分配比例稳定;上层左右落肥管实际施肥比例与目标施肥比例的误差低于4.1个百分点,排肥量稳定性变异系数低于4.8%,满足上层肥料按比例分施要求。田间试验表明,下层肥料平均施肥深度为141.2 mm,上层左侧肥料平均施肥深度为81.9 mm,右侧平均施肥深度为81.6 mm,上层左、右侧肥料间的平均间距为67.8 mm,满足油菜分层施肥要求。该研究可为油菜肥料按比例分层施用提供技术支撑。

Design and experiments of layered and quantitative fertilization device for rapeseed seeder

Overuse of chemical fertilizers is one of the important factors that cause the agricultural nonpoint source pollution to aggravate in precise agriculture. The middle and lower reaches of the Yangtze River are the main producing areas of oilseed rape in China. In sowing, the mixed and extensive application of chemical fertilizers with low utilization has become a severe restriction on the sustainable production of rape in green agriculture. Layered and quantitative fertilization is an alternative way to reduce the excessive amount, while increasing the efficiency of chemical fertilizers. In layered fertilizing, the proportion of fertilizers in the upper and lower layer can be accurately controlled with a high utilization rate for the later advantageous growth of crops in different areas. However, the traditional extensive mode of operation has posed a great challenge on the direct seeding of rapeseed in the middle and lower reaches of the Yangtze River. In this study, a layered and proportional fertilizing device was proposed for the uniform distribution of fertilizer flow in a rape seeder, according to the planting and growth pattern of the root system. A proportional control system was applied to adjust the amount of fertilizer in the upper and lower layers, while separately fertilizing at the left and right of the upper layer. A quadratic regression orthogonal test was conducted to take the diameter of blocking rod, the number of the blocking rod groups, and the distance between blocking rods as the experimental factors. The optimal structural parameters of the device were determined: the rod diameter was 3 mm, the number of rod groups was 5, and the distance between the rods was 8.9 mm. A performance test of fertilizer discharge was carried out under the optimal combination of parameters. The evaluation indexes were set as the error between the target fertilizing ratio and the actual fertilizing ratio, the variation coefficient of stable discharge volume for the upper and lower pipes, and the variation coefficient of stable discharge volume for the left and right sides of the upper pipe. The test results showed that the maximum error between the actual and target fertilizing ratio was 4.1 percentage points for the upper and lower layers, indicating very little influence on the later growth of rape. The variation coefficient of stable fertilizer discharge in the upper and lower layers was lower than 3.9%, indicating a stable distribution of fertilizer ratio for the standard requirements in the layered fertilization of rape. The error between the actual and target fertilizing ratio was less than 4.1 percentage points in the upper pipe, meaning an excellent fertilization effect for the standard requirements in the upper layer. The variation coefficient of stable discharge volume was lower than 4.8% in the upper pipe. There was no obvious relationship with the rotational speed of the discharge device, indicating excellent stability of discharge volume for the left and right sides. The field test showed that the fertilizing device was stable for the high requirements in the layered fertilization of rape. This finding can provide potential technical support for the proportional layering of fertilizer during large-scale production of oilseed rape.