Abstract: An adequate and uniform seeding depth is crucial for the homogeneous development of a crop, as it affects time of emergence and germination rate. The considerable depth variations observed during seeding operations-even for modern seed drills-are mainly caused by variability in soil resistance acting on the drill coulters, which generates unwanted vibrations and, consequently, a non-uniform seed placement. Therefore, a proof-of-concept dynamic coulter depth control system for a low-cost seed drill was developed and studied in a field experiment. The performance of the active control system was evaluated for the working speeds of 4, 8 and 12 km/h, by testing uniformity and accuracy of the coulter depth in relation to the target depth of -30 mm. The evaluation was based on coulter depth measurements, obtained by coulter position sensors combined with ultrasonic soil surface sensors. Mean coulter depth offsets of 3.5, 5.3 and 6.3 mm to the target were registered for the depth control system, compared to 8.0, 9.1 and 11.0 mm without the control system for 4, 8 and 12 km/h, respectively. However, speed did not affect the coulter depth significantly. The control system optimised coulter depth accuracy by 15.2% and at 95% confidence interval it corresponded to an absolute reduction in the coulter depth confidence span of 10.4 mm. The spatial variability, due to variation in soil mechanical properties was found to be ±8 mm, across the blocks for the standard drill and when activating the coulter depth control system this variability was reduced to ±2 mm. The system with the active control system operated more accurately at an operational speed of 12 km/h than at 4 km/h without the activated control system.

Key words: seed drill, coulter depth control system, spring barley, precision seeding

摘要： 适当且均匀的播种深度对作物的发育至关重要,因为它会影响出苗时间和发芽率。在播种作业中的深度变化主要是由于作用在播种机犁刀上土壤阻力的变化引起的,产生的振动导致播种深度不均匀。为此,研制一种低成本概念播种机,并验证动态犁头深度控制系统,并进行田间试验研究。在4 km/h、8 km/h和12 km/h的工作速度下进行主动控制系统的性能评估,测试控制犁头深度为-30 mm时的均匀性和准确性。由犁头位置传感器结合超声波土壤表面传感器获得犁头深度测量数据,在4 km/h、8 km/h和12 km/h作业速度时,系统控制深度与目标犁头平均深度偏移量分别为3.5 mm、5.3 mm和6.3 mm,而没有控制系统时,犁头平均深度偏移量分别为8.0 mm、9.1 mm和11.0 mm。可见,速度对犁头深度控制效果没有显著影响。该控制系统将犁头深度精度优化了15.2%,在95%置信区间下,犁头深度置信范围的绝对降幅为10.4 mm。由于土壤力学特性的变化,标准犁头的深度变异性为±8 mm,当激活犁头深度控制系统时,该变异性降低到±2 mm。采用主动控制系统在12 km/h的运行速度下,比未采用主动控制系统在4 km/h运行速度时的深度控制更准确。

关键词: 条播机, 犁头深度控制系统, 春小麦, 精密播种