Effects of center pivot sprinkler fertigation on the yield of continuously cropped soybean.

Continuous cropping is a common agricultural practice in Northeast China. Focusing on soybeans cropped continuously for two consecutive years, this article fully explores the effects of the amount of water, fertilizing rate, and fertilizing method on the growth and yield of soybean. Specifically, an orthogonal experimental plan was designed involving these three factors. Each factor was divided into three levels: the amount of water was set as 52.62 mm (W1), 73.41 mm (W2), and 138.6 mm (W3); the fertilizing rate was set as 6.75 kg/hm2 (N1), 9.75 kg/hm2 (N2), and 13.5 kg/hm2 (N3); and the fertilizing method was set as center pivot sprinkler (CPS) fertigation (F1), microspray (MS) fertigation (F2), and MS fertilizing + CPS spraying and leaching (F3). During the experiments, the growth traits at each growth stage were monitored, and the soybean yield was measured. The following results were obtained through the analysis of the experimental data: the amount of water significantly affects the growth traits of soybean in the early stage of growth; the fertilizing rate greatly affects the stem diameter; and the fertilizing method is a major influencer of soybean yield. The highest yield (2811.88 kg/hm2) was observed in zone 4 (W2N1F2). This means irrigation and fertilization are very important to the normal growth of continuously cropped soybean; the yield loss induced by continuous cropping can be mitigated effectively through timely and adequate irrigation and topdressing, plus fertilization by the suitable method. To prevent yield loss, farmers in Northeast China are suggested to replace continuous cropping with crop rotation. If continuous cropping is unavoidable, foliage fertilizer should be sprayed timely for topdressing at the flowering and seed-filling stages.