Integrated crop-livestock systems (ICLS) are diversified agroecosystems characterized by the rotation, succession or mixtures of agricultural, livestock or forestry activities, in no-tillage systems. In ICLS with trees, the tree modifies the light and water availability, and might generate root competition for nutrients, like potassium (K). The study aims to evaluate dry matter (DM) and macronutrients accumulation in white oat, DM and grain yield of maize, and the K use efficiency (KUE) by these crops cultivated in an ICLS with eucalyptus. The experimental design was a randomized block in a split-plot design with three replications. Plots consisted of four cultivation positions (CP) between the tree rows, where CP1 (0 to 4 m distance) refers to a position close to the trees; CP2 (4 to 8 m distance) and CP4 (12 to 16 m distance) corresponds to two intermediate positions between rows; and CP3 (8 to 12 m distance) corresponds to a central position between rows. In subplots, four potassium oxide (K₂O) annual doses were assigned, with potassium chloride being applied on the surface, where each rate was half the rate applied at sowing of each crop. DM and macronutrients accumulation in white oat shoot decreased due to eucalyptus shadow (64.5% light restriction). Responses of maize DM and grain yield to K₂O addition were different among CPs, possibly owing to different light patterns. No changes in the maize yield were observed with K₂O application in CP1 and CP2. However, for other positions, quadratic responses in grain yield were observed. In ICLS with eucalyptus in a subtropical region of Brazil, the reduction of K fertilization led to lower yields in white oat and maize. As KUE was high in plots with low K rate, the production cost in ICLS with trees may be decreased if massive production is not required.

中文翻译：

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免耕农牧一体化体系中白燕麦和玉米的钾肥施肥

综合作物畜牧系统 (ICLS) 是多样化的农业生态系统，其特点是在免耕系统中进行农业、畜牧业或林业活动的轮作、演替或混合。在有树木的 ICLS 中，树木改变了光和水的可用性，并可能导致根部竞争养分，如钾 (K)。该研究旨在评估白燕麦中干物质 (DM) 和常量营养素的积累、玉米的 DM 和谷物产量，以及这些作物在 ICLS 和桉树中种植的钾素利用效率 (KUE)。实验设计是具有三个重复的裂区设计中的随机区组。地块由树行之间的四个栽培位置 (CP) 组成，其中 CP1（0 到 4 m 距离）是指靠近树木的位置；CP2（4~8m 距离）和CP4（12~16m 距离）对应行间的两个中间位置；CP3（8～12m的距离）对应于行间的中心位置。在子图中，四氧化钾（K₂ O) 指定年剂量，在表面施用氯化钾，其中每次施用量是每种作物播种时施用量的一半。由于桉树阴影（64.5% 光照限制），白燕麦枝条中 DM 和常量营养素的积累减少。玉米 DM 和谷物产量对 K ₂ O 添加的响应在 CPs 之间不同，可能是由于不同的光照模式。使用 K _{2 未}观察到玉米产量的变化O 在 CP1 和 CP2 中的应用。然而，对于其他位置，观察到谷物产量的二次响应。在巴西亚热带地区种植桉树的 ICLS 中，钾肥施用量的减少导致白燕麦和玉米的产量降低。由于 KUE 在 K 率低的地块中较高，如果不需要大规模生产，ICLS 的生产成本可能会降低。