Impact of the Nitrogen on Nutrient Dynamics in Soybean–Grass Intercropping in a Degraded Pasture Area

The development of an efficient agricultural system depends on the correct choice of crops and the management of nutrient supply and distribution within the system. This study aimed to determine how nitrogen (N) rates applied to rows of maize and tropical grass during the autumn-winter season (previous crop) influence subsequent intercropped plants. Treatments were arranged in a randomized complete block design with a split-plot scheme and four replications. The main plots comprised three cropping systems: soybean monoculture, soybean intercropped with Aruana Guinea grass (<i>Megathyrsus maximus</i> cv. Aruana), and soybean intercropped with Congo grass (<i>Urochloa ruziziensis</i> cv. Comum). The subplots consisted of four N rates (0, 50, 100, and 150 kg ha^-1) applied to the rows of maize and tropical grass during the previous crop. Macronutrient accumulation and efficiency indices were determined for intercropped plants. Aruana Guinea grass increased the accumulation of N, phosphorus (P), potassium (K), and sulphur (S) in the soybean crop. N applied to the previous crop negatively affected the accumulation of P, K, and S in soybean monoculture. The maximum physiological efficiency of soybean was related to N supply. The efficiency indices for Aruana Guinea grass highlighted its ability to recover residual N applied to the previous crop.