Does the intercropping with legumes provide a higher nitrogen content in the forage?

Abstract

Pasture renewal grows every day in Brazil, especially when the production system is the crop-livestock integration. The adoption of this system is important for the recovery of degraded pastures, especially in regions with sandy soils. The major challenge in this environment is to increase the productivity of forages, especially in winter, when there is no nitrogen fertilization efficiency. For this to happen, nitrogen input into the system is critical. Due to the impracticability of application and mineral N in the dry period, the contribution through biological nitrogen fixation (BNF) may be a promising alternative. Therefore, the objective of this work will be to evaluate if during the intercropping of legumes with grasses occurs the transfer of N between species. The experimental design will be completely randomized in factorial 3x2, with 4 replications. The treatments will consist of Brachiaria brizantha cv. Paiaguás (single, intercropped with cowpea and intercropped with soybean) combined with two levels of phosphorus (P) in the soil (75 and 150 mg dm-3). The evaluations to be performed will be: analysis of gas exchange, nitrate reductase enzyme activity, biometric measurements in brachiaria (number of tillers, shoot and root dry matter and leaf stem ratio), biometric measurements in soybean and cowpea (shoot and root dry matter, number and dry mass of nodules), nitrogen and phosphorus content in the brachiaria, bromatological analysis of the brachiaria, dry matter of the brachiaria after regrowth. The results will be analyzed by analysis of variance (ANOVA, p <0.05). The mean values will be compared by Tukey test and Pearson correlation test (p d 0.05). (AU)