Agronomic performance of maize and Brachiaria grasses cultivated at monocropping and intercropping in a compacted Latossolo

Abstract

Obtaining adequate yields by intercropping maize and grasses in soils with poor physical quality is a challenge for managing crop-livestock systems in the Cerrado region. The aim of the present study was to verify the viability of maize in intercropping with Brachiaria grasses in the second crop season in a physically degraded Latossolo. The experiment was carried out in accordance with a split-plot completely randomized block design with four replications. Seven treatments (T) were evaluated in the plots: Brachiaria brizantha cv. Paiaguas (p), Brachiaria brizantha cv. Xaraes (x), Brachiaria ruziziensis (r) and maize (m) as monocrops (Tp1, Tx1, Tr1 and Tm1) and maize in intercropping with each of the three Brachiaria species (Tp2, Tx2 and Tr2). Two grass management systems were evaluated in each subplot: with (M1) and without simulated grazing (M2) of the grasses. Soil physical quality was estimated by the least limiting water range of undisturbed soil samples collected at layers of 0-0.05, 0.05-0.10 and 0.10-0.20 m. Crop agronomic yield evaluations were carried out for maize, and both the forage biomass and mulch biomass of the grasses were evaluated. Water deficit during the reproductive crop phase and soil compaction explained the low productivity observed in the experiments. The replacement of the maize crops with pasture during the second crop season is indicated in physical degradation soil conditions. Use of the Brachiaria ruziziensis grass in the intercropping system under simulated pasture grazing resulted in a satisfactory forage yield in the off-season and was the best alternative for oversowing in the intercropping systems. Mulch biomass production in intercropping systems with simulated grazing did not reach adequate amounts for soil cover, and suppression of the last cut could potentially result in increased biomass accumulation and system viability. Overall, it is recommended that maize cultivation during the second crop season in Brazil be preceded by a soil compaction diagnosis.