Banca de QUALIFICAÇÃO: EDINELIA ROOS

CULTIVATION OF CORN IN INTERCONSORTIUM WITH FORAGE IN DIRECT AND CONVENTIONAL PLANTING AND ITS EFFECTS ON SOIL AND CROPS ATTRIBUTES

Tropical Forages; Crop-Livestock Integration; Productivity; Cropping System.

The implementation of integrated systems promotes nutrient cycling and improves soil quality. However, in the Amazon region, traditional soil use is common, which can cause significant damage and reduce the productivity of subsequent crops. This makes the adoption of conservationist strategies for soil management and conservation increasingly necessary. Thus, the present research aimed to evaluate the effect of intercropping corn with different forage species, cultivated under both no-till and conventional systems, on corn productivity and the soil’s physical-chemical properties. The experiment was conducted in the municipality of Vilhena/RO (12°46'15.00"S - 60°5'50.48"W), during the period between 2023 and 2024. The selected corn cultivar was the MG 447 PWU hybrid, and the forage species sown between corn rows were Brachiaria brizantha (piatã, marandu, and xaraés cultivars), and Panicum maximum (mombaça and miyagi cultivars). The soil’s physical attributes evaluated were: bulk density, total porosity, macroporosity, microporosity, and water infiltration rate. For chemical attributes, the following were evaluated: potential acidity, pH in water, exchangeable aluminum, exchangeable calcium, magnesium, and potassium, available phosphorus, base saturation, potential CEC, effective CEC, base saturation percentage, aluminum saturation percentage, and soil organic matter. Regarding forage productivity, the green and dry biomass of the aerial parts were assessed. For corn, the following were evaluated: plant height to the first ear insertion, ear length, stem diameter, ear diameter, number of grains per row, rows of grains per ear, number of grains per ear, P.1000G, grain yield in sacks, and kilograms per hectare. A randomized block design was used in a 2x6 factorial scheme. Factor 1 consisted of the cropping system, and Factor 2 consisted of the intercropping of corn with the forage species. An analysis of variance was performed, and means were compared using the Scott-Knott test at a 5% probability level. In general, bulk density was higher in the no-till system, and there were no significant differences for total porosity, macroporosity, and microporosity between the evaluated systems. However, differences were observed among treatments in the 2024 season. No interactions were found for the water infiltration rate in the soil between the systems or treatments. The pH showed no significant interactions. In the no-till system, soil organic matter in the 10-20 cm layer during the second year of evaluation showed differences between systems, with miyagi and mombaça presenting higher average values. The phosphorus content in the no-till system was higher in the surface layer during both years of evaluation. Potassium content was also higher in the surface layer, and exchangeable calcium and magnesium showed no significant interactions. Base saturation percentage remained above 50%, differing only in the 2023 season in the surface layer. Green and dry biomass of the forage species showed no significant differences, with higher averages in the intercropping of corn with the miyagi and mombaça cultivars in the no-till system. Corn yield in kg.ha^-1 showed no significant differences. The piatã and mombaça cultivars showed significant differences for P.1000G between the systems only in the first year of evaluation. The results found in this research indicate that the intercropping of corn with the miyagi and mombaça cultivars resulted in better averages for corn productivity. Additionally, the intercropping with different forage species and planting systems influences the physical-chemical properties of the soil. However, further studies are needed to evaluate such influences on soil attributes in the long term.