Effect of eucalyptus proximity and weed presence on soybean grown in a CFI system
The growing demand for food, bioenergy, and forest products requires solutions that encourage socioeconomic development without compromising the sustainability of natural resources. It is in this scenario that the integration strategy has been pointed as an alternative to reconcile conflicts of interest. This study evaluates possible changes in nodulation, photosynthetic efficiency, and yield of soybean grown in a Crop-Forest Integration system with eucalyptus as a tree component. The experiment was conducted in a randomized complete block design with four replications. Treatments were arranged in a 3x5 factorial scheme, corresponding to three sowing conditions (near eucalyptus stands; 3.0 meters away from the stands, in a clean seedbed; and 3.0 m away from the stands, among the vegetation) and five points of distance between soybean and the stands, represented by planting rows, namely: 1st, 2nd, 3rd, 11th, and 21st row. We evaluated morphophysiological and productive variables of soybean plants. Soybean cultivation near eucalyptus stands does not affect the number and dry matter of soybean nodules, but reduces yield in the first two rows. The presence of weeds in the range between eucalyptus stands and soybean plants impaired the photochemical apparatus and the chlorophyll α fluorescence of soybean crop, decreasing the shoot dry matter accumulation, number and dry matter of nodules, and yield of plants present in the first planting rows.