Feijão caupi cultivado em solo proveniente de área de pastagem de Brachiaria brizantha adubada com cinza vegetal e inoculado com Rhizobium tropici

Abstract

Cowpea (Vigna unguiculata L. Walp.) is considered a rustic crop that adapts to different climate and soil conditions, with high genetic variability, ensuring its versatility and use in different production systems. The objective of this study was to evaluate the development of cowpea cultivated in soil from a Brachiaria brizantha pasture area fertilized with vegetable ash and inoculated with Rhizobium tropici. The experiment was carried out in a greenhouse, located at the Federal University of Rondonópolis. The soil used was collected in an area originating from the cultivation of B. brizantha cv Paiaguás, in which vegetable ash was applied at doses of 0, 8, 16, 24 and 32 t ha-1 and two forms of ash application: incorporated and not incorporated into the soil. For the experiment in a greenhouse, the same factorial scheme of the field cultivation was used (5x2 – doses of ash and forms of application), where the soil was collected in the points corresponding to each dose of ash. The experimental design was completely randomized, with four replications, totaling 40 experimental units, composed of pots with capacity for 5 dm-3 of soil and sown with cowpea, cultivar BRS Imponente, and inoculated with the MT 15 strain of R. tropici. The variables analyzed were plant height, falker chlorophyll index, stem diameter, shoot and root dry mass, root volume, number of nodules and nitrogen concentration in shoot, root and shoot + root. The maximum yields of cowpea were observed in the range of vegetable ash doses between 16 to 32 t ha-1 , except for the number of nodules and root nitrogen concentration, which did not obtain significant results. In addition, the analysis of nitrogen concentration of shoot and shoot + root showed better results without the addition of plant ash, regardless of management. Vegetable ash showed efficiency as a fertilizer, with emphasis on the incorporated management and inoculation of the MT15 strain, which fixes the nitrogen necessary for the development of cowpea plants.