Initial Development of Cowpea Submitted to Wood Ash Doses

Cowpea (Vigna unguiculata (L.) Walp.) constitutes one of the principal protein sources for the economically constrained low-income sector. The composition of the wood ash reveals macro and micronutrients, which form an alternative source of high-added value fertilizers, very suitable for low-cost farming systems. The aim of this study was to estimate the use of wood ash as a fertilizer during the early developmental stages of the cowpea. A randomized block design with four replications was selected for the experiment. It was performed in a greenhouse, in pots 1.5 dm-3 capacity, to which five wood ash doses (0, 8, 16, 24 and 32 g dm-3) were added. The following variables were analyzed, viz. plant height, stem diameter, number of leaves, chlorophyll index, shoot and root dry masses, mass and number of nodules, water consumption and water use efficiency. Increased values of plant height, stem diameter and number of leaves were observed post the addition of the following doses of wood ash: 24.61, 23.25 and 27.03 g dm-3, respectively. The chlorophyll index, dry shoot and root masses, water consumption and water use efficiency rose to 54.18, 93.83, 90.50, 34.09 and 90.14%, respectively. No significant difference, however, was noted in the values for dry mass and number of nodules. The wood ash was found to promote conditions favorable to the initial development of the cowpea, and can be used as a corrective and a fertilizer for this culture. Based on this improvement in the fertility of the soil, it is safe to assume that there are also gains in sustainability and that the application of vegetal ash can contribute to combating soil degradation.