Efeito residual da adubação orgânica na fertilidade do solo, na nutrição e produção de cajueiro-anão

Abstract

The Northeast region is the main cashew producer in Brazil, however, cashew culture still lacks information that allows its sustainable exploitation in soils poor in organic matter, a situation commonly found in the region. It is also common to recommend organic fertilizers in the planting hole for fruit trees, however, for the dwarf cashew tree crop there are still gaps regarding the management of this type of fertilization and its residual effect on the soil and on the development of the plants in the years following the planting. The study was carried out in the field, in the municipality of Pacajus, Ceará, following a randomized block design and a 2x5x2 factorial scheme, with two sources of manure (bovine and chicken), five doses (0, 5, 10, 15 and 20 L per hole) and two years of evaluation (third and fourth years of cultivation), with four replicates. Soil fertility, growth, nutritional status and productivity of cashew trees were evaluated annually. The data obtained were subjected to analysis of variance, using the F test, and comparison of means, using the Tukey test, or regression analysis. Both cattle and chicken manure influenced soil chemical attributes. With the increase in manure doses, there was an increase in the concentrations of organic matter and nutrients in the soil, mainly Phosphorus (P), in the two depths of the soil layer. The residual effect in the soil was more accentuated for chicken manure than for bovine manure, extending its effect until the fourth year of cultivation. In the plant, mainly bovine manure had an effect until the third year of cultivation, with emphasis on doses between 5 and 10 L of bovine manure per hole, which promoted the greatest growth. On the other hand, the residual effect of chicken and cattle manure was not significant for plant nutrition, with the residual effect of the two types of manure practically null. In the fourth year of cultivation, no residual effect was detected in 'BRS 226' cashew plants due to organic fertilization with different doses of bovine and chicken manure applied in the planting hole, except for the productivity of nuts under the fertilization with chicken manure that obtained the highest averages in relation to the highest doses applied.