Nitrogen Doses and Humic Substances in Custard Apple Nutrition

Abstract

Custard apple production (Annona squamosa L.) in the Brazilian Northeast occurs throughout the year. Its management involves pruning, irrigation, and proper nutrition. The objective of the present work was to verify the influence of different doses of nitrogen and the use of humic substances on soil chemical attributes and tree custard apple nutrition. The experiment was conducted in a commercial orchard in the municipality of Anagé, Southwest region of the state of Bahia, in a randomized block design in a 4 x 2 factorial scheme, four nitrogen doses (0, 284, 568 and 852 g per plant, urea) with and without the application of humic substances (Ks100), with 4 replicates. Soil chemical characteristics, macro and micronutrient contents were evaluated in the leaves of the custard apple tree. Nitrogen rates reduced soil pH and the availability of calcium, magnesium and boron. The application of humic substances increased the content of potassium in leaves. Under the conditions studied, high nitrogen doses influence soil fertility and the application of humic substances does not improve the absorption of most of the nutrients, except potassium, and it did not influence the chemical attributes of the soil.