Organic recycling through cocoa litter

Abstract

A field experiment was conducted in the cocoa fields of Cadbury – KAU Co-operative Cocoa Research Project, College of Horticulture, Vellanikkara, to study the organic recycling through cocoa litter. The objectives of the study were to find out the time required for natural senescence of cocoa leaves, to estimate the quantity of litter produced in a cocoa field in an year, to quantify the nutrient return through litter fall and to find out the rate of decomposition of cocoa litter. The studies were carried out both in shaded and unshaded cocoa fields, except the litter decomposition study which was carried out in the shaded field only. The lifespan of cocoa leaves was found to be significantly different in the shaded and open fields, ranging from 94 to 193 days in the open condition and from 108 to 159 days in the shaded condition. The quantity of litter produced was significantly influenced by the season, shaded/open condition and their interaction. The total annual litter fall was 5.3 t ha-1 in the shaded field and 8.2 t ha-1 in the open field. In both the fields, litter fall was maximum during December to march with the peak occurring in the first fortnight January. Litter fall was lower during the wetter months of the year. The nutrient return through litter fall was higher in the unshaded field. In the shaded field, the nutrient return through litter fall from a hectare for an year was 66.9, 5.0, 59.7, 84.9 and 40.3 kilograms of N,P,K Ca and Mg. respectively. In the open field, the annual nutrient addition through litter fall from a hectare was 109.7, 6.8, 104.2, 103.7 and 57.4 kilograms of N,P,K, Ca and Mg. respectively. Litter decomposition followed a biphasic pattern with an initial rapid phase and a subsequent slower phase. About 95 per cent of dry weight of litter was decomposed during the rapid phase of first four months and it took eight more months for decomposition of 98.9 per cent of the original weight.