Nutrient Cycling in Organic Coffee Production in a Tropical Ecoregion Nor Yungas of La Paz, Bolivia.

Abstract

Fresh organic matter added to soil influences nutrient cycling, plant availability, and soil fauna. The objective was to assess the nutrient contributions to the soil from different tropical forest stratums.

The total of biomass added annually to the tropical soil was 8467 kg (ha yr)^-1 of which the higher stratum genus Inga (Sikili) provided 5183 kg (ha yr)^-1. This biomass contained 96 kg N (ha yr)^-1, 19 kg P (ha yr)^-1, 2 kg K (ha yr)^-1 and 28 kg Ca (ha yr)^-1. The middle stratum coffee (Coffea arabica L.) provided  3284 kg biomass (ha yr)^-1. This biomass contained 60 kg N (kg yr)^-1, 12 kg P (ha yr)^-1, 48 kg K (ha yr)^-1, 46 kg Ca (ha yr)^-1, and 6 kg Mg (ha yr)^-1. In the lower stratum, the Oxalis mollissima provided 36 kg N (ha yr)^-1, Solanum nodiflorum provided 59 kg K (ha yr)^-1, and Urtica sp. provided 18 kg Ca (ha yr)^-1. The coffee is certified organic and traditionally cultivated under a shaded canopy of trees. Coffee cherry yields were 1.8 Mg/ha resulting in a return of $1.33/lb at 12% moisture. The  biomass layer on the agroforetal system was important for microarthropod communities consisted of 33% collembolas, 12% glomerida, 10% plecoptera, and 9% arachnids.

 

Keys: Stratum tree, biomass, microarthropod, Inga (Sikili), Coffea arabica