Biomass decomposition dynamic in agroforestry systems with iTheobroma cacao/i L. in Rionegro, Santander (Colombia)

Abstract

The study was carried out in an agroforestry system (AFS) withcacao trees already established in La Suiza Research Center, Corpoica, located in Rionegro, Santander (Colombia). The objective was to evaluate biomass input and nutrient release rate of the species that comprise the AFS (Gmelina arborea, Gliricidia sepium, Cedrela odorata, Theobroma cacao). The plant material decomposition process of the species was monitored with decomposition bags after 8, 15, 23, 84 and 113 days, evaluating remnant weight and nitrogen, phosphorous, potassium, calcium and magnesium content. Results showed significant differences in plant material decomposition of the species considered. The largest weight loss was found in G. arborea (87.55%) and the lowest in C. odorata (40.01%). The highest nutrient release value was found in G. arborea followed by G. sepium, and the lowest in T. cacao and C. odorata. Therefore, depending on the species that comprise the AFS there is a differential leaf biomass decomposition dynamic and hence, of the nutrient input to the soil. Of the species evaluated the highest input of new organic matter to the soil in this AFS comes from G. arborea. Altogether, the litter generated by the species evaluated contributed with 10% of the nutrients required for a cacao harvest.

El estudio se realizo en un sistema agroforestal (SAF) con cacao establecido en el C.I. La Suiza, Corpoica, Rionegro, Santander (Colombia). En este trabajo se evaluo el aporte de biomasa y la tasa de liberacion de nutrientes de las especies del SAF (Gmelina arborea, Gliricidia sepium, Cedrela odorata, Theobroma cacao). El proceso de descomposicion del material vegetal por especie se monitoreo con bolsas de descomposicion los dias 8, 15, 23, 84 y 113, evaluando el peso remanente y contenido de nitrogeno, fosforo, potasio, calcio y magnesio. Los resultados mostraron diferencias significativas en la descomposicion del material vegetal de las especies. La mayor perdida de peso se observo en G. arborea (87,55%) y la menor en C. odorata (40,01%). La mayor tasa de liberacion de nutrientes la presento G. arbórea seguida de G. sepium, y las menores T. cacao y C. odorata. Por tanto, dependiendo de las especies utilizadas, se presenta una dinamica diferencial de descomposicion de biomasa foliar y por ende del aporte de nutrientes al suelo. La mayor entrada de nueva materia organica al suelo proviene de G. arborea. La hojarasca de todas las especies evaluadas juntas aporto 10% de los nutrientes requeridos para una cosecha de cacao.