Sustainability Assessment of the Production, Decomposition Rate and NPK Content of Litterfall under the Coffea arabica–Based Agroforestry Systems in Atok, Benguet, Philippines

Abstract

The study assessed the sustainability of coffee-based agroforestry systems in Atok, Benguet based on litterfalls. Data on the litter production, decomposition rate and NPK contents from 36 established experimental plots following the split-split plot design were gathered and analyzed. Sustainability levels were assessed using a Likert scale derived from published threshold levels. Analysis of data showed that average litter production was 10.585.2 t/ha/yr with a range of 4.421 to 17.65 t/ha/yr and was not significantly affected by elevation, type of shade trees and coffee ages. The average monthly litter decomposition rate was 4% and was significantly higher under the coffee-Alnus combination than those under the coffee-fruit trees. The average nutrient contents were 1.75% N, 0.14ppm P and 0.80% K, equivalent to an annual return of nutrients at an average of 185.51 kg/ha N, 28.50 kg/ha P and 85.39 kg/ha K. Only the N contents of the litters were significantly affected by the type of shade trees. Sustainability levels of litter production, decomposition rate, and NPK contents based on the computed average weighted means (AWM) were moderate to high with an overall AWM of 1.61 or “moderately sustainable”.