Author : Lapitan, Lorenzo C. Jr.

Summary : Litterfall and leaf litter decomposition were assessed and effects of certain surface activities (i.e., weeding and litter removal) on soil nutrients in three coffee-based agroforestry cropping systems were determined. The cropping systems were CS (subscript 1) (coffee + kakawate + dapdap + black pepper), CS (subscript 2) (coffee + banana + guyabano), and CS (subscript 3) (coffee + banana + black pepper). The surface activities were SA (subscript 1) (no weeding and litter removal), SA (subscript 2) (weeding with all litter removed from the site). Results showed that litterfall varied greatly according to cropping system. CS (subscript 1) showed highest litterfall at an annual test of 4,386.2 kg/ha, CS (subscript 3) with 4,188.0 kg/ha. CS (subscript 2) had an annual output of only 1,376.0 kg/ha. Leaves composed the bulk of litterfall in all cropping systems. There was leaf litterfall throughout the study period while non-leaf litterfall was largely seasonal. Litterfall also varied among species. Kakawate in CS (subscript 3) had the highest leaf and total litterfall, while black pepper, also in CS (subscript 3), had the highest non-leaf litterfall. Generally, the proportion of nutrients returned to the soil followed the order nitrogen (N) > potassium (K) > calcium (Ca) > magnessium (Mg) > phosphorus (P). The rates of litter decay were different among cropping systems. After 24 weeks of decomposition, CS (subscript 1) lost only 75.73 percent of its original weight as agaist 88.63 percent in CS (subscript 3). On the other hand, decomposition in CS (subscript 2) was almost complete (94.67 percent) after 24 weeks. The general pattern from the most released to the most retained nutrient in this study was K > Mg > Ca > P > N>. Generally, the N, P, and K contents of the topsoil and the subsoil were similarly affected by cropping system and surface activities. For both soil horizons after the experiment, the trends were CS (subscript 2) > CS (subscript 3) > CS (subscript 1) and SA (subscript 2) >.