Decomposition and nutrient mineralization from oil palm empty fruit bunch
The expansion of oil palm plantations strongly reduces the quality of ecosystem functions provided such as severe reductions in organic carbon stock in above ground biomass and below ground (i.e. soil carbon stocks). This consequently reduces soil microbial biomass and soil nutrient retention efficiency, changes nitrogen cycling and changes trace gas fluxes. To counter these effects organic matter addition is needed. It would be especially useful if the organic matter came from oil palm residues. My current study aimed to: 1) measure nutrient mineralization from oil palm waste products (EFB, Fibre, and EFB + Fibre), and 2) assess decomposition rate and nutrient mineralization from different techniques application of EFB. For the first objective, we conducted incubation experiment in the laboratory by applying EFB, Fibre, and EFB + Fibre in two soil types which was collected from Desa Baru and Sungkai villages – Jambi province and having differences in soil texture (i.e clay Acrisol and sandy loam Acrisol). Soil samples (400 g) and organic matter (~ 16 ton ha-1) were mixed in plastic bag, and nutrient mineralization were measured for total C, total N, available P, and exchangeable K in the soil at 0, 4, 6, 8, 10, and 12 week after incubation. For the second objectives, we set up field research in smallholder oil palm plantation, located in Sungkai Village – Jambi Province. The fresh EFB (~ 16 ton ha-1) was inserted in the litterbag (nylon mesh bags with 2-mm mesh in diamater and size 20 cm X 20 cm X 10 cm), then placed in soil surface as mulch and buried in 10-cm depth of soil as organic fertilizer. Sample collection were conducted monthly from October 2017 to May 2018 for measuring dry weight and nutrient concentration (i.e C, N, P, K, Fe, Zn, Mn, B).