Graduate Studies

 

Date of Award

12-7-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Agronomy

First Advisor

Patricio Grassini

Abstract

Oil palm accounts for 40% of global vegetable oil production and Indonesia contributed 59% of the total production, with total planted area nearly 15 M ha in 2020. About 40% of the planted area is managed and owned by smallholders, and two thirds of them are independent, they are not bounded to a large plantation. Current efforts to increase yield of independent smallholder (ISH) fields focus on replanting programs promoting use of certified planting material, with little attention to improve management practices, in particular, plant nutrition. Here we investigated the degree to which poor nutrition can explain large yield gaps in ISH and how the yield gap can be narrowed down via better management practices (BMPs). We assessed nutrient deficiencies in 973 ISH fields using robust protocols for leaf sampling, and the impact of nutrient status on yield as influenced by planting material in 30 trials across five provinces. Each trial included two paired fields: one followed farmer management (‘reference’ fields) and the other receiving BMPs, including better harvest, nutrient, pruning, and weed management. There were widespread nutrient deficiencies, 88% (K), 65% (N & B) and 52% (P) and 34% (Mg). NPK-sufficient fields yielded 5.6 t ha-1 (+47%) than deficient fields, and planting material has a little effect on FFB yields, but a substantial effect on oil content. Implementation of BMPs led to higher (+40%) FFB yield and +20% net profit compared with REF during the second and third year after the trials started. Scaled out to the entire ISH area in Indonesia, BMPs can lead to an additional 3.4 MMT CPO (+8% of current national production), generating an additional revenue of +3.0 billion dollars. Such production increase via yield improvement is equivalent to 1.2 M ha at current yield level. We conclude that intensification provides an effective pathway to independent smallholders to increase their yields and profit, generating an economic benefit from local to national level, while relieving pressure on land conversion for oil palm cultivation. Advisor: Patricio Grassini

Comments

Copyright 2023, Hendra Sugianto

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