Cost-analysis for a sustainable nutrient management of fast growing-tree plantations in East-Kalimantan, Indonesia

Abstract Without fertilizer application intensively managed tree plantations generally have a negative nutrient balance: within one rotation more nutrients are lost from the system than gained. Constant nutrient exports result in a distinctive depletion of soil nutrient storage. To maintain a balanced nutrient budget and, thus, sustain site productivity it is necessary to compensate nutrient losses. We calculated the quantities of mineral fertilizer required to compensate management-dependent nutrient losses for a plantation site in East-Kalimantan, Indonesia. Calculations are based on estimated nutrient losses for three management scenarios: high-, medium- and low-impact management. Fertilizer compensation for nutrient losses incurred due to tree harvest will increase standard plantation establishment cost by 18–33% and total investment costs by 9–15%. Considering additional nutrient losses due to leaching and erosion as assumed for a low-impact management scenario, standard plantation establishment costs were increased by 20–35% and total investment costs increased by 9–16%, respectively. Fertilizer compensation for a high-impact management scenario, including large nutrient losses resulting from burning of residual phytomass, leaching and erosion, increased standard plantation establishment costs by 29–62%, while total investment costs increased by 13–29%. As a consequence, the internal rate of return (IRR) of the plantation investment dropped from 14% to 9–12%. We calculated major differences in the fertilizer expenses between species. Fertilization costs for Eucalyptus deglupta were generally higher than for Acacia mangium . Considering the high costs for fertilization, we conclude that strategies are to be developed to reduce management-dependent nutrient losses. A low-impact management including alternatives to slash burning and soil-conserving harvesting techniques as well as appropriate site selection are recommended. It is advised to consider nutrient costs in investment calculations of industrial plantations.