Conversion of tropical forests to smallholder rubber and oil palm plantations impacts nutrient leaching losses and nutrient retention efficiency in highly weathered soils

• Published in: Biogeosciences Vol. 15; no. 16; pp. 5131 - 5154
• Main Authors: Kurniawan, Syahrul, Corre, Marife D, Matson, Amanda L, Schulte-Bisping, Hubert, Utami, Sri Rahayu, van Straaten, Oliver, Veldkamp, Edzo
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 27-08-2018; Copernicus Publications
• Subjects: Biological fertilization; Cations; Clay; Clay soils; Conversion; Cycles; Disruption; Drainage water; Efficiency; Environmental aspects; Fats, oils and waxes industry; Fertilization; Forests; Land use; Landscape; Leaching; Loam; Lysimeters; Mineral nutrients; Nutrient availability; Nutrient cycles; Nutrient loss; Nutrient retention; Nutrients; Oil; Oil palm trees; Plantations; Retention; Rubber; Rubber industry; Rubber trees; Soil; Soil nutrients; Soil quality; Soil research; Soil suction; Soils; Solutes; Stocks; Tropical climate; Tropical forests; Vegetable oils; Water quality; Indonesia
• ISSN: 1726-4189; 1726-4170; 1726-4189
• DOI: 10.5194/bg-15-5131-2018

Conversion of forest to rubber
and oil palm plantations is widespread in Sumatra, Indonesia, and it is
largely unknown how such land-use conversion affects nutrient leaching
losses. Our study aimed to quantify nutrient leaching and nutrient retention
efficiency in the soil after land-use conversion to smallholder rubber and
oil palm plantations. In Jambi province, Indonesia, we selected two
landscapes on highly weathered Acrisol soils that mainly differed in texture:
loam and clay. Within each soil type, we compared two reference land uses,
lowland forest and jungle rubber (defined as rubber trees interspersed in
secondary forest), with two converted land uses: smallholder rubber and oil
palm plantations. Within each soil type, the first three land uses were
represented by 4 replicate sites and the oil palm by three sites, totaling
30 sites. We measured leaching losses using suction cup lysimeters
sampled biweekly to monthly from February to December 2013. Forests and
jungle rubber had low solute concentrations in drainage water, suggesting low
internal inputs of rock-derived nutrients and efficient internal cycling of
nutrients. These reference land uses on the clay Acrisol soils had lower
leaching of dissolved N and base cations (P= 0.01–0.06) and higher N and
base cation retention efficiency (P < 0.01–0.07) than those on
the loam Acrisols. In the converted land uses, particularly on the loam
Acrisol, the fertilized area of oil palm plantations showed higher leaching
of dissolved N, organic C, and base cations (P < 0.01–0.08) and
lower N and base cation retention efficiency compared to all the other land
uses (P < 0.01–0.06). The unfertilized rubber plantations,
particularly on the loam Acrisol, showed lower leaching of dissolved P (P=0.08) and organic C (P < 0.01) compared to forest or jungle
rubber, reflecting decreases in soil P stocks and C inputs to the soil. Our
results suggest that land-use conversion to rubber and oil palm causes
disruption of initially efficient nutrient cycling, which decreases nutrient
availability. Over time, smallholders will likely be increasingly reliant on
fertilization, with the risk of diminishing water quality due to increased
nutrient leaching. Thus, there is a need to develop management practices to
minimize leaching while sustaining productivity.