TY - JOUR

T1 - Linking yields of upland rice in shifting cultivation to fallow length and soil properties

AU - Bruun, Thilde Bech

AU - Mertz, Ole

AU - Elberling, Bo

N1 - Funding Information: Thanks to the State Planning Unit of Sarawak for granting permission to carry out this project and to the University Malaysia Sarawak and the Department of Agriculture for support. The project was funded by the Danish Ministry of Foreign Affairs through the Danish University Consortium on Environment and Development—Sustainable Land Use and Natural Resource Management (SLUSE), the North-South Travel Fund, University of Copenhagen and the Foundation of his Royal Highness Crown Prince Frederik of Denmark. Thanks to laboratories at the Agricultural Research Centre Semongok, Department of Agriculture, Kuching, the Institute of Geography and the Ecological-Chemical Laboratory of the Institute of Biology, University of Copenhagen for assistance with analyses. Many thanks are extended to Olivia Jikus and the residents of Rumah Muyang and Rumah Ulat for assistance in the field, hospitality and taking part in the project.

PY - 2006/4

Y1 - 2006/4

N2 - In many tropical cultivation systems, fallowing is a prerequisite for maintaining long-term plant-available nutrient pools and crop yields. This study examines the relationships between length of fallows, soil nutrient levels and yields of upland rice in a shifting cultivation system in Sarawak, Malaysia. A farmer managed field trial included 12 fields cultivated by means of slash and burn. Sites had been fallowed between 5 and 38 years or cropped for two successive years. Volume and horizon specific soil samples were analysed for nutrient contents including plant-available N and P. Yields from the test plots were measured and related to land use factors and soil properties. The stock of soil organic carbon (SOC) in the upper 30 cm of the soil profile ranged from 38 to 61 t ha-1 and the stock of plant-available N ranged from 13.3 to 84.7 kg ha-1. The stock of plant-available P was in the range of 0.6-23.0 kg ha-1. Plant-available N stocks were positively correlated with fallow length. A weaker correlation was found between plant-available P and fallow length. Stocks of SOC, total N and exchangeable base cations were not related to yields, fallow length or cropping intensity. A positive correlation was observed between length of fallow and subsequent rice yields, which has not been well documented for shifting cultivation systems before. Although shorter fallow periods may reduce the availability of N and P, the results do not point towards a long term degradation of the SOC as a result of decreasing fallow periods.

AB - In many tropical cultivation systems, fallowing is a prerequisite for maintaining long-term plant-available nutrient pools and crop yields. This study examines the relationships between length of fallows, soil nutrient levels and yields of upland rice in a shifting cultivation system in Sarawak, Malaysia. A farmer managed field trial included 12 fields cultivated by means of slash and burn. Sites had been fallowed between 5 and 38 years or cropped for two successive years. Volume and horizon specific soil samples were analysed for nutrient contents including plant-available N and P. Yields from the test plots were measured and related to land use factors and soil properties. The stock of soil organic carbon (SOC) in the upper 30 cm of the soil profile ranged from 38 to 61 t ha-1 and the stock of plant-available N ranged from 13.3 to 84.7 kg ha-1. The stock of plant-available P was in the range of 0.6-23.0 kg ha-1. Plant-available N stocks were positively correlated with fallow length. A weaker correlation was found between plant-available P and fallow length. Stocks of SOC, total N and exchangeable base cations were not related to yields, fallow length or cropping intensity. A positive correlation was observed between length of fallow and subsequent rice yields, which has not been well documented for shifting cultivation systems before. Although shorter fallow periods may reduce the availability of N and P, the results do not point towards a long term degradation of the SOC as a result of decreasing fallow periods.

KW - Fallow periods

KW - Plant-available N and P

KW - Shifting cultivation

KW - Soil organic carbon

KW - Yields

UR - http://www.scopus.com/inward/record.url?scp=32144443799&partnerID=8YFLogxK

U2 - 10.1016/j.agee.2005.09.012

DO - 10.1016/j.agee.2005.09.012

M3 - Journal article

AN - SCOPUS:32144443799

VL - 113

SP - 139

EP - 149

JO - Applied Soil Ecology

JF - Applied Soil Ecology

SN - 0929-1393

IS - 1-4

ER -