The management of rice straw, fertilisers and leaf litters in rice cropping systems in Northeast Thailand. 1. Soil carbon dynamics

• Published in: Plant and soil Vol. 209; no. 1; pp. 21 - 28
• Main Authors: Naklang, K. (Ubon Rice Research Center, Ubon Ratchathani (Thailand).), Whitbread, A, Lefroy, R, Blair, G, Wonprasaid, S, Konboon, Y, Suriya-arunroj, D
• Format: Journal Article
• Language: English
• Published: Dordrecht Kluwer Academic Publishers 1999; Springer
• Subjects: ABONOS VERDES; Acid soils; Agricultural management; Agricultural soils; Agronomy. Soil science and plant productions; Biological and medical sciences; Carbon; CARBON CYCLE; Chemical, physicochemical, biochemical and biological properties; CICLO DEL CARBONO; CYCLE DU CARBONE; ENGRAIS VERT; Forest soils; Fundamental and applied biological sciences. Psychology; GREEN MANURES; MATERIA ORGANICA DEL SUELO; MATIERE ORGANIQUE DU SOL; Organic matter; Organic soils; ORYZA SATIVA; PAILLE DE RIZ; PAJA DE ARROZ; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Plant litter; Rice; RICE STRAW; Sand soils; SOIL ORGANIC MATTER; Soil science; TAILANDIA; THAILAND; THAILANDE; Thailand; Asia; Green manure; Monocotyledones; Organic matter; Litter; Cropping system; Cajanus cajan; Organic fertilization; Biogeochemical cycle; Sustainable use; Cereal crop; Carbon cycle; Grain legume; Oryza sativa; Leguminosae; Gramineae; Dicotyledones; Angiospermae; Euphorbiaceae; Hardwood forest tree; Spermatophyta; Paddy field; Acacia auriculiformis
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/A:1004571015620

Declines in soil organic mailer (SOM) have occurred in most rainfed rice cropping systems in the world. Such declines threaten the sustainability of these systems and steps need to be taken to reverse the decline. Paired soil samples collected from forest and cropped areas in Northeast Thailand revealed an approximately 70% decline in both labile carbon (CL) and total carbon (CT) in the surface 10 cm as a result of cropping. CL was found to be higher in the 20-40 cm soil layer in the cropped than the forest soil indicating C leaching or soil mixing. In a field experiment it was found that CL, and a calculated Carbon Management Index (CMI), increased with annual applications of low rates (1500 kg/ha dry matter) of leaf litter from Cajanus cajan, Phyllanthus taxodifolius, Acacia auriculiformis and Samanae saman. Five seasons of leaf litter application increased the CT pool by 24-37% and more than doubled CL and soil C lability. The retention of rice straw improved CT in the first year of the trial but led to no significant increases in subsequent years. Higher rates of fertilisers did not result in increased soil C, despite increased yields. Crop residues, leaf litters and green manures with slow breakdown rates are needed to rehabilitate soil C. CL and the CMI can be used effectively to monitor the rate of change in soil C.