Soil–water conditions and efficient fertilization strategies to increase rice grain yield in rainfed lowland fields in Savannakhet Province
JIRCAS Working Report
Most lowland rice fields in Savannakhet Province, the main rice-producing region in Laos, are rainfed and cover both lowlands as well as gradual hilly terrain with sandy soils. The water and nutrient conditions of the lowland rice fields likely vary by location and geological conditions. Additionally, high risk of nutrient leaching from applied fertilizer is expected in such sandy rainfed fields. The objectives of this study are 1) to assess rice yield and water and soil conditions in the rainfed rice fields of Savannakhet Province, 2) to identify the determinants of variation in rice yield, and 3) to evaluate rice plant growth and nutrient leaching under different split chemicalfertilizer application patterns. The rice grain yield varied from 0.6 to 3.6 t ha-1, and the yield in the lower position fields was significantly higher than in the upper position fields. Surface water in the observed fields was mostly maintained above ground level throughout the planting period. Total carbon, total nitrogen, available phosphorus, and exchangeable potassium were extremely low, while the exchangeable calcium and exchangeable magnesium were relatively high. Exchangeable calcium was selected as the highest influential factor to rice grain yield, followed by total carbon. The grain yield from six split fertilization was higher than from three split fertilization (standard) and basal fertilization only. The split fertilization is advantageous in that it supplies nitrogen for panicle initiation and maturing stages in sandy paddy fields.
|作成者||Hiroshi Ikeura Sengthong Pongchanmixay Amphone Chomxaythong Bounson Bounyavong Phanthasin Khanthavong Thanouphone Khanthavong Naruo Matsumoto Kensuke Kawamura Laeh Homsengchanh Somphone Inkhamseng|
|公開者||Japan International Research Center for Agricultural Sciences|