|Author:||Chongpraditnun, P. ; Oda, M. ; Nakamura, K.|
|Book Group Author:||NA|
Water-saving cultivation is one of the most practical approaches in rainfed areas to improve the utilization of water stored in the subsoil during the rainy season for crops in the dry season. The elucidation of water and nutrient dynamics under water-saving cultivation background has been done since year 2003 by monitoring soil moisture, salt and nutrient in the soil profile under different types of second crop (mungbean [Vigna radiata], groundnut [Arachis hypogaea] and sunflower [Helianthus annuus]) cultivation in paddy located in Nong Saeng Village, Ampur Ban Had, Khon Kaen Province, Thailand, at an elevation of 184 and 180 m above sea level as upper and lower paddy, respectively. A survey of soil moisture and chemical properties from 11 farmer fields' profiles in the dry season indicated that the excess irrigation of farmers' practice at Tambon (T) Banthum, Bandangyai and Banfang, Ampur Muang, for their second crops after rice in the paddy kept 15-30% soil moisture through the profile, while a marked drop of moisture (3-12%) in the topsoil (0-40 cm-depth) occurred within 3 months in paddy without a crop. Normally, soil moisture gradually increased corresponding to soil depth except at ambur T. Banthum. Soil nutrient levels were low except for available P, and most of the nutrients were accumulated in the topsoil while K, Ca and Mg increased at depths beyond 50 cm. Only at T. Banthum, some accumulation of available Na (>160 mg/kg) was found at the depth of 40-50 cm in the control paddy without irrigation. The pattern of soil moisture content through the second crop cultivation period, soil moisture content at the top soil (0-10 cm depth) was higher than the wilting point only in February and the end of May in both upper and lower paddies either logth mulch or without mulch in the control and second crop fields. There was no significant difference in soil moisture content between the mulched and unmulched fields, even mulching retained slightly more moisture content than unmulched fields. There was no significant difference in moisture distribution pattern through the cultivation period among the second crops. Hence, we need to supply more water to the second crops to obtain soil moisture content at least above the wilting point (>22% by Vol.) in the topsoil (0-50 cm depth) in January, March and April for second crop cultivation, though the average moisture content of the whole profile (0-100 cm soil depth) was not less than the average wilting point. Therefore, additional irrigation of 15, 5, 15 and 20 L/m2 (% moisture by vol.) was recommended for the second crop in January, February, March and April, respectively. In the lower paddy, additional irrigation of 10, 10 and 20 L/m2 should be supplied in January, March and April, respectively as well. In paddy fields, most of the remaining soil nutrients existed in the surface layer down to 25 cm depth. Nutrients were hardly supplied from the subsoil by the capillary movement of subsoil water, because there were little nutrients below 50 cm depth. The nutrients moved with capillary movement mostly in the surface layer. Even in dry season, there is an occasional rainfall. The nutrients also occasionally move with water in loamy sand soils.
|Journal:||JIRCAS Working Report|
calcium, capillary rise, crop production, cropping systems,dry season, green gram, groundnuts, irrigation, magnesium, mulching,mung beans, nutrients, phosphorus, potassium, rice, sandy loam soils,sodium, soil chemical properties, soil depth, soil types, soil water,soil water content, sunflowers, topsoil, transport processes, waterconservation, water supply, water use, wilting point, Thailand, Arachishypogaea, Helianthus annuus, Oryza, Oryza sativa, Vigna radiata, SouthEast Asia, Asia, Developing Countries, ASEAN Countries, Arachis,Papilionoideae, Fabaceae, Fabales, dicotyledons, angiosperms,Spermatophyta, plants, eukaryotes, Helianthus, Asteraceae, Asterales,Oryza, Poaceae, Cyperales, monocotyledons, Vigna, capillarity, capillaryflow, chemical properties of soil, mung bean, paddy, peanuts, soilmoisture, soil transport processes, transport processes in soil systems,water supplies, watering, Horticultural Crops (FF003) (New March 2000),Field Crops (FF005) (New March 2000)