NGHIÊN CỨU THỰC NGHIỆM ĐỘNG THÁI ẨM CỦA ĐẤT TRONG KỸ THUẬTTƯỚI NHỎ GIỌT ĐỂ XÁC ĐỊNH CHẾ ĐỘ TƯỚI HỢP LÝCHO CÂY NHO LẤY LÁ VÙNG KHAN HIẾM NƯỚC (VÙNG KHÔ HẠN)

Abstract

Experimental research on soil moisture dynamic of drip irrigation technique for Grape leaves in three crop seasons with 3 irrigation frequencies: 2days (CK2), 3days (CK3) and 4days (CK4), at the water scarce region, Binh Thuan province. Moisture dynamic of the soil layers has a distinct difference, water content of the layer containing the active roots (5÷20cm) was smaller than the surface layer (0÷5cm) and the below one (20÷30cm) at the end of the irrigation frequency, the smallest is the layer 10÷15cm: from 11.8÷12.5% (CK2-V3), from 8.1÷8.2% (CK3-V3), 4.7÷4.9% (CK4-V3). At the end of the irrigation frequency, water content of CK2 was still greater than that one at water stress point (θp), water content in the CK3 (except the surface and bottom layer without roots) and the CK4 has decreased lower than θp, it sometimes approached the water content at wilting point (θwp), caused the plant to be deprived of water. Daily soil moisture dynamic was very different in each period, the day water content decreased more greately than the evening and night ones, and the afternoon one decreased more greately than the morning one. The water content decrease was the greatest during 9:00÷15:00, the next ones were in period’s 15:00÷21:00, 3:00÷9:00 and the lowest was in 21:00÷3:00 of the next morning. These studied results have been an important basis for the application to detemine a suitable water-saving irrigation schedule for Grape leaves in particular and for dry crops (similar characteristics) in general in the water scarce region (droughty region) of the South Central part.