Comparison of Wetting and Drying Characteristics in Differently Textured Soils under Drip Irrigation
2009
Kim, H.J., Pusan National University, Miryang, Republic of Korea | Son, D.W., Pusan National University, Miryang, Republic of Korea | Hur, S.O., National Academy of Agricultural Science, RDA, Suwon, Republic of Korea | Roh, M.Y., National Institute of Horticulture and Medicinal Crop, RDA, Busan, Republic of Korea | Jung, K.Y., National Institute of Crop Science, RDA, Miryang, Republic of Korea | Park, J.M., Pusan National University, Miryang, Republic of Korea | Rhee, J.Y., Seoul National University, Seoul, Republic of Korea | Lee, D.H., Sungkyunkwan University, Suwon, Republic of Korea
Maintenance of adequate soil water content during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil water movement for precision irrigation would allow efficient supply of water to crops, thereby resulting in minimization of water drainage and contamination of ground water. This research reports on the characterization of spatial and temporal variations in water contents through three different textured soils, such as loam, sandy loam, and loamy sand, when water is applied on the soil surface using an one-line drip irrigation system and the soils are dried after the irrigation stops, respectively. Water contents through each soil profile were continuously monitored using three Sentek probes, each consisting of three capacitance sensors at 10, 20, and 30cm depths. Spatial variability in water content for each soil type was strongly influenced by soil textural class. There were big differences in wetting pattern and the rate of downward movement between loam and sandy loam soils, showing that the loam soil had a wider wetting pattern and a slower rate of downward movement than did the sandy loam soil. The wetting pattern in loamy sand soil was not apparent due to a low variability in water content (less than 10%) by a lower-water holding capacity as compared to those measured in the loam and sandy loam soils, implying that the rate of water drainage below a depth of 30cm was high. When soils were dried, there were highly exponential relationships between water content and time elapsed after irrigation stops (r² greater-than or equal to 0.98). It was estimated that equilibrium moisture contents for loam, sandy loam, and loamy sand soils would be 17.6%, 6.2%, and 4.2%, respectively.
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