Reduction of soil water content fluctuations and soil temperature variations under retrievable drip irrigation

Abstract

Wide soil water content and temperature variations affect crop yields for reasons ranging from rate of seed germination, seed development, to plant growth. This study aimed at evaluating the extent to which drip irrigation can reduce soil water content and temperature variations. An experiment was carried out in a 154 m 2 glasshouse with Tottori dune sand of Japan. Two irrigation levels of 60 and 100% of evapotranspiration, and two dune sand covers of 2 and 5 cm on the drip lines were used. Soil water content and temperature variations were significantly (P < 0.001) reduced under the 5 cm dune sand cover but insignificantly reduced under the 2 cm dune sand cover. Minimum soil temperature was increased, and maximum soil temperature was decreased under the 5 cm dune sand cover. Irrigation level of 100% of evapotranspiration under 5 cm dune sand cover resulted in 20% dry matter yield increase of sorghum. Irrigation level of 60% of evapotranspiration under 5 cm dune sand cover resulted in no significant dry matter yield increase of sorghum. From this study, we conclude that the practical minimum depth of dune sand cover on the drip lines can be 5 cm.