Soil Moisture and Soil Temperature beneath Film Mulching in Tobacco Culture

Abstract

The influences of mulching methods on soil moisture, soil temperature, and tobacco growth were studied. Clear polyethylene film of 95 and 120 cm width and black polyethylene film of 95 cm width were used as mulching materials, and six kinds of ridges were made in tobacco field at the Okayama Tobacco Experiment Station. They were as follows ;1) Unmulched ridges (no mulch)2) Uumulched ridges high (no mulch high)3) Ridges low at start and heightened by soil dressing being covered with film of 95 cm throughout cultivation (mulch)4) Mulched high ridges (mulch high)5) Mulched high ridges covered with wide film (wide mulch high)6) Mulched ridges covered with black polyethylene film (black mulch)Soil moisture level was adequate for tobacco growth during days transplanting on April 2 to beginning of May. After middle of May at mulch and mulch high, where lower limits of film were kept open and water was admitted to evaporate from soil surface into open air, soil moisture tension rose above pF4.0-4.5. When soil moisture tension rose above pF4.5, ordinary rainfall did not increase soil moisture beneath film mulching.At the early growth stage of tobacco, soil temperature and dry matter production of tobacco were highly correlated.