THE INFLUENCE OF METEOROLOGICAL CONDITIONS ON SOIL WATER VAPOUR EXCHANGE RATE AND CO2 EMISSION UNDER DIFFERENT TILLAGE SYSTEMS

Tillage can significantly influence soil water regime and gas emission affecting global climate change. The study was aimed to determine the influence of meteorological nditions and tillage on soil moisture content and temperature changes at the 0-10 cm soil depth in two fields with different soil texture during the spring barely vegetation period and to evaluate the changes of soil water vapour exchange rate and CO2 emission. Investigations were carried out on an Endocalcari-Epihypogleyic Cambisol (CMg-p-w-can) at the Lithuanian Institute of Agriculture in 2008 in two different field trials which have been under management of different tillage systems for 10 successive years. On clay loam even the drizzle (0.8-1.2 mm) that occurred 1-3 days before measurements significantly increased WVF. On sandy clay loam, WVF response to small amount of rain water was weak. Higher amount of rain (9.5-13.5 mm) essentially increased WVF on both texture soil types. Under dry climate conditions direct drilling could serve as a moisture conserving measure at the 0-10 cm soil depth. But NT application oil different textured soils acts in a different way In conserving soil water, vapour exchange rate and CO2 emission. On clay loam soil under NT application the interaction of thermal and moisture conditions (higher moisture content and lower temperature than under conventional - CT and reduced - RT tillage application) resulted in an increase in CO2 emission by 60% as compared to that in CT and RT. On sandy clay loam, NT application might be a measure to reduce CO2 emission because it exhibits a lower vapour exchange rate.