Effect of Porosity, Volumetric Water content and Soil Temperature on the Water Uptake and Dry Matter Yield of Plant in Different Tillage Systems

Effects of five various tillage systems on soil porosity، volumetric water content، diurnal and nocturnal soil temperatures، plant water uptake and dry matter yield was investigated using a completely randomized design with five treatments and four replications in Gorgan University of Agricultural Sciences and Natural Resources research farm located in Seyed-Miran during 2009-2010 growing season. Tillage systems were: moldboard plough followed by one discing (20-25 cm); rototiller (12-17 cm); double disc (8-10 cm); Chisel plow (25-30 cm); No-tillage. Results show that during all stages of wheat growth، the highest and the lowest soil porosities at 0-8 cm depth were obtained by moldboard plough and No-tillage treatments respectively. For all stages except before tillering and harvest، the highest soil porosity obtained by moldboard treatment at 8-16 cm depth. Increasing tillage intensity increased those porosity that keep water in potentials greater than -5 and those in potentials less than -15 bar. No-tillage and moldboard induced the highest and the lowest soil temperatures respectively before earring stage. Tillage intensification، increased soil porosity and root density. More roots reduced soil water content in response to increased water uptake by wheat، resulting greater dry matter accumulation.