Tillage Effects On Dryland Soil Physical Properties in Northeastern Montana.

A study was initiated in 2005 to evaluate the effect of no-till (NT) chemical fallow and conventional tillage (CT) fallow management on soil penetration resistance (PR), bulk density (r_b), gravimetric water content (MC) and saturated hydraulic conductivity (K_s) in spring wheat fallow rotation under dryland conditions. Soil PR, BD and MC were measured  at 0 - 5, 5 - 10, and 10 - 15 cm depths while Ks was measured at 7.5 to 15 cm depth under each tillage practices at Sidney (clay loam) and Froid (sandy loam) sites in northeastern Montana. Soil measurements were made on June 6 and July 8 at the Sidney site and on May 19, June 23, and August 4 at the Froid site. Results showed that all soil properties did not differ significantly between NT and CT tillage practices except for PR at the Sidney site. At Sidney, PR was lower in CT than in NT at 0 - 5 and 5 - 10 cm depths in June but was greater in CT than in NT at 0 - 5 cm in August. At Froid, PR increased from May to August regardless of tillage treatment and soil depth.  Soil BD was greater at 5 - 10 and 10 - 15 cm depths than at 0 - 15 cm and increased in August at 10 - 15 cm but decreased at 5 - 10 cm depth in both tillage treatments and sites. Over the same duration, soil MC across tillage systems decreased regardless of soil depth at both sites. Soil Ks was slightly influenced by tillage at both sites. Higher soil PR values in August were attributed to lower moisture contents in the soil due to small amounts of precipitation at the end of growing season in northwestern Montana.