See more from this Session: Advances In Soil and Vadose Zone Hydrology: The Contributions of Glendon Gee: II
Monday, October 17, 2011
Henry Gonzalez Convention Center, Hall C, Street Level
The objectives of this study were to use soil penetration resistance (PR) as a measure for soil structure changes in areas undergoing forage renovation in central Kentucky. The relation between PR and some soil physical properties that affecting soil PR, were studied using classical statistical and geostatistical methods. The study area represents a common topographic setting, a sink hole site, in central Kentucky under going forage renovation. Four different forage varieties were planted in four parallel strips each is 3m wide X160m long with a 2m buffer strip in between forage strips. Soil in the studied area is classified as Murray silt loam.SR was measured in 5 cm increments to a depth of 50cm and every 5 m along each strip. Soil samples were collected at two depths (0–15 and 15–30 cm) of each sampling point to measure the associated soil moisture content. Bulk density (BD) had the minimum variability in proportion to water content, clay, silt, and sand contents, and PR had the maximum variability under all forage strips. PR values ranged from 300 to 5000 kPa. The correlation coefficients between BD, clay content and sand content, and water content and BD and PRs were significant. Soil properties with strong spatial correlations (low nugget variance/total semivariance ratio) were water content, clay, silt, and sand contents and PR and BD and all tratments. Semivariograms of these variables with high spatial dependence were fitted into the best fit model. Range values were greater than 100 m. Soil properties were considerably spatially varied at small distances at 15–30 cm depths under all treatments. PR had higher spatial variability at smaller distances under original forage treatment as compared to the new forage treatments. The results showed that spatial variability in PR depends on BD, clay content and sand content as well as water content.