William B. Bryan

EFFECT OF SOIL WATER AND NUTRIENTS ON PRODUCTIVITY OF KENTUCKY BLUEGRASS SYSTEM IN ACIDIC SOILS

The grasslands of the Appalachian region spread over undulating terrain with high annual precipitation rate which causes a large variation in soil and nutrient factors like water potential (WP), pH, nitrogen (N) and phosphorus (P) levels. There is a need to understand these factors and their interactive effects to design precise agronomic practices for acidic grasslands to maximize production. A pot experiment was conducted with an objective to quantify the effects of WP, pH, N and P rates on herbage accumulation and nutrient recovery of Kentucky bluegrass (Poa pratensis L.) cropping system. Centrally rotatable composite design was applied to study the effects of two levels of WP and five levels each of pH, N, and P fertilizer additions in order to optimize bluegrass herbage mass (yield). WP, pH, and N were significant main effects, as were the interactions WP × pH, WP × N, and pH × N. The yield response function was derived from these four factors. The order of importance for these model parameters based on their effect on herbage accumulation was WP > N > WP × pH > pH >WP × N > pH × N. The optimum levels of WP, soil pH, N, and P rates were predicted for Kentucky bluegrass by using the response surface yield model of this pot study i.e., WP of −422 kPa to −166 kPa, 5.5–6.1 soil pH, 50–68 N mg kg−1, 36–40 P mg kg−1. Concentration (%) of nutrients like N, P, potassium (K), calcium (Ca), and magnesium (Mg) were determined to study the impact of WP, pH, N, and P factors and their interactions on plant nutrient recovery. Main effects like WP, pH, and N levels had significant influence on N and P concentration in plant tissue. K, Ca, and Mg concentrations in plant tissue were significantly affected by WP, pH and their interaction. The results of this greenhouse study imply the necessity to incorporate the information about the variation of soil and nutrient factors in designing precise agronomic practices to low productive acid reclaimed grasslands with undulating topography and high annual precipitation rate.

Grouping Soils by Taxonomic Order to Improve Lime Recommendations

The success of a liming program is dependent upon the accuracy of the lime recommendation, which in turn depends on the quality of the underlying correlations and calibrations. Because of the expense, large-scale field calibration experiments are rarely conducted. The relatively low economic returns from pastures make it even more unlikely that a calibration experiment would be conducted, especially in West Virginia. Therefore, any improvements in lime recommendations have to be made from lime correlations. Moreover, it is unlikely that a single lime correlation can accurately identify appropriate lime rates for all soils. Hence, the objectives of this study were to improve the accuracy of lime recommendations by using quick tests that account for soil order and to develop lime correlations for acidic pasture soils of West Virginia. Twenty-five surface soil samples (0–7.5 cm) from the three major soil orders in the state (Alfisols, Inceptisols, Ultisols) were collected, most in cooperation with state soil scientists. Standard procedures for the determination of lime requirements by the Adams–Evans buffer (AEB), Mehlich single buffer (MB), and Shoemaker–McLean–Pratt single buffer methods (SMPB) were used. Statistically significant improvements in lime recommendations for target pH values of 6.5 and 5.5 were achieved by accounting for soil order. Mehlich single buffer recommendations were better for Alfisols and Ultisols than for Entisols to achieve pH 6.5. Lime correlations were developed for all three chemical buffers by multiple regression where the independent variables were target pH and soil-buffer pH. The AEB predicted lime rates better for target pH 5.5.

Winter Grazing in a Grass-Fed System: Effect of Stocking Density and Sequential Use of Autumn-Stockpiled Grassland on Performance of Yearling Steers

Winter grazing can help reduce the need for purchased feeds in livestock production systems, when finishing cattle on pasture. Our objective was to evaluate the influence of stocking density and grazing stockpiled forage on performance of yearling steers during winter. Three grasslands were winter grazed for two years: I, naturalized pastureland, and II and III, sown and managed for hay production during the growing season but grazed in winter. Two stocking densities were used: low 7.41 and high 12.35 steers ha−1. Herbage mass was estimated before and after each grazing event, and disappearance (consumption, weathering, and trampling) was the difference between both. Forage mass and residual differed by stocking density (SD), year (YR), and grazing interval (GI), and disappearance differed by YR and GI. Grass and dead constituents of botanical composition differed by YR and GI. No differences were found for legumes and forbs. CP differed by YR and GI, and NDF and ADF differed only by YR. Steer average daily gain was 0.15 kg d−1 in 2011 and 0.68 kg d−1 in 2012 and varied by YR and GI. Acceptable gains in 2012 may be a product of environmental conditions that influenced herbage mass and nutritive value during stockpile and animal behavior during winter.