PASTURE RENOVATION EFFECTS ON JIGGS BERMUDAGRASS PRODUCTION. Robert A. Lane 1. Abstract

Transcription

1 PASTURE RENOVATION EFFECTS ON JIGGS BERMUDAGRASS PRODUCTION Robert A. Lane 1 Abstract Due to its rapid rate of establishment when planted from vertical stems (tops) and high biomass production, Jiggs bermudagrass is among the most popular of the improved bermudagrass cultivars in Southeast Texas. It is also being widely utilized across the southern U.S. due to its ability to tolerate poorly drained soils better than most improved bermudagrasses. Local producers have indicated that hay yields were increased in year-old Jiggs bermudagrass pastures following renovation with either chisel plowing or disking, presumably due to improved water infiltration and root penetration. A study was conducted at Sam Houston State University s Gibbs Ranch during the summer of 2012 comparing the effects of renovation on a 15 year-old Jiggs bermudagrass field v. an adjacent paddock established in 2011, each approximately 4.5 acres in size. The second hay cutting from the field including both paddocks occurred on June 21. Two 1000 ft strips (two replicates per treatment) in each paddock were subjected to renovation on July 6, 2012 by disking (6 ft Frontier heavy duty tandem disk with notched blades set for relatively low sod disturbance) and chisel plowing (Hay King, penetrating 8-11 inches deep with a chisel spacing of 14 inches). The treated strips were approximately 15 ft apart, allowing space for control (untreated strips) between them. The soil is a Falba fine sandy loam, classified as a claypan soil. While the underlying massive clay of Falba soils ranges from 7 to 13 inches from the surface, the chisels did not contact an underlying clay layer at this site. The soil was dry at the time of treatment (no precipitation for three weeks prior) but the site received over 2 inches of rain the week following treatment with little to no runoff. Plots measuring 40 sq ft from each treatment were harvested on July 23 and October 12, 2012 for determination of dry matter production. The analysis of variance for dry matter production on July 23 showed no significant differences for either renovation treatment or paddock. There were also no significant differences among renovation treatments for the October harvest, however, the ANOVA for dry matter production on that date did indicate a paddock effect. All treatments in the 15 year-old paddock outyielded those in the newer (1 year-old) paddock by an average of 687 lb dry matter per acre. Under the circumstances of this study, there was no dry matter yield benefit to renovation of an improved bermudagrass pasture. 1 Professor, Department of Agricultural and Industrial Sciences, Sam Houston State University, Huntsville, TX Introduction: Interest in renovation of bermudagrass pastures is common following serious drought conditions. The drought of 2011 was one of historical proportions throughout Texas, causing extensive forage and livestock losses. It appears that when forage production experiences a steep decline due to lack precipitation, producers turn their attention to production practices that might allow them to trap and store as much soil moisture as possible. Many assume compaction and reduced water storage are

2 primary causes for losses in production. Wynne and Hancock (2009) suggest that aeration equipment may be used because thatch has built up to the point that it limits water infiltration into a soil or to remediate soil compaction. They state there is little clear research that shows aeration (renovation) is economically feasible and the temporary effects are primarily the result of a flush of nutrients being released by the mechanical tillage (aka breakdown or destruction) of organic matter in the soil. Hoveland (2000) describes results from a 2-year study on aeration done on a silty soil at the Brown loam Station and on sandy loam soil at the South Mississippi Station in Mississippi in which an aerator, shank renovator, disk, and deep chisel were compared to controls on bahiagrass pasture and bermudagrass hay fields at both locations. None of the treatments had any effect on soil penetration resistance, moisture content, or forage yield. However, in an Arkansas study by Self-Davis, et al. (1996) on a Hartsells fine sandy loam, Paraplow tillage and Aer-Way renovation increased forage yield 24% and 53%, respectively compared to plots that did not receive tillage following a dry spring (1995) but not in a wet year (1994). This experiment compared dry matter production of a recently established Jiggs bermudagrass pasture with a previously unrenovated older (15 years) Jiggs pasture following mid-season renovation with a disk, chisel plow, or no treatment. Materials and Methods: Six ft by 1000 ft strips in adjacent 1- and 15 year-old paddocks of Jiggs bermudagrass were subjected to disking (6 ft Frontier heavy duty tandem disk with notched blades set for relatively low sod disturbance), chisel plowing (Hay King, penetrating 8-11 inches deep with a chisel spacing of 14 inches) or untreated control in a randomized complete block design with two replications each on July 7, A hay harvest had been collected from the pasture on June 22, The treated strips were approximately 15 ft apart, allowing space for control (untreated strips) between them. The soil was a Falba fine sandy loam, classified as a claypan soil. However, the massive clay subsoil present at this site ranges from inches below the surface and was not disturbed by the chisel plowing treatment. The soil was dry at the time of treatment. Plots of 40 sq ft were harvested from each strip on July 23 and October 12, 2012, mowed with a Jari Chief 32 inch sickle bar mower and weighed for fresh matter. Subsamples were pulled from each plot, bagged and weighed, then dried at F for three days for moisture content determination and plot dry matter calculation. Dry matter (DM) data for each harvest date and total DM were subjected to an analysis of variance (SAS Institute, Inc., Cary, NC). Results and Discussion: Statistical analyses indicate no renovation treatment effect for either harvest date or total DM (Table 1). While the earlier harvest (23-July) showed no significant stand age effect, the older stand produced significantly more biomass (P < 0.05) than the younger stand at the second harvest (12-October) (Figure 1). The higher DM yields of the older stand from the second harvest were substantial enough to cause the total DM production to be significantly greater in the older stand as well (P < 0.05). While the one year-old stand was well established and actually 2-3 inches taller on average than the 15 year-old stand, vegetation in the older stand was considerably more dense than the young stand, accounting for the late season yield difference. The dry

3 conditions of late summer apparently favored the older stand, having a better established root system. This particular pasture has been used only for hay production, so compaction caused by livestock grazing was not an issue. The results of this indicate that bermudagrass pasture renovation under conditions similar to those seen in this study is neither beneficial to the grass nor economical. Literature Cited: Hoveland, Carl Does Aeration of Pastures and Hayfields Pay? The Georgia Cattleman, February, Self-Davis, M.L., M.S. Miller, R.L. Raper, and D.W. Reeves Pasture Soil and Vegetation Response to Renovation Tillage, in Proceedings: New Technology and Conservation Tillage, 19th Annual Southern Conservation Tillage Conference for Sustainable Agriculture. Wynne, T. and D. Hancock Does Aerating or Renovating Hay and Pasture Fields Pay? Forages FAQs. Retrieved From Table 1. Mean dry matter yields of Jiggs bermudagrass following renovation treatment, Huntsville, Texas, Renovation treatment First harvest (23-July) Second harvest (12-October) Total yield lb DM/A Chisel plow Disk Control Average CV (%) LSD (0.05) ns ns ns

4 Figure 1. Mean dry matter yields of Jiggs bermudagrass following renovation treatment as affected by age of paddock, Huntsville, Texas, Bars marked with different letters are significantly different at the.05 level of probability.

5 Interpretive Summary PASTURE RENOVATION EFFECTS ON JIGGS BERMUDAGRASS PRODUCTION Robert A. Lane 1 Bermudagrass hay producers are frequently concerned that declines in hay yields are due to issues related to soil compaction and reduced soil moisture storage, especially in older stands. Renovation treatments are thus often sought as a means of alleviating this perceived condition and increasing yield. The objective of this study was to determine if mid-season (early July) renovation treatments of disking or chisel plowing (8 to 11 inch depth) provided any yield increases over the control (no renovation) when applied to a 15 year-old and a one year-old stand of Jiggs bermudagrass grown in a fine sandy loam soil underlain by a claypan approximately inches deep. Plots were harvested twice (July 27 and October 12) following renovation treatment. Neither renovation treatment provided a yield increase over the untreated control for either harvest date. However, the older stand of bermudagrass produced significantly more dry matter than the younger stand at the October harvest, following a lengthy dry period, regardless of treatment. 1 Professor, Department of Agricultural and Industrial Sciences, Sam Houston State University, Huntsville, TX