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Port LaBelle, FL, United States

Interrante S.M.,Samuel Roberts Noble Foundation | Sollenberger L.E.,University of Florida | Blount A.R.S.,North Florida Research and Education Center | White-Leech R.,Natural Resource Conservation Service | Liu K.,University of Florida
Crop Science | Year: 2010

New bahiagrass (Paspalum notatum Flügge) genotype PCA Cycle 4 is more productive than existing bahiagrass cultivars during the cool season, but it may not persist as well when defoliated frequently or to short stubble. Characterizing tiller dynamics forms a basis for understanding mechanisms of grass yield and persistence responses to defoliation. A 2-yr field experiment studied the effects of two stubble heights (4 and 8 cm) and two harvest frequencies (7 and 21 d) on tiller dynamics of diploid (PCA Cycle 4, 'Pensacola', and 'Tifton 9') and tetraploid ('Argentine' and Tifton 7) bahiagrass. Tiller number of highly persistent Argentine and Pensacola was unaffected by defoliation treatment and generally greatest among cultivars. Tiller number of Tifton 9 and PCA Cycle 4 varied by up to 970 and 730 tillers m-2, respectively, among defoliation treatments and was greatest with frequent harvests at short stubble. PCA Cycle 4 tiller mass was relatively low. Net tiller appearance rate was positive in spring and early summer, and was nearly zero or negative throughout the remainder of the growing season. This study showed that Tifton 9 and PCA Cycle 4 responded to frequent, close defoliation by increasing tiller number, but tiller mass was the least or not different from the least among entries tested. Very small tillers may indicate a weakening stand under frequent, close defoliation, and management practices such as rotational stocking may be necessary for PCA Cycle 4 to persist. © Crop Science Society of America. Source

Woodard K.R.,University of Florida | Liu K.,China Agricultural University | White-Leech U.R.,Natural Resource Conservation Service | Sollenberger L.E.,University of Florida
Journal of Environmental Quality | Year: 2013

Research is limited for cow-calf operations as a potential nonpoint source of P within Florida's central highlands region (CHR). Th e study was conducted in a bahiagrass (Paspalum notatum Flügge) pasture. Th e soil is an excessively drained 'Candler' sand. In dungdesignated plots, 2 kg of fresh cattle dung was deposited across the surface of a 15-cm-radius circular zone (Zone 1 [Z1]) centered within 3 × 3 m plots. In urine plots, 1 L of urine was deposited on Z1 and 1 L on Zone 2 (Z2), an area extending outward from Z1 to 30 cm from plot center. In dung and urine plots, Zone 3 (Z3) extended from Z2 to 45 cm from plot center and Zone 4 (Z4) from Z3 to 60 cm. Excreta deposition frequencies (DFs) were 0, 1, 2, and 3 times per year during 2006 and 2007. Total apparent remaining P (ARP = [fertilizer P + excreta P] -forage P removal) for Z1 of dung plots was 21, 447, 905, and 1249 kg ha-1 for DF0, DF1, DF2, and DF3, respectively. In 2008, soil was incrementally sampled to a depth of 120 cm in all zones. Urine deposition did not increase soil P. Soil P levels and the degree of P saturation percentages increased with DF but only in the upper 10 cm of topsoil beneath Z1 of dung plots. Our results suggest that the risk of dung P reaching groundwater is low due to a considerable P retention capacity within the rooting zone of the Candler soil. © American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. Source

Liu K.,University of Florida | Sollenberger L.E.,University of Florida | Newman Y.C.,University of Florida | Vendramini J.M.B.,Research and Education Center | And 2 more authors.
Crop Science | Year: 2011

'Tifton 85' bermudagrass (Cynodon spp.) is an important forage in the southern United States, but its responses to the interaction of grazing frequency and intensity have not been studied. Sward persistence, herbage accumulation, and nutritive value were measured during 3 yr. Treatments were all combinations of three postgraze stubble heights (SH; 8, 16, and 24 cm) and three regrowth intervals (RI; 14, 21, and 28 d). Short SH (8 cm) with long RI (28 d) or tall SH (24 cm) with short RI (14 d) produced greatest herbage accumulation (11-15 Mg ha-1 yr-1). Lowest or nearly lowest herbage accumulation occurred with 14-d RI and 8-cm SH or 28-d RI with 24-cm SH (7.4-12 Mg ha-1 yr-1). Intermediate levels of RI (21 d) or SH (16 cm) produced consistent herbage accumulation regardless of level of the other factor. Nutritive value was primarily affected by RI, and P (3.1 to 2.8 g kg-1), crude protein (CP; 150 to 108 g kg-1), and in vitro digestible organic matter (IVDOM; 602 to 582 g kg-1) concentrations decreased as RI increased. Organic matter and nutrient mass of storage organs increased with increasing SH, but the 24-cm SH treatment exhibited greater reduction in percentage cover (~43% units) than the other SH treatments (~22% units) after 3 yr of grazing. These data indicate that intermediate levels of SH (16 cm) and RI (21 d) provided relatively high Tifton 85 herbage accumulation and nutritive value while minimizing negative impacts on persistence-related responses. © Crop Science Society of America. Source

Thomas M.G.,Colorado State University | Mohamed A.H.,Desert Research Center | Sawalhah M.N.,New Mexico State University | Holechek J.L.,New Mexico State University | And 4 more authors.
Rangeland Ecology and Management | Year: 2015

Forage and cow-calf productivity on two lightly and two conservatively grazed pastures were evaluated over a 15-year period (1997-2011) in the Chihuahuan Desert of south-central New Mexico. Spring-calving Brangus cows were randomly assigned to pastures in January of each year. Pastures were similar in area (1 098 ± 69 ha, mean ± SE) with similar terrain and distance to water. Utilization of primary forage species averaged 27.1 ± 3.0% in lightly stocked pastures and 39.4 ± 4.0% on conservatively stocked pastures. No differences in perennial grass standing crop (163.5 ± 52.2 kg·ha-1) and calf weaning weights (286.1 ± 2.6 kg) were detected (P > 0.10) between light and conservative treatments. Lightly grazed pastures yielded greater (P < 0.05) kg of calf weaned·ha-1 and calf crop percent than conservatively grazed pastures in 1998 due to complete destocking of conservatively grazed pastures during that slight drought (i.e., rainfall was 75% of normal in 1998). After the initial 5 years of study (1997-2001), all pastures were destocked for 4 years (2002-2005) due to drought as rainfall was only 50% or less of normal. Pastures were then restocked for another 6 years (2006-2011). Postdrought, the percentage change in perennial grass standing forage crop (kg·ha-1) was -4.0 and -14.4 ± 2.5 % (P < 0.09) in the light and conservative grazed pastures across the 6 years, respectively. While conservative stocking rates may provide higher net financial returns than light stocking rates during nondrought years as there were more AU per pasture, potential losses from cattle liquidation during short-term (i.e., 1-year) droughts could nullify this advantage. Results suggest that light grazing use of forage is a practical approach for Chihuahuan Desert cow-calf operations to minimize risk of herd liquidation during short-term drought. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved. Source

Olmstead V.G.,Arkansas Tech University | Webb E.B.,Arkansas Tech University | Johnson R.W.,Natural Resource Conservation Service
Wetlands | Year: 2013

To better understand the contribution of private lands enrolled in conservation easement programs to wintering waterfowl habitat and energetics, we evaluated effects of management strategies on seed biomass, species richness, and presence of beneficial (i.e., considered to have nutritional value to waterfowl) and introduced species on 32 Wetland Reserve Program easements in Arkansas and Mississippi. We collected soil core samples from seasonal wetlands with active and passive management strategies in 2008-2009. Overall mean (±SE) biomass for all seeds was 527.8 (±28.5) kg/ha, whereas mean biomass of beneficial seeds was 263.5 (±18.5) kg/ha. Actively managed sites in Mississippi had greater beneficial seed mass compared to passively managed sites, whereas management had no effect on beneficial seed mass in Arkansas in fall 2008 and in fall 2009, passive sites had greater beneficial seed mass than active sites. Our estimate of beneficial seed biomass on WRP easements represents a 47 % reduction in estimated food availability for waterfowl on privately owned wetlands. Lower estimates of food availability on privately owned, seasonal wetlands in the lower Mississippi Alluvial Valley may warrant increased conservation efforts for seasonal wetlands or additional emphasis on management techniques to increase moist-soil seed biomass on privately owned seasonal wetlands. © US Government 2013. Source

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