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'Mulato II' [Brachiaria spp.] is a warm-season grass with excellent nutritive value adapted to tropical regions; however, its herbage production and persistence in subtropical locations is unknown. Grazing and clipping studies were conducted in 2008 and 2009 in Marianna and Gainesville, FL, respectively. The treatments for the grazing study were beef heifers (Bos spp.) grazing Mulato II, 'Tifleaf 3' pearl millet [Pennisetum glaucum (L.) R. Br.], or 'Hayday' sorghum-sudangrassgrass [Sorghum bicolor (L.) Moench] pastures on a continuous stocking rate. In 2008, there were no differences in herbage allowance (HA) (0.9 kg dry matter [DM] kg-1 live weight [LW]), average daily gain (ADG) (0.5 kg d-1), and gain per hectare (168 kg) among treatments. However, Mulato II had greater HA (2.0 vs. 0.7 kg DM kg-1 LW) and ADG (0.78 vs. 0.41 kg d-1) than Tifleaf 3 and Hayday and similar gain per hectare (302 kg) in 2009. The treatments for the clipping study were Mulato II, evaluated as an annual and perennial, 'Tifton 85' bermudagrass (Cynodon spp.), Tifleaf 3 pearl millet, and Hayday sorghum-sudangrass. In 2008, Hayday and Tifleaf 3 established more rapidly than Mulato II; however, Mulato II grew later in the fall. In 2009, the perennial treatments (Mulato II and Tifton 85) had overall greater herbage accumulation than the annual treatments. In the clipping study, Tifton 85 had greater ground cover than Mulato II perennial in 2009 (73 vs. 36%) and 2010 (73 vs. 12%). Mulato II may be used as a high quality, short-lived perennial warm-season grass in subtropical areas. [ABSTRACT FROM AUTHOR]

Sweet sorghum [Sorghum bicolor (L.) Moench] is a potential bioenergy crop that is capable of high biomass and sugar yields, but production for biofuel in the Southeast is not well understood. The present study examined the effects of planting date (three dates from mid-March to mid-June) on primary and ratoon crop fresh biomass, brix, and estimated sugar yield of three sweet sorghum cultivars ('Dale', 'Topper 76-6', and 'M-81E') grown at three sites from North (29° 24′ to South Florida (26° 40′. Across all treatments, primary crop fresh biomass, brix and estimated sugar yields were 70 Mg ha-1, 148 g kg-1, and 5.69 Mg ha-1, respectively. Primary crop yields were greatest for the two earliest planting dates (mid-March to mid-May), and for our southernmost site. The yield potential for ratoon crops was in general only about half as much as the primary crop across all years, sites, and cultivars for the earliest planting date. An exception, however, was ratoon crop yields at the southernmost site, which were in some cases equal to or greater than primary crop yields. Low primary crop brix values were found for all cultivars on the muck soils in South Florida compared to the other two sites, and for M-81E compared to Dale and Topper 76-6. These low brix values were correlated with greater fresh biomass production. Further research is needed on planting dates for optimizing primary and ratoon crop yields along with varietal development with improved ratoon crop yields. [ABSTRACT FROM AUTHOR]

Despite evidence that forage crops can access P from the Bh horizon, routine soil testing focus only on P concentrations in the top 15 cm. We evaluated the role of the Bh horizon on the overall P budget for 2 yr in a bahiagrass (Paspalum notatum Flügge) pasture grown on a Spodosol. Treatments consisted of three P rates (0, 5, and 10 kg ha-1) arranged in a completely randomized design with each plot receiving a basal application of 56 kg N ha-1 and 47 kg K ha-1. Phosphorus application had no effect on bahiagrass P uptake (P = 0.2). Average P mass leached below the 45-cm soil depth was 0.08,0.08, and 0.09 kg P ha-1 for the 0, 5, and 10kg P ha-1 treatments, respectively. In 2007, the net balance of P in the Ap horizon was -10.8 kg P ha-1 for the control and -0.8 kg P ha-1 for the 10kg P ha-1 treatment. The same treatments had net P balances of-6.6 and 7.2 kg ha-1 in 2008. When soil P held in the Bh horizon was included in the P budget computation, the net P balance was positive for all treatments including the control. Results indicate that soil P concentrations were sufficient to maintain bahiagrass production with no additional P fertilization required. Phosphorus held in the Bh horizon is a significant supply of P to low-input pastures growing on Spodosols in Florida and should be considered in nutrient management programs for perennial grasses. [ABSTRACT FROM AUTHOR]

The increased cost of fertilizer and concerns about environmental impacts have led to a reduction in P use in grazed pastures in Florida; however, P fertilization may be necessary to sustain bahiagrass (Paspalum notatum Flugge) pastures. This study evaluated the impacts of reduced P fertilization on forage characteristics, soil and leachate P concentrations on bahiagrass pastures during 2007 and 2008. Treatments consisted of three P fertilization levels (0, 5, and 10kg P ha-1, applied as KH2PO4) arranged in a randomized complete block design with four replicates. Twelve 1.2-ha bahiagrass pastures were stocked continuously with a fixed stocking rate of two beef heifers [Bos sp; 380 ± 30kg live weight (LW)] per experimental unit. Forage was sampled at 14-d intervals for herbage mass (HM), crude protein (CP), and in vitro digestible organic matter (IVDOM) concentrations. Two suction lysimeters were installed at 60- and 90-cm depth to monitor leachate P. Phosphorus fertilization did not affect HM (4.4 Mg ha-1), herbage accumulation rate (HAR, 43 kg ha-1 d-1), CP (94 g kg-1), or IVDOM (500 g kg-1). Tissue P concentrations increased from 1.9 to 2.2 g kg-1 as P fertilization increased from 0 to 10 kg P ha-1. Soil P concentration in the Ap (7 mg kg-1) and Bh horizons (23 mg kg-1) and leachate P concentration (0.06 mg L-1) were not affected by P application. Despite the lack of yield response to P fertilization, P application at levels of 5 and 10kg P ha-1 showed no impacts on water quality. [ABSTRACT FROM AUTHOR]

Early weaned beef calves (Bos spp.) can be raised on cool-season pastures in Florida but more information on protein supplementation is necessary to optimize the performance of those calves. The objective of this study was to evaluate the effects of three levels of rumen-undegradable protein (RUP) supplementation on performance of early weaned calves grazing annual ryegrass (Lolium multiflorum Lam.) pastures. The study was conducted in Ona, FL in 2007 and 2008, Treatments were 1.5 g kg-1 body weight (BW) supplementation of three levels of supplemental RUP, soybean meal (SBM, 350 g kg-1 RUP), Soy- plus (SP, 600 g kg-1 RUP, modified expeller soybean meal, West Central, Ralston, IA), or a 50:50 mixture of soybean meal-Soyplus (SBMSP, 475 g kg-1 RUP). Pasture size was 0.3 ha and four early weaned calves were assigned to each pasture. There was a linear increase in herbage mass (HM, from 1.9-2.1 Mg ha-1) and herbage allowance (HA, from 1.1-1.4 kg dry matter [DM1 kg-1 live weight, LW) with increasing levels of RUP. Increased RUP supplementation decreased forage dry matter intake (FDMI) and total dry matter intake (TDMI) in 2008 but there was no effect in 2007. There was no difference in average daily gain (ADG, 0.76 kg d-1) among treatments. Increasing the levels of PUP supplementation has potential to increase stocking rates of early weaned calves grazing annual ryegrass pastures. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Bahiagrass (Paspalum notatum Flügge) is the most used forage for beef cattle (Bos sp.) in Florida; however, damage to bahiagrass pastures by mole cricket (Scapteriscus spp.) stimulated a search for other adapted grasses. The objective of this study was to test the effect of different stocking rates (SRs) on animal performance and herbage characteristics of 'Mulato' (Brachiaria sp.) and bahiagrass pastures. The experiment was conducted in Ona, FL, from May to September, 2007 and 2008. Treatments were three SRs (4, 8, and 12 heifers ha-1) and two forage species (Mulato and 'Pensacola' bahiagrass). There was a linear decrease in herbage mass (from 5.9 to 3.2 Mg ha-1) and herbage allowance (from 2.8 to 0.6 kg dry matter kg-1 liveweight) with increasing SR. Mulato had greater in vitro digestible organic matter concentration than bahiagrass (675 vs. 534 g kg-1) but similar crude protein concentration (130 g kg-1). There was a linear decrease in average daily gain (from 0.49 to 0.22 kg d-1) and a quadratic response of liveweight gain ha-1 as SR increased (190, 353, and 217 kg ha-1 for SRs of 4, 8, and 12 heifers ha-1, respectively). Mulato has potential to be an alternative forage to bahiagrass for beef cattle producers in Florida. [ABSTRACT FROM AUTHOR]

A genetically diverse population of Setaria sphacelata was developed at Gainesville, Florida by intercrossing the cultivars 'Narok', 'Kazungula' and 'Solander' and a local persistent population. To determine heritability of traits that may improve setaria as a forage plant in Florida, progeny of the intercrossed population underwent two cycles of selection for inflorescence number and one cycle for leaf width. The selected populations, together with cultivars and introductions, were evaluated for morphological characters, yield and forage quality in field experiments with close- and wide-spaced plants. Increase of inflorescence number was not obtained by selection but resulted in decreased plant height, inflorescence length, yield, leaf width, and leafiness. Leaf width was increased by selection and was associated with increased leafiness and whole-plant crude protein content. The results suggest good prospects for selection of setaria cultivars suited to Florida with improved yield and quality providing they tolerate winter cold and reliably produce seed. [ABSTRACT FROM AUTHOR]