In many grassland ecosystems, nutrient cycling via plant litter is important for plant growth and persistence. Understanding dynamics of litter decomposition and nutrient release under different management practices is critical to understanding nutrient cycling in grasslands, but this topic has received relatively little attention in C4 grass pastures. The objective of this study was to determine the effects of grazing intensity (defined as postgraze stubble height, SH) and N fertilization on litter decomposition and N release in ‘Tifton 85’ bermudagrass (Cynodon spp.) pastures. Three levels of SH (8, 16, 24 cm) were compared at the same interval between grazing events (28 d) and amount of N fertilization (250 kg N ha−1 yr−1). Three levels of N fertilization (50, 150, and 250 kg N ha−1 yr−1) were compared when SH (24 cm) and regrowth interval were constant (28 d). Loss of litter mass was most rapid early in the decomposition period. Pasture SH had no effect on decomposition of litter mass, but increasing N fertilization increased decomposition rate. Immobilization of litter N began almost immediately after placement in the field regardless of treatment, did not reach its maximum for up to 60 d, and lasted more than 128 d for most treatments. Increasing SH and N fertilization increased N immobilization in plant litter. Nitrogen immobilization in bermudagrass litter occurs across a wide range of pasture management practices, impacting N availability for plant growth.

There are about 1 million ha of bahiagrass (Paspalum notatum Flügge) pasture in Florida. Rapid population growth is reducing grassland area and may force beef cattle (Bos taurus) producers to achieve economic livelihood on less land. One alternative is to increase management intensity of existing pasture. This research evaluated management intensity effects on beef heifer and bahiagrass pasture performance. Management intensities were low (40 kg N ha−1 yr−1, 1.4 animal units [AU, one AU = 500 kg live weight] ha−1 stocking rate [SR]), moderate (120 kg N ha−1 yr−1, 2.8 AU ha−1 SR), and high (360 kg N ha−1 yr−1, 4.2 AU ha−1 SR). Across 4 yr, herbage mass (3.42 vs. 2.95 Mg ha−1) and allowance (4.8 vs. 1.4 kg forage kg−1 animal weight) were greater for low than high intensity. Herbage accumulation (41 vs. 17 kg ha−1 d−1), crude protein (140 vs. 99 g kg−1), and in vitro digestible organic matter (505 vs. 459 g kg−1) were greater for high than low intensity. Heifer average daily gain was greater for low than high intensity (0.34 vs. 0.28 kg), but gain per hectare (GHA) increased from low to high intensity (101 to 252 kg). Nitrogen fertilizer cost per additional kilogram of GHA above low intensity was $.76 for moderate and $2.01 for high intensity. Increasing management intensity increased bahiagrass herbage accumulation and nutritive value, but GHA did not increase sufficiently to compensate for the additional fertilizer cost, especially for high intensity. Therefore, if land limitations for cattle production become acute, use of more management‐responsive species than bahiagrass probably will be required.

Understanding the growth pattern of cool‐season annual clovers is necessary to develop management practices that maximize forage production and identify compatible grass associations and farming systems. Plant density, light interception, shoot yield, and root yield of arrowleaf (Trifolium vesiculosum Savi.), crimson (T. incarnatum L.), rose (T. hirtum All.), and subterranean (T. subterraneum L.) clovers were compared for 3 yr on a sandy loam at Overton, TX. Clovers were sampled every 2 wk when uncut, and after being cut once or twice. Initial plant densities ranged from 200 to 250 m−2 and then declined to 100 to 150 m−2 during the growing season. The uncut treatment resulted in 3‐yr average maximum shoot yields of 2480 g m−2 for arrowleaf, 1290 g m−2 for crimson, 1410 g m−2 for rose and 1000 g m−2 for subterranean clovers. Autumn growth and regrowth after cutting was greater for crimson and subterranean clovers than for arrowleaf and rose clovers. Crimson and subterranean clovers reached near 100% light interception 4 wk after cutting. Cutting usually decreased yield for all species except subterranean clover that increased with cutting because of a prostrate growth habit. When cut, rose clover always had one of the smallest shoot and root yields. Root yield increased for all clovers during the growing season when not cut and with no or small root yield decreases after cutting. Crimson and subterranean clovers are better suited for grazing and crop rotations because of their earlier maturity and response to defoliation.

‘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.

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