Plant litter is an important nutrient pool in grassland ecosystems. Management practices affect litter quality and may affect nutrient dynamics in pastures by altering the rates of nutrient mineralization and immobilization. The effect of management intensity on litter decomposition and nutrient disappearance was evaluated in a litter bag study on continuously stocked 'Pensacola' bahiagrass (Paspalum notatum Flü gge) pastures growing on Pomona and Smyrna sands. Treatments were three management intensities: Low (40 kg N ha 21 yr 21 and 1.3 animal units [AU, one AU 5 500 kg live weight] ha 21 stocking rate [SR]), Moderate (120 kg N ha 21 yr 21 and 2.7 AU ha 21 SR), and High (360 kg N ha 21 yr 21 and 4.0 AU ha 21 SR). Litter relative decomposition rate (k) was greater for High (0.0030 g g 21 d 21 ) than Low (0.0016 g g 21 d 21 ). Litter N, acid detergent insoluble N (ADIN), and lignin concentrations were greater for High than the other intensities at the end of the 168-d incubation period because of faster decomposition of soluble compounds. Across management intensities, approximately one-half of litter N remaining at the end of the incubation period was bound to acid detergent fiber (ADF). Net N mineralization through 128 d of incubation was only 200 to 300 g kg 21 of total N. Increasing management intensity resulted in faster litter turnover and greater nutrient release, but nutrient release from litter was small and significant quantities of nutrients were immobilized even under the most intensive management.

Nutrients cycle among pools within an ecosystem, and losses of nutrients to the environment accompany each transfer from pool to pool. Efficient recapture of nutrients by plants is critical in extensively managed grasslands if these swards are to persist. In intensively managed systems, the greatest contribution of efficient recapture of nutrients may be minimizing loss of nutrients to the environment and associated negative impacts. Regardless of management intensity, grassland management decisions should be informed by an understanding of the dynamics of nutrient cycling. A significant body of literature has emerged in recent years describing nutrient dynamics in warm‐climate grasslands. In warm climates globally, grasslands are most often low‐input production systems dominated by C4 grasses. These characteristics affect nutrient cycling, resulting in very different management challenges and opportunities than in higher input, C3–grass or legume‐dominated, grasslands. This paper will focus on warm‐climate grasslands. Within that context its objectives are (i) to describe the most prominent pools of C, N, P, and K, (ii) to discuss fluxes among nutrient pools, with emphasis on plant litter and animal excreta, iii) to describe the importance, management, and dynamics of soil organic matter, and (iv) to review the impact of grazing systems on nutrient cycling.

Warm‐climate grasslands are often N limited. Legume litter decomposition can contribute significantly to N input in grazing systems, but its contribution depends on litter deposition, decomposition, and chemical composition. We evaluated these responses for 2 yr in unfertilized (BG) and fertilized (BGN; 50 kg N ha−1) bahiagrass (Paspalum notatum Flügge) monocultures and in mixed swards of bahiagrass plus the legume rhizoma peanut (Arachis glabrata Benth.). Legume–grass mixture litter had greater initial N concentration (26 g N kg−1 organic matter [OM]) and lower C/N ratio (22) than BG and BGN, which did not differ from each other (18 g N kg−1 OM, C/N ratio of 31). Litter biomass relative decay rate was greater for mixtures than for bahiagrass monocultures. As a result, less biomass and N remained at the end of incubation in mixtures (62 and 76%, respectively) than in monocultures (69 and 80%, respectively). Litter deposition rate was similar across treatments, but faster decomposition and greater N concentration for legume–grass mixtures resulted in larger litter N release than in monocultures (44 and 26 kg ha−1, respectively). At the end of incubation, remaining litter biomass and remaining N decreased with increasing litter legume proportion, whereas litter N concentration and litter decay rate increased. Results indicate that legume–grass mixtures are an alternative to N fertilizer for increasing N cycling through plant litter in grasslands, and although litter deposition rates were similar across treatments, increasing legume proportion in mixtures is likely to be associated with greater litter N release.

Grasslands in warm‐climate regions are often based on grass monocultures, increasing their dependence on N fertilizers. Integrating perennial legumes into grass pastures is a logical option. The objective of this 2‐yr study was to assess seven rhizoma peanut (Arachis glabrata Benth) cultivars: Arbrook, Arblick, Ecoturf, Florigraze, Latitude 34, UF Peace, and UF Tito. Above‐ and belowground responses included biomass, in vitro organic matter disappearance (IVOMD), N concentration, N content, δ15N, proportion of N derived from atmosphere (%Ndfa), and biological N2 fixation (BNF). Arbrook was more productive than Florigraze in both years (P ≤ 0.05) but produced similar biomass to other varieties in 2014. In 2015, Arbrook also was more productive than Arblick and Latitude 34. Herbage N concentration ranged from 19.2 to 36.3 g kg−1. Arbrook tended to be less digestible than other rhizoma peanut cultivars. The BNF represented >80% of herbage N and averaged 200 kg N ha−1 yr−1, with values ranging from 123 to 280 kg N ha−1 yr−1. Root and rhizome biomass varied among cultivars, with Ecoturf (26.9 Mg organic matter [OM] ha−1) and Latitude 34 (27.8 Mg OM ha−1) presenting greater root and rhizome mass than Florigraze (10.5 Mg OM ha−1) but similar to other varieties. Roots and rhizomes represented a significant portion of the total biomass and N pool, and further studies are needed to assess turnover of these tissues as well as their N contribution in grazing systems using grass–rhizoma peanut mixtures.

Plant litter is an important pathway of nutrient return to the soil in grazed swards, but the effects of pasture management on litter mass and composition are not well understood. This research evaluated the effect of management intensity, defined in terms of N fertilization and stocking rate (SR), on litter mass, deposition rate, and chemical composition in continuously stocked 'Pensacola' bahiagrass (Paspalum notatum Flü gge) pastures growing on Pomona and Smyrna sands. Treatments were three management intensities: Low (40 kg N ha 21 yr 21 and 1.3 animal units [AU, one AU 5 500 kg live weight] ha 21 SR), Moderate (120 kg N ha 21 yr 21 and 2.7 AU ha 21 SR), and High (360 kg N ha 21 yr 21 and 4.0 AU ha 21 SR). Greater management intensity resulted in less litter mass on the pasture early in the growing season and more litter mass later in the season. Rate of litter deposition was generally greatest for High and ranged between 23 and 40 kg organic matter (OM) ha 21 d 21 compared with 13 to 30 kg OM ha 21 d 21 for Low and Moderate management intensities. Increasing management intensity from Low to High resulted in greater litter N (14.1 vs. 22.9 g kg 21 ) and P (0.8 vs. 1.3 g kg 21 ) concentrations and lesser C:N (f40 vs. 22), C:P (649 vs. 433), and lignin:N (5.8 vs. 4.4) ratios. More intensive pasture management was associated with greater litter deposition rate and litter quality than less intensive management, suggesting a larger nutrient contribution from litter in intensively managed swards.

Ecosystem services (ES) are the direct and indirect contributions of ecosystems to human well‐being. Grassland ecosystems cover >40% of Earth's ice‐free terrestrial surface, and grassland management affects the ES provided. Our objective was to synthesize the existing literature assessing management effects on regulating and supporting ES provided by grasslands, explore the related mechanisms, and determine which practices favor ES delivery. Current literature supports the following conclusions. Increasing management intensity of grasslands through planting more productive species or increasing fertilizer inputs generally increases soil organic C (SOC) accumulation. Increasing the number of plant species or functional groups, especially when legumes are added, often increases SOC accumulation. Grazed grasslands generally accumulate SOC more rapidly than undefoliated grasslands. Low or moderate stocking rates favor SOC accumulation relative to high stocking rates, especially in lower‐rainfall environments. Short‐term SOC accumulation rates observed after conversion of cropland to perennial grassland do not continue indefinitely. More digestible forages defoliated at optimal maturity may decrease CH4 emitted per unit of feed consumed or per unit of animal product. Substituting legumes for N fertilizer and reducing livestock N excretion through diet manipulation reduce N2O emissions. Managing grazing to increase uniformity of excreta deposition increases efficiency of nutrient cycling. Species‐rich grasslands with flower‐rich legumes and forbs increase foraging opportunities for pollinators. Finally, to optimize delivery of grassland ES, management practices that sustain ecosystem function likely need to replace those that maximize short‐term resource utilization or economic return. To encourage adoption, such practices may need to be incentivized.

Early weaning of calves (Bos spp.) increases pregnancy rates of beef cows; however, there is little information on nutritional management of the weaned calf on pasture. This research evaluated the effect of concentrate supplementation level on performance of early weaned (90 d of age) beef calves grazing annual ryegrass (Lolium multiflorum Lam.)–rye (Secale cereale L.) mixtures on Adamsville (uncoated, hyperthermic, Aquic Quartzipsamment) and Pomona (sandy, siliceous, hyperthermic Ultic Alaquod) sands. Three levels of supplement (10, 15, and 20 g kg−1 of calf body weight [BW]) were evaluated in a completely randomized design with three replicates. The concentrate contained 146 and 700 g kg−1 of crude protein (CP) and total digestible nutrients (TDN). Pastures were rotationally stocked with a 7‐d grazing and 21‐d rest period. Two calves were assigned as testers to each pasture, and additional animals were used to maintain a similar herbage allowance across treatments. There was no effect of concentrate supplementation level on herbage mass, accumulation, allowance, or nutritive value. Calf average daily gain (ADG; 0.74–0.89 kg), liveweight gain (LWG) per hectare (950–1320 kg), and stocking rate (SR; 5.5–6.5 animal units [AU] ha−1) increased linearly, and forage intake decreased linearly (18–11 g kg−1 BW) as concentrate rate increased. Grazing time was 284, 230, and 234 min d−1 (linear and quadratic effects) for the 10, 15, and 20 g kg−1 BW supplement treatments, respectively. Feeding systems with modest levels of supplementation (10 g kg−1 BW) of calves grazing cool‐season grasses are practical options for early weaned calves during winter in the southeastern USA.

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.