Total Herbage Accumulation Research Articles

Grazing intensity effects on sward responses of UF Riata Bahiagrass

AbstractBahiagrass (Paspalum notatum Flüggé) is a rhizomatous, perennial, warm‐season forage widely grown in the southeastern United States "UF Riata" bahiagrass is more upright growing with greater herbage production when days are shorter compared with most other cultivars. Lesser daylength sensitivity extends the grazing season, but in combination with more upright growth may negatively affect persistence under grazing, especially if out‐of‐season herbage production interferes with normal reserve storage. This 3‐year study investigated above and belowground sward responses of UF Riata bahiagrass to three levels of post‐grazing herbage mass (HM) (500 [heavy grazing, HG], 1500 [moderate grazing], or 2500 [light grazing, LG] kg DM ha−1, where DM is dry matter) imposed by mob stocking every 14 days. Total herbage accumulation (HA) and HA rate were not affected by treatment. Crude protein (CP) was affected by treatment × grazing cycle × year, whereas in vitro digestible organic matter concentrations were affected by treatment × year and grazing cycle × year. Root–rhizome biomass (12,940–9230 kg OM ha−1, where OM is organic matter) and soil cover percentage (97%–93%) decreased linearly as grazing intensity increased from LG to HG. Proportion of non‐planted grasses was 34% and 17% in HG and LG swards, respectively. Proportion of non‐grass weeds increased across treatments from 2% to 22% over the years. Moderate grazing could maintain similar CP to HG, and similar root–rhizome biomass to LG. Thus, considering both sward persistence and forage nutritive value, a target post‐grazing HM of ≈1500 kg DM ha−1 is recommended when UF Riata pastures are grazed every 2 weeks.

Herbage accumulation and nutritive value of stockpiled limpograss and ‘Tifton 85' bermudagrass

AbstractStockpiling limpograss [Hemarthria altissima (Poir.) Stapf & C.E. Hubb.] may be an option to extend the grazing season and decrease the needs for conserved forage in Florida. This 2‐yr study evaluated herbage accumulation (HA), in vitro digestible organic matter (IVDOM), and crude protein (CP) concentrations of four limpograss entries (‘Floralta’, ‘Gibtuck’, ‘Kenhy’, and Entry 1) and ‘Tifton 85′ bermudagrass [Cynodon spp.] during the growth (May–August) and stockpiling (September–January) periods. During the growth period, treatments were the five grasses. During the stockpiling period, treatments were allocated in a split‐plot arrangement with five grasses (main plot) and four stockpiling periods (5, 10, 15, or 20 wk; subplot). Limpograss and Tifton 85 had similar total HA (mean = 8,150 lb dry matter [DM] acre–1) during the growth period, and Gibtuck had greater HA per harvest than Kenhy and Entry 1 (2,360 vs. 1,940 lb DM acre–1, respectively). Regardless of the stockpiling period, HA was similar among treatments. At 15 wk, HA was maximized in both years, despite being similar to 10 and 20 wk in the first year. In general, limpograss had greater IVDOM and lesser CP concentration than Tifton 85 during growth and stockpiling periods. The decline in IVDOM was slower for stockpiled limpograss than Tifton 85, with greater differences occurring at 15 and 20 wk. Stockpiling limpograss may be an alternative to extend the grazing season in livestock operations, however protein supplementation might be needed to maintain or improve animal performance.

Seeding rate affects the performance of oat and black oat

AbstractBasic management practices, including ideal seeding rates, are still lacking for black oat (Avena strigosa Schreb.) in the southeastern United States. This study evaluated the performance of five seeding rates (15, 30, 60, 120, and 240 lb acre−1) on ‘Legend 567’ oat (Avena sativa L.) and ‘UF‐10’ black oat at three harvest dates (early, mid‐season, and late) per year. Seeding rates of 60, 120, and 240 lb acre−1 tended (P = .07) to increase total herbage accumulation [4,760 lb dry matter (DM) acre−1] compared with 15 lb acre−1 (3,945 lb DM acre−1). Tiller density was usually greater for black oat than for oat. Seeding rate was positively associated with tiller density and explained 84 to 98% and 96 to 98% of the variation for black oat and oat, respectively. Tiller mass was greater for oat (0.045 oz tiller−1) than black oat (0.034 oz tiller−1), and greater for the mid‐season harvest (0.043 oz tiller−1), compared with the early and late harvests (0.037 oz tiller−1 on average). There was a negative effect (P < .001) of seeding rate on tiller mass. Increasing the seeding rate had a negative effect on leaf length at the early and middle harvests (P < .05), and decreased leaf width from 0.56 to 0.39 inches in oat, and from 0.32 to 0.29 inches in black oat when changing from 15 to 240 lb acre−1. To maximize herbage accumulation at a lower seeding rate, we recommend 60 lb acre−1 for both oat and black oat for multiple harvests.

Herbage responses and nitrogen agronomic efficiency of bermudagrass–legume mixtures

AbstractBermudagrass (Cynodon spp.) is an importantwarm‐season grass for livestock in the southern United States. To be productive, bermudagrass requires supplementary N. This 2‐yr study assessed whether N fertilization could be halved by introducing alfalfa (Medicago sativa L.) or rhizoma peanut (RP; Arachis glabrata Benth.) into ‘Tifton‐85’ bermudagrass monocultures without compromising productivity. Treatments were: bermudagrass, N‐fertilized bermudagrass, alfalfa (‘Alfagraze 600 RR’), RP (‘Florigraze’), and the mixtures bermudagrass–alfalfa and bermudagrass–RP. Mixtures were fertilized with 45 kg N ha–1 harvest–1, whereas N‐fertilized bermudagrass received 90 kg N ha–1 harvest–1. Seven harvests were made each year. Nitrogen‐fertilized bermudagrass and mixtures had similar total herbage accumulation (HA) in 2017, but mixtures produced approximately 3,340 kg DM ha–1 yr–1 less than N‐fertilized bermudagrass in 2016, which had a drier summer. Percentage of alfalfa in the mixtures decreased from 68 to <1% by the end of the study. Rhizoma peanut proportion in mixtures was often low (max. 8%). Nitrogen‐fertilized bermudagrass had the greatest total harvested N in May of 2016 (96 kg N ha–1), but it did not differ from bermudagrass–RP in May of 2017. Nitrogen agronomic efficiency (NAE) was greater for mixtures (27.5 kg DM kg–1 N applied) than for N‐fertilized bermudagrass (21 kg DM kg–1 N applied). Greater NAE in mixtures occurred due to limited response to high N fertilization rates in the N‐fertilized bermudagrass. Further studies on establishment methods, cultivar selection, and management practices are still needed to adopt a successful bermudagrass–legume mixture in northern Florida.

Impacts of cutting frequency and position to tree line on herbage accumulation in silvopastoral grassland reveal potential for grassland conservation based on land use and cover information

AbstractIn agricultural grassland, high herbage utilisation efficiency (HEFF), which is the proportion of gross live‐green herbage production that is utilised before entering senescence, is ensured by frequent defoliation. The decision upon which defoliation frequency to apply depends on the farming intensity. Assuming a reduced total herbage accumulation near trees in silvopastoral systems, frequent defoliations with high HEFF become less worthwhile—at least in specific spatial configurations. This makes an extensive management near trees an interesting option because it promotes other grassland‐related ecosystem services such as biodiversity. The present study first analysed the interaction between defoliation frequency and position to trees on the total, dead and live herbage accumulation and the HEFF at two silvopastoral sites with short‐rotation coppices in Germany. In addition, the total grassland–tree interface in Germany was assessed from land use and land cover maps of Germany based on satellite data to approximate the potential of grassland extensification near trees. The total herbage accumulation near trees declined by up to 41% but the HEFF was not affected by the position. Consequently, any intensification is not paid‐off by adequate productivity and herbage quality in terms of HEFF and tree‐related losses in herbage accumulation are expected up to a distance of 4.5–6 m. Applying a 4.5 m border on satellite data, we found that up to 4.4% (approximately 2200 km2) of the total grassland area in Germany is at a tree interface and potentially suitable for extensification. These findings indicate substantial potential for biodiversity conservation in grasslands with low trade‐off for high‐quality yield.

Sward height determines animal performance on limpograss (

Changes in grazing intensity affect forage production and performance of animal on C4 grass pastures; however, these relationships are not well defined for cattle grazing on limpograss (Hemarthria altissima (Poir) Stapf & C.E. Hubb. cv. Flórida) under continuous stocking. The objective of this study was to quantify plant and animal production from Flórida limpograss pastures, managed at different grazing intensities by beef heifers (i.e. different sward heights) in order to define pasture management outcomes that maximise plant and animal responses. For a 3-year period, the influence exerted by the sward height (10, 20, 30 and 40 cm) was assessed. Greater total herbage accumulation and herbage accumulation rate were observed for the more lenient grazing heights (30 and 40 cm). The 20-, 30- and 40-cm heights revealed similar heifer average daily gain of 0.49 kg liveweight (LW) animal–1 day–1, reducing at the rate of 0.04 kg LW animal–1 day–1, for each cm decrease below 19 cm, according to a segmented equation. LW gain per area showed a quadratic response to the sward height, with optimum values (i.e. 2.1 kg LW ha–1 day–1) achieved at a pasture height of around 21 cm. Therefore, to optimise cattle performance on continuously stocked Flórida limpograss pastures, a sward height of ~20 cm should be maintained.

Seasonal herbage accumulation and canopy characteristics of novel and standard brachiariagrasses under N fertilization and irrigation in southeastern Brazil

AbstractUnderstanding seasonal changes in herbage accumulation (HA) and canopy characteristics of tropical grasses aids management of forage–livestock systems and optimizes use of novel cultivars in traditional and integrated systems. The objective of this study was to describe and explain seasonal HA and canopy characteristics of three standard brachiariagrass cultivars in southeastern Brazil under conditions of N fertilization and irrigation: ‘Basilisk’ signalgrass [Brachiaria decumbens (Stapf.); syn. Urochloa decumbens (Stapf) R. D. Webster]; two commercially released palisadegrass [B. brizantha (Hochst. Ex A. Rich.) Stapf.; syn. U. brizantha (Hochst. ex A. Rich.) R. D. Webster] cultivars, Marandu and Xaraés; and unreleased selections of palisadegrass, Arapoty and Capiporã. Grass plots were mechanically harvested every 28 d during the warm season and every 42 d during the cool season to 15‐cm stubble starting in September 2005 and ending in September 2008. Capiporã and Xaraés were the most productive (15.6 and 14.6 Mg dry matter [DM] ha−1, respectively) despite having greater seasonality of growth. Arapoty did not show advantages over the cultivars Basilisk and Marandu, with similar total annual HA (∼11 Mg DM ha−1). Arapoty and Basilisk forage averaged 50% more stems than the other grasses in the warm season. Leaf area index (LAI) and light interception (LI) at harvest did not vary among grasses in Year 1, with an average of 3.1 and 90.3%, respectively, and were generally greater for Marandu in Year 2. Capiporã and Xaraés are options for intensive pasture‐based livestock production systems and for pasture diversification in tropical areas because of their good HA with great leaf proportion.

Registration of ‘Mislevy’ bermudagrass

Abstract‘Mislevy’ (Reg. no. CV‐46, PI 693070) bermudagrass [Cynodon dactylon (L.) Pers.] was selected at the University of Florida, and a series of research projects was conducted to evaluate the merit of Mislevy to be released as a new bermudagrass cultivar in Florida. A grazing experiment was conducted in South Florida and clipping trials conducted in South Florida, north‐central Florida, and North Florida. In the grazing trial, Mislevy was compared with Jiggs, World Feeder, and ‘Tifton 85’ bermudagrass, and four stargrass (Cynodon nlemfuensis Vanderyst) cultivars/entries at four grazing frequencies. Mislevy, Jiggs, and Florona had the greatest overall herbage accumulation (HA), but Mislevy had greater HA at late maturity (7 wk). In the clipping trials, Mislevy was compared with Jiggs, Tifton 85, ‘Tifton 44’, ‘Coastal’, Alicia (North Florida only), and ‘Russell’ (North Florida only) bermudagrass. Mislevy and Jiggs had greater spring HA and total HA than the other cultivars/entries in South Florida and North Florida. In South Florida, all cultivars/entries had the presence of Bipolaris spp. in the aboveground forage at the 9‐wk regrowth interval; however, Mislevy and Tifton 44 had greater proportion of green tissue. In north‐central Florida, there was no difference in spring HA among cultivars, and Tifton 85 had greater total annual HA than Mislevy. Mislevy may be a viable option to increase bermudagrass genetic diversity and provide superior spring and annual HA in South Florida.

Combining perennial ryegrass cultivars in seed mixtures confers limited and situation-specific benefits for dairy pasture productivity

ABSTRACT Combining several cultivars within species in seed mixtures is often advocated as a means for improving crop or pasture performance. Herbage accumulation (HA) of perennial ryegrass-white clover pastures sown with a single cultivar representing different functional types of perennial ryegrass was compared with the HA of cultivar mixtures over three years in two contrasting environments (Waikato, dryland; Canterbury, irrigated) under dairy cattle grazing. Functional types were: mid-season flowering diploid, late-season diploid, and late-season tetraploid. Mixture treatments (n = 4 at each site) included all binary combinations plus the three-way combination. Mixture HA and the mean HA of the constituent cultivars did not differ for any of the mixture combinations in either environment, apart from winter in Waikato where the mid-diploid plus tetraploid mix out-yielded the mean of the individual cultivars and tended to increase total annual HA. The total annual HA of the mixtures was between 1.0 and 2.3 t DM/ha/year less than the HA of the highest-yielding individual cultivar included in the mixture in six of the eight mixture-environment combinations. While some benefits of mixtures for controlling grazing outcomes were observed, sowing individual high-performing cultivars is a better overall strategy than mixing cultivars to cover a spectrum of traits.

Grazing management strategies for Urochloa decumbens (Stapf) R. Webster in a silvopastoral system under rotational stocking

AbstractOur objective was to compare herbage accumulation and nutritive value of Urochloa decumbens (Stapf) R. Webster managed under pre‐grazing canopy light interception (LI) targets of 90%, 95% and 100% in silvopastoral system (SPS) and 95% in open pasture (OP; U. decumbens under full sunlight) to establish a pre‐grazing target for SPS of ~43% shade. The evaluations were made during two rainy seasons and one dry season. The total herbage accumulation in SPS was lower than in OP at all LI targets and seasons. However, the difference in total herbage accumulation between SPS and OP was reduced when SPS was harvested at 95% LI, with reductions of 20% and 28% in both rainy seasons (12,191 × 15,324 kg DM/ha and 11,158 × 15,424 kg DM/ha respectively). Moreover, under 95% LI in SPS, crude protein concentration was 18% and 19% greater than that in OP in both rainy seasons (155 × 131 g/kg DM and 144 × 121 g/kg DM respectively), thus representing the optimal pre‐grazing LI target for U. decumbens in SPS. In addition, a canopy height of 20 cm was necessary for 95% LI in OP and a height of 40 cm in SPS. Therefore, U. decumbens should be grazed at 40 cm canopy height, in SPS with ~43% shade to keep 95% LI as the target. However, this target will only be effective if the shade level is maintained, which will reduce height variation over time.

Herbage responses of Tamani and Quênia guineagrasses to grazing intensity

AbstractNew forage cultivars require defoliation studies for recommending proper grazing management. Our objective was to characterize herbage accumulation (HA), plant‐part composition and nutritive value of guineagrass [Megathyrsus maximus (Jacq.) B. K. Simon & S. W. L. Jacobs] rotationally stocked under two grazing intensities. The experimental design was a randomized complete block with three replicates of a 2 × 2 factorial arrangement of two guineagrass cultivars (‘BRS Quênia’ and ‘BRS Tamani’) and two grazing intensities. Heavy (HGI) and lax (LGI) grazing intensities were imposed as post‐grazing stubble heights: 15 and 25 cm for Tamani, and 20 and 35 cm for Quênia, respectively. The experimental period was from March 2015 to March 2017, comprising eight seasons (autumn 2015, winter 2015, spring 2015, summer 2016, autumn 2016, winter 2015, spring 2016, and summer 2017). In the spring 2016 and summer 2017, pre‐grazing HM was sampled as two strata above the stubble height, each comprising 50% of the sampled height (upper and lower stratum). Total herbage accumulation was similar across years, cultivars, and intensities (16,810 kg DM ha−1). Quênia and Tamani had the greatest HA during summer. The leaf proportion was least in the HGI pastures. Under HGI, the lower stratum of both cultivars had the greatest stem proportion and the least nutritive value. The greatest herbage CP concentration and the least NDF, ADF, iNDF and LIG concentrations occurred in the upper stratum. Based on these results, 35 and 55 cm are recommended as target heights for initiation of grazing, and 25 and 35 cm as post‐grazing stubble heights for Tamani and Quênia, respectively.

Performance of Purunã beef heifers and pasture productivity in a long-term integrated crop-livestock system: the effect of trees and nitrogen fertilization

The incorporation of trees in integrated crop-livestock systems (ICLS) has been suggested to recovery degraded pastures and to improve production and environmental outcomes in livestock systems. A challenge for their long-term productive stability is to minimize competition (especially for light) among components of the systems. The objective of this study was to evaluate the performance of beef heifers grazing cool-season grasses in two different ICLS, crop-livestock only and crop-livestock with trees (CLT), and at two N supply levels (90 and 180 kg N ha−1), in the subtropical region of Brazil. This study was performed over two consecutive years (2017 and 2018), in 11–12-year-old tree plantation (238 trees ha−1) and after a drastic reduction in tree density (remaining ~ 40 eucalyptus trees ha−1). The experimental design was randomized blocks with treatments set up in split plots with three replications. Main plots were treatments (ICLS * N) and subplots were years. The results indicate that the moderate shading level (~ 36%) provided by trees in the CLT system affected pasture growth (the total herbage accumulation was reduced in 2.02 Mg ha−1), the daily gain per animal (− 27%) and, consequently, decreased carrying capacity (− 28%) and weight gain per area (− 42%). An increase in N availability was not enough to overcome these differences. The possible influence of previous periods with intense shading (> 50%) in this long-term experiment on the current results, via reduction in the quantity of residues (plant and animal) deposited on soil surface, is discussed, as well as possible strategies to reduce losses in animal production in CLT systems.

Harvest frequency effects on herbage characteristics of ‘Mavuno’ brachiariagrass

Abstract‘Mavuno’ brachiariagrass (Brachiaria spp.) is a warm‐season perennial grass cultivar released in Brazil with potential to be used as forage in subtropical regions. The objective of this study was to evaluate herbage accumulation (HA), nutritive value, and the persistence of Mavuno under different harvest frequencies. The experiment was conducted in Ona, FL, from April to November in 2016 and 2017. Treatments were the factorial arrangement of four grasses: Jiggs bermudagrass [Cynodon dactylon (L.) Pers], ‘Tifton 85’ bermudagrass (Cynodon spp.), ‘Mulato II’ brachiariagrass, and Mavuno and two regrowth intervals (3 or 6 wk), distributed in a randomized complete block design with four replicates. Mavuno and Mulato II had similar total annual HA (11.0 Mg ha−1), and in vitro digestible organic matter (IVDOM, 644 g kg−1), but greater total annual HA and IVDOM than Jiggs (7.8 Mg ha−1 and 500 g kg−1) and Tifton 85 (8.4 Mg ha−1 and 550 g kg−1). Mavuno had the least crude protein (CP) among all treatments (111 vs. 124 g kg−1), and CP and IVDOM were greater at the 3‐wk regrowth interval than at the 6‐wk interval (130 vs. 111 g kg−1 and 610 vs 548 g kg−1, respectively). Root mass was greater at 3 wk than at 6 wk for Tifton 85 (9.4 vs. 5.4 Mg ha−1) but was not affected by regrowth interval for Jiggs, Mavuno, and Mulato II (6.5 Mg ha−1). Mavuno and Mulato II had superior HA and IVDOM, and Mavuno may be a viable forage source in subtropical regions.

Sward Responses of Bahiagrass Cultivars under No Nitrogen Fertilization

ABSTRACTBahiagrass (Paspalum notatum Flüggé) is the base of cow‐calf operations in Florida. Nitrogen is usually the most limiting mineral in pasture‐based systems. Various bahiagrass cultivars have been released over the years; however, an evaluation of their performance under no N fertilization has not been reported. There is some evidence that bahiagrass can associate with free‐living bacteria and fix atmospheric N2. This study investigated the performance and potential biological N2 fixation (BNF) of six bahiagrass cultivars (‘Argentine’, ‘AU Sand Mountain’, ‘Pensacola’, ‘TifQuik’, ‘Tifton‐9’, and ‘UF‐Riata’) under no N fertilization during the growing seasons of 2014, 2015, and 2016. Results showed no differences among cultivars for total herbage accumulation (2835 kg dry matter ha−1), total N aboveground (28 kg N ha−1 yr−1), and BNF (9 kg N ha−1 yr−1). Pensacola had greater crude protein than Tifton‐9 (84 vs. 78 g kg−1, respectively), whereas AU Sand Mountain had greater in vitro digestible organic matter (494 g kg−1) than other cultivars, except for Argentine. Argentine had greater root‐rhizome mass (24,914 kg organic matter ha−1) than UF‐Riata and TifQuik (15,367 and 14,682 kg organic matter ha−1, respectively). Carbon and N stocks in belowground biomass were greater in Argentine (8575 and 155 kg ha−1, respectively) than UF‐Riata (4514 and 85 kg ha−1, respectively). Root‐rhizome/shoot ratio averaged 37 across cultivars. Managing bahiagrass cultivars under no N fertilization inhibits the cultivar herbage potential; however, cultivar differences in nutritive value and root‐rhizome responses can still be detected.

Herbage Responses and Biological N2 Fixation of Bahiagrass and Rhizoma Peanut Monocultures Compared with their Binary Mixtures

Bahiagrass (Paspalum notatum Flüggé) and rhizoma peanut (RP, Arachis glabrata Benth.) are widely used in Florida, and growing them in association may decrease the need for N fertilization. This study evaluated herbage responses of mixed RP–bahiagrass swards in comparison with their monocultures. The eight treatments were two bahiagrass entries (‘Argentine’ and DF9, receiving 90 kg N ha−1 harvest−1) and two RP entries (Ecoturf and Q6B) in monoculture and the combinations of each bahiagrass with each RP (Argentine–Ecoturf, Argentine–Q6B, DF9–Ecoturf, and DF9–Q6B). There was no difference in total herbage accumulation (HA) in 2015. In 2016, total HA was greatest for Argentine + N (9630 kg dry matter [DM] ha−1), followed by the mixture Q6B–DF9 (5910 kg DM ha−1). Mixtures produced as much biomass as RP monocultures and DF9 + N. In mixtures, Argentine was the most competitive bahiagrass, whereas Q6B was the most competitive RP. Crude protein concentration of DF9 in the mixture with Q6B was similar to that of N‐fertilized DF9. The total aboveground N was usually greatest in RP monocultures (50–53 kg N ha−1 harvest−1). Percentage of N derived from the atmosphere increased by 22% in Q6B from 2015 to 2016. Biological N2 fixation ranged from 11 (Ecoturf–Argentine) to 44 kg N ha−1 harvest−1 (Ecoturf and Q6B). Entry growth habit affected the proportion of each component in the sward, and this information is crucial when combining warm season grasses and legumes. Rhizoma peanut will add N to bahiagrass systems and improve forage nutritive value but have less HA than heavily fertilized grass.

Annual and Perennial Peanut Mixed with ‘Pensacola’ Bahiagrass in North Florida

Fertilization of perennial grass pastures is a major expense in beef cattle operations, and grass pastures may degrade in the absence of N fertilization. Grass–legume mixtures can reduce the demand for N fertilizer use while increasing productivity of the system. Arachis spp. have shown potential for use in association with grasses in the southeastern United States. During 2014, 2015, and 2016, we evaluated one annual peanut species (Arachis hypogaea L. TUFRunner ‘727’) and two perennial peanut species, pintoi peanut (A. pintoi Krap. & W.C. Greg ‘Amarillo’) and rhizoma peanut (A. glabrata Benth. ‘Florigraze’ and germplasm Ecoturf), when planted into previously established ‘Pensacola’ bahiagrass (Paspalum notatum Flügge) sod. Responses measured included herbage accumulation (HA), botanical composition, nutritive value, biological N2 fixation, and belowground root‐rhizome responses. TUFRunner 727 showed reseeding ability, illustrating potential for use as a short‐term forage, but by 2016, its contribution was negligible. In 2016, Ecoturf–bahiagrass had greater HA than unfertilized bahiagrass (4160 and 2710 kg ha−1, respectively), and the Ecoturf contribution to HA was ∼30% in 2016. Average N concentrations for Ecoturf and Florigraze were 25 and 22 g kg−1, respectively, and in vitro digestible organic matter concentration was 700 g kg−1 for both. Pintoi peanut contributed little to mixture HA in the first 2 yr, but it persisted and increased in proportion with time. Over the course of 3 yr, Ecoturf rhizoma peanut performed better than all other entries, exhibiting increasing participation in mixtures each year and the greatest total HA in 2016.

The relative strengths of phosphate fertiliser application and white clover cultivar introduction for hill pasture improvement

Abstract Combinations of four phosphorus (P) fertiliser rates (0, 8.5, 22.5 or 26.5 kg/ha/year of citrate-soluble P) and three pasture types with different white clover germplasm, 'resident' cv. Huia and cv. Tahora were compared in self-contained, replicated farmlets grazed by sheep over 4 years. Fertiliser increased white clover herbage accumulation (HA) 3- to 4-fold compared with the control treatment, and increased total sward HA by 50%. Introduction of Tahora white clover significantly increased white clover and total sward HA and nitrogen fixation compared with the resident and Huia-sown swards. Sheep liveweight gain was significantly greater in all systems fertilised with P (438 versus 243 kg/ha for the unfertilised control) and in systems sown with Tahora (425 versus 372 kg/ha for resident and Huia). Keywords: phosphorus fertiliser, white clover, cultivars, herbage accumulation, animal production

<b>Sward structure, light interception and herbage accumulation in forage peanut cv. Belmonte subjected to strategies of intermittent grazing management

Nitrogen fertilization ensures productivity and persistency of pastures, but may be expensive. Perennial forage peanut, becomes an interesting alternative for N supply. Little is known about its use under grazing. The objective of this study was to evaluate regrowth process of forage peanut using an experimental protocol analogous to tropical forage grasses under rotational grazing. Treatments corresponded to two pre- (95% and maximum canopy light interception – LI95% and LIMax) and two post-grazing (post-grazing heights of 40 and 60% of pre-grazing height) conditions, in a 2x2 factorial arrangement in a randomized complete block design (n = 4). Targets of LI pre-grazing affected pre-grazing height and LI post-grazing. The residual sward LAI did not vary, resulting in similar grazing interval. Greater rates and total herbage accumulation were recorded for LIMax target, consequence of the greater accumulation of stolons at the lower strata of the swards. Greater percentage of leaflets was recorded for the LI95% target. Given the stoloniferous growth habit of forage peanut, stolon accumulation in the lower strata of the sward do not represent a limitation to leaf accumulation and morphological composition. The greater pre-grazing sward height associated with the LIMax target facilitate herbage prehension and intake, further investigation is needed.

White clover: the forgotten component of high-producing pastures?

The contribution of white clover (Trifolium repens L.) to nitrogen fixation and feed quality in mixed pastures is indisputable, but the benefits of clover inclusion to total herbage accumulation (HA) are less clear. Results from four experiments comparing mixed pastures of white clover–perennial ryegrass (Lolium perenne L.) with perennial ryegrass monocultures are presented. These experiments covered a range of environments (dryland northern New Zealand and irrigated southern New Zealand), management inputs (nitrogen (N) fertiliser rates and defoliation management), and genotypes of ryegrass and white clover. Mixtures resulted in a significantly greater HA than did monocultures in 7 of the 8 years for which data were available; the interaction between pasture type (monoculture or mixture) and N rate was significant in six of those years, with a greater advantage in HA for mixtures under low N rates (mean = 3.08 t DM/ha.year) than under high N rates (mean = 1.54 t DM/ha.year). Two-thirds to four-fifths of the yield advantage under grazing was due to the direct effect of clover contribution (which ranged between 10% and 30% of total annual yield) to HA, most of which accrued in summer. The remainder was due to the capture of additional clover-derived N by the grass component of the mixture, estimated to equate to 50–60 kg N/ha under low N-fertiliser rates and 15–35 kg N/ha under high N rates. The magnitude and consistency of the yield advantages observed here indicates that there are unrealised yield and other benefits not currently being captured in New Zealand dairy production systems, largely because they are negated by the use of high N-fertiliser rates. The agronomic practices required to support clover-rich mixed pastures receiving moderate rates of N fertiliser are well documented and can be applied to help deal with nutrient loss limits required by environmental regulations plus volatility in farm-gate milk prices.

Seasonal Herbage Accumulation and Nutritive Value of Irrigated ‘Tifton 85’, Jiggs, and Vaquero Bermudagrasses in Response to Harvest Frequency

ABSTRACTGrasses within the Cynodon genus are widely used perennial forages, and ‘Tifton 85’ (Cynodon spp.) is one of the most popular commercial cultivars. Jiggs and Vaquero are new C. dactylon (L.) Pers. grasses, but there is little information comparing their performance with Tifton 85 under tropical conditions. The objectives were to describe and explain variation in seasonal herbage accumulation (HA) and nutritive value of irrigated Tifton 85, Jiggs, and Vaquero bermudagrasses in response to harvest frequency (14, 28, and 42 d). The trial was performed for 2 yr in Piracicaba, Brazil, on a Kandiudalfic Eutrudox soil. In the warm season, total HA of Jiggs was similar to Tifton 85, and both were more productive than Vaquero. Under the 42‐d frequency, Jiggs had greater annual HA than the other grasses (28.5 vs. 23.7 and 20.1 Mg ha−1, for Tifton 85 and Vaquero, respectively), but when harvested every 28 d, Tifton 85 and Jiggs HA were similar (18.5 Mg ha−1). For the 42‐d harvest interval in the cool season, Jiggs had the greatest HA (10.2 Mg ha−1). Less frequent harvests in both seasons resulted in greater HA. Tifton 85 had a greater proportion of leaves than Jiggs and greater in vitro digestible organic matter (IVDOM) than the other grasses in the warm season. Considering these responses, harvest frequency of Jiggs and Tifton 85 should be ∼28 d in the warm season, while that of Vaquero should be ∼42 d. No single harvest management will be appropriate for all Cynodon grasses.