Marandu Palisadegrass Research Articles

Inter-row cover crops influencing the development of conilon coffee

The use of forage as a cover crop is an alternative for the sustainable management of conilon coffee (Coffea canephora Pierre ex Froehner) crops. The objective of this study was to evaluate the herbage accumulation and nutritive value of forages used as cover crops and their effect on the productivity and physiology of conilon coffee plants. The inter-row management assessed were 1- Congo grass [Urochloa ruziziensis (R. Germ. & C.M. Evrard) Crins], 2- Mombaça guineagrass [Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L. Jacobs], 3- Marandu palisadegrass [Urochloa brizantha (Hochst. ex A.Rich.) R.D.Webster], 4- weeds, 5- weeding and herbicide application. The experiment was conducted in 2020 and 2021 using a randomized block design (split-plot) with four replications and a plot size of 24 m2. Herbage accumulation of Congo grass, Mombaça guineagrass and Marandu palisadegrass (1.12 to 3.81 t/ha) were higher than weeds (0.18 to 1.95 t/ha) in seven periods evaluated. Mombaça guineagrass had the highest average herbage accumulation (1.47 to 3.81 t/ha). The forage cover crops did not differ among themselves for dry matter concentration, crude protein and C:N ratio in three periods evaluated. The inter-rows management with cover crops did not reduce productivity, grain/fruit ratio, grain size, vegetative vigour and physiology of the coffee plants compared to the management with weeding and herbicide in 2021. In 2022, they stagnated or reduced productivity by up to 49%, with changes in plant physiology. Adjustments in the management of cover crops are needed for the development of competitive and sustainable coffee crops.

Nutritional Performance of Grazing Beef Cattle Supplemented with High-Protein Distillers' Dried Grain.

The objective was to evaluate the effects of including high-protein distillers dried grains (HP-DDG; 430 g/CP) in supplements for beef cattle in an intensive finishing pasture system. Five Nellore bulls with an average body weight (BW) of 413.5 ± 32 kg were distributed in a 5 × 5 Latin square design. The animals were randomly allocated to Marandu palisade grass paddocks (Urochloa brizantha cv. Marandu), with 0.32 ha each. Protein-energy supplements were evaluated and formulated with different replacement levels (0, 250, 500, 750 and 1000 g/kg) of soybean meal (SBM) by HP-DDG. Supplements were offered once a day in the amount of 6.0 kg/animal. Replacing SBM with HP-DDG had no effect (p > 0.10) on the intake of total and pasture DM, OM, CP, NDFap, digestible organic matter (DOM), metabolizable protein and CP:DOM ratio. Total and pasture DM intake averaged 6.07 and 11.54 kg/day, respectively. Replacing SBM with HP-DDG reduces and increases, respectively, the intake of degradable (RDP) and undegradable (RUP) protein in the rumen (p < 0.10) with a consequent linear reduction in ruminal ammonia concentration (RAN), nitrogen excretion in urine and serum N concentration (SUN) (p < 0.10). In supplements offered in the amount of 6.0 kg animal/day, SBM can be completely replaced by HP-DDG.

Using sentinel-2 satellite images and machine learning algorithms to predict tropical pasture forage mass, crude protein, and fiber content.

Grasslands cover approximately 24% of the Earth's surface and are the main feed source for cattle and other ruminants. Sustainable and efficient grazing systems require regular monitoring of the quantity and nutritive value of pastures. This study demonstrates the potential of estimating pasture leaf forage mass (FM), crude protein (CP) and fiber content of tropical pastures using Sentinel-2 satellite images and machine learning algorithms. Field datasets and satellite images were assessed from an experimental area of Marandu palisade grass (Urochloa brizantha sny. Brachiaria brizantha) pastures, with or without nitrogen fertilization, and managed under continuous stocking during the pasture growing season from 2016 to 2020. Models based on support vector regression (SVR) and random forest (RF) machine-learning algorithms were developed using meteorological data, spectral reflectance, and vegetation indices (VI) as input features. In general, SVR slightly outperformed the RF models. The best predictive models to estimate FM were those with VI combined with meteorological data. For CP and fiber content, the best predictions were achieved using a combination of spectral bands and meteorological data, resulting in R2 of 0.66 and 0.57, and RMSPE of 0.03 and 0.04g/g dry matter. Our results have promising potential to improve precision feeding technologies and decision support tools for efficient grazing management.

Evaluation of marandu palisadegrass regrowth intervals in silvopastoral and monoculture systems

Silvopastoral systems (SPS) offer a sustainable alternative for animal production in tropical ecosystems. This study aimed to evaluate the effects of deferment days on herbage accumulation, plant-part composition, and canopy structural characteristics of Marandu palisadegrass (Urochloa brizantha Hochst. ex A. Rich.) in SPS with Eucalyptus urophylla and monoculture (MC). The experiment was conducted using a randomized block design, with each system individually allocated at the center of each plot in a 3 x 4 factorial arrangement, consisting of three systems: monoculture, and silvopastoral systems with tree row spacings of 12 m and 18 m, and tree intra-row spacing of 2 m, across four regrowth periods (60, 90, 120, and 150 days), each with three replications. Increasing deferment days reduced the proportion of green components in the forage, affecting tiller population density (TPD), leaf dry mass (LDM), and leaf/stem ratio. Maximum LDM production occurred at approximately 88 days with 0.63 Mg ha-1, while peak green dry mass (GDM) was at 94 days, reaching 1.11 Mg ha-1. Both dead material dry mass (DMDM) and total dry mass (TDM) increased linearly with regrowth periods, although TDM comprised about 47% dead forage. A regrowth period of 94 days from March is feasible for Marandu palisadegrass in SPS with 12 m and 18 m between tree rows, demonstrating that this spacing does not hinder forage production.

Integrated crop‐livestock versus conventional systems: Effects on the chemical and physical characteristics of an Oxisol

AbstractStudies have reported improvements in soil quality in integrated crop‐livestock systems (ICLS) when compared to conventional systems. The hypothesis of this study was that ICLS improve Oxisol quality due to the use of intercropping, adding pasture and cattle to the systems. The aim of the study was to evaluate the chemical and physical characteristics of an Oxisol and pasture production in the integrated system versus conventional system. We compared two conventional systems: crop system (maize grain production) and livestock system (beef cattle on single pasture) and, four ICLS: maize plus Marandu palisade grass sown simultaneously without herbicide (ICLS‐1); maize plus Marandu palisade grass sown simultaneously with herbicide (ICLS‐2); maize plus Marandu palisade grass in lagged sowing (ICLS‐3); and maize plus Marandu palisade grass sown simultaneously in maize rows and inter‐rows with herbicide (ICLS‐4). A randomized block design with six treatments and three replicates was used. The results suggest improvements in soil quality, including soil organic carbon (ICLS‐4), total nitrogen, and nitrogen stocks (ICLS‐1, ICLS‐2, and ICLS‐4). The intercropping technique influenced pasture production and soil quality during the implementation of integrated systems. The lowest soil strength was obtained for the crop system compared to systems with grazing animals but there were no changes in the soil physical characteristics that could compromise the production system.

Nitrogen fertilization regulates crosstalk between marandu palisadegrass and Herbaspirillum seropedicae: An investigation based on 15N isotopic analysis and root morphology

Strategies seeking to increase the use efficiency of nitrogen (N) fertilizers and that benefit plant growth through multiple mechanisms can reduce production costs and contribute to more sustainable agriculture free of polluting residues. Under controlled conditions, we investigated the compatibility between foliar inoculation with an endophytic diazotrophic bacterium (Herbaspirillum seropedicae HRC54) at control and low, medium and high N fertilization levels (0, 25, 50 and 100 mg of N kg−1 as urea, respectively) in Marandu palisadegrass. Common procedures in our research field (biometric and nutritional assessments) were combined with isotopic techniques (natural abundance - δ15N‰ and 15N isotope dilution) and root scanning to determine the contribution of fixed N and recovery of N fertilizer by the grass. Overall, the combined use of 15N isotopic techniques revealed that inoculation not only improved the recovery of applied N-urea from the soil but also provided fixed nitrogen to Marandu palisade grass, resulting in an increase in the total accumulated N. When inoculated plants grew at control and low levels of N, a positive cascade effect encompassing root growth stimulation (nodes of smaller diameter roots), better soil and fertilizer resource exploitation and increased forage production was observed. In contrast, increasing N reduced the contributions of N fixed by H. seropedicae from 21.5% at the control level to 8.6% at the high N level. Given the minimal to no observed growth promotion, this condition was deemed inhibitory to the positive effects of H. seropedicae. We discuss how to make better use of H. seropedicae inoculation in Marandu palisadegrass, albeit on a small scale, thus contributing to a more rational and efficient use of N fertilizers. Finally, we pose questions for future investigations based on 15N isotopic techniques under field conditions, which have great applicability potential.

Carbohydrates and protein digestive traits in beef cattle grazing fertilised or mixed tropical pasture

ABSTRACT This study was performed to investigate the nitrogen (N) and carbohydrate digestive traits of grazing heifers. The experiment was carried out at the Federal University of Lavras. The treatments were a Marandu palisadegrass (Urochloa brizantha [Syn, Brachiaria brizantha] Stapf. A. Rich. cv. Marandu) monoculture fertilised with 150 kg N/[ha ∙ year] (FP) or Marandu palisadegrass mixed pasture with forage peanut (MP). The pastures were grazed by six rumen-cannulated zebu heifers. A double cross-over design was used in four periods. Nutritive value, intake and apparent digestibility of forage, ruminal traits and kinetics and N balance were evaluated. Apparent total-tract digestibility of dry matter (DM) and neutral detergent fibre (NDF) were greater for FP than for MP. There was no effect in apparent total-tract digestibility of N. The estimated intestinal digestibility of nutrients was greater on MP than FP. Even though N intake and faecal N output were greater on MP than FP, there was no effect in urine N output. The N balance tended to be greater on MP than FP. The forage peanut, which contains condensed tannins, decreased ruminal fibre degradation, apparent digestibility and ruminal protein degradation, increased N flow from the rumen. Inclusion of forage peanut in the mixed pasture decreased the ruminal fibre degradability but increased N retention by the animals.

Sistema de silvipastoril com alta densidade de árvores acelera a degradação de capim tropical

ABSTRACT Tree density is an important aspect in silvopastoral system (SPS) planning, since low luminosity can limit forage perenniality, especially for tropical forages of C4 metabolism. The objective with this study was to verify if an SPS with high tree density accelerates the pasture degradation process and changes the forage chemical composition. The experiment was carried out by comparison of marandu palisade grass [Urochloa brizantha (Hochst. ex A. Rich.) R. D. Webster] pasture in two systems: silvopastoral and open pasture. In the SPS, teak (Tectona grandis) was planted with a density of 750 trees ha-1. Evaluations were carried out over three years (2015, 2016 and 2017). SPS shading reduced herbage mass, tiller density and soil cover over the years. In the marandu palisade grass in the SPS there was a greater stem proportion, which favoured lesser potential digestible dry matter in the first year. Even with a higher amount of stem, higher crude protein concentration and minerals were observed in the SPS. Due to the high density of trees, excessive shading accelerated the process of degradation of the pasture, which demonstrates that planning of the spatial arrangement of tree species is crucial.

Cover crop diversity for sustainable agriculture: Insights from the Cerrado biome

AbstractBrazil is one of the largest soybean producer of the world and the Cerrado biome has played a pivotal role in this expansion. Because of the economic and agronomic challenges associated with the maize production as a second summer crop in this region, cover crops are gaining popularity as a strategy to diversify the agricultural system while enhancing soil health. This study assessed the benefits of single species of cover crops and a mix of cover crop species in between harvest seasons to the soybean grain yield and nematode suppression. The study was carried out for 3 years in two locations within the Cerrado biome. We evaluated six cover crop treatments after soybean cultivation: (1) Mix of cover crops (Pennisetum glaucum, Crotalaria spectabilis and Urochloa ruziziensis), (2) P. glaucum (Pearl millet), (3) C. spectabilis, (4) U. ruziziensis (Congo grass) (5) Urochloa brizantha cv. Marandu (Marandu palisadegrass) and (6) U. brizantha BRS Paiaguás (Paiaguás palisadegrass). Pennisetum glaucum and U. brizantha cv. Marandu produced highest amounts of biomass on a 3‐year average. In one site, P. glaucum produced more biomass than other cover crops by 210%. Tropical grasses (U. ruziziensis, Marandu and Paiaguás), along with the cover crop mixture, exhibited intermediate biomass levels in the site with higher P. glaucum biomass production and did not differ from P. glaucum in the other site. Cover crops varied nutrient uptake depending on the species. Decomposition rates varied among cover crops as expected, with C. spectabilis decomposing rapidly and releasing substantial amounts nutrients, particularly nitrogen. In contrast, the cover crop mixture had a slower decomposition. The choice of cover crop significantly influenced soybean population and yield, with some variability across years and locations. The cover crop mixture consistently supported higher soybean populations and yields, highlighting its potential for enhancing soybean production, nutrient cycling and nematode suppression. It effectively reduced nematode abundance in soybean roots, highlighting its role in nematode management. Our findings emphasize the robustness and versatility of cover crop mixtures in mitigating weather variability across years and sites. They consistently performed well in terms of biomass production, nutrient uptake, soybean yields and nematode control. This study highlights the vital role of cover crops in the Cerrado ecosystem, enhancing soil health, crop productivity and environmental sustainability. The choice of cover crop species and mixtures offers a valuable tool for farmers seeking resilient and sustainable agricultural practices amid changing environmental conditions.

Chemical composition of marandu palisade grass fertilized with nitrogen and potassium

The goal was to evaluate the chemical composition of Urochloa brizantha cv. Marandu through the use of fertilization with nitrogen and potassium. The experiment was carried out at the Experimental Farm of UFMT, Cuiabá Campus, from December to April 2017/2018 and 2018/2019 - rainy season; and from May to September in 2018 and 2019 – dry season. Treatments corresponded to a 5x2 factorial scheme, with five nitrogen doses (0; 25; 50; 75; 100 kg ha-¹) and two potassium doses (0; 25 kg ha-1). The sample was unified as one for each individual period.The chemical characteristics evaluated were crude protein (CP), mineral matter (MM), neutral detergent fiber (NDF), acid detergent fiber (ADF), indigestible neutral detergent fiber (iNDF),total digestible nutrients (TDN) and net energy of lactation (NEF). For CP, a positive linear effect was observed for nitrogen fertilization, with 15.87% and 11.68% for the highest dose inthe rainy and dry seasons, respectively. Likewise, a linear increase in TDN and in NEL was observed. For NDF, ADF and iNDF content there was a linear reduction in both rainy and dryseasons. For potassium fertilization, there is little influence on the chemical characteristics, in fact, only in the rainy season for fiber, TDN and NEL contents. However, nitrogen fertilizationpromoted an increase of 51.13% in the CP content at the highest applied dose. The NDE, ADF and iNDF content decrease linearly with nitrogen input, on the contrary, there was an increase in TDN and NEL.

Effects of tree species and planting density on the total yield of an agroforestry system in the Brazilian Cerrado

ABSTRACT This study aimed to evaluate the effects of spacing and population density of three tree species on the primary yield of an agroforestry system in the Cerrado. The experiment was conducted in the experimental area of the State University of Goiás, São Luís de Montes Belos, Brazil. The experiment was designed to assess the effects of tree species, density, and spacing in a factorial scheme of 3 × 2 × 3, totaling 18 treatments with two tree rows each. The tree species assessed were Corymbia citriodora (seedlings), Eucalyptus cloeziana (seedlings), and an Eucalyptus urophylla clone. The trees were planted in single and triple rows (Trees planted in single and triple rows, varying density). In the first year of the experiment, maize (Zea mays) and Crotalaria juncea were sown, maize and Marandu palisadegrass (Uroclhoa brizantha cv. Marandu) in the second year, and a monoculture of Marandu palisadegrass during the third and fourth years. Due to the larger tree-covered area, the arrangement in triple rows reduced maize yield by 36% in the first year, silage yield by 40% in the second year, and pasture yield by approximately 30%. Reducing tree density is crucial to ensure the functionality of the agroforestry system.

Agronomic and physiological responses of corn intercropped with palisadegrass growing in full sun or in a crop‐livestock‐forestry systems

AbstractThere is a need to enhance agricultural intensification and diversification by establishing alternative crop‐livestock‐forestry systems. Our objective was to compare the production and physiological characteristics of corn (Zea mays L.) either intercropped with Marandu palisadegrass [Brachiaria (syn. Urichloa) brizantha (Hochst. ex A. Rich.) R. D. Webster] growing in full sun (FS), or in a crop‐livestock‐forestry with single‐row (CLFs) and triple‐row (CLFt) groves of Eucalyptus urograndis (hybrid of Eucalyptus grandis W. Hill ex Maiden and Eucalyptus urophylla S. T. Blake). In the CLFs and CLFt, the trees were spaced at 37 m (90 tree ha−1) and 30 m (135 tree ha−1), respectively. The experiment was carried out for 2 years in a randomised complete block with three replications in a strip‐split‐plot arrangement with measurements at 5 sites between groves (7 and 13 m on the south face, central, and 7 and 13 m on the north face). The forage mass for full sun, CLFs, and CLFt was 10.9, 9.5, and 6.2 Mg DM ha−1 in 2017 and 28.9, 21.5, and 14.0 Mg DM ha−1 in 2018, while the grain yield was 3.38, 3.34, and 1.66 Mg DM ha−1 in 2017 and 7.90, 4.66, and 2.55 Mg DM ha−1 in 2018. The forage mass (10.1 Mg DM ha−1 in 2017 and 23.9 Mg DM ha−1 in 2018) and grain yield (3.3 Mg DM ha−1 in 2017 and 5.0 Mg DM ha−1 in 2018) in the central and 13 m north distances were greater than in the 7 m north and south, with less light transmission and red: far‐red ratio. We concluded that corn intercropped with palisadegrass in an integrated crop‐livestock‐forestry system was negatively affected by the reduction in radiation transmission, resulting in reduced corn height, forage mass, and grain yield than in the full sun.

Crop-livestock-forestry systems as a strategy for mitigating greenhouse gas emissions and enhancing the sustainability of forage-based livestock systems in the Amazon biome

Intensification of livestock systems becomes essential to meet the food demand of the growing world population, but it is important to consider the environmental impact of these systems. To assess the potential of forage-based livestock systems to offset greenhouse gas (GHG) emissions, the net carbon (C) balance of four systems in the Brazilian Amazon Biome was estimated: livestock (L) with a monoculture of Marandu palisade grass [Brachiaria brizantha (Hochst. ex A. Rich.) R. D. Webster]; livestock-forestry (LF) with palisade grass intercropped with three rows of eucalyptus at 128 trees/ha; crop-livestock (CL) with soybeans and then corn + palisade grass, rotated with livestock every two years; and crop-livestock-forestry (CLF) with CL + one row of eucalyptus at 72 trees/ha. Over the four years studied, the systems with crops (CL and CLF) produced more human-edible protein than those without them (L and LF) (3010 vs. 755 kg/ha). Methane contributed the most to total GHG emissions: a mean of 85 % for L and LF and 67 % for CL and CLF. Consequently, L and LF had greater total GHG emissions (mean of 30 Mg CO2eq/ha/year). Over the four years, the system with the most negative net C balance (i.e., C storage) was LF when expressed per ha (−53.3 Mg CO2eq/ha), CLF when expressed per kg of carcass (−26 kg CO2eq/kg carcass), and LF when expressed per kg of human-edible protein (−72 kg CO2eq/kg human-edible protein). Even the L system can store C if well managed, leading to benefits such as increased meat as well as improved soil quality. Moreover, including crops and forestry in these livestock systems enhances these benefits, emphasizing the potential of integrated systems to offset GHG emissions.

Forage intake and nitrogen metabolism of beef cattle grazing palisadegrass‐calopo mixed pasture managed using canopy light interception

AbstractTo define the best grazing management strategy, it is important to assess animals' responses to variations in the structure and composition of tropical forages. This 2‐year study evaluated animal response to Marandu palisadegrass (Urochloa brizantha)‐calopo (Calopogonium mucunoides) mixed pastures managed under rotational grazing. Treatments consisted of three defoliation frequencies defined by rest periods interrupted at 90% (90LI), 95% (95LI) and 100% (100LI) of photosynthetically active radiation interception (LI). The stubble post‐grazing height target was 15 cm. Statistical difference was declared at p &lt; .10. The 100LI had lowest crude protein (CP) and in vitro dry matter digestibility (IVDDM) for the Marandu palisadegrass (p = &lt;.001 both) and calopo (p = .003 and p = .067, respectively). Also, the OM digestibility decreased 7.0% in the 100LI condition than 90LI and 95LI treatment (p = .005). There was no difference in forage, grass, and legume intakes between the treatments (p &gt; .10). The 100LI treatment decreased CP intake from grass in 33.3% (p = &lt;.001) compared to other treatments. Greatest production of microbial N (p = .093) occurred with the 90LI treatment. The CP/digestible organic matter (DOM) ratio, urinary N excretion and retained N were lowest in the 100LI treatment (p = &lt;.001, p = .007 and p = .014, respectively). The recommendation for grazing between 90 and 95% of LI is recommended because of greater CP intake and N utilization for the animals and improved the nutritive value of Marandu palisadegrass and calopo mixed pastures.

Biochar, compost, and their mixtures influence the dry mass of the shoot of Marandu palisade grass and soil nutritional status

Biochar, compost, and their mixtures influence the dry mass of the shoot of Marandu palisade grass and soil nutritional status

Light competition is the key factor determining spatio-temporal variability in legume proportion within Marandu palisadegrass–forage peanut mixed pastures

Context Understanding ecology in grass–legume pastures can help support strategies aimed at maintaining canopy stability in terms of botanical composition. Aims This 2-year study evaluated spatial variability, focusing on plant structural characteristics in a Marandu palisadegrass [Urochloa brizantha (Hochst. Ex A. Rich.) R.D. Webster cv. Marandu]–forage peanut (Arachis pintoi Krapov. and W.C. Greg. cv. BRS Mandobi) mixed canopy under grazing in continuous stocking management. Methods The pasture was managed with canopy height of 20–25 cm. The experimental area had a permanent sample grid containing 50 pre-established and georeferenced plots. Principal component analysis was performed, and spatial dependence structure of the first principal component and structural variables were separately characterised by geostatistical analysis. Key results There was spatial dependence of the structural characteristics, with marked spatial heterogeneity in the distribution of all variables. Taller grass canopies caused competition for light between species, reducing legume contribution and inducing more erect forage peanut growth habit. Conversely, in areas with lower grass canopy height, forage peanut botanical composition increased to up to 70%, as it propagated more effectively by stoloniferous propagation. Conclusions The canopy structure spatial variability of a Marandu palisadegrass–forage peanut mixed pasture determines the overall average pasture grass/legume proportion. In regions with taller canopies, Marandu palisadegrass was favoured, while in areas with shorter canopy, forage peanut proportion was promoted. Satisfactory legume proportions can be reached in the canopy despite areas with reduced legume contribution. Implications Our findings using geostatistical techniques facilitate the development of useful and innovative tools allowing better comprehension for the management of mixed pastures.

Response of Pasture Nitrogen Fertilization on Greenhouse Gas Emission and Net Protein Contribution of Nellore Young Bulls.

This study aimed to evaluate the greenhouse gas (GHG) emission and net protein contribution (NPC) of Nellore young bulls grazing marandu palisade grass (Urochloa brizantha cv. Marandu) under three levels of pasture nitrogen (N) fertilization during backgrounding and finished on pasture or feedlot, based on concepts of sustainable intensification. The treatments were: System 1: pastures without N fertilizer during backgrounding, and animals finished on pasture supplemented with high concentrate at a rate of (20 g of concentrate per kg of body weight; P0N + PS); System 2: pastures fertilized with 75 kg N ha-1 year-1 during backgrounding and animals finished on feedlot fed a total mixed ration (TMR; P75N + F); and System 3: pastures fertilized with 150 kg N ha-1 year-1 during backgrounding, and animals finished on feedlot fed a TMR (P150N + F). During backgrounding, all pastures were managed under a continuous and put-and-take stock grazing system. All animals were supplemented with only human-inedible feed. Primary data from systems 1, 2 and 3, respectively, in the field experiment were used to model GHG emissions and NPC (a feed-food competitiveness index), considering the backgrounding and finishing phases of the beef cattle production system. Average daily gain (ADG) was 33% greater for the N fertilizer pastures, while carcass production and stocking rate (SR) more than doubled (P75N + F and P150N + F). Otherwise, the lowest GHG emission intensity (kg CO2e kg carcass-1) was from the P0N + PS system (without N fertilizer) but did not differ from the P75N + F system (p &gt; 0.05; pastures with 75 kg N ha-1). The main source of GHG emission in all production systems was from enteric methane. Moreover, NPC was above 1 for all production systems, indicating that intensified systems contributed positively to supply human protein requirements. Moderate N fertilization of pastures increased the SR twofold without increasing greenhouse gas emissions intensity. Furthermore, tropical beef production systems are net contributors to the human protein supply without competing for food, playing a pivotal role in the food security agenda.

N-fertilization of tropical pastures improves performance but not methane emission of Nellore growing bulls.

Grazing management and N-fertilizer have been reported to improve tropical forage productivity and quality, however, their effect on methane emission of grazing animals remains uncertain. Therefore, this study aimed to assess the effects of increasing application rates of nitrogen (N) fertilization of Marandu palisadegrass under continuous stocking on intake, digestibility, nitrogen balance, and enteric methane emissions of Nellore growing bulls. We hypothesized that changes in the forage nutritive value caused by N fertilization of pastures combined with adequate grazing management (e.g., greater crude protein [CP] and digestibility) would lead to an increase in animal productivity (e.g., greater average daily gain [ADG] and gain per area), and then, to a decrease in methane emission intensity. Treatments consisted of different annual application rates of nitrogen fertilization: 0, 75, and 150 kg N/ha using ammonium nitrate (32% N) as the nitrogen source. The experimental design was completely randomized, with three treatments and four replications (12 paddocks). Intake, digestibility, N balance, and methane emissions were measured in eight animals per treatment. CP intake, digestibility and N balance increased linearly with the increase in N fertilization (P < 0.05). In addition, stocking rate (SR) and ADG linearly increased from 1.75 animal unit (AU = 450 kg)/ha and 0.62 kg/d (0 kg N/ha) to 3.75 AU/ha and 0.82 kg/d (150 kg N/ha), respectively. Individual methane emissions nor methane emission intensity were affected by treatment with an average of 164.7 g/d and 199.7 g/kg ADG (P > 0.05). Annual N fertilization with ammonium nitrate between 75 and 150 kg N/ha in palisadegrass pastures under continuous stocking enhances animal performance per unit area yet not affecting neither methane production nor intensity.

Applying the CROPGRO Perennial Forage Model for long-term estimates of Marandu palisadegrass production in livestock management scenarios in Brazil

The use of long-term forage production simulation is important to studies of strategic scenarios, yield-gap predictions and production risk analysis. However, forage models have only been tested using short period data. Therefore, this study aimed to apply the CROPGRO Perennial Forage Model (CROPGRO-PFM), a mechanistic model from Decision Support System for Agrotechnology Transfer (DSSAT) platform, to simulate long-term forage production of Marandu palisadegrass {Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster [syn. Brachiaria brizantha (Hochst. ex A. Rich.) Stapf]} in different locations of Central Brazil, under different fertilization levels. We chose nine locations distributed in Amazon, Cerrado, and Atlantic Forest Biomes to simulate Marandu palisadegrass production over 36 years (1980–2016). The simulations were carried out using prior calibrations for DSSAT’s CROPGRO-PFM and, as a reference point of growth and herbage simulation, model results were initially contrasted against an agrometeorological model, the Integrated Agrometeorological Model (IAM), to check the consistency between these two different models. Then the CROPGRO-PFM was applied to simulated scenarios represented three beef cattle livestock production systems: (1) Potential production water-not-limiting and highly fertilized, (2) rainfed with high N fertilization, and (3) rainfed with low N maintenance fertilization. In general, the long-term simulations of annual forage production and seasonality were similar for the CROPGRO-PFM and IAM models. As expected for the Central Brazil region, historical averages of monthly herbage accumulation rate of potential yield scenarios were relatively constant throughout the year, declining in the winter period for most locations due to mild temperature reduction and decline of solar radiation. In general, rainfed scenarios simulations showed a seasonal cycle following the rainfall pattern, with reduction in growth rates in the dry season. During the winter season climate is the major limiting growth factor, simulated growth rates were low and similar regardless of N fertilization. Although the CROPGRO-PFM presented consistent results for long term grazing systems, further model changes, calibration, and validations are recommended to improve the process-based model as well as the knowledge about these systems.

PSXII-9 Application of Machine Learning Algorithms to Estimate Tropical Pasture Biomass Based on Satellite Images

Abstract The proper quantification of forage allowance for ruminants in grass-based production systems has always been challenging. At the field scale, pasture management based on ground-level measurements, such as clipping or plate meter, is labor intensive and hampers the assessment of spatial and temporal variability. On the lookout for a solution, this study aimed to estimate marandu palisade grass forage mass based on satellite images using two machine learning (ML) algorithms, Multiple Linear Regression (MLR) and Artificial Neural Network (ANN). The experimental area comprised Marandu palisade grass pasture (Brachiaria brizantha ‘Marandu’), summing 33 paddocks (42 ha), receiving or not N fertilization. Pastures were managed under continuous stocking to maintain grazing height fixed at 25 cm during the growing season, using the put-and-take methodology with young beef bulls. Field dataset collection (total forage mass and morphological composition) and satellite images were assessed from Dec/2015 to Mar/2019 during the growing or wet season. The satellite images (Landsat-8 and Sentinel-2) were downloaded from US Geological Survey (USGS, http://earthexplorer.usgs.gov). Six spectral bands (Bd) and five vegetation indices (VI, Table 1) were used as input variables to MLR and ANN models. Datasets were randomly divided into a training set (80%) and a testing set (20%). Analyses were run in Python 3 (version 3.7). ML models are generally data-driven and require a large amount of data for better performance, and the best accuracy was achieved by using all Bd and VIs as input variables for both models (Table 1). In general, ANN produced better estimates than MLR models. Bd+VI better predicted leaf mass than total forage mass. Our results show that remotely sensed observations, based on satellite images, are a promising and effective tool for tropical grassland monitoring and management under continuous stocking rates. São Paulo Research Foundation (FAPESP) (grant ≠15/16631-5; 17/18750-7; 20/14367-7).