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Much of deforested Amazonia is dominated by pastures planted with exotic Urochloa (syn Brachiaria) grass, containing interspersed, ruderal Babassu palm (Attalea speciosa). This two‐species system offers the opportunity to investigate how two very competitive species interact. We investigated three monospecific Urochloa pastures containing dispersed Babassu palm clusters in the eastern periphery of Amazonia. We mapped 0‐ to 50‐cm Babassu and Urochloa root profiles at three distances representing contrasting relative dominance: "within clusters" (0.4–0.6 m from adult palm, Babassu‐dominated), "close" (2.5–4.0 m), and "far" (>8.0–10.0 m, Urochloa‐dominated). Total Babassu root share count was 76.0% within Babassu clusters, as opposed to Urochloa root share count (80.0%) far from clusters, confirming our experimental dominance gradient. Babassu and Urochloa root diameter composition differed strongly, whereas 44.6% of all Babassu roots were mid‐diameter or coarse; 83.0% of all Urochloa roots were fine graminoid. Vertical root profiles likewise differed: Babassu coarse and mid‐diameter roots concentrated within clusters at 20–50 cm depth, well protected against disturbance, though Babassu mid‐diameter roots did extend up to 10 m, indicating active foraging at long distances. By contrast, Urochloa mid‐diameter and coarse roots concentrated in the topsoil (70.4% in top 20 cm). Notably, 45.0% of all Urochloa fine roots but only 29.3% of deeper rooting Babassu concentrated in the top 0–10 cm. Both Urochloa mid‐diameter (R = 0.49) and fine roots (R = 0.40) correlated positively with Urochloa aboveground biomass. Fine‐root fine‐scale variability was high, with high‐density hotspots of both species in the topsoil. Babassu vertical root profiles were unaffected by the degree of interspecific competitive confrontation, whereas Urochloa fine roots were significantly shallower within than outside of Babassu clusters. Though differing Babassu and Urochloa vertical root profiles do support the notion of niche expansion caused by Babassu clusters within the vast Urochloa pastures throughout Amazonia, we also find a strong horizontal and vertical niche overlap with no indication of fine‐scale root segregation, indicating direct competition between both species, possibly in a dynamic state of "mutual invasability." In practical terms, our findings call for the diversification of Amazonian pastures beyond this two‐species system in order to increase productivity and ecological efficiency. [ABSTRACT FROM AUTHOR]

Abstract Much of deforested Amazonia is dominated by pastures planted with exotic Urochloa (syn Brachiaria) grass, containing interspersed, ruderal Babassu palm (Attalea speciosa). This two‐species system offers the opportunity to investigate how two very competitive species interact. We investigated three monospecific Urochloa pastures containing dispersed Babassu palm clusters in the eastern periphery of Amazonia. We mapped 0‐ to 50‐cm Babassu and Urochloa root profiles at three distances representing contrasting relative dominance: “within clusters” (0.4–0.6 m from adult palm, Babassu‐dominated), “close” (2.5–4.0 m), and “far” (>8.0–10.0 m, Urochloa‐dominated). Total Babassu root share count was 76.0% within Babassu clusters, as opposed to Urochloa root share count (80.0%) far from clusters, confirming our experimental dominance gradient. Babassu and Urochloa root diameter composition differed strongly, whereas 44.6% of all Babassu roots were mid‐diameter or coarse; 83.0% of all Urochloa roots were fine graminoid. Vertical root profiles likewise differed: Babassu coarse and mid‐diameter roots concentrated within clusters at 20–50 cm depth, well protected against disturbance, though Babassu mid‐diameter roots did extend up to 10 m, indicating active foraging at long distances. By contrast, Urochloa mid‐diameter and coarse roots concentrated in the topsoil (70.4% in top 20 cm). Notably, 45.0% of all Urochloa fine roots but only 29.3% of deeper rooting Babassu concentrated in the top 0–10 cm. Both Urochloa mid‐diameter (R = 0.49) and fine roots (R = 0.40) correlated positively with Urochloa aboveground biomass. Fine‐root fine‐scale variability was high, with high‐density hotspots of both species in the topsoil. Babassu vertical root profiles were unaffected by the degree of interspecific competitive confrontation, whereas Urochloa fine roots were significantly shallower within than outside of Babassu clusters. Though differing Babassu and Urochloa vertical root profiles do support the notion of niche expansion caused by Babassu clusters within the vast Urochloa pastures throughout Amazonia, we also find a strong horizontal and vertical niche overlap with no indication of fine‐scale root segregation, indicating direct competition between both species, possibly in a dynamic state of “mutual invasability.” In practical terms, our findings call for the diversification of Amazonian pastures beyond this two‐species system in order to increase productivity and ecological efficiency.

Context: Energy supplementation with highly fermentable carbohydrates can be a strategy to maximise the efficiency of nitrogen use (ENU) from high-nutritional value forages. Aims: The study aimed to investigate the independent or associated effects of two diurnal feeding times (0900 or 1700 hours) with two sources of energy supplementation (corn or citrus pulp) in the growing of F1 Angus × Nellore young bulls on palisade grass pastures, and their implications on the forage chemical composition, nutrient intake and digestibility, ENU, microbial protein synthesis, animal performance, and gain per area. Methods: There were 36 bulls used as experimental animals, with initial bodyweight (BW) of 290 ± 5 kg, and 32 similar bulls were used in a put-and-take system to maintain sward characteristics. The experiment was conducted in a complete randomised design with four treatments and three replications (paddocks). The treatments consisted of energy supplementation at 0.3% BW with corn or citrus pulp fed at 0900 or 1700 hours for four periods of 28 days. For evaluation of ruminal and blood parameters, ENU, intake, and nutrient digestibility, eight ruminal cannulated 1/2 Aberdeen Angus × 1/2 Nellore young bulls were used, with 280 ± 7 kg of initial BW, distributed in a 4 × 4 double Latin square design, consisting of four periods and four treatments. Key results: Supplementation at 0.3% of BW with corn or citrus pulp at 0900 or 1700 hours can reach up to 1.06 kg/day of young bulls reared on palisade grass pastures fertilised with 180 kg nitrogen/ha/year and managed at 25 cm of height compared with corn-based supplements. There were no effects on microbial protein synthesis or its efficiency. Conclusions: Citrus pulp can be used as an alternative energy source to corn, because it has the same potential for animal performance, ENU and microbial protein synthesis in tropical pastures with a high proportion of soluble protein, and structural and non-fibrous carbohydrates with high dry matter digestibility. Implications: Supplementing grazing beef cattle at 0.3% BW with corn or citrus pulp in the morning or afternoon is an efficient nutritional strategy to improve animal performance. Different responses of energy supplementation to grazing beef cattle may occur due to the type of energy substrate and the supplementation time. Citrus pulp supplied in the afternoon can improve beef cattle performance. Citrus pulp can replace corn as an energy supplement and it is a non-human edible food. [ABSTRACT FROM AUTHOR]

Grass intercropping under no-till is an option to increase crop residues on the soil surface and crop diversity. Urochloa spp. is frequently selected for intercropping to improve land use and agricultural production because of its high residue production, slow residue decomposition, as well as its vigorous, abundant, and deep root system. However, the effects of intercropping Urochloa and maize, especially the effects of Urochloa residues, on subsequent crops in rotation have not been established. To address this knowledge gap, a field experiment was carried out over 5 years (from 2014 to 2018) comprising 2 years of maize monocropping or intercropping and 3 years of crop rotation (common bean-wheat-common bean-wheat-maize). We evaluated the medium-term effects of monocropped maize or maize intercropped with Urochloa brizantha on soil fertility and the development, yields, and grain nutrient accumulation of subsequent common bean, wheat, and maize crops. The cultivation of U. brizantha in the intercropping system improved soil fertility over at least 4 years, with increases in soil pH; soil organic matter (SOM); phosphorus (P); exchangeable potassium (K), calcium (Ca), and magnesium (Mg); sulfur (S–SO42−); cation exchange capacity (CEC); and base saturation (BS) at all soil depths. The benefits of U. brizantha extended to root dry matter and distribution; 70–77% of the total roots were concentrated within a soil depth of 0.0–0.2 m. The intercropping system improved the root dry matter mass, yield components, and grain yields of subsequent common bean, wheat, and maize crops in all cultivation years. These findings indicate that intercropping maize and U. brizantha provides medium-term benefits for subsequent common bean, wheat, and maize crops, and improves nutrient cycling to increase soil P; exchangeable K, Ca, and Mg; S–SO42−; and organic matter content.

• Condensed tannins are an efficient natural and organic compound to increase nitrogen use efficiency. • Pasture composition directly influences the supplementation strategy used and the response to the supplement. • Peanut skin is an efficient alternative supplement for pasture ruminant diets. • Alternative energy feedstuff supplementation increases animal performance and gain per area. This study aims to investigate the effects of alternative energy feedstuff supplementation containing condensed tannin (CT) on palisade grass pastures, focusing on intake, nutrient digestibility, animal performance, ruminal and blood parameters, nitrogen use efficiency (NUE), and its impacts on the ruminal bacterial community in backgrounding Nellore young bulls. Two experiments were conducted simultaneously. Animal performance was evaluated in Experiment 1. The experimental design was a completely randomized block; ninety Nellore bulls (Bos taurus indicus) with an average initial body weight (BW) of approximately 240 ± 5 kg were used (64 as testers and 26 as regulators). The feed intake, digestibility of dry matter and nutrients, ruminal parameters, NUE, and the impact on the ruminal bacterial community were evaluated in Experiment 2. The experimental design was a 4 × 4 double Latin square involving eight Nellore bulls with an average initial BW of 290 ± 8 kg, all of which were cannulated in the rumen. The treatments consisted of energy supplementation at 0.3 % of BW with peanut skin (PS), 0.3 % of BW with sorghum grain (SG), 0.3 % of BW with soybean hulls (SHs), and a control treatment with a supply of mineral salt ad libitum. The total digestible nutrient intake was lower in animals that received only mineral supplements (p < 0.005). The dry matter (DM) intake decreased with treatment PS, while the DM and nutrient digestibility increased (p < 0.005). There was a reduction in ruminal ammonia nitrogen and an improvement in NUE in the PS treatment (p < 0.005). However, the bacterial and Archaea populations were unaffected (p = 0.619). Individual animal performance and gain per kg were increased in the treatment with supplements containing or without CT compared to the mineral supplement (p < 0.001). The NUE improved in treatments PS, SG, and SH (p < 0.01). Feedstuff supplementation using no edible foods by products containing CTs is an effective alternative energy source for Nellore bulls grazing on palisade grass during the rainy season. Additionally, it can be used to mitigate the environmental impacts of N excretion. [ABSTRACT FROM AUTHOR]

There are mixed reports about the advantages and disadvantages of the presence of shade produced by trees over the understory-growing grasses; thus, it is urgent to test grass species and cultivars with potential to develop in shaded conditions associated with trees that occur in silvopastoral systems. The objective of the present study was to identify Brachiaria spp. ecotypes adapted for cultivation under tree shade, typical of silvopastoral systems. The study was conducted at Kampepen ranch, located 14 km south of Merida, Yucatan, Mexico. A factorial 6 (ecotypes) x 2 (sunlight intensities) treatment structure was used, arranged in split-plot design; with sunlight intensity levels being the plots and ecotypes the subplots, with three replications. The ecotypes were T1: Brachiaria hybrid cv. Mulato II, T2: Brachiaria hybrid cv. Cayman Blend, T3: Brachiaria hybrid cv. Talisman (BR05/1467), T4: Brachiaria hybrid cv. Camello Blend, T5: Brachiaria brizantha cv. Marandu and T6 (the control): M. maximus cv. Mombasa, while the two sunlight intensity levels were higher and lower sunlight reductions with respect to full sunlight (25% and 50% light transmission with respect to full sunlight, respectively). Variables were plant height, forage yield and chemical composition; leaf, stem and dead material fractions and leaf:stem ratio; plant canopy cover, plant maturity, and growth rate. Significant (p < 0.050) ecotype x sunlight intensity interactions were recorded for most of the studied variables. Independent of the shading levels, ecotype Talisman showed superior performance compared with the other assessed ecotypes, yielding up to 20 ton ha−1 under the highest light intensity, means across light intensities for crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) of 11.8%, 59.7%, and 34.7%, respectively, and more than 90% plant canopy cover. It is concluded that Talisman has promising characteristics for cultivation under silvopastoral systems, where tree shading is common, in the dry tropics of Yucatan, Mexico. [ABSTRACT FROM AUTHOR]

There are mixed reports about the advantages and disadvantages of the presence of shade produced by trees over the understory-growing grasses; thus, it is urgent to test grass species and cultivars with potential to develop in shaded conditions associated with trees that occur in silvopastoral systems. The objective of the present study was to identify Brachiaria spp. ecotypes adapted for cultivation under tree shade, typical of silvopastoral systems. The study was conducted at Kampepen ranch, located 14 km south of Merida, Yucatan, Mexico. A factorial 6 (ecotypes) x 2 (sunlight intensities) treatment structure was used, arranged in split-plot design; with sunlight intensity levels being the plots and ecotypes the subplots, with three replications. The ecotypes were T1: Brachiaria hybrid cv. Mulato II, T2: Brachiaria hybrid cv. Cayman Blend, T3: Brachiaria hybrid cv. Talisman (BR05/1467), T4: Brachiaria hybrid cv. Camello Blend, T5: Brachiaria brizantha cv. Marandu and T6 (the control): M. maximus cv. Mombasa, while the two sunlight intensity levels were higher and lower sunlight reductions with respect to full sunlight (25% and 50% light transmission with respect to full sunlight, respectively). Variables were plant height, forage yield and chemical composition; leaf, stem and dead material fractions and leaf:stem ratio; plant canopy cover, plant maturity, and growth rate. Significant (p < 0.050) ecotype x sunlight intensity interactions were recorded for most of the studied variables. Independent of the shading levels, ecotype Talisman showed superior performance compared with the other assessed ecotypes, yielding up to 20 ton ha−1 under the highest light intensity, means across light intensities for crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) of 11.8%, 59.7%, and 34.7%, respectively, and more than 90% plant canopy cover. It is concluded that Talisman has promising characteristics for cultivation under silvopastoral systems, where tree shading is common, in the dry tropics of Yucatan, Mexico.

Grasses of the Urochloa genus have been widely used in crop-livestock integration systems or as cover crops in no-till systems such as in rotation with maize. Some species of Urochloa have mechanisms to reduce nitrification. However, the responses of microbial functions in crop-rotation systems with grasses and its consequence on soil N dynamics are not well-understood. In this study, the soil nitrification potential and the abundance of ammonifying microorganisms, total bacteria and total archaea (16S rRNA gene), nitrogen-fixing bacteria (NFB, nifH), ammonia-oxidizing bacteria (AOB, amoA) and archaea (AOA, amoA) were assessed in soil cultivated with ruzigrass (Urochloa ruziziensis), palisade grass (Urochloa brizantha) and Guinea grass (Panicum maximum). The abundance of ammonifying microorganisms was not affected by ruzigrass. Ruzigrass increased the soil nitrification potential compared with palisade and Guinea grass. Ruzigrass increased the abundance of N-fixing microorganisms at the middle and late growth stages. The abundances of nitrifying microorganisms and N-fixers in soil were positively correlated with the soil N–NH4+ content. Thus, biological nitrogen fixation might be an important input of N in systems of rotational production of maize with forage grasses. The abundance of microorganisms related to ammonification, nitrification and nitrogen fixing and ammonia-oxidizing archea was related to the development stage of the forage grass. [ABSTRACT FROM AUTHOR]

Five cultivars of Urochloa brizantha (Hochst. ex A.Rich.) R.D. Webster (syn. of Brachiaria brizantha) were evaluated for nutritional value and an anti-nutritional factor (protodioscin), in order to determine whether protodioscin content was correlated with reduced feed quality. We evaluated cvv. Arapoty, Paiaguas, Xaraes, Marandu and Piata and grouped the results into summer, autumn, winter and spring seasons. Protodioscin content and chemical composition of leaves, in vitro digestibility and cumulative gas production were analysed. Data were evaluated by analysis of variance as a completely randomised experimental design in a factorial arrangement (five cultivars × four seasons). There was no significant interaction between cultivar and season. All grasses showed highest protodioscin contents during autumn. Protodioscin contents ranged from 5.6 g kg–1 (spring) to 19.2 g kg–1 (autumn). Crude protein content varied significantly across seasons. No significant effect was detected for neutral detergent fibre (NDF) content among seasons. Cultivar Arapoty showed the highest NDF content in summer (669.3 g kg–1) and the lowest in spring (601.9 g kg–1). The best in vitro digestibility coefficients were observed in spring. The protodioscin content of U. brizantha cultivars can negatively affect their digestibility and some parameters of cumulative in vitro gas production. We evaluated the quality of five Urochloa cultivars during the four seasons of the year. These grasses contain an anti-nutritional compound called protodioscin, which can reduce feed quality to ruminant animals when consumed, causing metabolic disturbances and resulting in intoxication. The results showed that all cultivars had higher protodioscin contents in autumn and reduced nutritional quality. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine a temporary strategy for increasing the legume population in an established pasture of brachiaria grass (Brachiaria brizantha) and forage peanut (Arachis pintoi). The treatments comprised four previous long‐term canopy heights (10, 20, 30 and 40 cm) from the establishment (the first 32 months after treatment initiation). From September 2014, all of the experimental units were kept at 10 cm height. The pastures were evaluated for their forage harvest, forage mass, botanical composition and stolon and tiller density. The tiller density and brachiaria grass mass were maintained in all pastures since the first season of evaluation (p > 0.10). The stolon density and legume mass were initially lesser at 30 and 40 cm than those at 10 and 20 cm, early in the experiment, but progressively increased over time. After 1 year under 10 cm height, the population and mass of legume were similar in all treatments. Therefore, reducing the canopy height to 10 cm at the beginning of the rainy season is an efficient method to increase the botanical composition of forage peanut in mixed pastures with brachiaria grass. [ABSTRACT FROM AUTHOR]

In silvopasture system, the coexistence of eucalyptus seedlings with other species may result in growth reduction, especially during eucalyptus early development. Therefore, studies elucidating how forage species affect the eucalyptus growth can provide important information for their rational management aiming to obtain the maximum gain of the system. The aim of this work was to evaluate the effect of increasing densities of Urochloa brizantha cv. Marandu in the early development of Eucalyptus urograndis. An experiment was conducted in 20 L pots, in an open and semi-controlled area, during 90 days after planting of eucalyptus. A completely randomized design with four replications was used, in a 6 × 7 factorial system, meaning six evaluation periods and seven densities of U. brizantha: 0 (control), 22, 33, 44, 67, 89 and 111 plants m−2. Fortnightly, eucalyptus height, stem diameter and chlorophyll fluorescence (Fv/Fm) were evaluated. At the end of experimental period, the net assimilation rate, stomatal conductance and transpiration rate of eucalyptus plants were determined, in addition to the dry matter of eucalyptus (leaves and stem) and U. brizantha (leaves). In coexistence with 111 plants m−2, eucalyptus had reduction of 63.9% on total dry matter and 72.7% on leaf area, compared to the control. From the density of 22 plants m−2, U. brizantha negatively interfere significantly the growth of E. urograndis. Up to 8 plants m−2 there are no reductions greater than 5% in eucalyptus height and stem diameter. [ABSTRACT FROM AUTHOR]

Among the forage species cultivated in South America, the genus Urochloa is the most used, and the cultivar Marandu of U. brizantha is the most widely planted in Brazil. The objective of this study was to evaluate forage performance in association with Azospirillum brasilense , combined with nitrogen (N) fertilisation. The study was conducted under field conditions in Araguaína, Tocantins, in the central region of Brazil, between March 2016 and March 2017. Four N fertiliser rates (0, 12.5, 25 and 50 kg/ha of N per cutting cycle) were combined with two inoculation treatments (inoculated and non-inoculated), with evaluations carried out in three periods of the year (transition, dry and wet seasons). Marandu grass plants inoculated with A. brasilense had greater plant height, number of tillers and forage production than non-inoculated plants, regardless of the N rate. Inoculation with A. brasilense allowed a 20% reduction in N fertilisation. Our results indicate that inoculation with A. brasilense in Marandu grass, as well as increasing forage production, can help to mitigate the stresses caused by the dry season. Marandu grass is the most planted in Brazil, with great importance in the bovine productive chain. In our study, we sought to increase productivity and reduce nitrogen fertilization of this grass by association with plant growth promoting bacteria. We observed that, in addition to increased production and reduction of nitrogen fertilization, the association with these bacteria became a sustainable and beneficial practice in the dry period of the year. [ABSTRACT FROM AUTHOR]

Palisade grass is a forage plant that is widely used in pasture cropping in the Brazilian savannah. The aim of this experiment was to evaluate palisade grass (Brachiaria brizantha cv. MG–5) seeds subjected to priming and stress at high humidity and temperature (before and after conditioning). The experimental design was completely randomized in a 2x5 factorial arrangement. Seeds were exposed to stress under high humidity and temperature (before and after conditioning) and five priming treatments [Water (Control), potassium nitrate (KNO3) at 0.2%, calcium nitrate Ca(NO3)2 at 0.2%, gibberellin (GA3) at 0.2% and glucose at 10%] with four replications. Two experiments were performed: Experiment I - seed with chemical scarification using H2SO4 and Experiment II - without scarification. The stress on the seed was applied using artificial aging at 41°C for 96 hours. Seed priming was accomplished by immersion at 25°C for 2 hours. Thereafter, the seeds were oven-dried at 35°C until they regained hygroscopic equilibrium. Seed germination and vigor were evaluated. Priming using KNO3 and Ca(NO3)2 produced seeds with high tolerance to stress under high temperature, and this process is efficient to overcome dormancy.

- In the Cerrado region the consortium between corn and forage grass has been widely used aiming at establishment or renovation of pasture. The efficiency of the consortium can be obtained by suppression of competition between species consorts with the use of reduced doses of selective herbicides to corn. The objective of this study was to test different herbicides applied postemergence on growth performance of maize and Urochloa brizantha cv. Marandu intercropping. The randomized block design was used with four replicates. The treatments tested were tembotrione (42 g ha-1), tembotrione+atrazine (42+1,500 g ha-1, respectively), tembotrione+bentazon (42+720 g ha-1, respectively), atrazine+nicosulfuron (4+1,500 g ha-1 and 8+1,500 g ha-1, respectively), nicosulfuron+bentazon (4+720 g ha-1 and 8+720 g ha-1, respectively), atrazine (3,000 g ha-1) and bentazon (960 g ha-1) and two witnesses (weeded and no hoed). Herbicides contributed to weed suppression, mainly dicotyledonous, in evaluations corn harvest. The tembotrione and nicosulfuron associated with atrazine and bentazon herbicides reduced forage yield, without affecting the leaf:stem ratio. As for the grain yield of maize not differences between statistical methods of weed control were observed. However, reduction in the yield of corn and palisade grass, when subjected to live with the weed infestation. = - O consórcio entre a cultura do milho e espécies forrageiras tem sido amplamente utilizado na região do Cerrado visando à formação ou renovação de pastagens. A eficiência do consórcio pode ser obtida pela supressão da competição entre as espécies consorciadas com o uso de doses reduzidas de herbicidas seletivos à cultura do milho. Objetivou-se com este trabalho avaliar diferentes herbicidas aplicados em pós-emergência no desempenho produtivo do consórcio entre o milho e o capim-marandu (Urochloa brizantha cv. Marandu). Utilizou-se o delineamento de blocos ao acaso, com 11 tratamentos e 4 repetições, sendo testados: tembotrione (42 g ha-1), tembotrione+atrazine (42+1.500 g ha-1), tembotrione+bentazon (42+720 g ha-1), nicosulfuron+atrazine (4+1.500 g ha-1 e 8+1.500 g ha-1), nicosulfuron+bentazon (4+720 g ha-1 e 8+720 g ha-1), atrazine (3.000 g ha-1) e bentazon (960 g ha-1), além de duas testemunhas (capinada e não capinada). Os herbicidas contribuíram para a supressão das plantas daninhas, principalmente de dicotiledôneas, em avaliações realizadas na colheita do milho. O tembotrione e o nicosulfuron associados com atrazine e bentazon reduziram o rendimento da forrageira, sem afetar a relação folha:colmo (RFC). Quanto ao rendimento de grãos de milho, não foram observadas diferenças significativas entre os métodos de controle de plantas daninhas. Todavia, houve redução do rendimento do milho e do capim-marandu, quando submetidos à convivência com a infestação de plantas daninhas.

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Abstract: A well‐established canopy is crucial for a stable mixed grass–legume forage pasture. The aim of this study was to assess a defoliation intensity that can ensure the establishment of mixed pasture of brachiaria grass (Brachiaria brizantha) intercropped with forage peanut (Arachis pintoi). The treatments comprised four canopy heights: 10, 20, 30 and 40 cm, maintained throughout the first 3 years of pasture establishment. Canopy structure, morphogenetic and structural characteristics were measured. A block design was used with four replicates, and seasons of the year were considered using repeated measurements over time. Light interception during the experimental period was 86.3%, 95.9%, 97.6%, and 99.1% for 10, 20, 30 and 40 cm of defoliation respectively (p < .001). Competition for light in taller canopies (at 30 and 40 cm) caused etiolation of forage peanut (greater internode, petiolate and stolon lengths). This response promoted its upward growth, leading to a lower stolon density compared with 10 and 20 cm. The treatment at 10 cm displayed a predominance of forage peanut (up to 0.614), potentially compromising community stability. Overall, the 20 cm canopy height showed a desired botanical composition (from 0.20 to 0.45 of legume in forage mass) and thus was considered an ideal defoliation intensity for establishment of mixed canopies of brachiaria grass and forage peanut. [ABSTRACT FROM AUTHOR]

The senescent material of plant and animal origin deposited on the soil surface is called litter, which is important to provide nutrients that will be used by plants during the production cycle. Decomposition rate means the relationship between the material on the soil surface (existing litter – EL) and the litter that was deposited previously (deposited litter – DL). The objective of this study was to evaluate the amount of existing litter, deposited litter and the decomposition rate of litter in monoculture and crop-livestock systems, during summer and winter seasons. The experiment was conducted at the Institute of Animal Science in Sertãozinho, Sao Paulo state. The experimental treatments (designed in randomized blocks) were: corn (C), palisade grass (G), corn and palisade grass seeded simultaneously (CG), corn and palisade grass seeded simultaneously plus herbicide (CGH), corn and palisade grass seeded at corn top dressing fertilization (CGT), and corn and palisade grass seeded in the row and inter-row of corn plus herbicide (CGL). All treatments were implemented in December 2015. In all treatments except for the C there was continuous grazing of beef cattle. Existing litter (EL) was monitored at 28-day intervals by sampling quadrants (0.5 × 1.0 m), which were randomly positioned in the paddocks (four samples per paddock). The place where EL samples were collected was demarcated for deposited litter (DL) collection 14 days later. During the summer and winter, the collection procedure was repeated four times. The interval between collections was 28 days. The samples were sent to the laboratory for drying in an air circulation oven for 72 h at 65 oC and weighing. The decomposition rate (k) was calculated based on a single exponential decay function derived from the equation K = -ln[(Xeq – XN)/Xeq]/tN, where Xeq is the LE, Xn is the LD and tN is the time (14 days). Statistical analyses performed using the PROC MIXED routine of SAS®. EL averages in the summer ranged between 139 g m-2 (G) and 312 g m-2 (C). During the winter, EL averages ranged between 162 g m-2 (CGT) and 440 g m-2 (C). On average, all the treatments during the winter presented higher amount of EL and DL compared to the summer (P

A sound understanding of the effects of defoliation management in a grass–legume pasture is key in balancing populations between species. The aim of this study was to quantify the morphogenetic and structural characteristics and forage production of brachiaria grass and forage peanut mixtures under four defoliation strategies. A two-year experiment was carried out in Brazil (Cwa climate), where the following treatments were studied: rest period interruption by cattle grazing when the canopy attained light interception (LI) of 90%, 95% and 100%, and grazing performed every 42 d. Morphogenetic and structural characteristics of both species were measured. The forage and leaf accumulation rates were also quantified. The design was randomised blocks, with three replications, and repeated measurements over time. The 100% LI had greater stem and stolon elongation rates and a lower leaf appearance rate in both species and fewer tillers or stolons when compared with the other strategies. Conversely, rest periods of 90–95% LI promoted an increase of about 30% on forage and leaf accumulation rates of both grass and legume. Therefore, to enhance productivity and stability when these species are associated we recommend defoliating at 90–95% LI, which represents a canopy height ranging from 26 to 32 cm. [ABSTRACT FROM PUBLISHER]

Considerando a possibilidade de atrasar o crescimento inicial de gramíneas forrageiras por meio de semeaduras em maior profundidade, de forma a proporcionar vantagem competitiva à cultura de grãos em sistemas consorciados, foram avaliados a emergência e o crescimento de cultivares de Urochloa spp. em diferentes profundidades de semeadura. O experimento foi conduzido em casa de vegetação com U. brizantha cv. Marandu e cv. Piatã e U. decumbens cv. Basilisk, semeadas nas profundidades de 0, 3, 6, 9 e 12 cm. Observou-se comportamento semelhante entre os cultivares de U. brizantha quanto à porcentagem e velocidade de emergência, à altura e à massa de matéria seca de plantas aos 28 dias após a semeadura (DAS); entretanto, esses resultados diferiram dos de U. decumbens, à exceção da altura de U. brizantha cv. Piatã. As variáveis avaliadas, para todos os cultivares, tenderam à redução em profundidades maiores que 6 cm. O atraso na emergência a 0 cm, para todos os cultivares de Urochloa, não resultou em redução na altura e massa de matéria seca das plantas.The emergence and growth of Urochloa spp. at different sowing depths was evaluated, considering the possibility of delaying the initial growth of forage grass by sowing it deeper to provide competitive advantage to the grain culture in crop-pasture association systems. The experiment was conducted in a greenhouse with U. brizantha cv. Marandu and cv. Piatã and U. decumbens cv. Basilisk, and sowing depths of 0, 3, 6, 9, and 12 cm. Similar behavior between U. brizantha cultivars was observed for daily emerged seedlings, emergence percentage, height and dry matter of plants at 28 days after sowing (DAS); however, these results differed from those obtained for U. decumbens, except for the height of U. brizantha cv. Piatã. The evaluated variables, for all cultivars, tended to be reduced when sown deeper than 6 cm. The delay in emergence at 0 cm without reduction, for all cultivars of Urochloa, did not result in reduced height and dry matter weight.

O objetivo deste trabalho foi avaliar o efeito do pastejo animal sobre a produção de forragem e sobre os componentes estruturais dos pastos das cultivares Marandu, Xaraés e Piatã de Brachiaria brizantha. O delineamento experimental foi o de blocos ao acaso, com três tratamentos e duas repetições. Os piquetes com 2 ha foram subdivididos em dois e submetidos a pastejo alternado, com 28 dias de utilização e 28 dias de diferimento. Foram utilizados três animais avaliadores por piquete, e animais reguladores foram adicionados e retirados de cada piquete, para manter resíduos pós-pastejo em torno de 3 Mg ha-1 de matéria seca. Os pastos foram amostrados, no pré e no pós-pastejo, a fim de se estimarem a massa de forragem e a proporção dos componentes morfológicos. A massa de forragem no pré-pastejo foi superior para a cultivar Xaraés, quando comparada à Marandu; a cultivar Piatã apresentou massa semelhante às das outras duas. As principais diferenças nas estruturas dos dosséis, entre as cultivares, foram acúmulo de colmo e, conseqüentemente, redução na relação lâmina foliar:colmo, na cultivar Piatã no período das águas e na Xaraés no período seco, o que indica que o manejo do pastejo deve ser diferenciado para essas cultivares. À semelhança da 'Marandu', as cultivares Xaraés e Piatã são bem adaptadas aos solos do Cerrado e são alternativas à diversificação de forragem.The objective of this work was to evaluate the animal grazing effect on forage yield and on the pasture structural characteristics of cultivars Marandu, Xaraés and Piatã of Brachiaria brizantha. The experimental design was a randomized complete block, with three treatments and two replicates. The paddocks (2 ha) were divided into two, and submitted to alternated grazing, with 28 days of grazing and 28 days of rest. Evaluations were made with three tester steers per paddock, and additional steers were added and removed from each paddock, to ensure post-grazing residues of about 3 Mg ha-1 dry matter. All pastures were sampled, before and after grazing, in order to estimate forage mass and percentages of the morphological components. The pre-grazing forage mass for 'Xaraés' pasture was greater than for 'Marandu'. 'Piatã' had pre-grazing forage mass similar to the others. The main differences in the sward structures between cultivars were stem accumulation and, consequently, the reduction in the leaf blade: stem ratio, in 'Piatã' during the rainy season and in 'Xaraés' during the dry season, which suggests different grazing management for these cultivars. Similarly to 'Marandu', Piatã and Xaraés cultivars are well adapted to Cerrado soils, and are new alternatives for forage diversification.

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Palisade grass is a forage plant that is widely used in pasture cropping in the Brazilian savannah. The aim of this experiment was to evaluate palisade grass (Brachiaria brizantha cv. MG-5) seeds subjected to priming and stress at high humidity and temperature (before and after conditioning). The experimental design was completely randomized in a 2x5 factorial arrangement. Seeds were exposed to stress under high humidity and temperature (before and after conditioning) and five priming treatments [Water (Control), potassium nitrate (KNO3) at 0.2%, calcium nitrate Ca(NO3)2 at 0.2%, gibberellin (GA3) at 0.2% and glucose at 10%] with four replications. Two experiments were performed: Experiment I - seed with chemical scarification using H2SO4 and Experiment II - without scarification. The stress on the seed was applied using artificial aging at 41?C for 96 hours. Seed priming was accomplished by immersion at 25?C for 2 hours. Thereafter, the seeds were oven-dried at 35?C until they regained hygroscopic equilibrium. Seed germination and vigor were evaluated. Priming using KNO3 and Ca(NO3)2 produced seeds with high tolerance to stress under high temperature, and this process is efficient to overcome dormancy. [ABSTRACT FROM AUTHOR]

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Highlights: [•] We studied intercropping time of sorghum with guineagrass or palisadegrass. [•] Intercropping done at topdressing sorghum fertilization produced the highest grain yield. [•] Sole sorghum produced lower than intercropping done at topdressing sorghum fertilization. [•] Intercropping done at sorghum sowing day allowed the highest forage dry matter production. [ABSTRACT FROM AUTHOR]

Abstract: The objective of the present experiment was to evaluate the ability of n-alkanes to estimate dry matter (DM) intake (DMI) and digestibility (DMD) in Nellore beef cattle fed a tropical grass cut at two growth stages (30 or 60days). The effect of two different faecal sampling procedures (daily pool–Total- or rectal spot–Spot–samples) was also tested. Differences in faecal concentration between sampling methods were lower than 2% and 0.7% for 30-d and 60-d old grass, respectively, with slightly higher values in Spot samples. Faecal recoveries were not affected by the grass growth stage, except in the cases of C31, C33, and C35 (P <0.05), which were lower for 30-d compared to 60-d. There was lower ratio (P<0.05) between internal and external recovery alkane pairs C31/C32, C33/C32 and C35/C36 in treating 30-d treatment than in 60-d old grass. Faecal recovery of natural alkanes increased with chain length, recoveries up to 77.0% (C35), whereas dosed alkanes C28, C32 and C36 showed average recoveries of 94.2%, 97.2% and 86.8%, respectively. Estimates of DMI were different from current values (P<0.05) when used C31/C32, C33/C32 and C35/C36 natural/dosed alkane pairs, regardless of the sampling procedure. An exception was the DMI estimated using the C35/C36 alkane pair of the samples of total sampling, which does not differ from the actual values (P>0.05). However, using recovery-corrected faecal concentrations reduced the differences between observed and estimated values (P>0.05). Similarly, the DMD was underestimated with the alkanes C31, C33 and C35, regardless of the method of sampling. Observed effect of forage development stage in the estimates of DMD (P<0.05), (lower values for 30-d treatment were observed than in the 60-d), due to lower faecal recovery of alkanes in the 30-d treatment. By correcting the concentrations of alkanes with the faecal recovery of the individual alkane, the differences between the estimated and actual values were canceled (P>0.05), regardless of age of forage, the alkane used or the sampling method. [Copyright &y& Elsevier]