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Sorghum intercropping with Brachiaria has the potential to improve grain yield and dry matter in the Cerrado region, but there are no studies on the ideal density of Brachiaria seeds for adoption in intercropping when the system is deployed at the beginning of the rainy season. Thus, the objective of this study was to determine the intercropping of sorghum with Brachiaria ruziziensis that may provide higher yield of grain sorghum and dry mass of both crops. We also evaluated the performance of soybeans in succession after intercropping. The test was conducted in 2013/14 and 2014/15 in tropical climate region with wet and dry seasons. The experimental design followed a randomized complete block in a factor 3 x 5 + 1 + 5, corresponding to three intercropping Brachiaria ruziziensis seeding systems (row, inter-row and broadcast sowing) associated with five densities of Brachiaria (2, 4, 6, 8 and 10 pure viable seeds m-2) plus the additional treatments related to monocultures of the grain sorghum and the five densities of the Brachiaria. The Brachiaria ruziziensis association with sorghum cultivation proved to be a promising technique for improving grain yield and dry matter at different times of the year without affecting the development and yield of the soybean crop culture. The best results were achieved with planting of Brachiaria ruziziensis in the line at the sowing density of 8 viable pure m-2 seeds and the inter-row sowing density of 6 viable pure m-2 seeds

This study aimed to evaluate sowing methods of different tropical grasses in integrated production systems on morphogenic and structural characteristics, chemical composition, and corn yield. The experiment was carried out in a completely randomized design, with a 3 x 3 + 1 factorial arrangement, with three forages: andropogon grass (Andropogon gayanus Kunth cv. Planaltina), massai grass (Megathyrsus maximum cv. Massai) and ruziziensis grass (Urochloa ruziziensis), three ways of sowing intercropped with corn (one row, two rows and broadcast) with four replications and corn in monoculture. Soil preparation, corrective practices and monitoring were carried out as recommended by the species. The results revealed that the sowing methods did not interfere with the interaction for morphogenic and structural characteristics of the grasses. Leaf elongation rate (LER) did not differ among grasses and sowing forms for Andropogon, Massai, and Ruziziensis grasses. There was an interaction effect (P0.05) of interaction for the variables of the chemical composition of grasses. Maize production was not altered due to the different consortia; however, a much lower value was found when producing corn in monoculture. The average production of intercropped corn was 3420 kg and ha-1, against 1680 kg of single cultivated corn. Massai grass and Ruziziensis grass is an attractive alternative for intercropping with corn in integrated systems

New feed assessment systems and methodologies for ruminants are being used with the aim of maximizing the use of nutrients by animals. The Cornell Net Carbohydrate and Protein System (CNCPS) considers the dynamics of ruminal fermentation and the potential loss of nitrogen in feed evaluation. We used this system to evaluate the protein and carbohydrate fractionation of silages made from maize and Urochloa species alone and in combination (70:30). The experiment was carried out under a completely randomized experimental design with 4 replications. Treatments comprised silages made from the following forages: maize (Zea mays); Congo grass (Urochloa ruziziensis); Xaraes palisadegrass (U. brizantha 'Xaraés'); Paiaguas palisadegrass (U. brizantha 'BRS Paiaguás'); 70% maize + 30% Congo grass; 70% maize + 30% Xaraes palisadegrass; and 70% maize + 30% Paiaguas palisadegrass. The results showed that despite the Urochloa exclusive silages having higher crude protein concentration than maize and mixed silages, they have a higher proportion of unavailable fractions with slow degradation rates, which can compromise animal performance. The maize silage and mixed silages had higher percentages of protein and carbohydrates with high degradation potential than Urochloa exclusive silages. Therefore, mixed silages represent one more alternative to provide forage with good nutritional value for ruminant feeding in times of feed shortage. Mixing grass and maize at ensiling would increase the volume of silage produced relative to ensiling maize alone without any significant reduction in quality of the silage produced. However, further studies are needed to determine the appropriate combinations of maize and grass at ensiling to produce silage with the desired nutritional value for the particular application and class of animals being fed. Feeding studies with animals would verify production levels achieved with the various silages.

The intercropping of corn and grass allows for the production of grains, and simultaneously, the recuperation and renovation of pastures. This study aimed to evaluate the effects of N doses on the yield, structure, chemical-bromatological characteristics, and the N use efficiency of Brachiara brizantha cultivars in an integrated crop-livestock system. The experimental design was completely randomized, with four replications, in a slip-plot scheme. The plots were formed of two grass plants, Marandu and Paiaguás, intercropped with corn and subplots composed of nitrogen doses (70, 100, and 130 kg N ha-1). During the system’s establishment (1st cycle), the Paiaguás grass presented higher values for all morphogenic and structural characteristics and higher forage yield when compared to Marandu grass. After the corn harvest, the interaction effect of the N doses and the cultivars for the foliar structure emergence and the number of living leaves was observed. The variables foliar elongation rate, stem elongation rate, and phyllochron were not influenced by any of the investigated factors (P>0.05). The highest DM content was obtained with the application of 100 kg ha-1 of N, whereas, for the other chemical characteristics, there was only an effect among the cultivars. Paiaguás grass exhibited the highest levels of NDF, ADF, lignin, and MM. CP levels were not influenced by the factors studied. Marandu grass and the use of 70 kg N ha-1 are recommended for intercropping with corn

Crop-livestock integration is the production strategy that consists of the diversification and integration of the different productive, agricultural and livestock systems, within the same area. Thus, the goal was to evaluate the production, forage quality and cattle performance in Paiaguas palisadegrass and Tamani grasses in different forms of animal supplementation in crop-livestock integration. The study was set up a randomized block experimental design, with four replicates, in a 2 x 2 factorial arrangement of two forages (BRS Tamani and BRS Paiaguas) and two animal supplementation strategies (mineral and protein-energy supplementation), in a crop-livestock integration system. Paiaguas palisadegrass showed higher forage production in all grazing cycles. Both forages showed satisfactory results in terms of average daily weight gain and total weight. The provision of protein supplementation to animals did not interfere with animal performance. Paiaguas palisadegrass and Tamani guinea grass showed potential in crop-livestock integration in succession to soybean and may be an alternative of quality food to be offered in the dry season. The system contributed to maintaining the sustainability of animal production on pasture.

Soil compaction negatively affects the physical properties of soil. The study of plants with the potential for mechanical loosening of soil is important for improving soil management and crop yield. In this context, the millet and sorghum are used as an alternative crop in the off-season in the mainly agricultural soil tropical. These roots can be a alternative to of soil mechanical loosening and avoiding mechanic tillage practices and keep soil conservation. Based on this, we assessed the aerial and root growth of millet and sorghum cultivars under different levels of soil compaction. The experiment was conducted in greenhouse conditions using a completely randomized design with four replicates. The treatments comprised of four cultivars of millet (ADR300, ADR500, BN2 and BRS1501) and two sorghum hybrids (Cober crop Atlantica and Monsanto) at four levels of subsurface soil bulk density (1.34, 1.53, 1.72, and 1.81 Mg m-3). We measured the root dry matter, root length density, mean root diameter for the upper, compacted and lower layers, and also the total dry matter. At soil bulk density 1.72 Mg m-3, both sorghum hybrids showed higher aerial dry matter production. At the highest level of soil bulk density, roots accumulated in the upper layer. Millet cultivar BN2 showed a decrease in root dry matter with increasing density in the compacted layer. All millet cultivars exhibited similar average root diameter at higher levels of compaction, except Millet ADR500 that showed less root diameter in the Upper compacted layer. Cober crop showed potential for soil decompaction, indicating the potential of this sorghum hybrid to soil mechanical loosening in the tropical soils

The production of mixed silages is a technique that has emerged as a viable alternative for supplying nutrients during food-shortage periods in the dry season, in addition to guaranteeing the highest ensiled mass production. The aim of this study was to evaluate the fermentation profile and nutritional value of maize silage with Brachiaria species. The experiment was carried out under a completely randomized experimental design with four replications. The treatments comprised the following types of silage: maize; Congo grass; Xaraes palisadegrass; Paiaguas palisadegrass; maize + 30% Congo grass; maize + 30% Xaraes palisadegrass; and maize + 30% Paiaguas palisadegrass. For ensilage, maize and grasses were harvested in a 105-day cycle at a depth of 20 cm from the soil surface. According to the results, the maize silage and mixed silages presented an adequate fermentation profile and improved nutritional value. Among the investigated Brachiaria species, Paiaguas palisadegrass emerged because of its protein increase and low ADF content; therefore, this species is recommended for use in mixed silage production. Thus, mixed silage can be used as an alternative for animal feed supplementation

Among integrated crop–livestock systems, forage succession is an advantageous strategy for the use of pasture to feed cattle in periods of low rainfall, as well as for the generation of biomass for the no-till system for the next crop. Different species have different abilities to accumulate nutrients in their biomass, which are then released into the soil through the decomposition of crop residues. This study aimed to evaluate soybean yield in an integrated crop–livestock system in comparison to soybean–maize succession system through the production, decomposition and nutrient accumulation in the biomass. The experiment had a randomized block design with four replicates. The treatments were three cropping systems: integrated crop–livestock with Paiaguas palisadegrass (Brachiaria brizantha cv. BRS Paiaguas), integrated crop–livestock with Tamani guinea grass (Panicum maximum cv. BRS Tamani) and maize grown in succession to soybean. The results showed that the use of the integrated crop–livestock system in the form of forage succession provided greater soil cover and nutrient cycling as a result of the better utilization of the animal's excreta, than the cropping of maize in succession and resulted in higher soybean productivity, thus contributing to agricultural sustainability. Paiaguas palisadegrass and Tamani guinea grass showed a C:N ratio greater than 30:1, indicating slow decomposition of plant residues. The forages accumulated amounts of nutrients in their biomass that met the soybean demand, resulting in higher grain yield.

Intercropping systems have become an interesting alternative for grain and forage production because they are sustainable systems that reduce carbon emissions in degraded pasture areas. However, few studies have used forage species recently introduced into the market, and more studies that assess the performances of these species in integrated systems are needed. Therefore, the objective of this study was to evaluate the agronomic characteristics of intercropped sorghum and Paiaguas palisadegrass (including the species name) in a crop-livestock integration system for pasture recovery. The field experiment was conducted in the municipality of Rio Verde, Goiás, Brazil, using a randomized block design with four replications. The treatments consisted of the following forage systems: monocropping of sorghum, monocropping of Paiaguas palisadegrass, row intercropping of sorghum with Paiaguas palisadegrass, interrow intercropping of sorghum with Paiaguas palisadegrass and intercropping of sorghum with oversown Paiaguas palisadegrass. To obtain a desired population of 240,000 plants ha-1, 12 seeds of sorghum and 5 kg of viable pure seeds of the forage species were planted per meter and hectare, respectively. The growth of Paiaguas palisadegrass in the same row as sorghum reduced the sorghum grain yield. The intercropping of sorghum with oversown Paiaguas palisadegrass hindered the initial development of Paiaguas palisadegrass in terms of plant height and number of tillers due to shading, and this effect was reflected in the dry mass production. Row and interrow intercropping provided higher dry mass production without affecting the forage quality. Therefore, the interrow intercropping of sorghum with Paiaguas palisadegrass was found to be a promising agricultural technique for grain and forage production that could be used for the establishment of new pastures or pasture recovery.

On the basis of the natural seasonality of pastures during the dry season, preservation of forage, especially silage, is necessary. However, the effects of soil compaction within sunflower and grass crop fields on the nutritional quality of the silage produced are unknown. Therefore, the aim of this study was to evaluate the fermentation and nutritional quality characteristics of sunflower silage under both monocropping and intercropping systems [with Paiaguas palisadegrass (Brachiaria brizantha)] under various degrees of soil compaction. A split-plot randomized complete block design was adopted. In the main plots, the treatments were bulk density values affected by the following traffic intensities: 0, 2, 10 or 30 passes of a tractor with tire wheels weighing 4.9 Mg. The subplots involved forage systems composed of sunflower as a monocrop or intercropped with Paiaguas palisadegrass. The fermentation, nutritional characteristics and in vitro digestibility of the silage were evaluated. Under the various aforementioned conditions, the agronomic characteristics of the forage were affected by increased soil compaction, resulting in changes in the fermentation and nutritional characteristics of the silage. The results showed that intercropping with Paiaguas palisadegrass and adequate proportions of sunflower allow good fermentation. This study recommends the adoption of practices that mitigate soil compaction and intercropping because of the increased forage productivity and the possibility of indirect renewal of the pasture.

Integrated crop-livestock systems maximize land use, infrastructure and labor; diversify production; and minimize costs, thereby reducing risks and adding value to agricultural products. However, growing mechanically harvested crops can negatively affect soil structure, reducing plant biomass productivity. The present study aimed to evaluate soil compaction and its effects on the forage productivity of sunflower and Brachiaria brizantha cv. BRS Paiaguas during the second cropping period. The experiment was conducted as a split-plot randomized complete block design with four replications. Four compaction levels represented by traffic from an agricultural tractor were established: 0 (absence of compaction), 2, 10 and 30 passes over the same spot. Two forage systems were established in the subplots: sunflower grown solely as a monocrop (40,000 plants ha-1) or intercropped with Paiaguas palisadegrass (10 plants linear m-1). The following parameters were quantified: soil bulk density, plant height, capitulum diameter and 1000-achene weight for sunflower; stem length and the leaf/stem ratio for Paiaguas palisadegrass; and total and partitioned forage productivity. The results showed that sunflower was highly sensitive to soil compaction and that the development and productivity of this species decreased in response to the greatest bulk density, which in turn affected the Paiaguas palisadegrass. Overall, intercropping is recommended for increased forage productivity.

With the adoption of integrated production systems, relative gains in soybean yield have been achieved due to the permanence of vegetal residues on the soil surface. These residues favour the soil microbiota responsible for the decomposition of organic matter and nutrient cycling, which makes integrated agrosystems sustainable. The objective of this study was to evaluate the agronomic characteristics of soybeans under the production and decomposition of sunflower and Paiaguas palisadegrass biomass in different integrated production systems. The experiment was conducted off season in a dystroferric Red Latosol soil in a randomized block experimental design with four replicates. The treatments consisted of the following forage systems: monocropped sunflowers; monocropped Paiaguas palisadegrass; row sunflowers x Paiaguas palisadegrass; inter-row sunflowers x Paiaguas palisadegrass; and oversown sunflowers x Paiaguas palisadegrass. The results showed that the monocropped sunflower and Paiaguas palisadegrass presented the highest biomass production throughout the soybean development cycle, with the slowest decomposition, representing a strategy to increase soil cover efficiency mainly in the period prior to summer planting. The soybean cultivated in the biomass of the monocropped Paiaguas palisadegrass and the Paiaguas palisadegrass intercropped in rows and in inter-rows presented better yields and was positively influenced by the production parameters compared with soybean cultivated otherwise. Therefore, sunflower intercropped with Paiaguas palisadegrass during the off season in the Central-West Region of Brazil was shown to be a promising and sustainable cultivation technique for the production of biomass for no-tillage systems.

Owing to its contribution to the maintenance of carbon stocks, soil nitrogen and nutrient cycling for subsequent crops, the integrated systems become increasingly important for agricultural conservation. Thus, the objective of this study was to evaluate the biomass production of and total nutrient in Brachiaria spp. and Panicum maximum forage grasses used as mulch and soybean yields in an integrated crop–livestock system and second-crop maize succession system. The treatments consisted of the following cropping systems: Xaraes palisadegrass intercropped with soybean, Congo grass intercropped with soybean, Mombaça guinea grass intercropped with soybean, Tamani guinea grass intercropped with soybean and a soybean/maize succession system. The forage grasses were established during the soybean R6–R7 stage. Compared with Congo grass, Xaraes palisadegrass, Mombaça guinea grass and Tamani guinea grass produced more biomass and equivalent amounts of fertilizer returned to the soil and resulted in greater nutrient cycling, indicating the benefits of these grasses for use as mulch in integrated production systems. Maize had a greater C/N ratio, but the forage grasses also exhibited high potential by protecting the soil until the end of the soybean development cycle. The use of an integrated crop–livestock system combined with a forage cropping system provided greater soil nutrient cycling than the maize cropping system did, which resulted in increased soybean yields, thus contributing to the sustainability of agricultural systems.

Nitrogen in the soil-plant system is extremely complex, and any change in soil management or cultivated species can modify its dynamics. To minimize environmental problems and sustainably optimize ...

Soil compaction affects physical soil properties, which in turn influence crop growth, development and yield. The present study tested the hypothesis that the yield of sunflower achenes and Paiaguas palisadegrass biomass are influenced by soil physical properties. The effects of compaction were measured by the least limiting water range (LLWR), and its relationship with crop yield were studied. The experiment was conducted in the Rio Verde municipality, south-western Goias State, Brazil, on a Latossolo Vermelho Acriferrico tipico (Typic Haplustox) soil and in accordance with a randomized complete block design, in which the treatments consisted of compaction levels established by zero, two, 10, and 30 passes of an agricultural tractor (with four replicates each). In the subplots, sunflower and Paiaguas palisadegrass were grown as monocropping and intercropping systems. The following indicators of soil physical quality were determined: bulk density (Bd), the LLWR, the Bd/alert bulk density of the LLWR (Bdalert) ratio, and the Bd/critical bulk density of the LLWR (Bdc) ratio. The correlations of these indicators with crop yield were calculated to define critical resistance values specific to each crop. The LLWR adequately described the physical quality of the soil resulting from compaction and was significantly correlated with crop yield. The relationship between sunflower and Paiaguas palisadegrass yield was modelled by a second-order equation featuring Bd and the Bd/Bdalert ratio (R2 = 0.77, ** and 0.74 **, respectively), with the greatest yield recorded when the Bd/Bdalert ratio was 1.0. Sunflower cultivation was extremely sensitive to soil compaction: when sunflower was grown as a monoculture or intercropped with palisadegrass, its yield decreased by 50 % or 80 %, respectively. However, the Paiaguas palisadegrass yield was influenced little by soil compaction. The limiting penetration resistance values for sunflower and Paiaguas palisadegrass were 1.5 MPa and 4.2 MPa, respectively.

Agricultural production systems that include the production of mulch for no-tillage farming and structural improvement of the soil can be considered key measures for agricultural activity in the Cerrado region without causing environmental degradation. In this respect, our work aimed to evaluate the chemical and physical-hydric properties of a dystrophic Red Latosol (Oxisol) in the municipality of Rio Verde, Goias, Brazil, under different soil management systems in the between-crop season of soybean cultivation five years after first planting. The following conditions were evaluated: Brachiaria brizantha cv. Marandu as a cover crop during the between-crop season; Second crop of maize intercropped with Brachiaria ruziziensis; Second crop of grain alone in a no-tillage system; Fallow soil after the soybean harvest; and Forest (natural vegetation) located in an adjacent area. Soil samples up to a depth of 40 cm were taken and used in the assessment of chemical properties and soil structure diagnostics. The results demonstrated that the conversion of native vegetation areas into agricultural fields altered the chemical and physical-hydric properties of the soil at all the depths evaluated, especially up to 10 cm, due to the activity of root systems in the soil structure. Cultivation of B. brizantha as a cover crop during the summer between-crop season increased soil water availability, which is important for agricultural activities in the region under study. Sistemas de produção agrícola que contemplam produção de palhada para o plantio direto e que atuam na melhoria estrutural do solo podem ser considerados medidas-chave para a atividade agrícola na região do Cerrado, sem a contrapartida da degradação ambiental. Nesse sentido, este trabalho objetivou avaliar os atributos químicos e físico-hídricos de um Latossolo Vermelho distrófico do município de Rio Verde, Goiás, sob diferentes sistemas de manejo do solo na entressafra da cultura da soja, após cinco anos da sua implantação. Foram avaliados: Brachiaria brizantha cv. Marandu como planta de cobertura na entressafra; Safrinha de milho consorciada com Brachiaria ruziziensis; Safrinha de grãos solteira em sistema plantio direto; Solo sob pousio, após a colheita da soja; e Mata (Vegetação Natural), situada ao lado. Foram feitas amostragens de solo até 40 cm de profundidade, utilizadas na avaliação dos atributos químicos e no diagnóstico estrutural dele. Os resultados demonstraram que conversão de áreas de vegetação nativa em campos de agricultura alterou os atributos químicos e físico-hídricos do solo em todas as profundidades avaliadas, principalmente até 10 cm, em razão da ação do sistema radicular sob a estrutura do solo. O cultivo de B. brizantha como planta de cobertura no período de entressafra das culturas de verão aumentou a disponibilidade hídrica do solo, assumindo relevância para a atividade agrícola na região em estudo.

Forages of the genus Brachiaria stand out among those used in integrated systems. Little is known about the potential value of new species and cultivars when intercropped with sorghum and planted in the second crop season. The objective of this study was to evaluate the performance (agronomic characteristics) of grain sorghum and the production and nutritional characteristics of forage plants of the genus Brachiaria in an integrated agricultural production system in the second season. The experiment had a randomized block design with four replicates. The treatments consisted of the intercropping of sorghum with forage plants of the genus Brachiaria (Ruziziensis grass, Marandu, Xaraes, Piata, Paiaguas palisadegrass and Ipypora grass), in addition to an extra treatment with sorghum in monoculture. The results showed that sorghum intercropping with Ruziziensis grass, Paiaguas palisadegrass, Piata, and Ipypora grass did not cause a reduction in grain yield. The Xaraes, Piata, and Paiaguas palisadegrass showed higher forage production. However, the Paiaguas, Piata palisadegrass, and Ipypora grass showed better nutritional value. The sorghum intercropping with forage plants of the genus Brachiaria were promising alternatives for grain and forage production in the off-season. The right forage grass combined with sorghum in an integrated system can intensify agricultural production, optimizing the use of the area and increasing sustainability.

In the south-central region of Brazil, there is a trend toward reducing the sugarcane inter-harvest period and increasing traffic of heavy harvesting machinery on soil with high water content, which may intensify the compaction process. In this study, we assessed the structural changes of a distroferric Red Latosol (Oxisol) by monitoring soil water content as a function of the Least Limiting Water Range (LLWR) and quantified its effects on the crop yield and industrial quality of the first ratoon crop of sugarcane cultivars with different maturation cycles. Three cultivars (RB 83-5054, RB 84-5210 and RB 86-7515) were subjected to four levels of soil compaction brought about by a differing number of passes of a farm tractor (T0 = soil not trafficked, T2 = 2 passes, T10 = 10 passes, and T20 = 20 passes of the tractor in the same place) in a 3 × 4 factorial arrangement with three replications. The deleterious effects on the soil structure from the farm machinery traffic were limited to the surface layer (0-10 cm) of the inter-row area of the ratoon crop. The LLWR dropped to nearly zero after 20 tractor passes between the cane rows. We detected differences among the cultivars studied; cultivar RB 86-7515 stood out for its industrial processing quality, regardless of the level of soil compaction. Monitoring of soil moisture in the crop showed exposure to water stress conditions, although soil compaction did not affect the production variables of the sugarcane cultivars. We thus conclude that the absence of traffic on the plant row maintained suitable soil conditions for plant development and may have offset the harmful effects of soil compaction shown by the high values for bulk density between the rows of the sugarcane cultivars. Na região centro-sul do Brasil, há a tendência de redução do período de entressafra canavieira, condicionando tráfego de máquinas para colheita em condições de elevados conteúdos de água do solo, o que pode contribuir para a intensificação do processo de compactação. Os objetivos deste estudo foram avaliar as alterações estruturais de um Latossolo Vermelho distroférrico por meio do monitoramento do conteúdo de água do solo em razão do Intervalo Hídrico Ótimo (IHO) e quantificar seus efeitos sobre o rendimento agrícola e o industrial da primeira soqueira de cultivares de cana-de-açúcar, com diferentes ciclos de maturação. Foram avaliados três cultivares de cana-de-açúcar (RB 83-5054; RB 84-5210; e RB 86-7515) submetidos a quatro níveis de compactação do solo, atingidos pelo número de passadas de um trator agrícola, correspondendo a T0 = solo não trafegado; T2 = 2; T10 = 10; e T20 = 20 passadas do trator no mesmo lugar, em esquema fatorial 3 × 4, com três repetições. Os efeitos deletérios causados na estrutura do solo pelo tráfego de maquinário agrícola ficaram limitados à entrelinha de cultivo das soqueiras, na camada superficial do solo. O IHO foi reduzido a valores próximos de zero com 20 passadas do trator, nas entrelinhas de cultivo da cana-de-açúcar. Foi detectada diferença entre os cultivares estudados, com destaque para o RB 86-7515, quanto à qualidade tecnológica da matéria-prima, independentemente dos níveis de compactação do solo a que estiveram sujeitos. O monitoramento da umidade do solo indicou exposição da cultura a condições hídricas estressantes, embora a compactação do solo não tenha influenciado as variáveis produtivas dos cultivares de cana. Concluiu-se então que a inexistência de tráfego sobre as linhas de cultivo, mantendo o solo desses locais em condições adequadas ao desenvolvimento das plantas pode ter compensado os efeitos prejudiciais da sua compactação, evidenciada pelos elevados valores de sua densidade, presentes nas entrelinhas de cultivo dos cultivares de cana-de-açúcar.

Pastures are the most practical and cost-effective way to feed cattle and are the basis of livestock production in Central Brazil. Grass–legume intercropping is essential for increasing production in sustainable animal-feeding systems. The aim of the present study was to evaluate the productive and nutritional characteristics of Brachiaria brizantha (A.Rich.) Stapf (palisade grass) cultivars intercropped with Stylosanthes cv. Campo Grande (multiline 80% S. capitata and 20% S. macrocephala) in different forage systems, in different seasons of the year, over a 2-year period. A randomised block experimental design was used, with three replicates. The treatments consisted of the following seven forage systems: Piata palisade grass, Paiaguas palisade grass, Stylosanthes cv. Campo Grande, row intercropping of Piata palisade grass and Stylosanthes, mixed intercropping of Piata palisade grass and Stylosanthes, row intercropping of Paiaguas palisade grass and Stylosanthes, and mixed intercropping of Paiaguas palisade grass and Stylosanthes. Evaluations were performed in each season of the year (winter, spring, summer, autumn) on the same plots over the 2-year period. Piata and Paiaguas palisade grass behaved similarly in all forage systems, indicating that both can be intercropped with Stylosanthes. Grass–legume intercropping had a positive effect on the productive and nutritional characteristics of the forage plants, increasing dry matter production, crude protein concentrations and in vitro dry matter digestibility, and decreasing the fibre fractions. Row intercropping was more efficient at maintaining high proportions of legume plants in the system, resulting in greater forage production and quality.

A reconstituição da fertilidade do solo é um dos caminhos para se recuperar a capacidade produtiva da pastagem em degradação. A adubação nitrogenada é fundamental para o aumento da produção de forragem, principalmente, quando se trata da recuperação de pastagens. Diante disso, o objetivo do trabalho foi avaliar as características estruturais e o acúmulo de massa seca (MS) de lâminas foliares e colmos mais bainhas do capim-marandu de pastagem em estágio moderado de degradação, sob doses e fontes de nitrogênio (N), por três anos. O experimento foi conduzido de julho de 2003 a março de 2006, na Fazenda Modelo da Universidade Estadual de Goiás (UEG), em uma área de 882 m², com parcelas de 20 m² e área útil de 6 m². O delineamento experimental utilizado foi o de blocos ao acaso, com três repetições. Os tratamentos nas parcelas foram caracterizados pelo fatorial 2 x 4, sendo duas fontes de N (sulfato de amônio e uréia) e quatro doses de N (0; 100; 200 e 300 kg ha-1 ano-1). Na subparcela, os tratamentos foram representados pelos anos (2004; 2005 e 2006), referentes ao tempo de recuperação da pastagem. A adubação nitrogenada foi parcelada em três aplicações, após cada corte de avaliação da forrageira. Os resultados obtidos mostraram que a adubação nitrogenada influenciou as características estruturais e o acúmulo de massa seca do capim-marandu, e, consequentemente, a sua recuperação. A dose de 300 kg ha-1 ano-1 de sulfato de amônio proporcionou maiores valores de altura de plantas, densidade de perfilhos e massa seca das lâminas foliares. To replenish soil fertility is one of the ways of recovering the productive capacity of degraded pasture. Nitrogen fertilisation is fundamental to increasing forage production, especially when it comes to the recovery of pasture. With this in mind, the objective of this work was to evaluate the structural characteristics and dry matter (DM) accumulation of the leaf blades and sheathed stems of marandu-grass pasture at a moderate stage of degradation, for different dosages and sources of nitrogen, during a three-year period. The experiment was carried out from July, 2003 to March, 2006 at the Model Farm of the Goiás State University (UEG), over an area of 882 m² with plots of 20 m² and usable area of 6 m². The experimental design was of randomized blocks with three replications. The treatments in the plots were characterized by a 2 x 4 factorial, being two nitrogen sources (ammonium sulphate and urea) and four nitrogen dosages (0; 100; 200 and 300 kg ha-1 yr-1). For each sub-plot, treatments were represented by the years (2004, 2005 and 2006), as relating to the time of the recovery of the pasture. Nitrogen fertilization was divided into three applications, following each harvesting of the grass for forage evaluation. The results showed that nitrogen fertilisation influenced the structural characteristics and dry matter accumulation of marandu grass, and hence its recovery. The dosage of 300 kg ha-1 yr-1 of ammonium sulphate resulted in greater values for plant height, tiller density and leaf-blade dry matter.

Developed the study objective of was to evaluate nutrient cycling and accumulation in pearl millet and Paiaguas palisadegrass biomass under different forage systems and sowing periods in integrated crop-livestock. The experiment followed a randomized block design with a 5 × 2 factorial arrangement and three replications, under five forage systems (monocropped pearl millet, monocropped Paiaguas palisadegrass, pearl millet intercropped in rows with Paiaguas palisadegrass, pearl millet intercropped between rows of Paiaguas palisadegrass and pearl millet oversown and intercropped with Paiaguas palisadegrass) and in two sowing periods (February and March). The results showed that Paiaguas palisadegrass monocropped or intercropped in rows or between rows, exhibited the highest nutrient cycling and accumulation in the remaining biomass. Nutrient accumulation the under all of the examined forage systems showed the following decreasing order: K > N > Mg > Ca > P > S. Potassium was the nutrient exhibiting the greatest accumulation in the biomass and it exhibited a higher percent decrease with decomposition time. The first sowing period for the forage systems led to higher nutrient cycling and accumulation in the biomass. Intercropped systems through in integrated crop-livestock showed a promising technique to maintain the nutrient cycling and accumulation with sustainability.

No cenário da pecuária brasileira, as pastagens são cultivadas em solos de baixa fertilidade, com teores muito baixos de cálcio, magnésio e enxofre. A calagem e a gessagem são os meios mais comuns para aumentar o nível de cálcio nesses solos. Diante disso, objetivou-se avaliar o efeito de fontes de cálcio no desenvolvimento de gramíneas solteiras e consorciadas. O experimento foi conduzido em casa de vegetação da Embrapa Arroz e Feijão, em um Latossolo Vermelho de textura argilosa. O delineamento experimental utilizado foi blocos ao acaso com esquema fatorial 3 x 2 x 2, sendo três tratamentos referentes ao cálcio (testemunha, calcário e gesso), duas gramíneas (Brachiaria brizantha cv. Marandu e Brachiaria humidicola) e duas gramíneas consorciadas com leguminosa (Brachiaria brizantha cv. Marandu + Calopogônio e Brachiaria humidicola + Calopogônio), com 4 repetições. Aos 60 dias após a germinação foi realizado o corte das forrageiras a uma altura de 5 cm distante do solo, para avaliação da produção de massa seca, comprimento da raiz e concentração de cálcio e enxofre no tecido foliar. As melhores alturas de plantas e desenvolvimento do sistema radicular foram verificadas na Brachiaria brizantha cv. Marandu solteira e consorciada com Calopogônio. A aplicação de cálcio na fonte de gesso resultou em maior produção de massa seca na Brachiaria brizantha cv. Marandu, solteira e consorciada. A calagem promoveu maiores concentrações de cálcio e a gessagem maiores concentrações de enxofre no tecido foliar em todos os sistemas, sendo maiores nos consorciados. Considering the cattle-raising in Brazil, the pastures are cultivated in very low soil fertility conditions, with very low calcium, magnesium and sulfur concentrations. The liming and the gypsum usage are the most common ways to increase the calcium level in these soils. In this context, this research aimed to evaluate the effect of calcium sources on the development of monocultured and intercropped grasses. The experiment was carried out in a greenhouse at Embrapa Rice and Beans, on Red Latosol of clay texture. The experimental design used was the randomized blocks with a 3 x 2 x 2 factorial scheme, being three treatments related to calcium (control, lime, and gypsum), two forage species (Brachiaria brizantha cv. Marandu and Brachiaria humidicola), and two forage species intercropped with a leguminous plant (Brachiaria brizantha cv. Marandu + Calopogonio and Brachiaria humidicola + Calopogonio), with four replications. At 60 days after germination a cutting was done at 5 cm height from the ground, for evaluation of the dry mass production, root length, and content of calcium and sulfur in the leaf tissue. The best plant height and root development was verified in the monocultured Brachiaria brizantha and also when intercropped with Calopogonio. Calcium application through the gypsum source resulted in higher production of dry mass in the monocultured Brachiaria brizantha as well as when intercropped with Calopogonio. Liming promoted higher calcium concentrations in the foliar tissue in all systems while gypsum promoted higher sulfur concentration, both being higher in the intercropped systems.

A adubação nitrogenada influencia positivamente no aspecto nutricional das gramíneas forrageiras, a ponto de resultar na recuperação adequada de pastagem. Objetivou-se com este estudo, avaliar a nutrição do capim-marandu, submetido a doses e fontes de N, pela determinação indireta de clorofila e pela concentração de N total, bem como a relação entre eles e os teores de N inorgânico (N-NH4+ e N-NO3-) nas folhas das plantas por um período de três anos. O experimento foi realizado de julho de 2003 a março de 2006, na Fazenda Modelo da UEG, numa área de 882 m², com pastagem estabelecida há mais de dez anos, com baixa produção de forragem. O delineamento experimental utilizado foi em blocos casualizados, com parcelas subdivididas no tempo, com três repetições. Foi utilizado o esquema fatorial 2 x 4, sendo duas fontes de N (sulfato de amônio e uréia) e quatro doses de N (0, 100, 200 e 300 kg ha-1 ano-1). Em cada um dos anos, foram realizados três cortes para avaliação da planta forrageira. Os teores de clorofila aumentaram com as doses de N e anos de avaliação da pastagem. A maior concentração de N foi encontrada na maior dose de N aplicada na forma de sulfato de amônio. Verificou-se uma relação direta entre os teores de clorofila e as concentrações de N nas folhas recém-expandidas de capim-marandu. O N inorgânico (N-NH4+ e N-NO3-) representou pequena fração do N total das folhas de capim-marandu. Nitrogen fertilization positively influences nutritional aspects in grass and can result in largely recovered pastures. The research objective was to study the nutrition of marandu grass treated with nitrogen doses and sources, by methods of indirect determination of chlorophyll (SPAD) and total nitrogen concentration and the relation between them and inorganic nitrogen contents (N-NH4+ and N-NO3-) in plant leaves. The experiment was carried out from July of 2003 to March of 2006 on a model farm of the Universidade Estadual de Goiás, in an area of 882 m². The pasture had been used for more than ten years and the herbage yield was low and considered moderately degraded. A split-plot with three replications was used. The experiment had a complete randomized block, 2 x 4 factorial design, with two nitrogen sources (ammonium sulfate and urea) and four nitrogen doses (0, 100, 200, and 300 kg ha-1 yr-1 ). In each year, marandu grass was cut and evaluated three times. Chlorophyll contents increased owing to the nitrogen doses and over the years. Nitrogen concentration was highest after the application of highest nitrogen doses in form of ammonium sulfate. The chlorophyll content and leaf nitrogen concentration in newly expanded leaves of marandu grass were directly related. Mineral nitrogen concentration (N-NH4+ and N-NO3-) represented little total nitrogen fraction of forage lives. Chlorophyll meter can be used for evaluation of nutritional state of marandu grass to know nitrogen absorption. The inorganic nitrogen concentration (N-NH4+ and N-NO3-) represented a small fraction of total nitrogen in the forage leaves.

O experimento foi conduzido em casa-de-vegetação, com objetivo de avaliar o efeito de doses de P e K na altura, produção de massa seca e nutrição da crotalária em ARGISSOLO VERMELHO-AMARELO-Eutrófico, sob vegetação do cerrado.O delineamento utilizado foi blocos ao acaso em esquema fatorial 4 x 4, com 3 repetições. Os tratamentos constituíram de quatro doses de P (0, 25, 50 e 75 kg ha-1 de P2O5) e quatro de K (0, 25, 50 e 75 kg ha-1 de K2O). Aos 60 dias após a germinação, antes do período de floração, foi realizado o corte da leguminosa. Foram realizadas análises químicas da parte área para determinação das concentrações de macro e micronutrientes. A aplicação de 75 kg ha-1 de P2O5 e K2O, promoveu melhores resultados na altura de planta e produção de massa seca da crotalária. As maiores concentrações de P e Ca foram observadas com as doses de 75 kg ha-1 de P2O5 e a maior concentração de K foi obtida com a aplicação de 75 kg ha-1 de K2O. The experiment was carried under greenhouse conditions with the objective of evaluating P and K effects on plant height, dry matter production and nutrition of crotalaria in an eutrophic Red - Yellow Argisol (alfisol), under cerrado vegetation. The experimental design was a randomized blocks in a 4 x 4 factorial scheme, with three replications. The treatments involved four phosphorus levels (0, 25, 50, and 75 kg/ha of P2O5) and four potassium levels (0, 25, 50, and 75 kg/ha of K2O). At sixty days, after sowing and before flowering period, plants were harvested. Shoot's macro and micronutrient concentrations were determined by chemical analysis. Application of 75 kg ha-1 P2O5 and K2O promoted the best reults in plant height and dry matter production of crotalaria. Highest P and Ca concentrations were observed by applying 75 kg ha-1 of P2O5 and the highest K concentration was verified when 75 kg ha-1 of K2O were applied.

O experimento foi realizado em um Latossolo Vermelho Escuro, na Fazenda Modelo da Universidade Federal de Goiás, com o objetivo de avaliar o efeito de doses da formulação N: K com o uso do S na produção de massa seca do capim-Tanzânia. Também foram avaliadas a eficiência de conversão em massa seca e a recuperação relativa do N e do S. A formulação N:K foi aplicada em cobertura, nas doses de 150, 300 e 450 kg/ha, com adição de enxofre de 20, 40 e 60 kg/ha. O delineamento experimental foi de blocos completos ao acaso, em esquema fatorial 3 x 3, com três repetições. O período de avaliação da forrageira foi seis meses e as amostras foram coletadas à altura de 30 cm acima do solo. Melhores ECN e ECS são observadas quando se aplica menores doses de N:K e S, mesmo não havendo diferenças significativas nas concentrações destes nutrientes no tecido da planta sob a ação de doses crescentes dos mesmos. Ao contrário, as maiores RRN e RRS foram observadas quando se aplicou 450 kg/ha da formulação N:K na presença de 60 kg/ha de S. The experiment was carried out in a Dark Red Latosol at Fazenda Modelo, Federal University of Goiás, in order to evaluate the effect of N:K rates with the use of S in the production of dry mass of Tanzania grass. Also, the efficiency of N and S conversion and recovery in dry mass were evaluated. Rates of 150, 300 and 450 kg/ha of N:K aditioning 20, 40 and 60 kg/ha of S were applied as broadcast covering. The experimental design was a randomized complete blocks in a 3x3 factorial with three replications. The forage evaluation period was six months and the samples were collected at 30 cm-plant height. The highest productions of dry mass of Tanzania grass were obtained with applications of greater N:K and S rates. The highest efficiencies of nitrogen and sulfur conversions were verified with applications of the lowest N:K and S rates, with no significant differences in concentration of these nutrients in the plant tissues as their rate of application increased. Higher S contensts in leaf tissue and relative recovery of N and S were observed by applying 450 kg/ha N:K and 60 kg/ha of S.

The agricultural potential of Latosols of the Brazilian Cerrado region is high, but when intensively cultivated under inappropriate management systems, the porosity can be seriously reduced, leading to rapid soil degradation. Consequently, accelerated erosion and sedimentation of springs and creeks have been observed. Therefore, the objective of this study was to evaluate structural changes of Latosols in Rio Verde, Goiás, based on the Least Limiting Water Range (LLWR), and relationships between LLWR and other physical properties. Soil samples were collected from the B horizons of five oxidic Latosols representing the textural variability of the Latosols of the Cerrado biome. LLWR and other soil physical properties were determined at various soil compaction degrees induced by uniaxial compression. Soil compaction caused effects varying from enhanced plant growth due to higher water retention, to severe restriction of edaphic functions. Also, inverse relationships were observed between clay content and bulk density values (Bd) under different structural conditions. Bd values corresponding to critical soil macroporosity (BdcMAC) were more restrictive to a sustainable use of the studied Latosols than the critical Bd corresponding to LLWR (BdcLLWR). The high tolerable compression potential of these oxidic Latosols was related to the high aeration porosity associated to the granular structure. Apesar do elevado potencial agrícola dos Latossolos da região do Cerrado brasileiro, quando inseridos no processo produtivo sob sistemas de manejo inadequados, o seu espaço poroso pode ser seriamente alterado, levando à sua rápida degradação. Como consequência, tem-se observado aceleração do processo erosivo e assoreamento dos mananciais associados na paisagem. Dessa forma, o presente trabalho teve por objetivo avaliar as alterações estruturais de Latossolos do município de Rio Verde, GO, por meio da caracterização do intervalo hídrico ótimo (IHO), e as relações entre IHO e demais propriedades físicas desses solos. O estudo foi conduzido utilizando-se amostras coletadas no horizonte Bw de cinco Latossolos oxídicos representativos da variabilidade textural observada nos Latossolos ocorrentes no bioma Cerrado. Foram determinados o IHO e os atributos físico-hídricos dos solos em diversos estados de compactação induzidos por compressão uniaxial. Os resultados indicaram que a compactação do solo resultou desde benefícios ao crescimento das plantas, relacionados ao aumento na retenção de água, até condições de severas restrições às suas funções edáficas, sendo observadas relações inversas entre o conteúdo de argila e os valores de densidade do solo (Ds) nas diversas condições estruturais. A Ds correspondente à macroporosidade crítica do solo (DscMAC) foi mais restritiva ao manejo sustentável dos Latossolos estudados que a Ds crítica correspondente ao IHO (DscIHO). A maior compactação permissível observada nesses Latossolos oxídicos deve-se à elevada porosidade de aeração conferida pela estrutura do tipo granular.

O presente estudo foi desenvolvido sob condições de campo, visando avaliar a eficiência no uso e no aproveitamento do nitrogênio pelo capim-marandu por meio de diversos índices. O experimento foi conduzido na Fazenda Modelo da Universidade Estadual de Goiás (UEG) num Latossolo Vermelho distrófico, no período de julho de 2003 a março de 2006. O delineamento experimental utilizado foi de blocos ao acaso, com três repetições. Os tratamentos nas parcelas foram caracterizados por um fatorial 2 x 4, sendo duas fontes de N (sulfato de amônio e uréia) e quatro doses de N (0, 100, 200 e 300 kg/ha). Na subparcela, os tratamentos foram representados pelos anos (2004, 2005 e 2006), referentes ao tempo de recuperação da pastagem. A adubação nitrogenada foi parcelada em três aplicações após cada corte de avaliação da forrageira. Foram realizados três cortes da forrageira por ano, avaliando-se a massa seca e os teores de N nos tecidos. Com esses resultados, avaliaram-se os índices de Eficiência de Utilização do N (EUN), Recuperação do N Aplicado (RNA), Eficiência Agronômica do N Aplicado (EA) e Eficiência Fisiológica (EF) ou Eficiência Biológica. Os resultados mostraram que a EUN aumentou, enquanto que a RNA, EA e a EF diminuíram com o aumento das doses de N aplicadas. Em todos os casos, os índices foram influenciados pelos anos de recuperação da forrageira estudados, mas não pelas fontes de N. This study was accomplished under field conditions, to evaluate the use and efficiency of nitrogen uptake, through various indexes, in pasture of Brachiaria brizantha. The experiment was conduced at the Model Farm of the Goiás State University in a distrophic Dark Red Latosol, from 2003 July to 2006 March. The experimental design was randon blocks, with three replicates. The treatments were placed in parcels characterized by a 2x4 factorial, with two sources of N (ammonium sulfate and urea) and four doses of N (0, 100, 200 and 300 kg/ha/year). In sub - parcel, the treatments were represented per years (2004, 2005 and 2006) refering to time of pasture recovery. The use of nitrogen was divided in three times, after each cut evaluation of the forage pasture. Three cuts were made per year, evaluating dry mass and N accumulation in the tissue. Nitrogen Utilization Efficiency, Recovery from the N Applied, Agronomic Efficiency from the N Applied, Physiological or Biological Efficiency indexes were evaluated. The results showed that EUN increased, while RNA, EA and EF reduced with the increase in the N doses applied. In all cases, the indexes were influenced by the years of recovery the herbage, and not by the sources of N.

O presente trabalho objetivou avaliar a influência do sombreamento sobre o desempenho de cultivares de sorgo granífero. O ensaio foi realizado em casa-de-vegetação, utilizando-se delineamento inteiramente casualisado, em esquema fatorial 4 x 2, correspondendo aos quatro híbridos de sorgo granífero (DKB 599, AG 1040, BRS 308 e AG 1040) submetidos a pleno sol e sombreado, com três repetições. Determinou-se a altura de planta, área foliar, matéria seca das folhas, caule, raízes e panícula, além do comprimento do pendão e da panícula. Os resultados obtidos permitiram constatar que o ambiente sombreado proporcionou maior altura de plantas de sorgo, porém menores valores de área foliar. A redução na luminosidade proporcionou ainda maior acúmulo de massa seca de folhas e caule de todas as cultivares avaliadas. Somente a cultivar BRS 308 apresentou estabilidade produtiva indiferente do ambiente cultivado. This study aimed to evaluate the effects of shading on the performance of cultivars of grain sorghum. The test was conducted in a greenhouse using randomized design in a 4 x 2 factorial scheme, corresponding to the four hybrids of grain sorghum (DKB 599, AG 1040, AG 308, BRS 1040) submitted to a condition with and without shade, all treatments with three replications. We evaluated plant height, leaf area, dry matter of leaves, stems, roots, panicles, and the length of the tassel and panicle. The results show that the shaded environment led to greater height of plant sorghum, but lower values of leaf area. The reduction in brightness provided even greater accumulation of dry mass of leaves and stems of all evaluated cultivar. The BRS 308 showed stable production regardless of growth environment.

A produção de forragens conservadas utilizando-se um tráfego intenso de maquinário sob condições inadequadas de água no solo, tem condicionado compactação do solo e a degradação das pastagens. No enfrentamento desta grave questão faz-se necessário o conhecimento do potencial de descompactação do solo, promovido por algumas forrageiras. Objetivou-se, com o presente trabalho, avaliar a descompactação de um Argissolo ao ser cultivado com capim-tifton 85 e sua produção. O experimento foi conduzido na Universidade Federal de Lavras, no período de fevereiro a junho de 2007, em delineamento inteiramente casualizado cultivando-se o capim-tifton nos seguintes graus de compactação do solo: 66, 83, 88, 92 e 98%. Avaliaram-se os atributos físicos, o comportamento compressivo do solo e a produção de massa seca do capim. A descompactação foi quantificada pela redução da pressão de preconsolidação após o cultivo. Os modelos de capacidade de suporte de carga refletiram as alterações na macroporosidade do solo. Nas condições do estudo o capim-tifton 85 promoveu a descompactação do solo, a qual é diretamente proporcional ao grau de compactação inicial. A produção de forragem aumenta sempre que o solo é descompactado. The production of conserved forages using an intense traffic of machinery under inadequate conditions of water content in the soil has caused soil compaction and the degradation of pastures. In order to face this serious problem it is necessary to know the potential of soil loosening by some forage plants. The objective of the present study was to evaluate the loosening of an Argisol cultivated with Tifton 85 grass, as well as its production. The experiment was conducted at the Federal University of Lavras, from February to June 2007, using a completely randomized design, cultivating the Tifton 85 grass under the following compaction degrees: 66, 83, 88, 92 and 98%. The physical attributes, the compressive behavior of soil and the production of dry mass of grass were evaluated. The loosening was quantified by the reduction of the preconsolidation pressure after cultivation. The bearing capacity models reflected the changes in soil macroporosity. Under study conditions, the Tifton 85 grass promoted the soil loosening proportional to the initial compression degree. The production of forage increased as the soil is loosened.

O nitrogênio (N) é considerado um dos nutrientes responsável pelo crescimento vegetativo das plantas, mantendo as pastagens produtivas e com bom valor nutritivo. Diante disso, objetivou-se avaliar o efeito da adubação nitrogenada na produção de massa seca, valor nutritivo e nutrição nitrogenada de cultivares de Brachiaria brizantha (A. Rich) Stapf. O delineamento utilizado foi blocos ao acaso em esquema fatorial 3 x 4 (três cultivares de Brachiaria brizantha: Marandu, Xaraés e MG-4; e quatro doses de N: 0, 50, 100 e 150 mg.dm-3, tendo como fonte a uréia), com três repetições. Avaliaram-se três cortes nas forrageiras, com intervalos de 30 dias. A adubação nitrogenada proporciona aumentos lineares nas produções de massa seca, teores de PB, nitrato, amônio e clorofila (unidade SPAD); e redução nos teores de FDN e FDA nos cultivares de Brachiaria brizantha. O cultivar Xaraés apresenta maior produção de massa seca, teor de PB, clorofila (unidade SPAD) e menores teores de FDN e FDA que os cultivares Marandu e MG-4.

O experimento foi conduzido em casa de vegetação, na Embrapa Arroz e Feijão, com objetivo de avaliar o efeito de doses de N e K na produção de massa seca e extração de macronutrientes pela fitomassa do capim xaraés. O delineamento utilizado foi bloco ao acaso, com esquema fatorial 4 x 4, sendo quatro doses de Nitrogênio: 0; 25, 50 e 100mg dm-3, e quatro doses de Potássio: 0; 25, 50 e 100mg dm-3, com três repetições. Foram realizados três cortes de avaliação da forrageira. Todos os macronutrientes sofreram variações significativas em função das doses de Nitrogênio e Potássio aplicadas. O efeito mais pronunciado sobre a extração dos macronutrientes foi proporcionado pelas doses de Potássio. A ordem decrescente de extração para o capim-xaraés, considerando extração máxima de cada nutriente, foi: N = K > Ca > Mg > P > S. Contudo, sugerem-se estudos dessas variáveis, em condições de campo, de modo a se obter mais informações sobre esse cultivar para que as estratégias de manejo da cultura sejam mais eficientes. The experiment was carried out in a greenhouse at Embrapa Arroz e Feijão station, with the objective of evaluating the extraction of macronutrients by the phytomass of Brachiaria brizantha cv. 'Xaraés'. The experimental design was randomized blocks in a factorial scheme 4 x 4 (four rates of nitrogen aplication: 0; 25, 50 e 100mg dm-3, and four rates of potassium aplication: 0; 25, 50 e 100mg dm-3), with three repetitions. Three cuttings were performed with 30-day intervals, where the forage plant was cut at a height of 5cm from soil. All the nutrients underwent significant variations as related with the doses of N e K applied. In general, the most marked effect on the extraction of macronutrients was provided by the K rates. The decreasing order of macronutrient extration for capim-Xaraés, considering maximum extration of each nutrient, was: N = K > Ca > P > S. However, one suggests studies of these nutrients, in field conditions, in order to get more information on this forage plant so that the handling strategies one becomes more efficient.

O experimento foi conduzido em casa de vegetação, na Embrapa Arroz e Feijão, com o objetivo de avaliar o intervalo de corte na produção de massa seca, altura de planta e composição químico-bromatológica da Brachiaria brizantha cv. MG-5. O delineamento utilizado foi o inteiramente casualizado. Os tratamentos constituíram de quatro intervalos de corte (15, 20, 30 e 60 dias), com cinco repetições, totalizando 20 parcelas. Foram aplicados 100 mg dm-3 de nitrogênio, utilizando como fonte o sulfato de amônio, em todas as parcelas. A adubação nitrogenada foi parcelada, de acordo com os cortes de avaliações. Foram realizados quatro cortes para o intervalo de 15 dias, três cortes para o de 20 dias, dois cortes para o de 30 dias e um corte para o de 60 dias. A forrageira foi cortada a uma altura de 5 cm do solo. O aumento no intervalo de corte na Brachiaria brizantha cv. M-5 determina acréscimos na produção de massa seca e teores de FDN e FDA. Contudo, o inverso pode ser observado no teor de PB e concentrações de P, Cu e Fe.

Soil compaction associated with pastures degradation can decrease animal productivity, forage longevity and compromise environmental sustainability. To confront this serious issue, the loosening potential of forages should be recognized. We evaluated the least limiting water range as indicator of biological loosening potential in relation to cultivation of grasses the genus Brachiariain crop-livestock integration. We also evaluated the water availability to soybean crop that succeeded these grasses. Our studies were performed in two stages. In the first stage, we divided 32 plots into four randomized blocks in which we cultivated corn combined with following treatments: 1 - Brachiaria brizanthacultivar Marandu; 2 - Xaraes; 3 - Piata; 4 - MG4; 5 - B. decumbens; 6 - B. ruziziensis; 7 - Invasive plants; and 8 - uncovered soil. We evaluated soil, to quantify the biological soil loosening, and also forages. In the second stage, we cultivated soybean and added: 9 - conventional tillage as a control treatment, increasing number of plots to 36. Our results suggest that it is possible to cultivate Brachiaria brizantha or Brachiaria decumbens as management strategy to aid edaphic recovery. Xaraes and Piata grasses provide greater soil loosening while increasing water availability to successive soybean crop. A compactação do solo associada à degradação das pastagens reduz a produtividade animal e da forrageira e compromete a sustentabilidade ambiental. No enfrentamento desta grave questão, faz-se necessário o conhecimento do potencial de descompactação do solo promovido por algumas forrageiras. Este trabalho objetivou avaliar o intervalo hídrico ótimo como indicador da descompactação biológica do solo decorrente do cultivo de capins do gênero Brachiaria em integração agricultura-pecuária, bem como a disponibilidade hídrica à soja cultivada em sucessão. O estudo foi realizado em duas etapas. Inicialmente foram implantadas 32 parcelas em quatro blocos casualizados, cultivando milho consorciado com os seguintes com os tratamentos: 1 - Brachiaria brizantha cultivares Marandu, 2 - Xaraes, 3 - Piata e 4 - MG4, 5 - B. decumbens, 6 - B. ruziziensis, 7 - Plantas invasoras e, 8 - Solo descoberto. Foi avaliado o solo para quantificação da descompactação biológica, e também as forragens. Na segunda etapa cultivou-se soja, acrescentando-se como tratamento testemunha: 9 - plantio convencional, totalizando 36 parcelas. Os resultados sugerem o cultivo de B. brizantha ou B. decumbens na recuperação edáfica. Destacam-se os capins Xaraes e Piata que proporcionaram maior descompactação do solo e, consequentemente, aumento da disponibilidade hídrica à soja em sucessão.