Manuel Cláudio Motta Macedo

Integração lavoura e pecuária: o estado da arte e inovações tecnológicas

Sustainability is an actual theme and very present in all discussion in the tropical agriculture world, including Brazil. This country experienced high taxes of development in agribusiness, increasing exportation trading, producing foods of better quality and raising incoming rates of farmers. However, two mains aspects call the attention in respect to sustainability: excessive soil preparation with monoculture of annual crops and pasture degradation. These situations have brought losses in crop and livestock yields, increased soil degradation and collapse of natural resources. Continuous cropping of monoculture accelerates attacks of insects and diseases, specially the ones related to soil interactions. Technologies such as minimum tillage, crop rotation and crop-livestock integration can alleviate these problems and drive agriculture to sustainability. Minimum tillage has increase to more than 60% of soil tillage usage in Brazil. Adoption of this system in large scale, covering more regions, with different clime and soil, is highly dependent of crops that produce high amounts of residues and straw for better soil coverage. Crop-livestock integrated systems (CLIS) have been cultivated with many crops, such as: soybeans, corn, pearl millet, sorghum, cotton, sunflower, etc. and especially perennial tropical grasses asBrachiaria spp, intercropped or not. CLIS can be one important alternative to pasture recuperation and improvement of annual crops. They increase straw to minimum tillage systems, improve soil chemical, physical and biological properties, and better use of equipments, farmers income, and jobs in rural area. This paper analyze the state of the art in CLIS research, later results, and bring some considerations for the near the future of CLIS in Brazil.

Intervalo hídrico ótimo na avaliação de sistemas de pastejo contínuo e rotacionado

Soil physical quality in continuous and short-duration rotational cattle grazing systems was evaluated using the Least Limiting Water Range (LLWR) approach. Soil samples were collected on an experimental site at the Embrapa - Beef Cattle Research Center (Campo Grande, MS, Brazil). The studied soil was a Typic Acrudox. Four sampling sites were selected: two under a short-duration continuous grazing system and two under intensive short-duration rotational grazing system. Thirty soil cores were collected in each site under the continuous grazing system, planted with Brachiaria decumbens cv. Basilisk grass. One of the continuous grazing sites had received biannual fertilization (Cc) while the other had not been fertilized (Cs). Thirty soil cores were also collected in each site under the intensive rotational grazing system, planted with Panicum maximum cv. Tanzania grass. In the intensive rotational grazing system the two sites differed in relation to the post-graze residue level left. In one site (R1) it varied from 2.0 to 2.5 t total dry matter (TDM) ha-1 and in the other R2 it varied from 3.0 to 3.5 t TDM ha-1. The cores were subjected to a soil water suction gradient, and then used for soil bulk density (Db), soil resistance to penetration (SR), volumetric water content (qv), and LLWR determinations. The intensive short-duration rotational grazing system presented the worse physical soil conditions for plant growth, as evaluated by the LLWR. The highest Db and the lowest LLWR were found in R1, which could be a consequence of the heavier stocking rates used on this site.

Consumo voluntário de forragem de três cultivares de Panicum maximum sob pastejo

Os objetivos deste trabalho foram estimar o consumo de materia seca de animais pastejando tres cultivares de Panicum maximum e relaciona-lo com ganho de peso, tempo de pastejo (TP) e algumas caracteristicas quimicas e estruturais do pasto. O delineamento experimental foi o de blocos casualizados com tres tratamentos e tres repeticoes. O consumo voluntario de materia seca (CVMS) foi estimado em quatro ocasioes (maio, setembro, novembro e fevereiro). Para calcular a producao de fezes, foi usado o oxido cromico como marcador externo. Foram estimados a digestibilidade in situ da materia seca e o tempo de pastejo, respectivamente, por intermedio de extrusas e tacografos. Foram estimadas as disponibilidades da forragem e dos componentes da planta. Apesar de os CVMS pelos animais terem sido semelhantes entre as cultivares, foram observadas maiores diferencas nos ganhos de peso, para os animais pastejando o capim Tanzânia, seguidos daqueles pastejando os capins Coloniao e Tobiata. Diferencas tambem foram observadas entre as cultivares para TP, que foi menor para os animais em pasto de Tobiata, quando comparados aos que pastejaram as outras duas cultivares. O aumento no TP observado durante o periodo da seca nao foi suficiente para impedir queda no consumo de forragem neste periodo. O CVMS foi correlacionado (r2 = 0,77) com ganho diario de peso. As caracteristicas estruturais das pastagens, disponibilidade de folhas e relacao material verde:material morto, influenciaram mais o CVMS, ganho de peso diario e TP que os valores nutritivos das mesmas.

Brazilian scientific progress in pasture research during the first decade of XXI century

This paper aims to discuss the scientific progress obtained in the past ten years in genetics and plant breeding, soil fertility and plant nutrition and the importance of target sward conditions for planning, controlling and recommending management grazing of tropical grasses. In addition, progress in crop-livestock integration systems and management alternatives for mitigation of greenhouse gas emission by beef cattle production systems, two very important areas related to sustainable production systems, will also be discussed.

Valor nutritivo da forragem e produção animal em pastagens de Brachiaria brizantha

The objectives of this work were to evaluate animal production and its relationship with pasture characteristics of Brachiaria brizantha cultivars Marandu, Xaraes and Piata. The experiment had a randomized complete block design, with three treatments and two replicates. Two-ha paddocks were divided into two and submitted to alternated grazing, with 28 days of grazing and 28 days of rest. Three tester steers were kept in each paddock; additional steers were placed in each paddock by the put and take technique, to assure post grazing residues of about 3 Mg ha-1 of dry matter. The pastures were sampled monthly to estimate the nutritive value of the forage. The animals were weighted, and the stocking rate was adjusted twice a week. Despite the lower average daily gain (ADG), in the cv. Xaraes pasture, the stocking rate was greater, which resulted in greater productivity, in comparison with cvs. Marandu and Piata. The pasture with cv. Piata had the highest ADG. These results indicate that cvs. Xaraes and Piata are new alternatives for Cerrado pastures. The choice of the forage cultivar should fit the animal and production system targets.

Sistemas de integração lavoura-pecuária na região do Cerrado

O objetivo deste trabalho foi analisar os beneficios e as perspectivas potenciais de sistemas de integracao lavoura-pecuaria no processo de intensificacao de uso das areas em exploracao com lavoura de graos e pastagens no Cerrado, e apontar as principais lacunas de informacao sobre o sistema. Os principais beneficios da integracao lavoura-pecuaria sao: melhoria das propriedades quimicas, fisicas e biologicas do solo; reducao da ocorrencia de doencas, insetos-pragas e plantas daninhas; maior produtividade das plantas e dos animais; e reducao de riscos pela diversificacao de atividades. No entanto, a adocao do sistema de integracao lavoura-pecuaria ainda e pequena, provavelmente em virtude da maior complexidade desse sistema. Concentrar esforcos nos fatores que limitam a adocao desse sistema no Cerrado parece ser um ponto estrategico para novos estudos. A busca por melhoria na qualidade de cobertura de solo para o sistema plantio direto, por meio de gramineas forrageiras, pode auxiliar na adocao da integracao lavoura-pecuaria no Cerrado. A expectativa e de que a adocao de sistemas de integracao lavoura-pecuaria resulte em melhorias significativas na sustentabilidade socioeconomica e ambiental das propriedades e da sua regiao de influencia.

Teor e dinâmica do carbono no solo em sistemas de integração lavoura-pecuária

The objective of this work was to evaluate the ability of soil management systems to change the contents and dynamics of soil carbon. Natural vegetation and systems composed of perennial tropical pastures, annual crops under conventional tillage and no-tillage systems, and pasture rotation with annual crops were evaluated in long-term experiments carried out in Dourados, Maracaju and Campo Grande, Mato Grosso do Sul state, Brazil. The experiments were set in a completely randomized block design, in Dourados and Maracaju, and in a randomized complete block design in Campo Grande. Contents and stocks of total C in soil and in soil organic matter (SOM) fractions were measured. The quality of SOM was estimated by the ratio of C in labile and nonlabile fractions, and expressed in the form of lability. Permanent pasture or pasture in rotation with crops increased C in the particulate fraction and the SOM lability. Lower rates of accumulation and of stocks of soil C were observed in systems explored only with annual crops, while higher values were recorded in systems with pasture.

Avaliação de três cultivares de Panicum maximum Jacq. sob pastejo: composição da dieta, consumo de matéria seca e ganho de peso animal

Three varieties of Panicum maximum Jacq. were evaluated by measuring the botanical and chemical composition of the diet, and the dry matter intake and weight gain of the animal under rotational grazing, before and after a period of grazing. The treatments were: 1) v. Tanzânia + 50 kg N/ha, 2) v. Tanzânia + 100 kg N/ha, 3) v. Mombaca + 50 kg N/ha, and 4) v. Massai + 50 kg N/ha. Of the diets selected by the animals, v. Massai tended to show lower values for digestibility and crude protein, and higher values for neutral detergent fiber; however, in general, the diets containing v. Mombaca had higher values for silica. The animals selected an average of 92.4% green leaves, independent of treatment and season of sampling. The animals consumed similar quantities of forage on the diverse treatments, with average intakes of 1.9, 2.8, 3.4, and 2.3 kg DM/100 kg BW, respectively, for June, September and November of 1998 and March of 1999. Low weight gains of the animals on v. Massai were verified, but due to the higher availability of forage during the rainy season, the weight gains per hectare were higher than for v. Mombaca + 50 kg N/ha and v. Tanzânia+ 50 kg N/ha. Factors which had the most positive influence on weight gain of the animals were quantity of leaves, height of the pasture, crude protein content of the diet selected by the animals, and size of the bite.

Avaliação de três cultivares de Panicum maximum Jacq. sob pastejo: disponibilidade de forragem, altura do resíduo pós-pastejo e participação de folhas, colmos e material morto

Three cultivars of Panicum maximum Jacq. under rotational grazing were evaluated for one year, before and after grazing, when measurements were made of the availability of total dry matter, height, residual dry matter, forage density, leaf dry matter, participation of leaves, stems and dead material, and ratios of leaf:stem and leaf:dead plant material. The treatments were 1) v. Tanzania + 50 kg N/ha, 2) v. Tanzania + 100 kg N/ha, 3) v. Mombaca + 50 kg N/ha, and 4) v. Massai + 50 kg N/ha. The Mombaca cultivar presented the poorest results, lowest production of leaves and the highest proportion of stems. However, the cv. Massai deservers attention for characteristics such as higher density of DM and higher leaf lamina:stem ratio; however, it presented a lower ratio of leaves:dead material. There were no significant differences in percentage of leaves among the cultivars. In the cv. Tanzania, nitrogen fertilization at the end of the rainy period had beneficial effects only in March when there was an increase in the leaf:stem and leaf:dead plant material ratios. The residual dry matter correlated positively with the height of the forage. The animals grazed 41% of the height of the pasture in the dry period, and 47% in the rainy period.

Avaliação de três cultivares de Panicum maximum Jacq. sob pastejo: comportamento ingestivo de bovinos

Three varieties of Panicum maximum Jacq. were evaluated by measuring ingestive behavior components (bite size, grazing time, and rate of eating) for one year under rotational grazing. The treatments were: 1) v. Tanzânia + 50 kg N/ha, 2) v. Tanzânia + 100 kg N/ha, 3) v. Mombaca + 50 kg N/ha, and 4) v. Massai + 50 kg N/ha. The values for bite size were probably overestimated, even so, values lower than 300 g DM/bite size were observed, a critical consideration, in the dry period. There was a tendency for smaller size bites with v. Massai during the dry period, probably due to distribution of leaves and dead material present in the pasture. There were no differences in time of pasturing among treatments and between seasons of evaluation, but the standard of distribution for time spent grazing along with the day was modified by the different seasons. Few differences in rate of eating were observed among the varieties. The rate of eating tended to increase with the length of time in the plots. Among the components of ingestive behavior the only significant correlation observed was between time of pasturing and bite size (r = -0.45).