Moacyr Corsi

Efeito da freqüência de pastejo e da época do ano sobre a produção e a qualidade em Panicum maximum cvs. Tanzânia e Mombaça

Two experiments were carried out to evaluate the effects of three grazing frequencies (28, 38 and 48 days) on forage mass, dry matter (DM) accumulation rate and leaf:stem ratio in Tanzania and Mombaca, from September 1995 to May 1996 period. A split plot experimental design was used, with grazing frequency as main plots and period of the year as subplots. The forage mass per grazing was greater when the grazing frequency was small, however did not have an effect on the DM accumulation in the Tanzania and Mombaca cultivars. The rates of forage accumulation for the two cultivars were greater in January/February; so we should work with greater grazing frequency or stocking rate. The leaf:stem ratio of the two cultivars was small, mainly during the reproductive phase, indicating that we should work with greater grazing frequency (grazing at each 28 days or less) in order to control the stems development.

Composição química e fracionamento do nitrogênio e dos carboidratos do capim- Tanzânia irrigado sob três níveis de resíduo pós-pastejo

The objective of this work was to determine the chemical composition of irrigated Tanzaniagrass (Panicum maximum Jacq.). and to validate the Cornell system. Simulated-grazed samples were collected on three periods of the year (spring, summer and fall, totaling 10 grazing cycles) on irrigated paddocks, rotationally grazed to three post grazed stubbles (low, medium and high). Although there were no statistical differences imposed by the treatments during the year, the neutral detergent fiber (NDF) and acid detergent fiber (ADF) showed higher values in the spring/summer, and lignin in the winter grazing cycles. Along the year the carbohydrate C fraction, TDN and CP varied from 14.14 to 23.21%, 55.26 to 59.31% and 11.29 to 14.61%, respectively. The Nsol, non protein nitrogen (NNP) and nitrogen on ADF (nADF) (as CP%) varied from 18.23 to 28.77%, 24.97 to 35.97% and 6.48% to 11.94%, respectively. The average nitrogen on NDF (nFDN) (as CP%) was 49.1%. From July to September forage quality was the lowest, probably due to the slowest tissue replenishment and flowering tillers accumulation. The N largest proportion (average of 40% of the CP fraction) was recovered in the cell wall, specifically in the B3 fraction, which should be the most important fraction on ruminal fermentation kinetics studies.The objective of this work was to determine the chemical composition of irrigated Tanzaniagrass (Panicum maximum Jacq.). and to validate the Cornell system. Simulated-grazed samples were collected on three periods of the year (spring, summer and fall, totaling 10 grazing cycles) on irrigated paddocks, rotationally grazed to three post grazed stubbles (low, medium and high). Although there were no statistical differences imposed by the treatments during the year, the neutral detergent fiber (NDF) and acid detergent fiber (ADF) showed higher values in the spring/summer, and lignin in the winter grazing cycles. Along the year the carbohydrate C fraction, TDN and CP varied from 14.14 to 23.21%, 55.26 to 59.31% and 11.29 to 14.61%, respectively. The Nsol, non protein nitrogen (NNP) and nitrogen on ADF (nADF) (as CP%) varied from 18.23 to 28.77%, 24.97 to 35.97% and 6.48% to 11.94%, respectively. The average nitrogen on NDF (nFDN) (as CP%) was 49.1%. From July to September forage quality was the lowest, probably due to the slowest tissue replenishment and flowering tillers accumulation. The N largest proportion (average of 40% of the CP fraction) was recovered in the cell wall, specifically in the B3 fraction, which should be the most important fraction on ruminal fermentation kinetics studies.

Fertilização com N e S na recuperação de pastagem de Brachiaria brizantha cv. Marandu em neossolo quartzarênico

An experiment was carried out during two years on Cerrado soil with the objective of evaluating the response of degraded Brachiaria brizantha cv. Marandu pastures to different N and S fertilization doses. Seven treatments, six with different N and S combinations and a control (degraded pasture), were compared in a randomized complete blocks design. The combinations were: 70 kg ha-1 N without sulphur, 140 kg ha-1 N without sulphur, 210 kg ha-1 N without sulphur, 70 kg ha-1 N and 77 kg ha-1 S, 140 kg ha-1 N and 153 kg ha-1 S, 210 kg ha-1 N and 230 kg ha-1 S. Herbage yield response to nitrogen rates was linear, and the best efficiency of nitrogen use was obtained in the second year. The highest herbage yield was associated with higher extraction of N and smaller soil organic matter content. The sulfur extraction was lower than S doses. The N:S ratio as a criterion of the forage mineral nutrition was effective only in the rainy season. There was sulphur accumulation in deeper layers of soil.

Perda de amônia por volatilização em pastagem de capim-tanzânia adubada com uréia no verão

Parte do nitrogenio (N) do fertilizante aplicado a pastagem pode ser perdida do sistema e, em pastagens tropicais, a volatilizacao de amonia (NH3) e uma das principais vias de perda. Objetivou-se, com o presente estudo, estimar a perda de N-NH3 por volatilizacao em pastagem de Panicum maximum cv. Tanzânia adubada com ureia durante o verao. Adotou-se um delineamento inteiramente casualizado, com medidas repetidas no tempo e tres repeticoes. Nas parcelas, encontravam-se as doses de N-ureia (40, 80 e 120 kg/ha de N-ureia) e, nas subparcelas, o periodo depois da adubacao nitrogenada (1, 5 e 9 dias). A interacao entre o nivel de adubacao e o periodo depois da aplicacao de ureia foi significativa para as variaveis volatilizacao acumulada de N-NH3 e taxa diaria de volatilizacao de N-NH3. A combinacao de elevada umidade do solo, ausencia de chuvas durante o primeiro dia depois da adubacao e alta temperatura elevada determinaram elevadas perdas de amonia por volatilizacao. A perda acumulada de N-NH3 no periodo representou 48%, 41% e 42% do N aplicado nas adubacoes com 40, 80 e 120 kg/ha de N-ureia, respectivamente. A volatilizacao acumulada de N-NH3 (kg/ha) aumentou, enquanto a taxa diaria de volatilizacao de N-NH3 diminuiu com o aumento do tempo depois da adubacao.

Liming and fertilization to restore degraded Brachiaria decumbens pastures grown on an entisol

The reconstitution of soil fertility is essential in the process of pasture restoring, liming being the first action to be taken in this direction. The liming recommendation for pastures needs more technical information as the application method and rate. A field experiment was carried out to evaluate the liming and fertilization practices to restore a degraded Brachiaria decumbens pasture. The following factors were studied: liming method (incorporated in soil by disking or not); level of base saturation (40, 50 or 80%) and lime type (55, 70 or 90 of ECC). Liming and fertilization (NPK and micronutrients) increased both the forage yield and its root system, these being more evident in the second year, even using the same rates of lime and fertilizer used during the first year. After two years the levels of base saturation aimed for the 0 to 0.20 m soil layer were not achieved, neither was the neutralization of the Al. The disking impaired the development of the root system of B. decumbens and promoted the decrease of soil organic matter. The lime with the lowest ECC increased root growth and led to higher concentrations of Ca and Mg in the soil. Studies in other conditions are necessary to define liming requirements in established and degraded pastures.

Número de amostras e relação dimensão: formato da moldura de amostragem para determinação da massa de forragem de gramíneas cespitosas

In order to delineate efficient grazing systems it is important to periodically assess the herbage mass at the farm level. However, the knowledge concerning both, the number of samplings that should be performed and the quadrat (size and format) that should be used in these evaluations remains incomplete. In this context, three experiments were delineated to evaluate the effect of the number of samplings (varying from two to nine) and the dimension:format ratio of the quadrat (.25, 1.0, 2.0, and 3.0 m2 for quadrate and rectangular formats) on the coefficient of variation in herbage mass determinations performed on tussock-forming pastures. A randomized complete block design, following a factorial arrangement with three or four replicates, according to the experiment, was adopted. The interaction between the number of samplings and the dimension:format ratio of the quadrat was not significant. The overall analysis of the main factors indicated that at least four samplings with a 1 m2-quadrat (1 m x 1 m) should be performed in order to stabilize the coefficient of variation and provide a reliable estimate of the herbage mass.

Cinética da degradação ruminal do capim Tanzânia irrigado sob três níveis de resíduo pós-pastejo

The objective of this work was to study DM, NDF, CP and IPND ruminal kinectics of irrigated Tanzaniagrass (Panicum maximum Jacq.). Simulated grazed samples were collected on three periods of the year (spring, summer and fall), under three post grazed stubbles intensities (low, medium and high). Three rumen cannulated animals were assigned to a 3 x 3 Latin square design to determine the in situ degradability until 96 hours of incubation. NDF, CP and IPND were determined by NIRS in the residue remaining in the bags. Forage quality was the highest in the summer. The low post grazed stubble treatment showed the highest increase in degradability of all fractions from spring (74.96%) to summer (81.41%). The soluble protein fraction showed values up to 40% of the RDP, which ranged from 62 to 76% CP. NDF C fraction was underestimated by CNCPS. Data of this research suggest that the %lignin/%NDF should be multiplied by a factor from 2.91 to 3.35. CNCPS overestimated the IPND C fraction (12.11 to 17.08%), as compared to the wet lab analysis value, as regarded to be the N-ADF fraction (6.48 to 10.7%). CP and IPND degradability decreased, as the CP and IPND contents increased.The objective of this work was to study DM, NDF, CP and IPND ruminal kinectics of irrigated Tanzaniagrass (Panicum maximum Jacq.). Simulated grazed samples were collected on three periods of the year (spring, summer and fall), under three post grazed stubbles intensities (low, medium and high). Three rumen cannulated animals were assigned to a 3 x 3 Latin square design to determine the in situ degradability until 96 hours of incubation. NDF, CP and IPND were determined by NIRS in the residue remaining in the bags. Forage quality was the highest in the summer. The low post grazed stubble treatment showed the highest increase in degradability of all fractions from spring (74.96%) to summer (81.41%). The soluble protein fraction showed values up to 40% of the RDP, which ranged from 62 to 76% CP. NDF C fraction was underestimated by CNCPS. Data of this research suggest that the %lignin/%NDF should be multiplied by a factor from 2.91 to 3.35. CNCPS overestimated the IPND C fraction (12.11 to 17.08%), as compared to the wet lab analysis value, as regarded to be the N-ADF fraction (6.48 to 10.7%). CP and IPND degradability decreased, as the CP and IPND contents increased.

Efeito residual de fertilizantes fosfatados solúveis na recuperação de pastagem de Brachiaria brizantha cv. Marandu em Neossolo Quartzarênico

Dois experimentos foram realizados, por um periodo de dois anos, para avaliar a resposta de um sistema solo-pastagem a fertilizantes fosfatados de diferentes velocidades de solubilizacao (superfosfato simples, superfosfato triplo e termofosfato magnesiano) associados ou nao a calagem. Nao houve diferenca em producao de forragem entre as varias fontes de fosforo, quando as adubacoes fosfatadas foram feitas nos dois anos. A associacao de fertilizantes pode ser vantajosa, porque o termofosfato promoveu as maiores producoes de forragem quando se suprimiu a adubacao fosfatada no segundo ano, enquanto as adubacoes com superfosfatos resultaram nas maiores producoes no primeiro ano. A calagem favoreceu a producao de forragem e proporcionou aumento nos teores de nutrientes e reducao do aluminio no solo. A resposta a adubacao foi melhor no segundo ano, porque a pastagem estava em recuperacao.

Intensidade de desfolha e produção de forragem do capim-tanzânia irrigado na primavera e no verão

O objetivo deste trabalho foi determinar o efeito da intensidade de desfolha em Panicum maximum cv. Tanzânia irrigado sobre os componentes da producao forrageira. O delineamento experimental foi em blocos completos casualizados, no esquema de medidas repetidas no tempo, com quatro repeticoes. Nas parcelas, avaliou-se o efeito do residuo pos-pastejo (1.210, 3.036 e 5.471 kg/ha de materia seca do tecido verde da pastagem, folhas e hastes; nas subparcelas, o efeito do periodo de rebrota (9, 18 e 27 dias depois da adubacao nitrogenada) sobre os componentes da producao de forragem durante a primavera e o verao. A massa de materia seca total de forragem, a massa da materia seca de tecido verde de forragem (folhas+hastes) e a massa de materia seca de folhas aumentaram linearmente (P<0,05) com os acrescimos na massa de forragem residual e nos dias de rebrota. Nas duas epocas, observou-se interacao significativa (P<0,05) entre o periodo de rebrota e o residuo pos-pastejo em relacao a massa de materia seca de hastes. No verao, a relacao folha/haste diminuiu com o aumento da massa de forragem residual, mas na primavera houve interacao significativa entre o periodo de rebrota e o residuo pos-pastejo. A quantidade de material morto aumentou com o periodo de rebrota. O residuo pos-pastejo, considerando um ciclo de pastejo de 36 dias, deve ser de 1.650 a 2.700 kg/ha de massa de materia seca de tecido verde de forragem, para assegurar que a producao de folhas e a relacao folha/haste se aproximem do maximo.

Effects of post-grazing forage mass on a beef cattle grazing system on Tanzânia grass pastures

The objective of this study was to evaluate the effect of grazing intensity on herbage accumulation, animal performance, and total system yield on irrigated Tanzania grass pastures under rotational stocking. The experiment was conducted from October 1999 to January 2001, in a complete randomized block design with four replications. Treatments consisted of three grazing intensities, represented by the following quantities of green forage dry mass remaining after grazing: 1,000 (high intensity), 2,500 (intermediate intensity) and 4,000 (low intensity) kg ha−1. Grazing cycles were of 36 days (33 rest and 3 grazing). The values observed at the end of the experiment for post grazing forage mass were close to the proposed values. Forage yield was 25,278, 36,850, and 34,144 kg DM ha−1, whereas animal performance was 0.398, 0.541, and 0.564 kg BW day−1for high, intermediate and low intensities, respectively. Grazing intensity was positive related to the stocking rate (6.5, 5.2 and 4.1 AU ha−1 at high, intermediate and low intensities, respectively). Total system yield was not affected by treatments, ranging between 1,518 and 1,287 kg BW ha−1 year−1.