Dynamics of sward condition and botanical composition in mixed pastures of marandugrass, forage peanut and tropical kudzu

This study was carried out to evaluate the dynamics of sward condition and botanical composition of a mixed pasture of marandugrass (Brachiaria brizantha cv. Marandu), forage peanut (Arachis pintoi cv. Mandobi) and tropical kudzu (Pueraria phaseoloides), rotationally stocked at four daily forage allowance levels (6.6, 10.3, 14.3 and 17.9% of live weight). Sward condition was characterized in each stocking cycle by measuring pre- and post-grazing sward height, forage mass and percentage of bare ground. Botanical composition (grass, forage peanut, tropical kudzu and weeds) was evaluated before each stocking period. Swards under smaller forage allowances presented lower height, forage mass and ground cover. This condition favored the growth of forage peanut, which constituted 21.1, 15.2, 8.4 and 3.8% of forage mass in the last quarter of the experimental period, from the lowest to the highest forage allowance, respectively. Tropical kudzu was sensitive to all forage allowance levels and its percentage in the botanical composition was strongly reduced along the experimental period, especially during the dry season (July to September). Forage peanut cv. Mandobi and marandugrass form a more balanced mixture when pre-grazing sward height is maintained shorter than 45 cm. Tropical kudzu is intolerant to intensive grazing management systems when associated to marandugrass

Soil Carbon in Agroforestry Systems: An Unexplored Treasure?

Soil organic matter (SOM), which contains more reactive organic carbon (C) than any other single terrestrial pool, plays a major role in determining C storage in ecosystems and regulating atmospheric concentrations of carbon dioxide (CO2)^1^. Agroforestry, the practice of growing trees and crops in interacting combinations on the same unit of land^2^, primarily by resource-poor smallholder farmers in developing countries, is recognized as a strategy for soil carbon sequestration (SCS) under the Clean Development Mechanism (CDM) of the Kyoto Protocol^3^. The understanding about C storage and dynamics under agroforestry systems (AFS), however, is minimal. Our studies under various AFS in diverse ecological conditions in five countries showed that tree-based agricultural systems, compared to treeless systems, stored more C in deeper soil layers up to 1 m depth under comparable conditions. More C is stored in soil near the tree than away from the tree; higher SOC content is associated with higher species richness and tree density; and C3 plants (trees) contribute to more C in the silt- + clay-sized (<53 µm) fractions that constitute more stable C, than C4 plants, in deeper soil profiles4 - 8. These results provide clear indications of the possibilities for climate change mitigation through SCS in AFS, and opportunities for economic benefit - through carbon trading - to millions of smallholder farmers in developing countries

Grãos de soja como fonte de urease na amonização do bagaço de cana-de-açúcar com uréia

A urease é a enzima responsável pela hidrólise da uréia em amônia. A utilização de fonte de urease no tratamento de bagaço de cana-de-açúcar com uréia pode melhorar o processo da decomposição da uréia em amônia, beneficiando o tratamento de amonização e, conseqüentemente, o valor nutritivo do material. O objetivo do trabalho foi avaliar o efeito de níveis de soja crua, como fonte de urease, na amonização do bagaço de cana através da uréia. Utilizaram-se quatro níveis de soja crua (0; 2,5; 3,75; e 7,5% da matéria seca) em bagaço de cana-de-açúcar tratado com 7,5% de uréia (da matéria seca), armazenados por um período de 96 dias, em sacos de polietileno com capacidade de 50 litros. Foi utilizado o delineamento inteiramente casualizado com quatro níveis de soja crua e três repetições. Os teores de matéria seca, proteína bruta e hemicelulose não foram afetados pelos níveis de urease; entretanto, verificou-se efeito quadrático positivo para digestibilidade in vitro da matéria seca e linear negativo para o teor de fibra detergente neutro. A utilização de até 3,75% de soja crua na amonização com uréia propiciou melhoria na digestibilidade da matéria seca do bagaço de cana.The urease is the responsible enzyme for hidrolisis of urea into ammonia. The use of a urease source for the treatment of sugarcane bagasse with urea can improve the urea decomposition process into ammonia, improving the nutritious value of the material. The objective of this work was to evaluate the effect of the level of ground whole soybean as a urease source for sugarcane bagasse ammoniation through urea. Four levels of whole soybean (0, 2.5, 3.75 and 7.5% on dry matter basis), were added to sugarcane bagasse treated with 7.5% of urea (on dry matter basis) and stored during 96 days in plastic bags (50 L). A complete randomized design with four treatments and three replicates was used. Dry matter, crude protein and hemicellulose contents were not affected by urease levels, there was, however, a positive quadratic effect for in vitro dry matter disappearance and a negative linear effect for neutral detergent fiber disappearance. The use of 3.75% of whole soybean in the ammoniation through urea was beneficial for the improvement of the dry matter digestibility of sugarcane bagasse

SUSTAINABILITY IN AGROFORESTRY SYSTEMS: SOCIO-ECONOMICAL INDICATORS

It is wide the discussion involving the importance of production adjustment activities in general, to the concept of sustainable development. Among the agricultural activities, the agroforestry systems have been considered sustainable, coming as alternatives to the intensive systems of agricultural production. To monitor the sustainability of agricultural activities, includings  AF,  the  literature  emphasizes  the  biophysical  indicators,  in  detriment  of  the  socio-economical ones. Seeking to define a list of socio-economical indicators that can be adapted to the several models recommendations of  AF a study was developed, supported by specialists and technicians and wide literature review. The conclusions were: the categories related  to the operation of the systems had the largest number of indicators in the socioeconômic component, with larger concentration in the endogenous operations of the system, followed by the endogenous and exogenous resources; the largest number of indicators suggested in the category operation of the system was in the descriptors health and nutrition, employment, habitation and sanity and economic analysis; in the category operation of exogenous systems, there were certain larger number of indicators for the descriptors commercialization and rural infrastructure; practically there was no difference among the number of indicators obtained for the agroforestry systems with and without the animal component.</p

Long-term Bias of Internal Markers in Sheep and Goat Digestion Trials

Two digestion trials, one with sheep and another with goats, were conducted to evaluate the long-term bias (LTB) of the indigestible dry matter (iDM), indigestible neutral detergent fiber (iNDF) and indigestible acid detergent fiber (iADF) internal markers. The study used eight Santa Inês castrated male sheep (average body weight of 16.6 kg) distributed in two 4×4 Latin squares and eight Saanen castrated male goats (average body weight of 22.6 kg) distributed in two 4×4 Latin squares. The experiments were conducted simultaneously, and the animals were housed in 1.2 m2 individual pens with wood-battened floors equipped with individual feeders and drinkers. The animals received isonitrogenous diets that were offered ad libitum and contained 14% crude protein and 70% sugar cane (with 0, 0.75, 1.5 or 2.25% CaO, in natural matter percentage), corrected with 1% urea and 30% concentrate. The experiment consisted of four experimental periods of 14 d each, with the feed, leftovers and feces sampled on the last four days of each period. The marker concentrations in the feed, leftovers and fecal samples were estimated by an in situ ruminal incubation procedure with a duration 240 h. The relationship between the intake and excretion of the markers was obtained by adjusting a simple linear regression model, independently from the treatment (diets) fixed effects and Latin squares. For both the sheep and goats, a complete recovery of the iDM and iNDF markers was observed (p>0.05), indicating the absence of LTB for these markers. However, the iADF was not completely recovered, exhibiting an LTB of −9.12% (p<0.05) in the sheep evaluation and −3.02% (p<0.05) in the goat evaluation