Dynamics of soil microbiolotical attributes under integrated production systems, continuous pasture, and native cerrado.

2016

Soil carbon sequestration in grass and grass-legume pastures in the western Brazilian Amazon.

Land use change from native forests to pastures in the tropics have impact on global carbon (C) cycle through increased rates of C emissions to the atmosphere and the loss of above- and belowground C accumulation and storage capacity (SILVER et al., 2000). This study was conducted to determine the carbon stock in a Ultisol under a pure Brachiaria humidicola (Rendle) Scheick pasture and a mixed pasture of B. humidicola and Arachis pintoi Krapov. & W. C. Greg cv. BRS Mandobi, both without fertilization.

Modeling nitrous oxide emissions in grass and grass-legume pastures in the western Brazilian Amazon.

Mineral nitrogen (N) dynamics in soil and the exchange of N gaseous in the interface soil-atmosphere are intimately associated with animal manure in pastures. According to soil inorganic-N pools and the site studied, forest or pasture, and pastures age the soil inorganic-N pools of ammonium and nitrate can be similar in the forest or ammonium dominated in the pasture. Also annual average net nitrification rates at soil surface in forest can be higher than in pasture suggesting a higher potential for nitrate-N losses either through leaching or gaseous emissions from intact forests compared with established pastures (NEILL et al., 1995).

Mating system variation among populations, individuals and within and among fruits in Bertholletia excelsa.

The aim of this study was to investigate variation in mating system among three Brazilian Amazon populations of the tree Bertholletia excelsa with different levels of anthropogenic interventions. We collected open-pollinated seeds from one natural population, remnant trees dispersed in a pasture, and trees from a plantation. Outcrossing rate not varied among the populations and indicates that all seeds were originated from outcrossing (tm=1.0). Mating among relatives was significant higher in the plantation than forest and pasture populations, probably due the fact that many trees are related in the plantation. Correlated mating was significantly higher in pasture (rp=0.47) and plantation (rp=0.51) than in the natural population (rp=0.22), suggesting that trees in natural population are pollinated by a higher number of pollen donors. The paternity correlation was significantly higher within (rp(w)=0.41) than among fruits (rp(a)=0.18), showing a higher probability to find full-sibs within than among fruits. The fixation index was generally lower in seed trees than in their seedlings, suggesting selection for heterozygous individuals from seedling to adult stages. Progeny arrays collected from the natural population had a lower proportion of pairwise full-sibs than in pasture and plantation and higher variance effective size (2.75) than trees in pasture (2.15) and plantations (2.22). Results highlight that seed collections for conservation, breeding and reforestation programs preferentially should be carried out in natural populations due low proportion highest variance effective size within progeny.

Energy balance model applied to pasture experimental areas in São Paulo State, Brazil.

The Simple Algorithm for Evapotranspiration Retrieving (SAFER) was used to estimate biophysical parameters and theenergy balance components in two different pasture experimental areas, in the São Paulo state, Brazil. The experimentalpastures consist in six rotational (RGS) and three continuous grazing systems (CGS) paddocks. Landsat-8 images from2013 and 2015 dry and rainy seasons were used, as these presented similar hydrological cycle, with 1,600 mm and 1,613mm of annual precipitation, resulting in 19 cloud-free images. Bands 1 to 7 and thermal bands 10 and 11 were used withweather data from a station located nearthe experimental area. NDVI, biomass, evapotranspiration and latent heat flux(λE) temporal values statistically differ CGS from RGS areas. Grazing systems influences the energy partition and theseresults indicate that RGS benefits biomass production, evapotranspiration and the microclimate, due higher LE values.SAFER is a feasible tool to estimate biophysical parameters and energy balance components in pasture and has potentialto discriminate continuous and rotation grazing systems in a temporal analysis.

Uso de suplementos para acasalamento de bezerras Angus aos 14 meses de idade.

RESUMO: O experimento foi conduzido com o objetivo de avaliar o desenvolvimento de novilhas de corte em três sistemas alimentares: exclusivamente em pastagem de azevém (Lolium multiflorum Lam.) ou em pastagem de azevém e recebendo 0,93% do peso corporal de grão de milho inteiro ou grão de aveia branca como suplemento. O delineamento experimental foi o inteiramente ao acaso, com medidas repetidas no tempo. A utilização da pastagem de azevém, com ou sem uso de grão de milho ou aveia como suplemento, possibilita desenvolvimento reprodutivo para que as bezerras sejam acasaladas aos 14 meses de idade. O peso corporal ao início da utilização da pastagem é determinante para que as bezerras atinjam adequado desenvolvimento reprodutivo no início da estação de acasalamento. ABSTRACT: The experiment was carried out to evaluate the development of beef heifers in three feeding systems: exclusively on ryegrass pasture (Lolium multiflorum Lam.) or in ryegrass pasture and receiving 0.93% of body weight of corn whole grain or oats grain as a supplement. The experimental design was completely randomized with repeated measures in time. The utilization of ryegrass pasture, with or without the use of corn or oats grain as a supplement, provides reproductive development of heifers in order for them to be mated at 14 months of age. The body weight at the beginning of pasture utilization is crucial for heifers to reach adequate reproductive development at the beginning of the mating season.

Nutrient content in aboveground biomass of Brazilian peanut cultivars in conservation tillage on sugarcane straw and pasture area.

Fields studies were conducted in 2004/2005 in order to evaluate the effects of tillage on nutrient content in aboveground biomass of two peanut cultivars, cultivated in rotation after mechanical harvested sugarcane and pastures. These trials were carried out in two types of soils; Oxisol and Ultisol, respectively in Ribeir?ao Preto and Mirassol, S?ao Paulo State, Brazil. The experimental design was split-plot with four replications. Tillage treatments (conventional, minimum and no-tillage) were main plots while sub-plots were peanut genotypes IAC-Tatu ST (Valencia market-type, erect growth habit, red seed coat, maturity range around 100 days after planting) and IAC-Caiap´o (Runner market-type, prostate growth habit, pink testa, maturity range more than 135 days). From 15 to 90 days after emergence, samples of leaves and stems were harvested, dried, weighted and ground to determine macro and micronutrient concentration. At 75 days after sowing, the cultivar IAC-Caiap´o showed higher contents of N, P, K, Cu, and Zn while IAC-Tatu presented higher concentrations of Ca, Mg, and S. Zn content was higher in conservation tillage than in conventional, mainly in Oxisoil for both of cultivars.

Spatial variability of soil properties and yield of a grazed alfalfa pasture in Brazil.

2016

Classification of plant communities, structure and diversity of forests in Acre, Brazil.

2016

Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests.

The seasonal climate drivers of the carbon cy- cle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combina- tion of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measure- ments and 35 litter productivity measurements), their asso- ciated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonal- ity in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rain- fall is < 2000 mm yr-1 (water-limited forests) and to radia- tion otherwise (light-limited forests). On the other hand, in- dependent of climate limitations, wood productivity and lit- terfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosyn- thetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest pro- ductivity in a drier climate in water-limited forest, and in cur- rent light-limited forest with future rainfall < 2000 mm yr-1.

A survey of the meat goat industry in Queensland and New South Wales. 1. General property information, goat and pasture management.

This study aimed to survey farmers knowledge and practices on the management of pastures, stocking rates and markets of meat goat-producing enterprises within New South Wales and Queensland, Australia. An interview-based questionnaire was conducted on properties that derived a significant proportion of their income from goats. The survey covered 31 landholders with a total land area of 567 177 ha and a reported total of 160 010 goats. A total of 55% (17/31) of producers were involved in both opportunistic harvesting and commercial goat operations, and 45% (14/31) were specialised seedstock producers. Goats were the most important livestock enterprise on 55% (17/31) of surveyed properties. Stocking rate varied considerably (0.3?9.3 goats/ha) within and across surveyed properties and was found to be negatively associated with property size and positively associated with rainfall. Overall, 81% (25/31) of producers reported that the purpose of running goats on their properties was to target international markets. Producers also cited the importance of targeting markets as a way to increase profitability. Fifty-three percent of producers were located over 600 km from a processing plant and the high cost of freight can limit the continuity of goats supplied to abattoirs. Fencing was an important issue for goat farmers, with many producers acknowledging this could potentially add to capital costs associated with better goat management and production. Producers in the pastoral regions appear to have a low investment in pasture development and opportunistic goat harvesting appears to be an important source of income.

Effect of the pasture supplementation strategy in the growing period on performance and carcass traits of crossbred cattle finished in feedlot

2016

Forage mass and morphological composition of Marandu palisade grass pasture under rest periods.

2016

Soil carbon and nitrogen in pasture soil reforested with eucalyptus and guachapele.

Apesar de os teores de matéria orgânica serem normalmente baixos em solos arenosos, ela é responsável por quase a totalidade da CTC, armazenamento de água e disponibilidade de nutrientes desses solos. A avaliação de sistemas de exploração florestais alternativos, com vistas em incrementar a acumulação de C e N, devem ser incentivados. Este estudo compara plantios puros e mistos de Eucalyptus grandis e Pseudosamanea guachapele, leguminosa fixadora de N2, em relação os estoques de C e N do solo. Os plantios foram realizados em áreas anteriormente manejadas com Panicum maximum num Planossolo, que, por pelo menos dez anos, não recebeu qualquer fertilizante. Para estimar o C e o N estocado, foram retiradas amostras das camadas de 0-2,5; 2,5-5,0; 5,0-7,5; 7,5-10,0; 10,0-20,0 e 20,0-40,0 cm tanto nos plantios puros e mistos, quanto na área de pasto. A técnica da abundância natural do 13C foi utilizada na estimativa do C originado das árvores nos 10 cm superficiais. Os estoques de C e N, no plantio misto atingiu valores de 23,83 e 1,74 Mg ha-1, respectivamente. Nos puros, de guachapele e eucalipto, e no pasto os estoques de C estimados foram de 14,20; 17,19 e 24,24 Mg ha-1, respectivamente. Para os mesmos tratamentos, os estoques de N foram estimados em 0,83; 0,99 e 1,71 Mg ha-1, respectivamente. Mais de 40 % do C do solo sob o plantio misto foram estimados como sendo derivados das árvores, enquanto nos plantios puros de eucalipto e guachapele, a contribuição do C das árvores ficou em 19 e 27 %, respectivamente. Esses resultados evidenciam que a presença da leguminosa no plantio consorciado aumenta os estoques de C e N do solo.

Panicum maximum cv. Tanzânia: climate trends and regional pasture production in Brazil.

Projected change in forage production under a range of climate scenarios is important for the evaluation of the impacts of global climate change on pasture-based livestock production systems in Brazil. We evaluated the effects of regional climate trends on Panicum maximum cv. Tanzânia production, predicted by agro-meteorological model considering the sum of degree days and corrected by a water availa bility index. Data from Brazilian weather stations (1963?2009) were considered as the current climate (baseline), and future scenarios, based on contrasting scenarios interms of increased temperature and atmospheric CO2 concentrations (high and low increases), were determined for 2013?2040 (2025 scenario) and for 2043?2070 (2055 scenario). Predicted baseline scenarios indicated that there are regional and seasonal variations in P. maximum production related to variation intemperature and water availability during the year. Production was lower in the Northeast region and higher in the rainforest area. Total annual productionunder future climate scenarios was predicted toincrease by up to 20% for most of the Brazilian area, mainly due to temperature increase, according to each climate model and scenario evaluated. The highest increase in forage production is expected to be in the South, Southeast and Central-west areas of Brazil. In these regions, future climate scenarios will not lead to changes in the seasonal production, with largerincreases in productivity during the summer. Climate risk is expected to decrease, as the probability of occurrence of low forage productions will be lower. Due to the predicted increase in temperature and decrease in rainfall in the Northeast area, P. maximum production is expected to decrease, mainly when considering scenarios based on the PRECIS model for the 2055 scenario.