Nutritional evaluation of “Braquiarão” grass in association with “Aroeira” trees in a silvopastoral system

This study aimed at evaluating the influence of a silvopastoral system (SPS) composed of “Aroeira” trees (Myracrodruon urundeuva) on the nutritional value of Brachiaria brizantha cv. Marandu forage grass over the rainy season. The experiment was conducted in the SPS located in the “Cerrado” biome in Lagoa Santa County, Minas Gerais state, Brazil, in the agricultural year of 2004–2005. It was evaluated the influence of “Aroeira”, whose density in the area was 140 trees/ha, on the following parameters of the B. brizantha cv. Marandu forage grass: forage mass harvest above stubble height, morphogenic attributes, bromatological composition and nutritional value. The effects of “Aroeira” trees on the micro-climatic conditions were also evaluated. The experiment adopted a randomized block design with five blocks (cutting seasons), two treatments (a shaded pasture—B. brizantha cv. Marandu shaded by M. urundeuva—and a pasture in full sun—B. brizantha cv. Marandu in full sun), and three replicates. The tree component, composed of the tree species M. urundeuva in the experimental density adopted, increased dry matter and crude protein of the forage mass harvest above stubble height, without affecting the concentration of neutral detergent fibre or acid detergent fibre, thus causing dry matter and organic matter in vitro degradability as well as effective degradability of the forage grass to remain the same as those obtained in full sun. Therefore, the results of this study show the possibility of using trees and grass to increase both animal production and environmental services.     

Supplementary Calcium and Potassium Improve the Response of Tomato (Solanum lycopersicum L.) to Simultaneous Alkalinity,Salinity, and Boron Stress

Irrigation water of poor quality that is high in salts, alkalinity-inducing compounds, and boron (B) threatens global agricultural production. The objective of the present study was to determine whether supplementary calcium (Ca) and potassium (K) ameliorate the response of tomato plants to a simultaneous combination of these stress conditions. Irrigation water high in alkalinity, salinity, and B reduced plant growth, which was associated with a partial impairment in the antioxidant system (reduction in catalase activity), impairment in water relations (reduced relative water content), decreased nutrient acquisition [lower nitrogen (N), phosphorus (P), K, Ca, and magnesium (Mg) content]; and specific toxicity due to the increase in shoot sodium (Na) and B. However, stressed plants exhibited partially improved growth when supplemented with greater concentrations of Ca and K, which were associated with enhanced P concentration, maintenance of chlorophyll a concentration, and/or partially restored N, P, K, Ca, and Mg uptake.     

Differential phosphorus responses of leguminous cover crops on soils with variable history

The response of 8 leguminous cover crops to phosphorus (P) application (7.5 mg P₂O₅ kg^‐1 soil or 15 kg P₂O₅ ha^‐1 to the depth of 15 cm) on soils with variable history was evaluated in a pot trial supplemented with a field experiment in 1993. The soil from a livestock farmer's field showed higher total organic carbon content and extractable cations compared to that from a non‐livestock farmer's field. In the pot trial, P application, on average, increased shoot, root, nodule dry matter and nitrogen (N) accumulation of the legumes by 82%, 45%, 871%, and 900%, respectively, compared to the control. Cajanus cajan, Crotalaria ochroleuca, Centrosema pascuorum, and white‐seeded Mucuna pruriens showed a higher P response than Centrosenza brasilianum and Chamaecrista rotundifolia. The legumes grown on the manured soil showed not only higher biomass and N accumulation, but also higher increase (110% and 117%) in total dry matter and N accumulation because of P application than those grown on the un‐manured soil (27% and 45%). In the field experiment, spreading legume groundcover at 16 weeks after planting was increased by 40% in the un‐manured soil and by 31% in the manured soil. Centrosema brasilimmm even showed a negative response of groundcover to P application. There was little response in erect legume height to P, except for measurements at 6 and 8 weeks after planting, when P increased plant height for Crotaktria on un‐manured soil. Results imply high returns can be expected when P is applied to leguminous cover crops in fairly fertile soil. The relatively low response under the field conditions, compared to pot, suggests caution is needed when P is recommended for legumes grown under environmentally stressed conditions.     

Ecosystem services of regulation and support in Amazonian pioneer fronts: searching for landscape drivers

Landscape dynamics result from forestry and farming practices, both of which are expected to have diverse impacts on ecosystem services (ES). In this study, we investigated this general statement for regulating and supporting services via an assessment of ecosystem functions: climate regulation via carbon sequestration in soil and plant biomass, water cycle and soil erosion regulation via water infiltration in soil, and support for primary production via soil chemical quality and water storage. We tested the hypothesis that patterns of land-cover composition and structure significantly alter ES metrics at two different scales. We surveyed 54 farms in two Amazonian regions of Brazil and Colombia and assessed land-cover composition and structure from remote sensing data (farm scale) from 1990 to 2007. Simple and well-established methods were used to characterize soil and vegetation from five points in each farm (plot scale). Most ES metrics were significantly correlated with land-use (plot scale) and land-cover (farm scale) classifications; however, spatial variability in inherent soil properties, alone or in interaction with land-use or land-cover changes, contributed greatly to variability in ES metrics. Carbon stock in above-ground plant biomass and water infiltration rate decreased from forest to pasture land covers, whereas soil chemical quality and plant-available water storage capacity increased. Land-cover classifications based on structure metrics explained significantly less ES metric variation than those based on composition metrics. Land-cover composition dynamics explained 45 % (P < 0.001) of ES metric variance, 15 % by itself and 30 % in interaction with inherent soil properties. This study describes how ES evolve with landscape changes, specifying the contribution of spatial variability in the physical environment and highlighting trade-offs and synergies among ES.     

Tissue composition and allometric growth of carcass of lambs Santa Inês and crossbreed with breed Dorper

Tropical Animal Health and Production - This study aimed to assess the tissue composition and allometric growth of carcasses of Santa Inês and crossbred Dorper x Santa Inês lambs confined...     

Effects of marine climate variability on the relative abundance of Lutjanus purpureus (POEY, 1866) on the Amazon Continental Shelf

The aim of this study was to analyze the effects of climate and marine variability on the catches of Lutjanus purpureus in three sectors of the Amazon Continental Shelf. Remote sensing data were compared with landings (CPUE) between 1997 and 2007 and analyzed for partial influence obtained through the Generalized Additive Model. Additionally, significant variables were analyzed through Wavelet Cross-Spectrum, and periods of high correlation between variables in space and time were identified. The results indicated a high coherence between catch per unit effort (CPUE) and environmental variables on an interannual scale, suggesting that Red Snapper fishing is mainly influenced by the seasonal effects of oceanographic variables. These results suggest that fluctuations in Red Snapper catches between 1997 and 2007 may be the result of natural processes that occur in the Amazon Continental Shelf every year in synergy with environmental variables, which are also indirectly affected by the El Niño–Southern Oscillation (ENSO) pattern.