Intramuscular fat and fatty acid profile of muscle of lambs finished in irrigated pasture

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Performance and parasite control of different genetic groups of lambs finished in irrigated pasture

The aim of this study was to compare the following four genetic groups of hair sheep: Santa Inês (SI), Morada Nova (MN), Brazilian Somali (BS), and the F1 1/2Dorper x 1/2Morada Nova crossbreed on traits related to growth and parasitic infection. Thirty-three male lambs of the same age and of simple birth, under the same pre-weaning management conditions were used in the experiment. After weaning the animals were housed in a completely randomized design in paddocks made of Panicum maximum cv. Tanzania. Along the course of the research, the performance of the four groups of sheep was observed to be negatively affected by gastrointestinal parasites, but there was a genotype effect to the average daily weight gain (ADWG), where the SI and F1 genotypes presented higher values. The effects of genotype, time and genotype x time interaction were significant in weight and corporal score (CS) measurements. The BS lambs had the highest CS values throughout the experiment despite not presenting greater weight gain when compared to the SI and F1 breeds. There were also significant effects of time and genotype x time interaction for packed cell volume (PCV) and FAMACHA© score (FAM) and only the time effect was significant in the total number of eggs per gram (EPG) and total plasma protein (TPP). The MN lambs showed higher PCV values and unlike the other groups, presented a FAMACHA© score below 3 and PCV above 23% even having a higher EPG tendency, especially in the initial phase, indicating a possible higher resilience to infection caused by gastrointestinal parasites.

Soil shear strength under non-irrigated and irrigated short duration grazing systems

Pasture productivity can drop due to soil compaction caused by animal trampling. Physical and mechanical alterations are therefore extremely important indicators for pasture management. The objective of this research was to: draw and evaluate the Mohr failure line of a Red Yellow Latossol under different pasture cycles and natural forest; calculate apparent cohesion; observe possible physical alterations in this soil; and propose a correction factor for stocking rates based on shear strength properties. This study was conducted between March/2006 and March/2007 on the Experimental Farm of Fundação de Ensino Superior de Passos, in Passos, state of Minas Gerais. The total study area covered 6 ha, of which 2 ha were irrigated pasture, 2 ha non-irrigated pasture and 2 ha natural forest. Brachiaria brizantha cv. MG-5 Vitória was used as forage plant. The pasture area was divided into paddocks. The Mohr failure line of samples of a Red Yellow Latossol under irrigated pasture equilibrated at a tension of water content of 6 kPa indicated higher shear strength than under non-irrigated pasture. The shear strength under irrigated pasture and natural forest was higher than under non-irrigated pasture. At a tension of water content of 33 kPa no difference was found in shear strength between management and use. Possible changes in soil structure were caused by apparent cohesion. The values of the correction factor were close to 1, which may indicate a possible soil compaction in prolonged periods of management.

Effect of the application of different water depths and nitrogen and potassium doses on quality of Tanzania grass

The objective of this study was to evaluate the effects of the application of different water depths and nitrogen and potassium doses in the quality of Tanzania grass, in the southern of the state of Tocantins. The experiment was conducted on strips of traditional sprinklers, and used, as treatments, a mixture of fertilizer combinations of N and K2O always in the ratio of 1 N:0.8 K2O. This study determined throughout the experiment: plant height (PH), the crude protein (CP) and neutral detergent fiber (NDF). The highest plant height obtained was 132.4 cm, with a fertilizer dose of 691.71 kg ha-1 in the proportion of N:0.8 K2O, in other words, 384.28 kg ha-1 of N and 307.43 kg ha-1 of K2O, and water depth of 80% of the ETc. The highest crude protein content was 12.2%, with the fertilizer dose application of 700 kg ha-1 yr-1 in the proportion of 1 N to 0.8 of K2O, in other words, 388.89 kg ha-1 of N and 311.11 kg ha-1 of K2O and absence of irrigation. The lowest level of neutral detergent fiber was 60.7% with the application of the smallest dose of fertilizer and highest water depth. It was concluded in this study that there was an increase in plant height by increasing the fertilizer dose and water depth. The crude protein content increased 5.4% in the dry season, by increasing the fertilizer dose and water depth. In the dry season, there was an increase of NDF content by 4.5% by increasing the application of fertilizer and water depth.

Influência da irrigação na atividade e sazonalidade de besouros coprófagos (Coleoptera: Scarabaeidae) em pastagem

Pós-graduação em Agronomia - FEIS

Cobertura vegetal e erosão em entressulcos sob pastagem irrigada em Uberaba-MG

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Perdas de nutrientes por erosão entressulcos sob pastagem irrigada em Uberaba-MG

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Variabilidade espacial dos atributos químicos do solo sob pastagem irrigada e de sequeiro: impactos na produtividade e qualidade do capim tifton 85

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Afectación de los agrosistemas de la zona del Caño San Miguel por la salinización de los suelos

La degradación por salinización de los suelos regados con aguas salobres viene aumentando a escala mundial. El problema de la concentración de sales más solubles que el yeso depende principalmente del agua de riego, la aridez climática y la ausencia de drenaje. Estas condiciones se dan en el aluvium del río Limón, que es un tributario del lago Maracaibo, sito en el estado de Zulia de Venezuela. La regulación del río Limón mediante el cierre de los embalses de Manuelote y Tulé ha disminuido los aportes de aguas y sedimentos de las avenidas de inundación, que tienen carácter diluyente. Por otro lado, el balance de sales solubles en el suelo ha registrado una acumulación neta en los años de extrema aridez anteriores al año 2006, dado que la mayor dilución de las aguas ombrogénicas embalsadas procedentes de las lluvias no ha sido suficiente para compensar la concentración por evapotranspiración “in situ” de las aguas retenidas en la cuenca baja, sobre todo en ausencia de desagüe superficial y drenaje profundo. Las inundaciones posteriores a 2006 fueron suficientes para disminuir la salinidad superficial hasta los valores encontrados en 2010. El estudio experimental de esta problemática en el sector del caño San Miguel ha sido abordado mediante el establecimiento del perfil de salinidad acoplado con el perfil hipotético de humedad usado en la taxonomía de suelos. Este perfil define la disponibilidad del agua del suelo para la vegetación en función de tres potenciales: 1) el potencial físico-químico o matricial, que depende de la energía de adsorción a la superficie de las partículas; 2) el potencial gravitatorio, que depende de la profundidad; y 3) el potencial osmótico, que depende de la concentración de la solución del suelo; lo que supone un avance respecto a tener en cuenta sólo el perfil de humedad, que solamente considera el potencial gravi-químico integrado por el matricial y el gravitatorio. El perfil normalizado de 200 mm de de agua útil, retenida entre 33 y 1500 kPa de succión, incluye ocho fases gravi-químicas de 25 mm. La presente investigación incluye el potencial osmótico estimado por la conductividad eléctrica del extracto de pasta saturada. Los experimentos de lavado de sales en columnas de suelo, simulando la distribución de las lluvias en cinco años representativos de los cuartiles estadísticos de la serie disponible de 38 años completos, han determinado el comportamiento de las sales solubles en un suelo sometido a drenaje. Los resultados han evidenciado que el balance de sales unido al balance de agua controla la degradación de los agrosistemas por salinización. La alternativa frutícola puede ser aumentada en estas condiciones, porque el balance de sales favorece el establecimiento de cultivos permanentes a costa de otros usos del suelo de menor interés económico, como el cultivo de forrajes en regadío y el aprovechamiento de los pastizales en secano durante el barbecho de desalinización, cuya caracterización se ha completado con el estudio de la vegetación indicadora del grado de salinidad. ABSTRACT Saline degradation of soils irrigated with brackish water is increasing worldwide. The problem of salts concentration more soluble than gypsum depends on irrigation water quality, climatic aridity, and drainage limitations. These conditions meet in Limón River alluvium, which is tributary to Maracaibo´s Lake in Zulia State, Venezuela. Limón River regulation by closing Manuelote and Tulé reservoirs has diminished the input of water and sediments from inundations, which exerted dilutive effects. On the other hand, the soil balance of soluble salts has registered a net accumulation during those extremely dry years before 2006 because the greater dilution of ombrogenic dammed water coming from rain has not been enough to compensate salt concentration by “in situ” evapotranspiration in middle basin water, mainly in the absence of superficial runoff and deep drainage. Floods after 2006 were enough to reduce the high superficial salinity figures to those addressed in 2010. The experimental study of this trouble in San Miguel´s pipe area has been addressed through of the establishment of its salinity profile together to the hypothetic moisture profile typically used in soil taxonomy. This salinity profile describes soil water availability for vegetation according to three potentials: 1) physico-chemical or matrix potential, which depends on the adsorption energy of the soil solution to the surface of soil particles; 2) gravitational potential, which depends on soil depth; and 3) osmotic potential, which depends on the concentration of the soil solution. This represents an advance from just using moisture regime, which only considers the matrix and gravitational components of a gravi-chemical potential. The standardized moisture profile of 200 mm useful water being retained between 33 and 1500 kPa includes eight gravi-chemical stages of 25 mm. This research also includes the osmotic component, which is estimated by the electric conductivity of the saturated paste extract. Salts leaching trials in soil columns simulating rain distribution along five model years, representing the statistical quartiles of the available series of 38 complete years, have determined the behaviour of soluble salts in a soil being subjected to drainage. Results have evidenced that salt and water balances considered together are able to control the agrosystem’s degradation by salinization. The fruit production alternative could be improved under these conditions because the salts balance favours the establishment of permanent crops to the detriment of other soil uses of lower economical interest such as irrigated forage and non-irrigated pasture during desalinization fallow, which characterization has been completed through assessing the presence of salinity-indicator vegetation.

Effect of cultivation on soil C contents and saturated hydraulic conductivity

The irrigation of pasture with saline, Na-contaminated industrial wastewater typically results in an increase in soil ESP. From current knowledge (derived largely from cultivated agricultural soils), although these sodic soils are likely to remain stable whilst irrigated with effluent (due to the effluent’s large electrolyte concentration), during rainfall periods of low electrolyte concentration these soils would be expected to disperse. However, effluent irrigated pasture soils have been observed to maintain their structure even during intense rainfall events. Three soil types were collected (Sodosol, Vertosol and Dermosol), each with a cultivated/non-cultivated pair. The soils were equilibrated with various SAR solutions and then leached with deionised water to allow the measurement of saturated hydraulic conductivity (Ksat). At low SARs, Ksat tended to be greater in non-cultivated than cultivated soils and is attributable to a loss of structure associated with cultivation. In addition, as SAR increased, the reduction in relative Ksat tended to be significantly greater in cultivated than non-cultivated soils. The relatively rapid saturated hydraulic conductivity in the non-cultivated soils at large SARs is due to a greater aggregate stability due to greater soil C content. For the sustainable disposal of saline effluent, it is therefore necessary to ensure that soils remain undisturbed and preferably under pasture, thus maximising soil structural stability and hydraulic conductivity.

Simulation of irrigated Thanzania grass growth based on photothermal units, nitrogen fertilization and water availability

Simulation of irrigated Thanzania grass growth based on photothermal units, nitrogen fertilization and water availability. The mathematical model to predict the forage yield using photothennal units was utilized with success in Elephant grass, Thanzania and Brachiaria niziziensis in the absence of water stress and nitrogen stress. The aim of this study was to propose models to estimate the forage yield of Thanzania grass under different irrigation (25, 50,75, 100 e 125% of ETc) and nitrogen level in various regions of Brazil. As such, models were developed to estimate the dry matter production of Panicum maximum Jacq. frass cv Thanzania in different irrigation and nitrogen levels, using photothermal units. The models were adjusted to doses of 0, 30, 60, 110 and 270 kg of N ha(-1), doses were divided in applications after each evaluation, with a rest cycle of 35 days. The adjusted model presented good performance in predicting dry matter production of Thanzania grass, with r(2) = 0.9999. The results made it possible to verify that the proposed model can be used to predict forage production in different regions of Brazil. It can be estimated, with good precision. The production of Thanzania grass dry matter can be accurately estimated in specific places (in function of latitude and time of year), with the maximum and minimum temperature values.

White stem borer damage and grain yield in irrigated rice in West Java, Indonesia

Factors influencing the relationship between whiteheads caused by the white stem borer Scirpophaga innotata (Walker) and grain yield were investigated. We determined the effect of different numbers of whiteheads on grain yield using different cultivars, nitrogen application, and at different field locations in Cilamaya, West Java. At the same number of panicles and whiteheads per plant, yield reduction is greater in cisadane than in IR64. With increasing nitrogen application, the range in panicle height increased. Except for Ketan, more whiteheads were recorded in shorter panicles. Two locations planted to the same cultivar showed different relationships between whiteheads and grain yield. The relationship between whiteheads and grain yield depends on the distribution of whiteheads in the field. Unless these factors have been taken into consideration, it may be difficult to make a damage prediction of white stem borer in the field. (C) 1997 Published by Elsevier Science Ltd.

Nitrogen balance for an agroforestry system irrigated with saline, high nitrogen effluent

Land disposal is commonly used for urban and industrial wastewater, largely due to the high costs involved in alternative treatments or disposal systems. However, the viability of such systems depends on many factors, including the composition of the effluent water, soil type, the plant species grown, growth rate, and planting density. The objective of this study is to establish whether land disposal of nitrogen (N) rich effluent using an agroforestry system is sustainable, and determine the effect of irrigation rate and tree planting density on the N cycle and subsequent N removal. We examined systems for the sustainable disposal of a high strength industrial effluent. The challenge was to leach the salt, by using a sufficiently high rate of irrigation, while simultaneously ensuring that N did not leach from the soil profile. We describe the N balance for two plant systems irrigated with effluent, one comprising Eucalyptus tereticornis and Eucalyptus moluccana and a Rhodes grass (Chloris gayana) pasture, and the other, Rhodes grass pasture alone. Nitrogen balance was assessed from N inputs in effluent and rainfall, accumulation of N in the plant biomass, changes in soil N storage, N loss in run-off water, denitrification and N loss to the groundwater by deep-drainage. Biomass production was estimated from allometric relationships derived from yearly destructive harvesting of selected trees. The N content of that biomass was then calculated from measured N content of the various plant parts, and their mass. Approximately 300 kg N/ha/yr was assimilated into tree biomass at a planting density of 2500 tree/ha of E. moluccana. In addition to tree assimilation, pasture growth between the tree rows, which was regularly harvested, contributed substantially to N uptake. If the trees were harvested after two years of growth and grass harvested regularly, biomass removal of N by the mixed system would be about 700 kg N/ha/yr. The results of this study show that the current system of effluent disposal is not sustainable as the nitrate leaching from the soil profile far exceeds standards set out by the ANZECC guidelines. Hence additional means of N removal will need to be implemented. Biological N removal is an area that warrants further studies as it is aimed at reducing N levels in the effluent before irrigation. This will complement the current agroforestry system.

Carbon Stocks and Isotopic Composition of the Organic Matter in Soils Covered by Native Vegetation and Pasture in Sorocaba, SP, Brazil

Land cover change constitutes one of main way of alteration of soil organic matter in both quantitative and qualitative terms. The goal of this study was to compare the carbon stock and the isotopic signature of the organic matter in the soil of areas with different land use,covered with forest and grass (pasture). The study area is located at Sorocaba, SP, Brazil. Using un-deformed soil samples, we measured the carbon content and bulk density. The isotopic signature of soil carbon was determined through the analysis of isotopic ratio (12)C/(13)C. The pasture soil stocks 48% less carbon than the soil covered by natural forest. The isotopic signature indicated that 42.2% of organic matter of the soil covered by pasture is originated from grasses. This characterizes a highly degradation of organic matter in the environment, both quantitatively and qualitatively. Hence, some guidelines of recuperation are described in order to restore the soil organic matter, structure and porosity.

Influence of land-use change on near-surface hydrological processes: Undisturbed forest to pasture

Soil compaction that follows the clearing of tropical forest for cattle pasture is associated with lower soil hydraulic conductivity and increased frequency and volume of overland flow. We investigated the frequency of perched water tables, overland flow and stormflow in an Amazon forest and in an adjacent 25-year-old pasture cleared from the same forest. We compared the results with the frequencies of these phenomena estimated from comparisons of rainfall intensity and soil hydraulic conductivity. The frequency of perched water tables based on rainfall intensity and soil hydraulic conductivity was expected to double in pasture compared with forest. This corresponded closely with an approximate doubling of the frequency of stormflow and overland flow in pasture. In contrast, the stormflow volume in pasture increased 17-fold. This disproportional increase of stormflow resulted from overland flow generation over large areas of pasture, while overland flow generation in the forest was spatially limited and was observed only very near the stream channel. In both catchments, stormflow was generated by saturation excess because of perched water tables and near-surface groundwater levels. Stormflow was occasionally generated in the forest by rapid return flow from macropores, while slow return flow from a continuous perched water table was more common in the pasture. These results suggest that deforestation for pasture alters fundamental mechanisms of stormflow generation and may increase runoff volumes over wide regions of Amazonia. (C) 2009 Elsevier B.V. All rights reserved.