Sandra Furlan Nogueira

Variabilidade espacial do solo e da biomassa epígea de pastagem, identificada por meio de geostatística

O objetivo deste trabalho foi identificar a estrutura de dependencia espacial de atributos do solo e sua interferencia na producao de biomassa epigea de pastagem de capim‑marandu (Urochloa brizantha). Amostras de Latossolo Vermelho‑Amarelo foram coletadas em rede de pontos georreferenciados, para a determinacao de atributos fisicos e quimicos do solo e da producao de biomassa epigea da pastagem, no verao e outono de 2010/2011. Verificou-se dependencia espacial das variaveis, por meio de analise geoestatistica com construcao e ajuste de semivariogramas, interpolacao por krigagem ordinaria e espacializacao em mapas de isolinhas. A dependencia espacial ocorreu para alguns atributos fisicos e quimicos do solo (areia, densidade, resistencia a penetracao, infiltracao, pH, MO, P, K, Ca, Mg, H+Al, Al, CTC e V), e para a biomassa da pastagem medida nas estacoes verao e outono. A analise espacial de atributos fisicos do solo permite identificar areas degradadas da pastagem. A biomassa da pastagem e mais influenciada pelos atributos fisicos do solo do que pelos quimicos.

Water Type and Irrigation Time Effects on Microbial Metabolism of a Soil Cultivated with Bermuda-grass Tifton 85

This study investigated the microbial metabolism in Bermuda-grass Tifton 85 areas after potable-water and effluent irrigation treatments. The experiment was carried out in Lins/SP with samples taken in the rainy and dry seasons (2006) after one year and three years of irrigation management, and set up on an entirely randomized block design with four treatments: C (control, without irrigation or fertilization), PW (potable water + 520 kg of N ha-1 year-1); TE3 and TE0 (treated effluent + 520 kg of N ha-1 year-1) for three years and one year, respectively. The parameters determined were: microbial biomass carbon, microbial activity, and metabolic quotient. Irrigation with wastewater after three years indicated no alteration in soil quality for C and ET3; for PW, a negative impact on soil quality (microbial biomass decrease) suggested that water-potable irrigation in Lins is not an adequate option. Microbial activity alterations observed in TE0 characterize a priming effect.

Pasture evapotranspiration as indicators of degradation in the Brazilian Savanna: a case study for Alto Tocantins watershed

The Alto Tocantins watershed, located in the Brazilian Savanna (Cerrado biome), is under an intense land use and occupation process, causing increased pressure on natural resources. Pasture areas in the region are highly relevant to the rational use of natural resources in order to achieve economic and environmental sustainability. In this context, remote sensing techniques have been essential for obtaining information relevant to the assessment of vegetation conditions on a large scale. This study aimed to apply this tool in conjunction with field measurements to evaluate evapotranspiration (ET) against pasture degradation indicators. The SAFER algorithm was applied to estimate ET using MODIS images and weather station data from year 2012. Results showed that ET was lower in degraded pastures. It is noteworthy that during low rainfall period, ET values were 22.2% lower in relation to non-degraded pastures. This difference in ET indicates changes in the partition of the energy balance and may impact the microclimate. These results may contribute to public policies that aim to reduce the loss of the productive potential of pastures.

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 the energy balance components in two different pasture experimental areas, in the São Paulo state, Brazil. The experimental pastures consist in six rotational (RGS) and three continuous grazing systems (CGS) paddocks. Landsat-8 images from 2013 and 2015 dry and rainy seasons were used, as these presented similar hydrological cycle, with 1,600 mm and 1,613 mm of annual precipitation, resulting in 19 cloud-free images. Bands 1 to 7 and thermal bands 10 and 11 were used with weather data from a station located near the 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 these results 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 potential to discriminate continuous and rotation grazing systems in a temporal analysis.