INSECT RICHNESS IN DUNG PATCHES OF CATTLE RAISED IN TWO LIVESTOCK SYSTEMS

The negative impact of livestock breeding on the environment has been mitigated through the combination of pastures and trees, characterizing the silvopastoral systems (SPS), an alternative to conventional pasture systems (CPS). The SPS provides environmental services, particularly the recovery of degraded areas and carbon sequestration. Furthermore, the complexity of the SPS can improve other environmental services, for example, enhance biodiversity and reduce pests through biological control. However, it is not clear the relationship between microclimate, pasture, trees, cattle, and invertebrate present in this environment. The purpose of this research was to characterize the macrofauna and determine the richness and abundance of invertebrates associated with dung patches of cattle raised in SPS and CPS pasture systems during two years in Brazil. As a result, we verified that the presence of trees in pastures alters the environment, notably through the reduction of solar radiation; decreases the wind speeds; attenuates the air and soil temperature, and diversifies the food supply, with the promotion of beneficial insect richness in dung patches of cattle. The diversity index of invertebrate fauna associated with dung patches in the SPS and CPS were respectively, 1.9 and 1.3. Besides that, the SPS contributed to higher densities of pupal parasitoids insects represented by Aphaereta sp. and Spalangia sp., the most important cattle ectoparasite controllers. In this way, we concluded that the integrated pasture systems are an essential tool for biodiversity improvement, especially the beneficial insects living in dung patches, which can contribute to reducing cattle ectoparasite infestations

Dry matter production of Tanzania grass as a function of agrometeorological variables

O objetivo deste trabalho foi desenvolver e validar modelos de regressão linear para a estimativa de produção de matéria seca de capim‑tanzânia (Megathyrsus maximus, cultivar Tanzania) em função de variáveis agrometeorológicas. Para tanto, dados de períodos de crescimento da forragem entre 2000 e 2005, em condições de sequeiro em São Carlos, SP, foram correlacionados aos seguintes parâmetros climáticos: temperaturas mínima e média, graus‑dia, evapotranspiração potencial e atual. Foram realizadas regressões lineares simples entre as variáveis agrometeorológicas (independentes) e a taxa média de acúmulo (dependente). As estimativas foram validadas com dados independentes obtidos em São Carlos e Piracicaba, SP. Os melhores resultados estatísticos observados no desenvolvimento e na validação dos modelos foram obtidos para parâmetros agrometeorológicos que levem em consideração o efeito térmico e hídrico conjuntamente, como evapotranspiração real, acúmulo de graus‑dia corrigido pela disponibilidade hídrica e índice climático de crescimento, baseado na temperatura média, na radiação solar e na disponibilidade hídrica. Essas variáveis podem ser utilizadas em simulações e modelos para prever a produção do capim‑tanzânia.The objective of this work was to develop and validate linear regression models to estimate the production of dry matter by Tanzania grass (Megathyrsus maximus, cultivar Tanzania) as a function of agrometeorological variables. For this purpose, data on the growth of this forage grass from 2000 to 2005, under dry‑field conditions in São Carlos, SP, Brazil, were correlated to the following climatic parameters: minimum and mean temperatures, degree‑days, and potential and actual evapotranspiration. Simple linear regressions were performed between agrometeorological variables (independent) and the dry matter accumulation rate (dependent). The estimates were validated with independent data obtained in São Carlos and Piracicaba, SP, Brazil. The best statistical results in the development and validation of the models were obtained with the agrometeorological parameters that consider thermal and water availability effects together, such as actual evapotranspiration, accumulation of degree‑days corrected by water availability, and the climatic growth index, based on average temperature, solar radiation, and water availability. These variables can be used in simulations and models to predict the production of Tanzania grass

Simple agrometeorological models for estimating Guineagrass yield in Southeast Brazil

The objective of this work was to develop and evaluate agrometeorological models to simulate the production of Guineagrass. For this purpose, we used forage yield from 54 growing periods between December 2004-January 2007 and April 2010-March 2012 in irrigated and non-irrigated pastures in So Carlos, So Paulo state, Brazil (latitude 21A degrees 57'42aEuro(3) S, longitude 47A degrees 50'28aEuro(3) W and altitude 860 m). Initially we performed linear regressions between the agrometeorological variables and the average dry matter accumulation rate for irrigated conditions. Then we determined the effect of soil water availability on the relative forage yield considering irrigated and non-irrigated pastures, by means of segmented linear regression among water balance and relative production variables (dry matter accumulation rates with and without irrigation). The models generated were evaluated with independent data related to 21 growing periods without irrigation in the same location, from eight growing periods in 2000 and 13 growing periods between December 2004-January 2007 and April 2010-March 2012. The results obtained show the satisfactory predictive capacity of the agrometeorological models under irrigated conditions based on univariate regression (mean temperature, minimum temperature and potential evapotranspiration or degreedays) or multivariate regression. The response of irrigation on production was well correlated with the climatological water balance variables (ratio between actual and potential evapotranspiration or between actual and maximum soil water storage). The models that performed best for estimating Guineagrass yield without irrigation were based on minimum temperature corrected by relative soil water storage, determined by the ratio between the actual soil water storage and the soil water holding capacity.irrigation in the same location, in 2000, 2010 and 2011. The results obtained show the satisfactory predictive capacity of the agrometeorological models under irrigated conditions based on univariate regression (mean temperature, potential evapotranspiration or degree-days) or multivariate regression. The response of irrigation on production was well correlated with the climatological water balance variables (ratio between actual and potential evapotranspiration or between actual and maximum soil water storage). The models that performed best for estimating Guineagrass yield without irrigation were based on degree-days corrected by the water deficit factor.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Integrated farming systems influence soil organic matter dynamics in southeastern Brazil

Integrated farming systems are sustainable strategies to intensify land productivity by combining annual crop, livestock and/or forestry activities in different spatio-temporal arrangements. Therefore, they may help tackle global food and energy insecurity and climate change in the coming decades. We investigated the effects of integrated crop-livestock (ICL) and integrated crop-livestock-forestry (ICLF) systems on quantity, quality, and origin of soil organic matter (SOM) in southeastern Brazil. A native forest and an extensive low-grazing intensity pasture system were used as references. In integrated systems, corn (Zea mays) was alternated with two consecutive years of piatã grass (Urochloa bryzantha) for cattle grazing. In ICLF, eucalyptus trees (Eucalyptus urograndis) were planted in simple rows of 15 × 2 m. Soil sampling was performed three times; in 2014, after two years of grazing; in 2015, after crop cultivation; and in 2016, after a successive grazing year, to evaluate chemical and physical composition changes of organic matter (C, N, δ13C, δ15N, and organic matter fractions) with time. Our findings showed that from 2010 to 2016, all systems (extensive grazing, ICL and ICLF) promoted increments on soil C and N stocks. However, land intensification converting extensive low-grazing intensity pasture to ICL was the most promising strategy, increasing soil C stocks at the rate of 0.28 Mg C ha−1 yr−1 from 2010 to 2016. Annual crop cultivation (corn intercropped with piatã grass) promoted high organic matter inputs on the soil, increasing the amount of soil labile organic matter fractions, which presented higher δ13C and lower δ15N values over time. SOM in the integrated farming systems was originated mainly from C4 plants. Therefore, optimizing development of piatã grass and corn increases organic residue inputs and then, soil C and N stocks. In addition, the crop period increased soil fertility parameters, which favors plant growth, thus providing high labile C inputs to the soil. In contrast, land intensification by adding the forestry component into the system (i.e., conversion from ICL to ICLF) reduced soil C (-0.22 Mg C ha−1 yr−1) and N (-0.03 Mg N ha−1 yr−1) stocks from 2010 to 2016, likely due to the reduction of C and N inputs to the soil caused by limited growth of annual crop and grass species under tree shades. In conclusion, land use intensification through ICL system contributes towards a more efficient and low-C agriculture, whereas the studied ICLF system did not bring further benefits to increase the quantity and/or quality of SOM