Soil macrofauna communities in Brazilian land-use systems.

Background: Soil animal communities include more than 40 higher-order taxa, representing over 23% of all described species. These animals have a wide range of feeding sources and contribute to several important soil functions and ecosystem services. Although many studies have assessed macroinvertebrate communities in Brazil, few of them have been published in journals and even fewer have made the data openly available for consultation and further use. As part of ongoing efforts to synthesise the global soil macrofauna communities and to increase the amount of openly-accessible data in GBIF and other repositories related to soil biodiversity, the present paper provides links to 29 soil macroinvertebrate datasets covering 42 soil fauna taxa, collected in various land-use systems in Brazil. A total of 83,085 georeferenced occurrences of these taxa are presented, based on quantitative estimates performed using a standardised sampling method commonly adopted worldwide to collect soil macrofauna populations, i.e. the TSBF (Tropical Soil Biology and Fertility Programme) protocol. This consists of digging soil monoliths of 25 x 25 cm area, with handsorting of the macroinvertebrates visible to the naked eye from the surface litter and from within the soil, typically in the upper 0-20 cm layer (but sometimes shallower, i.e. top 0-10 cm or deeper to 0-40 cm, depending on the site). The land-use systems included anthropogenic sites managed with agricultural systems (e.g. pastures, annual and perennial crops, agroforestry), as well as planted forests and native vegetation located mostly in the southern Brazilian State of Paraná (96 sites), with a few additional sites in the neighbouring states of São Paulo (21 sites) and Santa Catarina (five sites). Important metadata on soil properties, particularly soil chemical parameters (mainly pH, C, P, Ca, K, Mg, Al contents, exchangeable acidity, Cation Exchange Capacity, Base Saturation and, infrequently, total N), particle size distribution (mainly % sand, silt and clay) and, infrequently, soil moisture and bulk density, as well as on human management practices (land use and vegetation cover) are provided. These data will be particularly useful for those interested in estimating land-use change impacts on soil biodiversity and its implications for below-ground foodwebs, ecosystem functioning and ecosystem service delivery. New information: Quantitative estimates are provided for 42 soil animal taxa, for two biodiversity hotspots: the Brazilian Atlantic Forest and Cerrado biomes. Data are provided at the individual monolith level, representing sampling events ranging from February 2001 up to September 2016 in 122 sampling sites and over 1800 samples, for a total of 83,085 ocurrences.

Nitrous oxide and methane emissions from soil under integrated farming systems in southern Brazil.

This study aimed at evaluating soil nitrous oxide (N2O) and methane (CH4) emissions from integrated farming systems. Soil N2O and CH4 fluxes were assessed in a subtropical Cambisol in southern Brazil, using manual static chambers, over two years, in five farming systems (cropland, livestock, integrated crop-livestock, integrated livestock-forestry, and integrated crop-livestock-forestry). The study was conducted in four growing seasons: summer-1, winter-1, summer-2, winter-2. Integrated farming systems had lower soil N2O emissions than livestock. The observed reduction was possibly due to lower water-filled pore space (WFPS) in soils under integrated systems (average 59.5-64.7%, vs 70.4% in livestock) as indicated by correlation (r = 0.74). Cropland, including cover-crops and maize, also had lower N2O emission (by 40%) relative to livestock, of levels similar to those observed in integrated systems. Methane was consumed in soil, but it was not affected by farming systems, and offset only ~1.4% of the N2O emissions. In the rainiest season of summer-2, the soil had the highest WFPS (on average 71.4%) and thus the highest N2O emission (on average 9.79 kg N2O-N ha-1 season-1) and the lowest CH4 consumption (on average - 0.40 kg CH4-C ha-1 season-1); while the opposite trend occurred in the driest season of winter-2 (on average 57.3% WFPS; 0.64 kg N2O-N ha-1 season-1 and -0.90 kg CH4-C ha-1 season-1). Integrated farming systems including crop-livestock, livestock-forestry and crop-livestock-forestry reduced soil N2O emissions relative to sole livestock by 27-40%, but did not affect CH4 emissions. Seasonal variations of precipitation, and therefore WFPS were driving factors of the N2O and CH4 emissions. Overall, integrated farming systems show the potential to mitigate soil N2O emission compared to livestock system.

What, how, and how much do herbivores eat? The Continuous Bite Monitoring method for assessing forage intake of grazing animals.

Determining herbage intake is pivotal for studies on grazing ecology. Direct observation of animals allows describing the interactions of animals with the pastoral environment along the complex grazing process. The objectives of the study were to evaluate the reliability of the continuous bite monitoring (CBM) method in determining herbage intake in grazing sheep compared to the standard double-weighing technique method during 45-min feeding bouts; evaluate the degree of agreement between the two techniques; and to test the effect of different potential sources of variation on the reliability of the CBM. The CBM method has been used to describe the intake behavior of grazing herbivores. In this study, we evaluated a new approach to this method, that is, whether it is a good proxy for determining the intake of grazing animals. Three experiments with grazing sheep were carried out in which we tested for different sources of variations, such as the number of observers, level of detail of bite coding grid, forage species, forage allowance, sward surface height heterogeneity, experiment site, and animal weight, to determine the short-term intake rate (45 min). Observer (Pexp1  = 0.018, Pexp2  = 0.078, and Pexp3  = 0.006), sward surface height (Pexp2  < 0.001), total number of bites observed per grazing session (Pexp2  < 0.001 and Pexp3  < 0.001), and sward depletion (Pexp3  < 0.001) were found to affect the absolute error of intake estimation. The results showed a high correlation and agreement between the two methods in the three experiments, although intake was overestimation by CBM on experiments 2 and 3 (181.38 and 214.24 units, respectively). This outcome indicates the potential of CBM to determining forage intake with the benefit of a greater level of detail on foraging patterns and components of the diet. Furthermore, direct observation is not invasive nor disrupts natural animal behavior.

Low-Intensity, High-Frequency Grazing Strategy Increases Herbage Production and Beef Cattle Performance on Sorghum Pastures.

We assessed the effects of high-intensity and low-frequency (HILF) vs. low-intensity and high-frequency (LIHF) grazing on herbage production and performance of beef cattle grazing sorghum pastures. The experimental design was a complete randomized block with two treatments and four replicates (paddocks), carried out in 2014/15. The management target of 50 and 30 cm for pre- and post-grazing, respectively, a LIHF grazing management strategy oriented to maximize beef cattle herbage intake per unit time, was compared with a HILF grazing management strategy of 80 and 20 cm for pre- and post-grazing, respectively, aiming to maximize herbage accumulation and harvest efficiency. Sixteen Brangus steers of 15-month-old and 265 ± 21 kg of live weight (LW) were randomly distributed to paddocks (experimental units). The LIHF resulted in shorter rest periods when compared with the HILF. The greater leaf lamina mass in LIHF allowed greater sward light interception at post-grazing, resulting in greater total herbage production than HILF (7581 and 4154 kg DM/ha, respectively). The average daily gain (ADG) of steers was greater for the LIHF than for the HILF treatment (0.950 and 0.702 kg/animal, respectively); however, even with a greater stocking rate in the HILF, there was no difference for LW gain per ha, with an average of 4 kg LW/ha/day. Our findings demonstrated that the LIHF strategy that is based on offering to the animals an optimal sward structure to favor the maximum herbage intake rate fosters greater herbage production, harvesting efficiency, and ADG without compromising LW gain per area of beef steers, despite the lower herbage harvested per stocking cycle.

Tall fescue sward structure affects the grazing process of sheep.

The study of factors influencing animal intake can provide a better understanding of the dynamics of the pasture ecosystem and serve as a basis for managing livestock in a more efficient way. We measured different sward surface heights of tall fescue in the process of short-term intake rate of sheep. There was a significant effect of sward surface height on herbage mass (P < 0.001), leaf lamina mass (P < 0.001), other species mass (P = 0.02), bite mass (P = 0.01) and short-term intake rate (P = 0.03) of sheep. There was a quadratic fit between time per bite and bite mass (P = 0.006). Multivariate analysis showed that the short-term intake rate and bite mass were positively correlated (r = 0.97), bite rate and total jaw movement rate were positively correlated but both were negatively correlated with time per bite. The sward surface height of tall fescue corresponding to the maximum short-term herbage intake rate was 22.3 cm. The underlying processes were driven by the bite mass, which was influenced by the leaf lamina bulk density and its consequences upon time per bite. This sward surface height can be adopted as a pre-grazing target for rotational stocking systems to optimize sheep nutrition on pastures.

Animal production and soil characteristics from integrated crop-livestock systems: toward sustainable intensification.

Sustainable intensification of land-use practices has never been more important to ensure food security for a growing world population. When combined under thoughtful management, cover cropping and crop-livestock integration under no-till systems can benefit from unexpected synergies due to their unique features of plant-animal diversification and complex agroecosystem functions. Mimicking the nutrient coupling/decoupling processes of natural ecosystems by diversifying plant and animal components of no-till integrated crop-livestock operations is an essential feature of the design of agroecological systems that support self-regulating feedbacks and lend resilience while increasing productivity and ecosystem service provision. Focusing on grazing animals as drivers of agroecosystem change, we highlight the benefits of grazed cover crops in rotation with cash crops for primary and secondary production and for soil physical, chemical, and biological parameters. However, careful management of grazing intensity is imperative; overgrazing drives soil deterioration, while light to moderate grazing enhances overall system functioning and allows for the generation of emergent properties.