Soil, water, and nutrient losses from management alternatives for degraded pasture in Brazilian Atlantic Rainforest biome

Land Use, Land Cover Change and Sustainable Intensification of Agriculture and Livestock in the Amazon and the Atlantic Forest in Brazil

The Amazon and the Atlantic Forest are Brazilian biomes that suffered an intense land use and land cover change, marked by the loss of native forest and expansion of agriculture and livestock. This article aims to analyze land use and land cover change history and to propose a sustainable alternative for agriculture and livestock as an opportunity for rural development in these biomes. The statistics of the platform from the Annual Mapping Project for Land Use and Land Cover in Brazil (MapBiomas) were used in an annual historical series from 1985 to 2020. The analysis of land use and land cover changes indicates that the Amazon native forest was reduced by 44.53 million hectares (Mha), while pasture, agriculture and planted forest increased by 38.10, 6.06 and 0.26 Mha, respectively, over the 35 years (1985 to 2020). In the Atlantic Forest, for the same period, forest and pasture reduced by 0.99 and 11.53 Mha, respectively, while agriculture expanded by 8.06 Mha and planted forest by 2.99 Mha. Sustainable land use strategies, such as the Integration Crop-Livestock-Forest (ICLF), can support the increase in agricultural production while recovering and preserving the environment. Policies and programs should consider regional particularities and barriers for more significant adoption of this strategy.

Production of zeolitic materials in pilot scale based on coal ash for phosphate and potassium adsorption in order to obtain fertilizer

The use of different types of zeolites (X, Na-P1, and 4A) synthesized by different methods and scales were tested in this work to adsorb nutrients present in synthetic solutions and industrial effluents for later application as fertilizer. Modifications with calcium chloride were performed on the zeolite with the best performance to increase its adsorption capacity. The best performing zeolite was type X (ZXH) produced on a pilot scale by the hydrothermal process. Its adsorption capacity without modification was 149 mg P-PO₄/g zeolite and 349 mg K/g zeolite. With the change, there was a fourfold increase in these results, which were up to threefold higher than reported in the literature. The kinetic model that best characterized the adsorption process was the intraparticle diffusion model, and the equilibrium isotherm was that of Freundlich. The adsorption tests performed with industrial effluent showed high removal of the nutrients of interest (> 90% for PO₄^3- and > 95% for K⁺). The desorption tests with zeolites nutrient-loaded from synthetic solutions showed 13 to 24% PO₄^3- and 14 to 47% K⁺ release within 24 h, while for zeolite nutrient-loaded from effluent the release were 7 and 100% for PO₄^3- and K⁺, respectively. The results we obtained in this work indicated the potential use of zeolites in the treatment of effluent and its application as a fertilizer.

Partial Grazing Exclusion as Strategy to Reduce Land Degradation in the Traditional Brazilian Faxinal System: Field Data and Farmers’ Perceptions

Land degradation is becoming a serious concern for the sustainability of traditional agrosilvopastoral systems such as the Brazilian faxinal. The IAP (Environmental Institute of the Federal State of Paraná) is favoring the partial exclusion to grazing for 10 years as strategy both to recover degraded lands and to reduce negative effects. Nevertheless, this strategy is being followed by a reduced number of owners (faxinalenses) and little is known about the effectiveness of these measures due to either lack of field data and knowledge on faxinalenses’ perceptions. We have identified one out of few farms that have followed this official strategy and, within the same farm, we have compared values of some soil properties (bulk density, porosity, water holding capacity, penetration resistance, soil organic matter and root density) from an excluded area to grazing for 10 years, with some areas that represent a gradient of grazing intensity (natural forest, secondary forest, degraded forest, grassland and a degraded area by pigs). In addition, we have interviewed some faxinalenses (one faxinal farm is owned by several farmers) in order to better understand how the risk of land degradation is perceived by them and their opinions about the usefulness of partial grazing exclusion as a strategy to improve the management of their farms. The results have shown that soil quality increases considerably as a consequence of grazing exclusion, in spite of land has been used for cropping yerba mate during the exclusion time, but faxinalenses are not mindful of these benefits and they are no longer interested in excluding other areas of their farms. They think this strategy is simply an obligation imposed by the environmental authority.

Multivariate analysis and modeling of soil quality indicators in long-term management systems

Soil management systems, as well as the long-term application of nitrogen fertilization, might promote changes in soil quality (SQ). The knowledge of how agronomic practices influence SQ is the main factor in the development of most sustainable management systems. Thus, the aim of this study was to evaluate the influence of long-term management systems on SQ through the analysis of 10 soil quality indicators (SQIs), to select the most sensitive SQIs through principal components analysis (PCA) and to propose a mathematical model that could estimate the activities of enzymes based on SQI values with simple and low-cost procedures in relation to enzyme measurement. Soil samples were collected from three experiments in which soils were used for this purpose over more than two decades. The first experiment consisted of winter fallow and maize seeding as a summer crop in a conventional tillage system (CT) that received nitrogen fertilization at doses of 0, 90 and 180 kg ha^-1. The second and third experiments consisted of no-tillage (NT) using maize/maize (NT M/M) and legume/maize (NT L/M) crop rotation, respectively, both using nitrogen fertilization at the same doses as in the first experiment. The no-tillage system with legume/maize crop rotation favored the development of microorganisms and improved the soil quality. The effects of nitrogen fertilization on SQIs varied according to the management system. The microbial respiration (MR), the metabolic quotient (q CO₂), total organic carbon (TOC), nitrogen microbial biomass (NMC), urease enzyme activity (UEA), dehydrogenase activity (DA) and amylase activity (AA) were the most efficient SQIs. The adjusted mathematical models presented a good predictive capacity to estimate the urease activity in CT and NT M/M and the amylase activity in the CT system.

Can short-term pasture management increase C balance in the Atlantic Rainforest?

Few studies have shown the importance of different pasture management practices on C storage and the reduction of CO₂-C emissions in tropical conditions. The objective of the present study was to determine short-term changes in C pools and C balance from different pasture management practices established in the Atlantic Rainforest. A field study was carried out in Alegre, ES, Brazil from September 2013 to August 2014 to investigate the first-year effect of pasture management practices on a Udult clayey soil. The different pasture management practices studied included the following: control (CON), chiseled (CHI), fertilized (FER), burned (BUR), integrated with crop-livestock (iCL) systems, and plowed and harrowed (PH). Monthly disturbed and undisturbed soil samples were taken at two different layers (0.00-0.05 and 0.05-0.20 m) for chemical, physical, and organic matter characterization. C inputs monitored in aboveground pools included plant aerial parts and litter, and belowground pools included roots and soil C stocks. C outputs monitored were CO₂-C emissions, erosion water, and sediment. C balance was considered the difference between inputs and outputs in each treatment during four seasons. The spring and summer seasons had a strong influence on C inputs and outputs where there is significant difference between spring and summer, while the autumn and winter seasons had less influence. All pasture management practices exhibited positive C balance after 1 year. High values of C balance were verified in pastures fertilized (FER) (53.04 Mg ha^-1 year^-1. Intermediate C balance was found in the burned (BUR) (40.84 Mg ha^-1 year^-1), traditional control (CON) (40.31 Mg ha^-1 year^-1), and in the plowing and harrowing (PH) (40.02 Mg ha^-1 year^-1) management practices. The practices of chiseled (40.00 Mg ha^-1 year^-1) and integrated crop-livestock systems (iCL) (59.06 Mg ha^-1 year^-1) resulted in low C balance.