Greenhouse gas emissions and carbon sequestration by agroforestry systems in southeastern Brazil

Carbon sequestration and credit potential of gamhar (Gmelina arborea Roxb.) based agroforestry system for zero carbon emission of India

The agroforestry system is the best option to achieve the net zero carbon emissions target for India. Keeping this view, carbon sequestration and credit potential of gamhar based agroforestry system has been assessed. The experiment was carried out in randomized block design in seven different treatments with five replications. Gamhar tree biomass accumulation was higher in gamhar based agroforestry system compared to sole gamhar. Among different tree components, stem contributed a maximum to total gamhar tree biomass followed by roots, leaves and branches. The average contributions of stems, roots, leaves and branches in total tree biomass in two annual cycles (2016-17 and 2017-18) varied between 50 and 60, 19.8 and 20, 19.2 and 20, and 10.7 and 12.7 percent, respectively. In case of crops, above ground, below ground and total biomass was significantly higher in sole intercrops than gamhar based agroforestry system. Total (Tree + interrops + Soil) carbon stock, carbon sequestration, carbon credit and carbon price were significantly affected by treatments, and was maximum in Sole Greengram-Mustard. Net carbon emission was also recorded lowest in Sole Greengram-Mustard for which the values were 811.55% and 725.24% and 760.69% lower than Sole Gamhar in 2016-17, 2017-18 and in pooled data, respectively.

The environmental cost of broiler production and carbon sequestration potential of eucalyptus plantations around farms in Mato Grosso do Sul, Brazil

The present study aimed to evaluate the environmental cost of the production process of broilers from the approach of emergy accounting and carbon sequestration potential for broiler farms. The study assessed a standard farm of the conventional system containing ten houses in 19 ha. We evaluated the following indices solar transformity (Tr), renewability (%R), emergy yield ratio (EYR), emergy investment ratio (EIR), environmental loading ratio (ELR), emergy sustainability index (ESI), and emergy exchange ratio (EER) and carbon sequestration potential of eucalyptus plantation. The total emergy input was 2.79E-06 seJ ha^-1 y^-1 for the broiler growth process. The highest investment in the production process was related to materials, which came from feeding and electricity. The renewability index indicated the low sustainability of the system with increased consumption of economical materials and equipment, with a low proportion of the emergy use of renewable resources. High investment in broilers production in the conventional system generates an environmental loading ratio that indicates high environmental degradation. Planting trees in the surrounding areas of the farm facilities can minimize the externalities of the production system with the plantation carbon sequestration potential.

Voisin Rational Grazing as a Sustainable Alternative for Livestock Production

Current livestock practices do not meet current real-world social and environmental requirements, pushing farmers away from rural areas and only sustaining high productivity through the overuse of fossil fuels, causing numerous environmental side effects. In this narrative review, we explore how the Voisin Rational Grazing (VRG) system responds to this problem. VRG is an agroecological system based on four principles that maximise pasture growth and ruminant intake, while, at the same time, maintaining system sustainability. It applies a wide range of regenerative agricultural practices, such as the use of multispecies swards combined with agroforestry. Planning allows grazing to take place when pastures reach their optimal resting period, thus promoting vigorous pasture regrowth. Moreover, paddocks are designed in a way that allow animals to have free access to water and shade, improving overall animal welfare. In combination, these practices result in increased soil C uptake and soil health, boost water retention, and protect water quality. VRG may be used to provide ecosystem services that mitigate some of the current global challenges and create opportunities for farmers to apply greener practices and become more resilient. It can be said that VRG practitioners are part of the initiatives that are rethinking modern livestock agriculture. Its main challenges, however, arise from social constraints. More specifically, local incentives and initiatives that encourage farmers to take an interest in the ecological processes involved in livestock farming are still lacking. Little research has been conducted to validate the empirical evidence of VRG benefits on animal performance or to overcome VRG limitations.

Soil carbon stock and stability under Eucalyptus-based silvopasture and other land-use systems in the Cerrado biodiversity hotspot

During the past few decades, commercial silvopastoral systems (SPS) with exotic Eucalyptus (hybrid) trees have become popular in the Brazilian Cerrado (savanna). With the increasing awareness about the role of carbon (C) storage in soils as a climate-change mitigation strategy and the relationship between the nature of soil aggregates and the soil's carbon sequestration potential, it is important to understand the influence of such SPS systems on soil organic carbon (SOC) storage. We studied C content in three aggregate size classes in six land-use systems on Oxisols in Minas Gerais, Brazil. The systems were planted forest, native secondary forest, managed pasture, and three 8-year-old SPS, differing in their tree-planting configurations. Eucalyptus hybrid was the tree in SPS and planted forest treatments, and Urochloa decumbens was the grass in SPS and pasture treatments. From each treatment, replicated soil samples were collected from four depth-classes (0-10, 10-30, 30-60, and 60-100 cm), fractionated by wet sieving into the three aggregate-size classes, 2000 to 250 μm, 250 to 53 μm, and <53 μm size classes representing macroaggregates, microaggregates, and silt + clay, respectively, and their C contents determined. Down to 1 m, total SOC stock values ranged from 260 Mg ha^-1 under pasture to 167 Mg ha^-1 under native forest, with 174 Mg ha^-1 for Eucalyptus plantation and about 195 Mg ha^-1 for the three SPS. Compared to the degraded native forest, the pasture system had significantly higher SOC in the whole soil and the aggregate size fractions, especially in the lower soil-depth classes. The lower SOC stock of Eucalyptus hybrid SPS compared to open pasture differs from the general trend of SPS having higher stock. Given that the Cerrado biome is a biodiversity hotspot, the use of native nitrogen-fixing trees, of which there are several, is worth investigating. In addition, the conversion from Eucalyptus monocultures to SPS could be considered as a strategy to increase the SOC stock.

Quorum quenching and anti-biofilm activities of halotolerant Bacillus strains isolated in different environments in Algeria

AIMS

The current study aimed to screen Bacillus strains with wide-spectrum quorum quenching (QQ) activity against N-acyl-l-homoserine lactones (AHLs), helpful in controlling virulence traits in Gram-negatives, including biofilm formation and also with anti-biofilm activity against Gram-positives.

METHODS AND RESULTS

A total of 94 halotolerant strains of Bacillus isolated from soil and salt-lake sediment samples in Algeria were examined for the presence of QQ activity against AHLs, the presence of the aiiA gene, encoding an AHL lactonase enzyme typical of Bacillus spp., antimicrobial and anti-biofilm activities against Pseudomonas aeruginosa and Streptococcus mutans. Of all strains of Bacillus spp. isolated, 48.9% showed antibacterial activity. In addition, 40% of these isolates showed a positive QQ activity against long-chain AHLs, of which seven strains presented the aiiA gene. Among the species with broad-spectrum QQ activity, the cell extract of Bacillus thuringiensis DZ16 showed antibiofilm activity against P. aeruginosa PAO1, reducing 60% using the Amsterdam active attachment (AAA) biofilm cultivation model. In addition, the cell extract of B. subtilis DZ17, also presenting a broad-spectrum QQ activity, significantly reduced Strep. mutans ATCC 25175 biofilm formations by 63% and 53% in the xCELLigence and the AAA model, respectively, without affecting growth. Strain DZ17 is of particular interest due to its explicit halophilic nature because it can thrive at salinities in the range of 6%-30%.

CONCLUSIONS

B. thuringiensis DZ16 and B. subtilis DZ17 strains have interesting antibacterial, QQ, and anti-biofilm activities. The high range of salinities accepted by these strains increases their biotechnological potential. This may open up their use as probiotics, the treatment and prevention of conventional and emerging infectious diseases.

SIGNIFICANCE AND IMPACT OF STUDY

The use of safe, economical and effective probiotics is limited to control the infections related to multi-resistant bacteria. In our study, we provide two promising agents with QQ, anti-biofilm and antibacterial activities.

Time to Revisit Oil Palm-Livestock Integration in the Wake of United Nations Sustainable Development Goals (SDGs)

To date, the idea of using livestock animals as biological tools to manage weeds, sequester carbon, and boost food security in oil palm plantations has not been seriously considered by industry stakeholders of major producing countries (e.g., Indonesia, Malaysia, Thailand, Colombia, and Nigeria). We revisit the integration of oil palm cultivation with livestock farming as a silvopastoral agroforestry practice in the wake of Sustainable Development Goals (SDGs). Oil palm-livestock integration has the potential to promote sustainable palm oil production because it can provide multiple environmental and socio-economic benefits, including carbon sequestration, restoring top soil, improving ecosystem biodiversity, reducing pesticide and fertilizer inputs, and boosting national food security. In contrast to monocultural outputs of most conventional plantations, an oil palm silvopastoral system is an ideal way to address the global food insecurity challenge as it produces bioenergy, vegetable oil/fat and animal-based protein sources (e.g., red meat). In addition, the potential of contract targeted grazing could be considered as a new type of business and income diversification for rural people. Oil palm-livestock integration is a strategy by the palm oil industry to achieve multiple SDGs. Out of the 17 SDGs, oil palm-livestock integration is likely to deliver nine SDGs. Palm oil certification bodies should recognize oil palm-livestock integration as a biological control method in weed management practices. We recommend that oil palm-livestock integration should be promoted to revitalize sustainable palm oil production and strategic biodiversity conservation policy. Policy makers should encourage major players in the palm oil industry to practice oil palm-livestock integration.

Changes in soil phosphorus pool induced by pastureland intensification and diversification in Brazil

The adoption of more intensive and diversified pasture systems is a promising alternative to improve sustainability of grazing lands in Brazil. Phosphorus (P) is one of the main determinants of ecosystem function in these management systems; therefore, we assessed the effects of adopting more intensive and diversified pasture management systems on soil P dynamics in a set of field experiments. Treatments included fertilized pasture (FP), integrated crop-livestock (ICL), integrated livestock-forest (ILF), compared to conventional management systems (CS) under contrasting climatic conditions (tropical humid, tropical mesic and subtropical). P fractions and total P were determined by soil layer to 1 m depth. Size and distribution of P stocks were related to soil organic matter (SOM) fractions and to clay type and content. Based on the results, P biological fraction represented 9% of P in the soil, on average, in CS under the three assessed climatic conditions. Management systems with FP and the ones with ICL and ILF mainly influenced labile (0.01, 0.02 and 0.03 Mg ha^-1 yr^-1, respectively), moderately labile (0.03, 0.01 and 0.07 Mg ha^-1 yr^-1, respectively) and total soil P fractions (0.21, 0.08 and 0.20 Mg ha^-1 yr^-1, respectively). Clay content and pH were the soil properties mostly related to P fractions; besides, P fractions presented close relationship with these fractions and with total soil C and N, as well as with different SOM fractions. These results can be the scientific basis for governmental initiatives focused on recovering degraded pasture sites in Brazil. The establishment of management practices that favor efficient P use are essential to improve the sustainability of production systems.

Energy Analysis, and Carbon and Water Footprint for Environmentally Friendly Farming Practices in Agroecosystems and Agroforestry

Agriculture accounts for 5% of the entire energy used worldwide. Most of it is not in a renewable form, so it can be linked to greenhouse gas emissions. According to the Paris Agreement, on climate change, one of its major targets is the reduction of greenhouse gas emissions. Therefore, the agricultural production process must drastically change. Currently, the sustainable use of water is critical for any agricultural development. Agricultural production effects water quality and sufficiency, as well as, freshwater wetlands. Energy balance, carbon, and water footprint are crucial for sustainable agricultural production. Agroforestry systems are important in reducing high inputs of non-renewable energy and greenhouse gas emissions, along with better water use, leading to the most minimal influence on climate change. Energy analysis, carbon, and water footprint can be applied to agroforestry systems’ production. An outline could be applied by adopting a modified—for agricultural production—life cycle assessment methodology to assess energy use, greenhouse gas emissions, and water consumption in agroforestry ecosystems.