Measured ammonia emissions from tropical and subtropical pastures: A comparison with 2006 IPCC, 2019 Refinement to the 2006 IPCC, and EMEP/EEA (European Monitoring and Evaluation Programme and European Environmental Agency) inventory estimates

Rumen Microbial Predictors for Short-Chain Fatty Acid Levels and the Grass-Fed Regimen in Angus Cattle

The health benefits of grass-fed beef are well documented. However, the rumen microbiome features in beef steers raised in a grass-fed regimen have yet to be identified. This study examined the rumen microbiome profile in the feeding regimes. Our findings show that the rumen microbiome of the grass-fed cattle demonstrated greater species diversity and harbored significantly higher microbial alpha diversity, including multiple species richness and evenness indices, than the grain-fed cattle. Global network analysis unveiled that grass-fed cattle's rumen microbial interaction networks had higher modularity, suggesting a more resilient and stable microbial community under this feeding regimen. Using the analysis of compositions of microbiomes with a bias correction (ANCOM-BC) algorithm, the abundance of multiple unclassified genera, such as those belonging to Planctomycetes, LD1-PB3, SR1, Lachnospira, and Sutterella, were significantly enriched in the rumen of grass-fed steers. Sutterella was also the critical genus able to distinguish the two feeding regimens by Random Forest. A rumen microbial predictor consisting of an unclassified genus in the candidate division SR1 (numerator) and an unclassified genus in the order Bacteroidales (denominator) accurately distinguished the two feeding schemes. Multiple microbial signatures or balances strongly correlated with various levels of SCFA in the rumen. For example, a balance represented by the log abundance ratio of Sutterella to Desulfovibrio was strongly associated with acetate-to-propionate proportions in the rumen (R2 = 0.87), which could be developed as a valuable biomarker for optimizing milk fat yield and cattle growth. Therefore, our findings provided novel insights into microbial interactions in the rumen under different feed schemes and their ecophysiological implications. These findings will help to develop rumen manipulation strategies to improve feed conversion ratios and average daily weight gains for grass- or pasture-fed cattle production.

Unveiling the social performance of selected agri-food chains in Costa Rica: the case of green coffee, raw milk and leafy vegetables

PURPOSE

Several frameworks coincide in the importance of addressing social impacts to ensure sustainability. However, the agri-food sector, regarded as key in sustainable production, still neglects to identify potential social impacts when applying life cycle approaches. This work contributes to understanding the social performance of three agricultural products from a Latin American and Caribbean developing country as Costa Rica while recognising the challenges of Social-Life Cycle Assessment (S-LCA) application in this context.

METHODS

S-LCA represents a powerful technique to evaluate the potential social impacts of a product. Three case studies were analysed through S-LCA, using the subcategory assessment method (SAM) to characterise the social impacts and detect hotspots in the production of green coffee, raw milk and leafy vegetables. Primary data was collected through questionnaires to relevant informants and observations. In addition to secondary information, these data and information were used to assess eight impact subcategories for the farmer and worker stakeholder groups and nine subcategories for the local community.

RESULTS AND DISCUSSION

The main results suggest that the Costa Rican institutional and market frameworks provide an enabling environment for a generally positive social performance in the studied cases. The assessed stakeholders can fulfil basic needs through access to inputs and services and achieve fair-trading conditions. Child labour, forced labour and evidence of environmental or health risks for the surrounding communities were absent. Important efforts to address the delocalisation, migration and child labour were observed, suggesting the potential development of social handprints in further studies. However, the farm production phase, related to farmers and workers, entails hotspots regarding social security and women's empowerment. Moreover, farmers appear as the most vulnerable group because of their overall social performance.

CONCLUSIONS

S-LCA helped identify relevant areas of intervention in the context of these particular case studies; however, further research and capacity building are recommended to tackle the detected challenges, both in the agri-food chains and in the use of S-LCA. Furthermore, these findings can aid in future decision and policy-making to improve and safeguard the positive social performance observed in the studied products.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11367-021-01964-4.

Using the Nitrification Inhibitor Nitrapyrin in Dairy Farm Effluents Does Not Improve Yield-Scaled Nitrous Oxide and Ammonia Emissions but Reduces Methane Flux

The application of dairy farm effluents (DFE) without previous treatment in paddocks was intensified due to the approval of this practice in Costa Rican legislation since 2012. Applying DFE instead of synthetic N fertilizer in grasslands is an opportunity to reach a circular economy; however, this practice increases the risk of emissions of nitrous oxide (N2O), methane (CH4), and ammonia (NH3), which contribute to global warming. A field experiment was carried out using a permanent grassland (90% Star grass and 10% Kikuyo grass) to simultaneously assess the effect of nitrapyrin on yield-scaled emissions of NH3, CH4, and N2O. The experiment lasted for 5 months in 2017, based on a randomized complete block design, including three treatments of control (CK) without N application, surface application of DFE with nitrapyrin (SNI), and without nitrapyrin (S). Total N applied was 149 ± 12 kg N ha−1 for both S and SNI treatments split into five applications. CH4 emissions from S, SNI, and CK showed a high temporal variation. Daily fluxes of CH4 from SNI were significantly lower than those of S in August (P < 0.05). Cumulative emissions of CH4, the majority produced in the soil, ranged from 4 to 168 g ha−1 for S, and from −13 to 88 g ha−1 for SNI. The ratio between the N2O cumulative emissions and the N applied as DFE were 1.6 ± 0.5 and 1.7 ± 0.2% for S and SNI, respectively. NH3 volatilization potential was very low (i.e., 0.6 ± 0.2% of the N applied). Under the prevailing experimental conditions, no significant difference between yield-scaled NH3 and N2O emissions were found between S and SNI, suggesting that nitrapyrin may not be a viable mitigation option for gaseous N losses from DFE application in Costa Rican grasslands in rainy season.