DESTiny tool to estimate on-farm nutrient and net carbon flows for dairy production

In this project we developed the exciting new DESTiny tool.  DESTiny (the Dairy Environment Sustainability tool), helps dairy farmers adopt sustainable practices, improve competitiveness, and reduce environmental risks while aligning environmental impact with profitability and building consumer trust. DESTiny is a science-informed evidence-based tool for estimating, monitoring and understanding nutrient and carbon flows in milk production.

DESTiny is a system dynamics model which aims to promote a nuanced discussion and resultant policy formulation within the dairy industry.  The tool assesses carbon capture and storage on dairy farms.  The tool analyses critical nutrient flows to determine if farms are carbon emission sources or sinks and can be used for individualised carbon footprint assessment. This tool aims to help dairy farmers adopt sustainable practices, improve competitiveness, and reduce environmental risks while aligning environmental impact with profitability and building consumer trust.

The South African economy and food security heavily rely on the dairy industry. However, this industry is confronted with various intricate challenges such as regulations, research, market forces, societal expectations, and environmental concerns. In order to gain a deeper understanding of the unique dynamics within the dairy farming sector, a customized system dynamics model is necessary. This will enable more detailed discussions and informed policy-making. To accurately estimate carbon sequestration and assess the impact of cows on carbon emissions, a complex system is required. This model encompasses numerous variables, taking into account the distinction between carbon in natural cycles and carbon in fossil fuels. It considers the natural carbon and nitrogen cycles, where trees and plants play a vital role in absorbing carbon from the atmosphere through photosynthesis.

By analysing nutrient availability, pasture production, and animal-related factors, this tool estimates emissions and sinks for carbon to gain a better understanding of the net carbon flux on a farm. The results of the model are disaggregated in such a manner that it provides a systems-view of the entire farm as a production unit while considering all the major factors needed to accurately calculate emissions and carbon storage. By doing so, producers, consumers, and the industry stakeholders can understand how carbon moves through their farms, calculate the net GHG, and measure the economic stability of the operations. The different sub-models within this tool are illustrated in Figure 1.

Figure 1: Causal loop diagram showing the flow of sources and sinks within a dairy farm system

Notes:

  • Red sub-model: belowground
  • Green sub-model: aboveground
  • Purple sub-model: animal model
  • Blue sub-model: within-product
  • Orange sub-model: external sources

The C that plants absorb is converted into cellulose to help them grow, while oxygen is released into the air. When plants decompose, the soil captures the C. Herbivores, like dairy cows, can eat these plants and turn them into nutrient-rich food. However, this process also releases methane into the atmosphere. Luckily, methane eventually converts back to CO2, which plants can use again. It takes a long time for C released from fossil fuels to be redeposited, but the C cycle from plants is much shorter. In the first project, efforts were made to estimate carbon capture and implement strategies for sustainable dairy production. This project focus on identifying more mitigation strategies to further reduce emissions. These strategies will not only help farmers understand greenhouse gas emissions on their farms, but also enable regenerative farming. Soil carbon has the potential to mitigate climate change and improve pasture production. It is estimated that soil carbon sequestration can reduce atmospheric C by 0.79 to 1.54 GtC per year.

Therefore, the DESTiny tool was developed with it’s main purpose to estimate, net GHG, monitor, and understand nutrient and carbon flows in milk production. By doing so, determine whether a farm is a net carbon sink or a source. It's important to note that this outcome is dependent on the management practices implemented on the farm. We hope this tool will assist dairy farmers in adopting sustainable practices, enhancing competitiveness, and reducing environmental risks. Additionally, it aims to align the environmental impact of dairy production with profitability and build consumer trust.

The principal research is Riana Reinecke, who is currently a PhD student at Stellenbosch University. With a BSc Agric (Animal Science) & MSc (cum laude) degrees from the University of Pretoria, Riana has worked in various positions within the dairy industry enhancing her expertise in sustainable dairy production and methods to calculate emissions on dairy farms.  She is pursuing a PhD program at Stellenbosch University, with the support of Milk-SA, to provide farmers with comprehensive guidance to optimize their enterprises, foster a healthier environment, and contribute to economic profitability. Riana's diverse experience and the valuable input from the research team, including ASSET Research, Stellenbosch University and Milk-SA, equips her with a holistic approach to this research, allowing her to offer valuable advice to farmers on improving their enterprises and promoting sustainable practices within the dairy industry. With her passion and dedication to the cause, Riana and her team are set to bring about a new era of sustainable dairy farming, one that benefits not only farmers but also the environment and society as a whole.