Environmental Impact Evaluation Of High-Yield Farming

Agriculture already covers around 40% of Earth’s ice- and desert-free land and is responsible for around two-thirds of freshwater withdrawals. Its immense scale means it is the largest source of threat to other species. High efficiency of the food system is often touted as the solution – on the demand side, cutting food waste and excessive consumption of animal products is essential, while on the supply side, farming at high yields has potential to restrict humanity’s impacts on biodiversity. Indeed, lowering the land cost of agriculture appears central in addressing the extinction crisis, provided that it can be combined with the restoration of natural habitats.

In this study, a cohort of 28 researchers stresses that how we manage farming and food systems is pivotal to biodiversity. They argue that comparisons of the overall impacts of different agricultural systems should focus both on yields and the sum of externalities generated per unit production. The study looked into four globally significant farm sectors: Asian paddy rice, European wheat, Latin American beef and European dairy. They also looked at five major externalities: greenhouse gas (GHG) emissions, water use, nitrogen use, phosphorous use, and soil losses.

The first key result of this study is that useable data are surprisingly scarce. Very few studies have paired their measurements of externality and yield information, or many have reported externalities in substantially incomplete ways. As such, suitable data was not found for all widely adopted practices. The data that were obtained, however, do not suggest that environmental costs are generally larger for high-yield farming systems. Actually, more commonly than not, high-yield and land-efficient systems also have lower costs in other dimensions.

Rice: Mathematical models revealed that greater application of organic nitrogen lowered land cost but increased emissions. On the other hand, there was little or no GHG penalty from boosting yield using inorganic nitrogen. Furthermore, this way of fertilizing led to reduced irrigation needs. 

Wheat: Main findings include that adding ammonium nitrate lowers land costs but increases embodied GHG emissions, while adding urea lowers land costs without increasing GHG emissions but increased ammonia losses.

Beef: In animal farming scenarios, all quality data indicate a link between land costs and externalities. Pasture systems with greater land demands, for example, also generate greater emissions, while both land and GHG costs are reduced upon pasture improvements.

Dairy: Conventional systems, especially those using less grazing and more concentrates, were shown to have substantially lower land and GHG costs, in part because concentrates reduce methane emissions from fibre digestion. Such systems also showed lower losses of nitrogen, phosphorous and soil. The impacts of farming dairy cows are usually mitigated as 57 % of global beef production originates from the dairy sector, hence the two are inter-linked.

Overall, the findings confirm recent suggestions by several other research teams that high-yield farming has the potential to make a substantial contribution to mitigating climate change. The available data do not suggest that negative associations between land cost and other environmental costs of farming are typical.

Pursuing high-yield systems is clearly not the same as encouraging business-as-usual industrial agriculture, though. Actually, the authors suggest that the framework they developed could serve as a means for identifying existing yield-enhancing systems that also lower other environmental costs, and act as a benchmarking tool for potential future advancements.

Despite the limitations of available data, and excluding some important impacts such as soil health or the effects of pesticide exposure on human health, the authors claim that for high-yield strategies to help solve society’s challenges, yield increases instead need to be combined with far-reaching demand-side interventions and effective measures to constrain agricultural expansion. What does a demand side intervention look like? You guessed it: eating less meat, or cutting out meat altogether.