Mitchell Beer
The Advocate
Cereal farmers can increase yields by more than one-third, cut climate-busting nitrous oxide emissions by 39 per cent and improve their operations’ greenhouse gas balance by a mind-bending 88 per cent by diversifying traditional wheat and maize monocultures with cash crops and legumes, according to a six-year study just completed in China.
The study published in the journal Nature Communications is one answer to the relentless spin farmers have been seeing from the national fertilizer lobby, adding to the growing body of evidence – both in theory and practice – that shows how new cropping practices contribute to more profitable operations with healthier soils.
Cereal grains aren’t nearly the biggest part of Quebec’s farm sector. But cereal farming still accounted for 2,159 jobs and $616.1 million in wages in 2023, according to Cereals Canada, while the wider value chain delivered 51,693 jobs and nearly $9 billion in economic impact.
Apply the overall conclusions of this study from more widely, by adapting the general approach to other farm sectors, and you only magnify the front-line value of a climate solution that goes to the heart of building stronger farm businesses and local economies.
Yields up, emissions down
The research team led by Xiaolin Yang, associate professor at Beijing’s China Agricultural University and conducted in the part of China known as the North China Plain, demonstrated the benefits of changing up a traditional cereal monoculture, adding sweet potato as a cash crop and peanuts and soybeans as legumes. In addition to the big gains in yield, reduced nitrous emissions, and greenhouse gas balance, adding legumes stimulated soil microbial activity and delivered a 45-per-cent gain in soil health, based on selected physiochemical and biological properties.
Some of the biggest gains showed up in subsoil stocks, down to a depth of 90 centimetres.
“The large-scale adoption of diversified cropping systems in the North China Plain could increase cereal production by 32 per cent when wheat–maize follows alternative crops in rotation, and farmer income by 20 per cent, while benefiting the environment,” the study states, “emphasizing the significance of crop diversification for long-term agricultural resilience and soil health.”
The study also paints a picture of what happens when farms try to boost output year after year without taking care of the basic systems that make it physically sustainable. Between 1986 and 2016, the authors say, China increased crop production by 74 per cent, at the expense of a more than three-fold increase in fertilizer use — and food-related climate pollution to match.
“The loss of soil fertility, which may go along with the intensification of crop production, further complicates food production and exposes it to climate risks and environmental health concerns,” they write.
By contrast, integrated farming practices “offer a range of food crops to meet consumer demand for plant-based, healthy food — an increasing dietary trend in high- and upper-middle-income countries — while providing other agricultural products such as animal feed, industrial fibre or multi-purpose biofuels.”
‘Social novelty’ meets a systems approach
The North China Plain researchers stressed a wider array of reasons to adopt better cropping practices. A diversified crop rotation “will add significant ‘social novelty’ to the challenge of bringing essential food nutrients to dining tables without adversely affecting soil health,” delivering benefits “far beyond the agricultural benefits of crop diversification that are broadly recognized worldwide.”
The study cites other studies from North America, Europe, Africa and China that show rotational diversification:
• Increasing crop yields;
• Reducing the impact of adverse weather on ecosystem productivity;
• Enhancing system robustness;
• Delivering a “substitutive interaction” with fertilizer use that increases yields with lower dependency on synthetic inputs.
All told, the researchers say, “cropping diversification offers a comprehensive systems’ approach to enhance agro-ecosystem productivity and adaptability to changing climates worldwide,” while boosting the basic economics the enable any farm to deliver anything at all.