The less intensively you manage the soil, the better the soil can function; for example, not plowing as often or using more grass-clover mixtures as cover crops. These are the conclusions of a research team led by the Netherlands Institute of Ecology (NIOO-KNAW).
Surprisingly, it applies to both conventional and organic farming. These important insights for making agriculture more sustainable are published in the journal Science.
"It offers clear evidence to help farmers manage soils better," says the research team.
Growing food more sustainably: What's the best way to do this? It is one of the big challenges: producing enough food without compromising the soil. After all, healthy soil has many functions—called multifunctionality—and for sustainable agriculture these must be preserved.
"A multifunctional soil is essential for sustainable food production, because plants get their food from it," state the researchers, from NIOO and Wageningen University & Research (the Netherlands), and the Universität Tübingen (Germany). "Soil also has indispensable roles in water storage, coping with climate change and disease suppression."
Organic vs. conventional
Research on farms across the Netherlands now shows that it is mainly the intensity of tillage that determines whether the soil can retain all its functions. Interestingly, the difference between conventional and organic farming has less of an influence. In both types of agricultural systems, a lot of variation is found in soil tillage and management.
"The good news is that in conventional agriculture, which is the vast majority, there is a lot to gain," states soil ecologist and NIOO professor Wim van der Putten. "On all farms, including organic ones, it is important at this point not to cultivate the soil too intensively. For example: plowing less. Inverting the soil during plowing is a very big disruption to soil life."
More than plowing less
Not only less frequent plowing, but also making more use of mixtures of grasses and plants from the bean family, such as clovers, contributes to multi-functional healthy soil. You can alternate these with growing cereals such as wheat, barley, spelt and rye.
The research team took samples and carried out measurements at more than 50 Dutch agricultural farms on both clay and sandy soils. This was always done in pairs: a farm with conventional agriculture plus an organic neighboring farm. The soil type and other conditions were then very similar.
"That way, we could compare them like twins," clarifies researcher Guusje Koorneef. Together with Sophie van Rijssel, she conducted her Ph.D. research on this topic.
Sustainable and productive
A wide array of soil properties was measured and farmers shared what farming practices they applied. The organic carbon present in the soil proved to be the best predictor of soil multifunctionality, and for biological indicators this was the bacterial biomass.
Koorneef adds, "We looked at both sandy and marine clay soils. These are two very different soil types in the Netherlands. And we see the same picture in both soil types."
"The popular term 'sustainable intensification' is contradictory to our results," argues contributing researcher Kyle Mason-Jones, now working at the Universität Tübingen. "More intensive soil management leads to reduction of soil functions and is thus less sustainable."
Therefore, the researchers propose a new, appropriate goal: "Productive de-intensification. If it is successful, you will get more functions from a less intensively cultivated soil while retaining the crop yield as much as possible," they state.
These findings are the final result of the Vital Soils project. The project was coordinated by NIOO and carried out together with Wageningen University & Research. Besides the scientific partners, there were also several social partners involved: Eurofins-Agro, BO Akkerbouw, Open Teelten (formerly PPO-AGV) and LTO-Noord.
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