Environmental and social benefits from diversified agriculture found in global study

Food security and biodiversity are both helped by diversified farming techniques, with little negative impact, according to a new paper that includes research from two Washington State University professors.

The study, published in the journal Science, involved 58 co-authors located at institutions on five continents.

David Crowder
David Crowder

“The results are overwhelmingly strong for all diversification strategies,” said David Crowder, a professor in WSU’s Department of Entomology. “The working theory is that diversity is good in agriculture, but I was surprised that the benefits were so strong.”

Crowder and his colleague Jeb Owen, a WSU associate professor in entomology, both contributed data to the paper, which was a meta-analysis of 28 global studies. In fact, neither Owen nor Crowder knew the other was involved in the paper until it was nearly published.

Owen’s contribution centered on wild birds and their impact on organic farms. His lab conducted surveys at 30 different locations in four states, including Washington, to look at costs and benefits from wild birds as well as each farm’s crop diversification.

“We found that the more complex and diverse a farm, the wider the diversity of wild birds it supported, and that the birds were a net positive for the farms,” Owen said.

Owen’s former graduate student, Olivia Smith, led his wild bird research and was another co-author on the new paper.

Wild, native birds fed on insect pests that damage crops, decreasing the need for pest-control measures, while not increasing pathogen spread or destroying crops, he said.

Owen holds a yellow piece of plastic and wears an orange jacket with a pond on the background.
Jeb Owen

Crowder’s contribution included his lab’s research on canola and different tillage processes used by growers.

“There’s a lot of research at WSU looking at diversified farming and ways we can improve the sustainability of farms,” Crowder said. “This paper shows that WSU is plugged into global issues, and I hope we see more of this out of the university.”

Laura Vang Rasmussen of the University of Copenhagen is lead author on the new study and worked for nearly four years to coordinate and synthesize data from around the world.

“Our results from this comprehensive study are surprisingly clear,” Vang Rasmussen said. “While we see very few negative effects from agricultural diversification, there are many significant benefits. This is particularly the case when two, three, or more measures are combined. The more, the better, especially when it comes to biodiversity and food security.”

The researchers saw the greatest positive effects on food security, followed closely by biodiversity. Furthermore, social outcomes in the form of well-being also improved significantly.

Among the many strategies adopted, livestock diversification and soil conservation had the most positive outcomes.

According to the researchers, previous studies investigated either the socioeconomic or environmental effects of agricultural diversification. This study investigates effects across the board, with surprisingly positive results.

“Agricultural diversification has been accused of perhaps being good for biodiversity, but having a few negative aspects too — especially with regards to not being able to achieve sufficiently high yields,” said Ingo Grass of the University of Hohenheim. “What we actually see is that there is no reduction in yield from diversified agriculture — not even when we include data from large-scale European agriculture.”

A small vegetable farm with several crops growing on small parcels.

In fact, the figures demonstrate that in the case of small farms and farms surrounded by lots of cultivated land, more diversified agriculture can significantly promote food security. This, according to the researchers, could be due to a number of factors.

“One example is fruit trees planted in maize fields in Malawi, which can help farming families improve their food security through improved diet and nutrition,” Vang Rasmussen said. “Partly because they eat the fruits themselves, and also because the trees generate extra income when their fruits are sold at market — income that provides small-scale farmers with purchasing power for other foods.”.

All 58 of the study’s authors participated actively in its design to attempt a robust and credible interweaving of the many data sets spread across the world — from maize production in Malawi, to rubber trees in Indonesia, to silvopastoral cattle farming in Colombia and winter wheat in Germany.

“The study unites many different situations from the many data sets that we used,” Vang Rasmussen said. “In Malawi, we have data on food security expressed, for example, in the number of hungry months for small-scale farmers where they have been short of food. Such metrics are not used for, for example, large European farms, where we have yield data instead, such as winter-wheat yields in Germany.

“But the point is that when we look across all data sets, our results show that applying more diversification strategies improved both biodiversity and food security, and didn’t have a negative effect on yields,” she added.

The researchers also investigated which diversification strategies result in “pairs” of favorable “win-win” outcomes. Their data showed that strategies beneficial for biodiversity also improved food security.

They also witnessed win-wins for biodiversity and people’s well-being.

“It’s a simple message to be able to pass on to different types of farms — whether it is small farms in South America or Africa or advanced European agriculture, there are lots of positive effects to be gained by introducing these various strategies — and very little to fear,” Grass said. “It is very positive that so many different things can be addressed, and that, in general, positive biodiversity outcomes seem to go hand in hand with well-being and food security.”