Plant diversity improves crop health and yields compared to monoculture

Friday, February 19, 2016 by: David Gutierrez, staff writer
Tags: plant diversity, crop yields, monoculture

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(NaturalNews) Planting multiple crops species together in the same field produces greater yields than conventional monocultures (large fields growing only a single crop), according to a study conducted by researchers from Germany, the Netherlands and Switzerland, led by ecologists from the University of Zurich and published in the journal Nature.

The findings suggest that a switch to diverse plantings (also known as companion planting or intercropping) may be a crucial strategy to assuring food security in the future, the researchers said.

Researcher Bernhard Schmid said the findings point to "an opportunity for the future of nutrition for humankind in the untapped potential of biodiversity."

Plants protect and aid each other

Both the United Nations Food and Agriculture Organization (FAO) and the Organization for Economic Co-operation and Development (OECD) have warned that agricultural yields are going to grow more slowly in the future, and that population is increasing at a greater rate. This is a recipe for food insecurity, which in turn leads to human suffering and political instability.

Monoculture remains the dominant method of food production globally, even though it has been repeatedly shown to be an agricultural method that does environmental damage to soil, water and biological diversity. One of the few advantages that some monoculture proponents have been able to claim is that the method produces greater crop yields.

In the new study, researchers spent 10 years comparing yields of grassland plants cultivated either in monocultures or in mixed plant communities. They found that diverse plantings consistently outperformed monocultures, delivering higher yields.

The researchers found several reasons for the success of mixed plantings.

"Due to their diversity, plant species in communities occupy all the niches available in an ecosystem," researcher Dan Flynn said. "This enables them to use soil nutrients, light and water far more effectively than monocultures, which ultimately leads to greater yields."

Researchers have long known that monocultures are significantly more vulnerable to pests and parasites, because they provide abundant food sources that produce population booms. That is why monocultures are typically associated with much higher pesticide use.

In mixed plantings, in contrast, parasites are able to spread less effectively -- the different species effectively form barriers against one another's parasites, protecting each other. Because the plants suffer less predation, they put less energy into defending themselves and more into growth.

"Diversity offers protection against pests and is a prerequisite for higher yields in plant communities," Schmid said.

To their surprise, the researchers also found that, within just a few generations, the plants had actually changed their physiologies to be more adaptive to a mixed planting environment. This phenomenon, known as short-term evolution, also produced higher crop yields.

The short-term evolutionary changes were allowed plants to make the most of their inter-planted environments. For example, grasses developed thicker leaves to take better advantage of the sunlight available at the top of a grassland habitat. Clover, in contrast, produced leaves that were larger yet thinner, for more efficient harvesting of the diffuse light found in the shady grassland understory.

Biodiversity benefits everyone

The findings reinforce the ecological premise that organisms -- including agricultural crops -- are healthiest in the most diverse environments.

"The research results reveal that diversity enables the functionality of the ecosystems to be stabilized at a high level in the course of time and in different environments," Schmid said.

The study also shows that implementing practices to protect cropland biodiversity could actually increase crop yield.

"Plant breeding and cultivation methods should therefore be geared towards mixtures instead of improving the output of monocultures," Schmid said.

This would lead to lower use of chemical pesticides and fertilizers, and a corresponding improvement in the environment surrounding agricultural fields.

Sources for this article include:

http://www.mediadesk.uzh.ch

http://www.nature.com

http://www.naturalnews.com

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