Fertilizer reduces plant damage caused by droughts

Fertilizer is often viewed as a tool to enhance plant growth under ideal conditions. But new research suggests it may have an unexpected power: helping plants survive during drought.

A global study involving 26 grassland sites across 9 countries – including the work of faculty at Binghamton University, State University of New York (SUNY) – has found that fertilizer can reduce or even cancel out the damage drought does to plant growth.

In a world increasingly impacted by climate stress, this insight could be significant for agriculture and food systems everywhere.

“Resources such as nutrients and water have been fundamentally altered by humans on a global scale, and this can disrupt how plants grow,” said Amber Churchill, assistant professor of ecosystem science at Binghamton University and co-author of the study.

“Extreme changes in these resources are therefore predicted to have an even larger potential impact, with implications for a range of economic sectors.”

Can fertilizer help plants survive drought?

To explore how grasslands might cope with drought and changing resource levels, scientists set up a large-scale field experiment – something rarely done at this scope.

The project looked at how adding nutrients like nitrogen, phosphorus, and potassium influenced plant resilience under severe drought conditions.

“It took what are often very site-specific methodologies, where we’re interested in the impacts of nutrients or the impacts of drought and water availability, and it scaled a single site experiment up to something at a much larger spatial scale,” said Churchill.

The novelty here wasn’t just the size of the study. It was the ability to look at interactions – not just what drought or fertilizer does individually, but how they affect one another when applied together.

Fertilizer reduces drought damage

The researchers discovered that drought alone cut plant growth by 19%. Fertilizer alone boosted it by 24%. But combining both? Surprisingly, it resulted in almost no net loss of growth.

This means that plants – particularly grasses – managed to maintain growth levels even in dry conditions, thanks to the added nutrients.

“The really big takeaway is that adding nutrients can offset the impact of drought, and this is really true in areas that are already pretty dry,” Churchill said.

This finding goes against a long-held assumption: that in arid environments, water limits plant growth so strongly that extra nutrients wouldn’t matter. But the study showed otherwise. Plants in drier locations actually responded better to added nutrients.

Data collection to new experiments

Churchill was hands-on at two of the global sites. At the Yarramundi site in Australia, she recorded plant presence and abundance. At Minnesota’s Cedar Creek site, she cleaned and organized massive amounts of data for the broader research network.

“In terms of drought, we get less growth; we add fertilizer, we get more growth,” Churchill explained. “Traditionally, we might hypothesize that if plants are already limited by water at, say, an arid site, plants may not be able to respond to adding nitrogen. But we actually found the opposite of that.”

Churchill is now bringing this research home. She will implement similar treatments at Binghamton University’s Nuthatch Hollow – a 75-acre open-air lab – as part of a new project called the Pasture and Lawn Enhanced Diversity Global-change Experiment (PLEDGE).

Long-term solutions need biodiversity

While the idea of fertilizer as a drought buffer is exciting, it’s not a silver bullet.

“In a forage production system where you need to offset the effects of drought, adding fertilizer will remove that effective drought,” Churchill said. “That’s a great benefit, but that costs a lot of money. So there’s a tradeoff there.”

There’s also the question of how ecosystems respond over longer timeframes. One factor that might prove just as important as nutrients is biodiversity. A more diverse plant community might be more resilient to environmental stress.

“We have a prediction that as you have more species, one of those species is more likely to withstand the drought,” Churchill said. “And so the idea is you’ll have more stable biomass over the long term if you have more species present.”

The research will be published in Nature Ecology & Evolution under the title: “Aridity modulates grassland biomass responses to combined drought and nutrient addition.”

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