Crop diversification shields Brazilian farms from extreme weather, lifting yields up to 76%

Farms in southern Brazil that diversified their crop rotations and kept soil covered with living plants through the year produced yields up to 76% above the state average across three seasons marked by drought and flooding, according to research from the University of São Paulo.

The study, by the Center for Carbon Research in Tropical Agriculture (CCARBON) at USP, followed 13 commercial farms in Rio Grande do Sul. It found that crop diversification with cover crops raised the soil’s capacity to store water and kept yields more stable than simpler cropping systems. The findings were published in Agriculture, Ecosystems & Environment.

For fertilizer and input suppliers, the work adds field evidence that soil management can protect the return on applied nutrients when weather turns extreme.

Crop diversification tested in a state hit by drought and flood

Rio Grande do Sul offered a severe test. The state suffered a three-year drought driven by consecutive La Niña events, followed by the catastrophic floods of 2024, which affected 471 of its 497 municipalities, according to Revista Pesquisa FAPESP.

Researchers compared farms using diversified rotations and cover crops with simpler systems over three seasons spanning these extremes. The diversified farms showed higher and steadier productivity, with yields up to 76% above the state average.

Soil water storage rose regardless of clay content

The analyses showed that diversifying crops significantly increased soil water storage, whatever the clay content of the soil. This matters because clay content is usually one of the main factors that determines how much water a soil can hold.

Mauricio Roberto Cherubin, a professor at the Luiz de Queiroz College of Agriculture (ESALQ-USP) and research director at CCARBON, presented the results during FAPESP Week Netherlands. He told Agência FAPESP that it is “essential to ensure the presence of living plants and vegetation cover throughout the year” to keep soil healthy and functional.

The researchers said a mix of cover crops keeps soil organisms active year-round, which supports nutrient cycling, biological nitrogen fixation and phosphorus availability for the following cash crop. Healthy soil with a wide variety of roots acts as a buffer for crops against both dry spells and waterlogging, they said.

The system has limits. Severe flooding disrupted cover crop use on some farms, the study found, showing that diversification reduces climate risk without removing it.

What crop diversification means for nutrient efficiency

Brazil is the world’s largest fertilizer importer, and higher input costs in 2026 have put pressure on growers’ margins. Practices that improve nutrient cycling and water retention can help farms get more yield from each tonne of fertilizer applied.

The study did not measure fertilizer savings directly. Its results on nitrogen fixation and phosphorus availability point to agronomic pathways that agronomists and input suppliers are already watching. Legume cover crops add biologically fixed nitrogen, and more active soil biology can release phosphorus bound in the soil.

The results fit a wider body of research on crop diversification. Long-term trials in Brazil’s Cerrado savanna have linked high-biomass cover crops to better soil health, higher soybean yields and greater yield stability. In the United States, recent studies have tested how rotation changes such as adding winter canola or reducing tillage affect productivity and emissions.

Outlook: farm-scale data for climate adaptation

Unlike plot experiments, the USP work drew on commercial farms operating through real weather shocks. That makes it relevant for lenders, insurers and cooperatives assessing climate risk in southern Brazil’s grain belt.

Cherubin’s group, which also coordinates the Brazilian Soil Health Partnership, is part of a growing push to quantify how soil management supports both carbon storage and farm resilience. As extreme weather becomes more frequent in southern Brazil, the question for growers may shift from whether to diversify to how quickly they can afford to.

Source: Phys.org