A grand challenge facing humanity is how to produce food for a growing population in the face of challenges from climate change while also improving environmental sustainability. Prior research has shown the potential for more biodiversified farming systems to provide substantial environmental benefits, but to what extent they also reduce risks from stressful weather conditions likely to occur more often in the future remains unclear. We use the most comprehensive synthesis to date of crop rotation, or the diversity of crops through time, to show that increasing rotational diversity in maize-based North American cropping systems improves maize yields over time and across all growing conditions, including during droughts. Agricultural systems that increase reliance on biodiversity can reduce risks from climate-change challenges and should be considered an essential component of meeting the grand challenge.

A grand challenge facing humanity is how to produce food for a growing population in the face of a changing climate and environmental degradation. Although empirical evidence remains sparse, management strategies that increase environmental sustainability, such as increasing agroecosystem diversity through crop rotations, may also increase resilience to weather extremes without sacrificing yields. We used multilevel regression analyses of long-term crop yield datasets across a continental precipitation gradient to assess how temporal crop diversification affects maize yields in intensively managed grain systems. More diverse rotations increased maize yields over time and across all growing conditions (28.1% on average), including in favorable conditions (22.6%). Notably, more diverse rotations also showed positive effects on yield under unfavorable conditions, whereby yield losses were reduced by 14.0%–89.9% in drought years. Systems approaches to environmental sustainability and yield resilience, such as crop-rotation diversification, are a central component of risk-reduction strategies and should inform the enablement of policies.

Introduction

1 Tigchelaar M.

Battisti D.S.

Naylor R.L.

Ray D.K. Future warming increases probability of globally synchronized maize production shocks. 2 Aguilar J.

Gramig G.G.

Hendrickson J.R.

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Liebig M.A. Crop species diversity changes in the United States: 1978-2012. , 3 Newbold T.

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et al. Global effects of land use on local terrestrial biodiversity. 4 Pretty J. Intensification for redesigned and sustainable agricultural systems. 5 Renard D.

Tilman D. National food production stabilized by crop diversity. 6 Seifert C.A.

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Lobell D.B. Continuous corn and soybean yield penalties across hundreds of thousands of fields. , 7 Plourde J.D.

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Pekin B.K. Evidence for increased monoculture cropping in the Central United States. , 8 Wang H.

Ortiz-Bobea A. Market-driven corn monocropping in the U.S. Midwest. 9 Davis A.S.

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Liebman M. Increasing cropping system diversity balances productivity, profitability and environmental health. , 10 Hunt N.D.

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Liebman M. Reducing freshwater toxicity while maintaining weed control, profits, and productivity: effects of increased crop rotation diversity and reduced herbicide usage. , 11 Sindelar A.J.

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Sparks D.L. Soil and human security in the 21st century. , 13 Turner R.E.

Rabalais N.N. Linking landscape and water quality in the Mississippi River Basin for 200 years. To avoid widespread disruptions of food supplies in the future,agricultural production must grow more resilient to climate variability while simultaneously meeting food security goals. However, the paradigm of input intensification and specialization that has contributed to large yield gains in staple crops has also led to dramatic declines in crop diversity,which is recognized for field-level benefits such as improving crop yields, soil health, and input use efficiency,and at the national scale for increasing the stability of food production.In regions such as the central US, where intensive cropping of grains and oilseeds predominates, at least 90% of the 55 million ha in production is composed of maize and soybean, and up to ∼30% contains just maize or soybean for at least two consecutive years.To sustain yields in such biologically simplified cropping systems, substantial inputs of agrochemicals supplant services traditionally supplied by biodiversity,leading to many well-documented tradeoffs, such as soil degradation and water pollution.

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Knippenberg E.

Chambers R.G. Growing climatic sensitivity of U.S. agriculture linked to technological change and regional specialization. , 15 Lobell D.B.D.

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Hammer G.L. Greater sensitivity to drought accompanies maize yield increase in the U.S. Midwest. 16 Al-Kaisi M.M.

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Helmers M.J.

Hodgson E.W.

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et al. Drought impact on crop production and the soil environment: 2012 experiences from Iowa. 17 USDA Risk Management Agency Cause of loss historical data files. 18 Pryor S.C.

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Patz J.

Robertson G.P. Chapter 18: Midwest. Specialization in maize and soybean production, together with sensitivity of rain-fed crop production to climatic factors, makes regions such as the central US increasingly sensitive to extreme weather events such as drought.For example, the 2012 drought in the central US reduced maize yields by ∼25% and caused significant related water-quality issues.Totaling $18.6 billion, 2012 was also the US government's most expensive year for crop-insurance payouts.Without risk-reduction strategies that increase climate-change adaptation, indemnity costs will continue to rise given projections of more frequent and intense heat waves and altered precipitation patterns.Policies to enhance agricultural resilience, and the information to support policy development, are thus urgently needed.

5 Renard D.

Tilman D. National food production stabilized by crop diversity. 19 Peterson C.A.

Eviner V.T.

Gaudin A.C.M. Ways forward for resilience research in agroecosystems. 20 Tiemann L.K.

Grandy A.S.

Atkinson E.E.

Marin-Spiotta E.

McDaniel M.D. Crop rotational diversity enhances belowground communities and functions in an agroecosystem. , 21 McDaniel M.D.

Tiemann L.K.

Grandy A.S. Does agricultural crop diversity enhance soil microbial biomass and organic matter dynamics? A meta-analysis. 22 Karlen D.L.

Varvel G.E.

Bullock D.G.

Cruse R.M. Crop rotations for the 21st century. 6 Seifert C.A.

Roberts M.J.

Lobell D.B. Continuous corn and soybean yield penalties across hundreds of thousands of fields. 23 Gentry L.F.

Ruffo M.L.

Below F.E. Identifying factors controlling the continuous corn yield penalty. 6 Seifert C.A.

Roberts M.J.

Lobell D.B. Continuous corn and soybean yield penalties across hundreds of thousands of fields. , 11 Sindelar A.J.

Schmer M.R.

Jin V.L.

Wienhold B.J.

Varvel G.E. Crop rotation affects corn, grain sorghum, and soybean yields and nitrogen recovery. , 22 Karlen D.L.

Varvel G.E.

Bullock D.G.

Cruse R.M. Crop rotations for the 21st century. , 24 Gaudin A.C.M.

Tolhurst T.N.

Ker A.P.

Janovicek K.

Tortora C.

Martin R.C.

Deen W. Increasing crop diversity mitigates weather variations and improves yield stability. , 25 Grover K.K.

Karsten H.D.

Roth G.W. Corn grain yields and yield stability in four long-term cropping systems. , 26 Snapp S.

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Harwood R. Management intensity—not biodiversity—the driver of ecosystem services in a long-term row crop experiment. 27 Chimonyo V.G.P.

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Chikowo R. Grain legumes increase yield stability in maize based cropping systems. 24 Gaudin A.C.M.

Tolhurst T.N.

Ker A.P.

Janovicek K.

Tortora C.

Martin R.C.

Deen W. Increasing crop diversity mitigates weather variations and improves yield stability. Crop diversity is increasingly recognized for its potential to reduce risk from climate-change-related threats.At the farm scale and beyond, crop diversity reduces economic and production risks due to the “portfolio effect,” whereby different crops respond differently to stress. Few studies have addressed another potentially important form of risk reduction at the field scale: how crop diversity affects yield resilience of individual crops across time, including resistance to yield declines in the face of stress.Farmers have used temporal crop diversity, e.g., crop rotation (the sequence of crops grown over time), for millennia to improve yields by regenerating soil healthand breaking cycles of herbivores, weeds, and pathogens.In the US, such well-studied benefits of crop rotation often lead to 5%–10% higher maize yields on average in even just a two-crop rotation of maize and soybean,despite the monoculture system typically requiring more inputs.Going beyond average yield increases, far less is known regarding how diversified crop rotations (beyond just two crops) affect yield resilience,especially in intensive agricultural systems in which inputs supplant some of the functions that rotations provide in low-input systems.In diversified rotations, increased yield resilience to drought and other types of stressful growing conditions may result from improved soil properties, such as increases in soil water capture and storage and abundance of beneficial soil microbes. One study recently showed 7% higher maize yields during hot and dry years in a diversified five-crop rotation than in a maize-soybean rotation,but whether this is a general effect of rotation diversification or a site-specific effect due to particular environmental conditions or crop-rotation composition is not known.

28 Ortiz-Bobea A.

Tack J. Is another genetic revolution needed to offset climate change impacts for US maize yields?. It is important to examine other aspects of how diversified crop rotations perform in tandem with yield resilience in order to assess potential tradeoffs or synergies. If, for example, yield benefits of diversified rotations are mainly concentrated in more stressful growing conditions, there may be opportunity costs to adopting them in ideal growing conditions. If, on the other hand, improvements in soil with diversified rotations contribute to greater yield increases over time than those provided by simplified systems, they may help to close yield gaps as yield potential increases with improved genotypes.Although yield gains with crop rotation are well known, whether these gains are mainly due to short-term effects or whether they continue to increase over time remains an important knowledge gap.

19 Peterson C.A.

Eviner V.T.

Gaudin A.C.M. Ways forward for resilience research in agroecosystems. 1 Tigchelaar M.

Battisti D.S.

Naylor R.L.

Ray D.K. Future warming increases probability of globally synchronized maize production shocks. To assess how diversified rotations can help agriculture adapt to increasingly stressful growing conditions while contributing to sufficient food production, we require analysis of long-term yield trends encompassing a range of crop rotations, key management practices such as fertilization, and climate and soil type. Although such integrated knowledge has urgent policy relevance, it has been hindered by a lack of adequate long-term agroecosystem research networks that synthesize cross-site results. Here, we evaluate the impacts of crop-rotational diversity on several aspects of maize yields on a greater spatiotemporal scale than has previously been done. In particular, we consider how diversified maize rotations affect yield responses to stressful conditions, an essential element of agroecosystem resilience,together with other aspects of cropping system performance, including yields under more productive conditions and yield trends over time. We focus on maize responses in maize-based rotations because it is one of the most important cash crops in the world, and disruptions to maize yields due to climate-change-driven heat waves and droughts could lead to widespread impacts on food production.