Perennial Staple Crops: Yields, Distribution, and Nutrition in the Global Food System

Maayan Kreitzman,Kai M A Chan,Eric Toensmeier,Navin Ramankutty,Sean Smukler

doi:10.3389/fsufs.2020.588988

Maayan Kreitzman, Kai M A Chan + Show 3 more

Open Access

https://doi.org/10.3389/fsufs.2020.588988

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Abstract

Staple crops, which have large amounts of carbohydrates, proteins, and/or fats, provide the bulk of calories in people's diets. Perennial plants, which can be productive for many years without the need for replanting, can produce staple foods and environmental benefits, but their agronomic and nutritional properties haven't been considered synthetically in comparison to annual staples. Here we offer a framework to classify perennial staple crops according to their nutritional categories and cultivation status. We assemble literature to report on the yield potential of 51 perennial staple crops, only 15 of which are well-characterized in existing global datasets. We show the extent and distribution of perennial staple crop production in relation to annual crop types, calculate the carbon stocks they hold, and analyze their nutritional content for three macronutrients and nine micronutrients. We found that most perennial staple crops are regional crops (not globally traded) that grow in the subtropics to tropics. At least one perennial staple crop in each of the five nutritional categories has yields over 2.5 t/ha, in some cases considerably higher, competitive with and in many cases exceeding those of nutritionally comparable annual staples. Perennial staple crops only comprise ~4.5% of total cropland. They hold a modest ~11.4 GtC above and below ground, less than one third of the anthropogenic carbon-equivalent emissions for the year 2018, but more than the ~9 GtC held by the same amount of annual cropland. If linear growth in land under perennial staple production continues to 2040, and replaces only annual cropland, an additional ~0.95 GtC could be sequestered. Many perennial crops also had competitive macronutrient density and yield (per unit area) compared to annual staples; moreover, specific perennial staples are abundant in specific micronutrients, indicating that they can be a nutrient-dense part of diets, unlike the most ubiquitous annual staple crops (corn, wheat, rice) that do not appear in the top 85th percentile for any of the nine micronutrients analyzed. Transition of land and diets to perennial staple crops, if judiciously managed, can provide win-win solutions for both food production and ecosystems.

Highlights

IntroductionThe challenge of growing and supplying food to a growing world population involves balancing the production of multiple outputs (food, fodder, raw materials, livelihoods) with multiple ecosystem services and impacts (climate regulation, soil conservation, wildlife habitat, energy use, pollution, etc.; Robertson and Swinton, 2005; Foley et al, 2011; Campbell et al, 2017; IPBES, 2019a)
The challenge of growing and supplying food to a growing world population involves balancing the production of multiple outputs with multiple ecosystem services and impacts
We expanded the set of available yield estimates for perennial staple crops from 15 to 51 (Supplementary Table 1)

Summary

Introduction

The challenge of growing and supplying food to a growing world population involves balancing the production of multiple outputs (food, fodder, raw materials, livelihoods) with multiple ecosystem services and impacts (climate regulation, soil conservation, wildlife habitat, energy use, pollution, etc.; Robertson and Swinton, 2005; Foley et al, 2011; Campbell et al, 2017; IPBES, 2019a). The current agricultural system worldwide is dominated by annual monocrops that do not constitute such favorable matrix environments, namely wheat (Triticum spp.), maize (Zea maysL.), soybean (Glycine max [L.] Merr.), and rice (Oryza sativa L.), which cover over 1.29 billion hectares of land globally (FAO, 2020) These systems, which experienced steep yield gains over the post-war decades in most of the world (Ray et al, 2012) are heavily reliant on external inputs of energy, fertilizers, and pesticides, leading to severe ecological consequences. Perennial agriculture, which includes both woody and herbaceous crops that are grown for multiple years without replacement, is a transformative alternative to the annual systems driving these impacts (Wolz et al, 2017)

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