Multiple cropping, or planting and growing several crops in space or time, is a method of intensifying and diversifying agriculture to help meet the demand of a growing population. Agricultural practices that fall under the umbrella term of “multiple cropping” are already being used in substantial parts of global agricultural lands, including double and triple cropping (12% of crop land), cover cropping (approx. 10%), and agroforestry (approx. 20%). In the U.S., more than 80% of the land where wheat is grown is double-cropped with soybean (Figure 1). Implementing the practice of multiple cropping offers various benefits to the ecosystem, including pest control, efficient nutrient cycling, biodiversity, increased land productivity, and enhanced carbon storage. Further, it helps curb the expansion of agricultural lands and preserve forested areas.

Despite the benefits of introducing multiple cropping to agricultural systems, there are drawbacks and uncertainties. Multiple cropping can pose additional pressures on both agricultural and natural ecosystems through the exacerbation of soil disturbance, nutrient export, production costs, greenhouse gas emissions, and irrigation water requirements. Multiple cropping may also pose economic risks, such as yield penalties from the competition for resources and the potential of crop failures due to a decreased margin of error from the maxed-out use of growing land. Finally, it is unclear how multiple cropping will be affected by climate change-related weather phenomena, such as increased temperatures and changing rainfall patterns.

In a new paper published in Communications Earth & Environment, Waha & Folberth et al. highlight that despite the widespread implementation of multiple cropping and its associated benefits, it is largely unaccounted for in agricultural, climate risk, and sustainability assessments. The authors call for improved large-scale modeling of multiple cropping and outline best practices in modeling and experimental design, new data collection methods, and research questions to support the improvement of multiple cropping modeling (Figure 2).

In conversation with Dr. Katharina Waha, co-lead author on the paper, she offered insights into the key findings, methods, and the urgent relevance of why this work is needed. 

Why is it important to account for multiple cropping when modeling agricultural systems, and what are the risks associated with its omission? 

The high relevance and complexity of multiple cropping is contrasted by the simplicity of crop cultivation assumed in the various types of land use modeling systems employed in agricultural assessment and foresight studies. These typically assume the cultivation of monocrops with productivity solely driven by fertilizer and irrigation water inputs. Consequently, policymaking informed by such modeling systems can only tap into a very narrow knowledge pool. This gap indicates an urgent need to improve the modeling of multiple cropping systems to fully assess their outcomes across geographies and over time.