Improving intercropping: a synthesis of research in agronomy, plant physiology and ecology

Abstract

SummaryIntercropping is a farming practice involving two or more crop species, or genotypes, growing together and coexisting for a time. On the fringes of modern intensive agriculture, intercropping is important in many subsistence or low-input/resource-limited agricultural systems. By allowing genuine yield gains without increased inputs, or greater stability of yield with decreased inputs, intercropping could be one route to delivering 'sustainable intensification'. We discuss how recent knowledge from agronomy, plant physiology and ecology can be combined with the aim of improving intercropping systems. Recent advances in agronomy and plant physiology include better understanding of the mechanisms of interactions between crop genotypes and speciesfor example, enhanced resource availability through niche complementarity. Ecological advances include better understanding of the context-dependency of interactions, the mechanisms behind disease and pest avoidance, the links between above-and below-ground systems, and the role of microtopographic variation in coexistence. This improved understanding can guide approaches for improving intercropping systems, including breeding crops for intercropping. Although such advances can help to improve intercropping systems, we suggest that other topics also need addressing. These include better assessment of the wider benefits of intercropping in terms of multiple ecosystem services, collaboration with agricultural engineering, and more effective interdisciplinary research.

Nutrient Concentrations of Bush Bean (Phaseolus vulgaris L.) and Potato (Solanum tuberosum L.) Cultivated in Subarctic Soils Managed with Intercropping and Willow (Salix spp.) Agroforestry

“…This study trial examined one cultivar for each crop within a single design of intercropping. Cultivar traits, crop density, configuration, and spacing all contributes to how two or more intercrops interact below and aboveground which impacts nutrient availability and overall field performance [16,22,28]; further investigation on bean-potato intercropping management is required to maximize positive (facilitative) interactions.…”

Functional traits in agriculture: agrobiodiversity and ecosystem services

“…For instance, although it is currently well established that intercropping can increase crop yields through niche complementarity [29], understanding of intercropping comes from examples of particular species interactions in particular contexts, rather than from principles that can be generally applied across different species compositions and environmental conditions. The statement that intercropping maize with cowpeas increases yield is less generalizable than the finding that, under conditions where plant-available NO 3 À concentrations are lower than a certain threshold, intercropping facultative N 2 -fixing species increases staple grain seed set and protein content.…”

“…Most work connecting species-based (rather than functional trait-based) measures of biodiversity to agroecosystem services focuses on pollination (e.g., [32]) and pest control (e.g., [33,34]); however, most research using traits has focused on the plant trophic level, such as intercropping (see [36] for a framework for bird traits, although this framework has not been thoroughly tested; Box 2). Research on the contribution of intercropping to productivity has largely focused on functional group classifications [29]. In a recent example, crops of broadly different functional types (legumes, fruits, and vegetables) were planted in different combinations and shown to increase overall production [37].…”

Effect of Two Patterns of Intercropping Soybean with Maize on Yield and Its Components under Different Nitrogen Fertilizer Levels

“…Intercropping is a way to increase diversity in the agricultural ecosystem, which is the combination between two or more crops in the same field and growing season (Fathi, 2014). Intercropping is considered an example of sustainable agricultural systems that contribute in achieving ecological balance, more utilization of available growth resources such as nutrients, water, and light, increase the productivity per unit of land and reduce yield damage by pests, diseases and weeds (Brooker et al, 2015). Consequently, the yields of intercrops may exceed the yield sum of the corresponding sole crops.…”