Intercropping—Evaluating the Advantages to Broadacre Systems

James G. Nuttall,Brendan P. Christy,Garry J. O’Leary,Meredith Mitchell,Penny A. Riffkin,Ashley J. Wallace,Kerry J. Stott,Roger Armstrong,Malcolm McCaskill,Frank Henry,Uttam Khanal,Thabo Thayalakumaran

doi:10.3390/agriculture11050453

Abstract

Intercropping is considered by its advocates to be a sustainable, environmentally sound, and economically advantageous cropping system. Intercropping systems are complex, with non-uniform competition between the component species within the cropping cycle, typically leading to unequal relative yields making evaluation difficult. This paper is a review of the main existing metrics used in the scientific literature to assess intercropping systems. Their strengths and limitations are discussed. Robust metrics for characterising intercropping systems are proposed. A major limitation is that current metrics assume the same management level between intercropping and monocropping systems and do not consider differences in costs of production. Another drawback is that they assume the component crops in the mixture are of equal value. Moreover, in employing metrics, many studies have considered direct and private costs and benefits only, ignoring indirect and social costs and benefits of intercropping systems per se. Furthermore, production risk and growers’ risk preferences were often overlooked. In evaluating intercropping advantage using data from field trials, four metrics are recommended that collectively take into account all important differences in private costs and benefits between intercropping and monocropping systems, specifically the Land Equivalent Ratio, Yield Ratio, Value Ratio and Net Gross Margin.

Highlights

Interest in the combined goals of increasing food production while simultaneously mitigating environmental impacts has gained increasing attention over recent decades, and sustainable intensification (SI) of agricultural systems is widely accepted as a guiding principle to progressive farmers, agricultural scientists e.g., [1] and agricultural economists [2] alike
To date, intercropping systems have not been widely adopted by landholders in broadacre production systems in countries such as Australia [13], where agricultural systems are dominated by intensive monocultures managed in the context of crop rotations, and where livestock can be integrated as mixed farming enterprises
If the land is the most important factor of production and the objective is to reduce or spare land compared to the current yield from monocultures, we suggest comparing land equivalent ratios (LER)

Summary

Introduction

Interest in the combined goals of increasing food production while simultaneously mitigating environmental impacts has gained increasing attention over recent decades, and sustainable intensification (SI) of agricultural systems is widely accepted as a guiding principle to progressive farmers, agricultural scientists e.g., [1] and agricultural economists [2] alike. To date, intercropping systems have not been widely adopted by landholders in broadacre (broadacre is a term used to describe farms involved in the production of crops on a large scale) production systems in countries such as Australia [13], where agricultural systems are dominated by intensive monocultures managed in the context of crop rotations, and where livestock can be integrated as mixed farming enterprises This is based on the economic perspective of specialization and economies of scale which arises when a producer increases the scale of production, thereby spreading fixed costs over many production units and lowering the per-unit costs of production.

Intercropping Systems

Review of Intercropping Metrics

Land Equivalent Ratio

Major Findings

Other Yield-Based Measures

Value Measures

Profit Measures

Risk Measures

Measures of Indirect Benefits

Valuation Method

Selecting the Most Appropriate Intercropping Metric

Objective