Forage Legume Intercropping in Temperate Regions: Models and Ideotypes

This chapter shows that our models of intercropping do not increase the costs of sowing. The crude protein content in forage dry matter remains high, even with short growing seasons. The models fit easily into various cropping systems and do not require synthetic fertilisers or herbicide. Intercropping is one of the oldest agricultural practices worldwide. Intercropping is beneficial in many ways, encompassing better utilisation of soil resources such as water and nutrients, improved tolerance to abiotic and biotic stress such as low temperatures, drought, pests and diseases and environment-friendly services such as decreased demand for chemical weed control and mineral fertilisers. Despite its long tradition, intercropping offers constant challenges in examining diverse aspects of newly-designed crop associations. One of the most recent and thoroughly studied is intercropping annual temperate legumes with each other for forage production. We established four main principles for such intercropping: same time of sowing; similar growing habit; similar cutting time; and one component has good standing ability (supporting crop) and another is susceptible to lodging (supported crop). Here we review the basic agronomic performance of three main intercropping groups, namely (1) autumn- and spring-sown ‘tall’ cool season legumes; (2) autumn- and spring-sown ‘short’ cool season legumes; (3) early and late maturing warm-season annual forage legumes. Intercropping autumn-sown faba bean with autumn-sown common vetch had balanced total forage dry matter yield and Land Equivalent Ratio (LER) of 1.42. All combinations of autumn-sown and spring-sown intercrops of semi-leafless and normal-leafed peas resulted in LER values higher than 1. The intercrop of pigeon pea and lablab bean had LER values of 1.12 and 1.10. Majority of the intercrops are justified as economically reliable by Land Equivalent Ratio (LER) values.