Factors affecting the yield of winter lupins.

Abstract

The white lupin (Lupinus albus) is a temperate legume whose seed contains high levels of protein (36-44%), oil (10-16%) and high quality dietary fibre in the dry matter. Modern varieties contain extremely low levels of alkaloids (<0.01%) and no anti-nutritional factors. Thus their composition is more similar to soya bean than peas and beans, which contain much less protein (23-27%) and no oil. Nitrogen fixation by autumn-sown, determinate varieties is large (ca. 300 kg/ha) and harvest index for nitrogen is high (more than 85% of the crop N is recovered in the grain). Lupins also have the ability to release phosphorus and iron from mineral sources in the soil. These two characteristics make the winter lupin crop an ideal choice as a low input alternative crop, particularly in nitrogen-sensitive areas. Attempts to introduce spring-sown lupins have failed, mainly due to low yield potential, poor yield stability and late harvest. The release of the first winterhardy determinate varieties by French breeders in 1994 promised the first real chance of success. The successful introduction of lupins offers the possibility of reducing soya bean imports and replacing it with a high-quality, home-grown protein source, with the added advantage of traceability. Autumn-sown lupins are capable of producing satisfactory yields (3.7-4.5 t/ha). The crop does require careful management, i.e. early sowing (by mid-September), at the correct seed rate (100 kg/ha), into well-structured free-draining soil and with a pH below 7. Sown in early September, the crop will mature from late August to mid-September.