Effect of soil pH and texture on the growth and nodulation of lupins

Abstract

Lupins characteristically grow poorly on fine-textured, alkaline or poorly drained soils. Little, however, is understood about which components of these soils affects lupin growth.Lupinus .sangustifolius, L. albus and L. cosentinii were grown at both an acid and an alkaline soil pH on a sandy clay loam and a sand with or without additional NH4NO3. Plant growth was poorest on the fine-textured, alkaline soil where emergence was inhibited and plants were chlorotic. Plant growth was also lower on the acidified fine-textured soil compared to the acid sand. Problems were related to the poor physical structure of the sandy clay loam. Poor growth and chlorosis of plants appeared to be caused by Fe deficiency and was unlikely to be due to Mn, Zn or Cu deficiencies. There was no effect of NH4NO3 on the growth of plants.Poor emergence and Fe deficiency therefore appear to be important factors restricting growth of lupins on the alkaline, sandy clay loam used in this experiment. Nitrogen fixation docs not appear to be a limiting factor.