Grain yield responses of faba bean (Vicia faba L.) to applications of fertiliser phosphorus and zinc.

Seed (grain) yield responses of faba bean (Vicia faba L. cv. Fiord) to applications of fertiliser phosphorus (0, 5, 10, 20 and 40 kg P/ha as triple superphosphate) and zinc (0, 0.5, 1 and 2 kg Zn/ha as zinc oxide) were measured in 3 field experiments conducted in 1997 and 1998 on neutral to alkaline soils in south-western Australia. Additions of fertiliser phosphorus significantly (P<0.001) increased grain yields by about 50 and 100% in 2 experiments, but in the third experiment differences in grain yield due to applications of fertiliser phosphorus were not significant (P>0.05). Increases in grain yields due to zinc fertiliser were small (<10%) and were only significant (P<0.05) in 1 experiment. This suggests the 3 sites chosen had adequate soil zinc for grain production of faba bean. In 1 experiment the increase in grain yield due to addition of phosphorus fertiliser was due to an increase in the number of pods per plant; numbers of seed per pod and mean seed weight were unaffected by additions of phosphorus and zinc fertiliser. Adding phosphorus and zinc fertiliser increased concentrations of both elements in grain, but had no effect on the concentrations of other nutrient elements (N, K, S, Ca, Mg, Na, Cu, Mn, Fe) measured in grain. These findings support results of a previous study in Western Australia indicating that phosphorus is the major nutrient element deficiency for grain production of faba bean in neutral to alkaline soils.