Response of lentil to Rhizobium leguminosarum bv. viciae strains at different levels of nitrogen and phosphorus

Response of lentil (Lens culinaris Medik) to inoculation with 3 local and 1 exotic Rhizobium leguminosarum by. viciae (lentil rhizobia) strains at dif ferent levels of nitrogen and phosphorus (00:00, 20:20, 20:40, 20:60, 20:80 , 40:20, 40:40, 40:60 and 40:80 kg/ha as N and P2O5, respectively) was stud ied. A field experiment was conducted on a soil deficient in nitrogen and a vailable phosphorus that had a very low indigenous population of lentil rhi zobia. Percentage strain recovery (nodule occupancy) revealed that the inoc ulant strains were highly competitive and occupied 71-95% of the nodules. I noculation had significant benefits for nodulation, biomass, grain yield, n itrogen and phosphorus uptake at all levels of nitrogen and phosphorus. Ino culation with the local strain Lc26 increased yield by 393 kg/ha compared w ith the uninoculated control. Maximum biomass, and nitrogen and phosphorus uptake were observed where nitrogen and phosphorus were applied at the rate s of 40 and 60-80 kg/ha, respectively. The 40:80 kg nitrogen and phosphorus per hectare combination gave the maximum nodule number, nodule dry weight and grain yield (904 kg/ha) with a net return of US$189 as compared to the unfertilised control and there was an income of US$7 for each dollar invest ed on fertiliser.