Nitrogen, phosphorus, and rhizobial strain responses of lentil

Abstract

Three field experiments were set out in 1987 to test the effect of nitrogen fertilizer, phosphorus fertilizer, and rhizobial strain on lentil yields and N2 fixation. The following treatments were laid out in a split-split-plot design: main plot treatments of uninoculated, Nitragin 'C' inoculated, and strain 99A1 inoculated lentil; sub-plot treatments of 0 and 30 kg P/ha, and sub-sub plot treatments of 0, 10, 20, 40, or 80 kg N/ha 15N-enriched fertilizer was applied to a 1.05 m2 microplot in each plot Barley was used as the non-N2-fixing reference crop. At all sites lentil inoculated with strain 99A1 had the greatest total dry matter yield, grain yield and N2 fixed. Uninoculated lentil had a strong N response at all sites, 'C' inoculated lentil had a starter N response at Kindersley and 99A1 inoculated lentil had no N response at all. P responses were only observed at Foam Lake. Lentil receiving low amounts of N fertilizer obtained between 60 and 75 % of their N from the atmosphere at all sites. A good agreement was observed in estimating percent N derived from N2 using the 15N isotope dilution, A-value, or classical N-difference methods. The amount of fixed-N in the seed ranged from 4 kg ha-1 under drought stressed conditions at Kindersley to 60 kg ha-1 under much better growing conditions at Foam Lake.