Yield and chemical composition responses of Lablab purpureus to nitrogen, phosphorus and potassium fertilisers

An experiment was conducted over 2 years to investigate the response of Lab lab purpureus plants and shed leaves to nitrogen, phosphorus and potassium fertilisers, applied alone or in combinations. No responses in plant DM yie ld were seen in the first year to any fertiliser combination. Applying both nitrogen and phosphorus fertilisers increased the yield of shed leaves. bu t adding potassium negated any advantage and also reduced plant modified ac id-detergent (MAD) fibre levels. In Year 2. no response to any fertiliser w as obtained. Sodium concentrations in both harvested plants and shed leaves were considerably below the requirements for ruminant growth or lactation, but tended to be increased by N + P + K fertiliser. In both years, the cru de protein and phosphorus levels in shed leaves were increased by most fert iliser treatments that contained phosphorus. It is concluded that, as consi stent benefits in DM yield or plant composition were not observed, the appl ication of N, P and K fertilisers cannot be recommended in these circumstan ces.