Growth, Yield and Leaf Nutrient Composition of Lettuce Grown in a Silty Loam Soil Amended with Compost at Different Rates

Application of compost has been reported to influence several soil physical, chemical and biological properties positively to increase food production and reduce or prevent the negative environmental impacts associated with conventional agriculture. Poultry manure and Leucena leucocephala leaf compost were incorporated to supply 0, 50, 100 and 200 kg N ha -1 respectively, based on the initial N content (% N) of the compost in three pot trials consecutively conducted between February and December, 2012. The fresh weight, dry weight and nutrient compositions of lettuce grown as a test crop were determined in each trial 6 weeks after transplanting. Fresh and dry matter contents were higher (P<0.05) in the compost amended soils than the control. All the compost treatments showed significantly higher (P<0.05) soil N (0.10 - 0.23%) than the control (0.03 % N). Similarly, leaf N, K, Ca, Na and Mg concentrations were significantly greater (P<0.05) in the samples from the compost treatments compared to those from the control. Only compost applied at 200 kg N ha -1 maintained high levels of N concentration in the lettuce leaves consistently in the 3 trials. The study confirmed earlier report that compost is a viable option for soil fertility management in organic vegetable production systems.