EFFECTS OF PHOSPHORUS AND ORGANIC FERTILIZERS ON THE GROWTH, YIELD AND NUTRIENT CONTENT OF LETTUCE (Lectuca sativa) IN SOUTHWESTERN NIGERIA

Abstract

Continuous crop production in the tropics has rendered vast area of land unproductive as a result of physical degradation, loss of soils organic matter and decreased cation exchange capacity (CEC). As these soils suffered multi-nutrient deficiencies, application of mineral fertilizers has become mandatory to increase crop yields. In light of the foregoing, a field experiment was conducted in 2011/2012 cropping season at the Teaching and Research Farms of Lagos State Polytechnic, Ikorodu and Horticultural Unit, Ondo Stare Ministry of Agriculture, Akure to evaluate the effect of different types of organic manure, phosphorus fertilizers and their combination on the growth, yield and proximate nutrient composition of lettuce. The study involved three types of organic manure (poultry dropping, pig manure and cow dung) and two types of phosphorus fertilizer (Ogun Rock Phosphate (ORP) and Single Super Phosphate (SSP)) and a control resulting in sixteen treatments combinations. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replicates. Growth parameters (plant height, number of leaves, leaf area) were collected at 40, 60 and 80 Days after Transplanting (DAT). Shoot dry matter was taken at 80 DAT, while yield was determined by weighing the harvested lettuce at 50 DAT. Soil sample were collected before and at harvest for analysis of N, P, K, Ca, Mg and lettuce harvested subjected to proximate composition analysis. The result of the study showed that lettuce grown on soil amended with organic manure combined with SSP and RP at 8t ha-1 and 4t ha-1 exhibited significant growth and yield, proximate composition and improved the soil nutrient composition positively at harvest compared to control and sole organic manure application. The result obtained clearly indicated that organic manure combined with phosphorus fertilizers prove to be a sound soil fertility management strategy in the study area.