Effects of Kraal Manure, Chicken Manure and Inorganic Fertilizer on Growth and Yield of Lettuce (Lactuca sativa L. var Commander) in a Semi-arid Environment

The experiment was carried out at the Horticulture Department Farm, Faculty of Agriculture, Luyengo campus of the University of Swaziland to determine the yield of lettuce (Lactuca sativa) when fertilized with kraal manure, poultry manure and inorganic fertilizer, and to assess the rate of weed emergence on plots fertilized with various materials. The treatments were of kraal or chicken manure applied at 40 t/ha and 60 t/ha, and chemical fertilizer 2:3:2 (22) applied at 80 kg/ha. The results showed that growing lettuce using the five treatments significantly affected its growth rate, leaf number, fresh mass, dry mass and weed infestation. Lettuce grown with chicken manure at 60 t/ha was found to have higher leaf number, fresh mass, dry mass and apparently higher weed infestation as compared to the other treatments. There were no significant (p>0.05) growth parameter differences from the kraal manure at 40 t/ha and the chicken manure at 40 t/ha treatments. Lettuce grown using inorganic fertilizer had the least leaf number, leaf area, leaf area index, fresh and dry mass as compared to the other treatments. Weed infestation was found to be higher in the chicken manure treatments which had severe weed coverage, followed by the kraal manure treatments with intermediate weed coverage and finally the inorganic fertilizers treatment with least weed coverage. The application of chicken manure at 60 t/ha is preferred as it was associated with higher leaf number, leaf area , fresh and dry weights of lettuce. The application of chicken manures at 60 t/ha is therefore recommended for farmers to use to obtain higher yields of lettuce.