This research was carried out at the university of Embu farm to determine the yield of
lettuce (Lactuca sativa) when fertilized with cow manure. The treatments were cow manure
applied at the rates of 0 t/ha, 5 t/ha, 15 t/ha and 20 t/ha. The results showed that growing lettuce
using the four treatments significantly influenced their growth rate, leaf number, height of the
plant, fresh weight and dry weight. Lettuces grown with cow manure at the rate of 20 t/ha were
found to have higher leaf number, fresh weight and dry weight. Lettuce gown using cow manure
at the rate of 0 t/ha had the least leaf number, fresh weight and dry weight. Among the manure
treatments, cow manure at the rate of 5 t/ha had the least leaf number, fresh weight and dry weight
followed by lettuce grown with cow manure at the rate of 15t/ha. The application of cow manures
at the rate of 20 t/ha is preferred as it was associated with higher leaf number, fresh weight and dry
weight of lettuce. The application of cow manure at the rate of 20 t/ha is therefore recommended
for farmers to use to obtain higher yields of lettuce.