Multivariate analysis for a split plot design with a covariate to determine the effects of different fertilizers levels for three potato varieties
Kenya's population is over forty million putting considerable pressure on production of food. This has led to continuous planting resulting to less fertile soils. The yield decreases season after season .This study seeks to find the effect of four different types of manure (poultry,goat,cow) and DAP(Di-Ammonium Phosphate) on three different varieties of potatoes(Annet,Dutch Robyn and Kenya Baraka).Each of the different type of manure was applied to each variety at three different levels. This experiment was carried out at Tigoni, Kenya measuring the difference in seed yield and dry matter content (DMC).The overall objective is to determine the most productive variety in a given ramy season and at what manure/fertilizer level. Soil nutrient deficit can be met from two sources: farmyard manure and commercial fertilizers. Potato varieties were planted for two seasons. The experimental design was such that treatments were laid out in a randomized complete block design replicated three times and consisted of poultrymanure;(2.5,5.0,1 0.Otonslha),goatmanure;(5, 10.0, 15.0tonslha),cowmanure;(15.0, 20.0,25.0) and DAP (18:46:0) at (.24, .28,.32tonslha).Split-plot designs are needed when the levels of some treatment factors are more difficult to change during the experiment than those of others. Analysis is done to determine superior treatments in each of the rainy seasons (short & long) for each variety. The optimal level was identified of the seed yield and DMC.The results show that DAP fertilizer had optimal level for the yields during short rains, long rains and combined seasons at .28tons/ha.The DMC had optimal level during short rains using goat manure at 10tonslha, while during long rains DAP had optimal level at.28 tons/ha.The combined seasons had optimal level using goat and DAP at 10tonslha and .28 tonslha respectively Key words: DMC (Dry matter content), Diarnmonium phosphate (DAP), Annet, Dutch Robyn, Kenya Baraka.