With the objective of evaluating the effect of three sources and three levels of application of organic fertilizers on maize yield Marginal 28TropicaJ variety, as well as the respective economic analysis, was carried out this work, which was carried out in 9-A lot of station Experimental "El Porvenir", Juan Guerra, the low may Valley District , province and region San Martfn (Peru), geographically characterized by the following coordinates: latitude South 06 ' 36' 15 "and length West 76 ° 21' 15"; an altitude of 232 msnmm, and be located in a dry Tropical Forest (b-ST); and with the following features physical and chemical soil: clayey texture, pH 7.1, available phosphorus 29.7 rngfl, potassium 0.41 meq / 100g, 3.24% organic matter and contents Ca + Mg of 42.0 meq / 100g. Was used the statistical design of completely randomized blocks, with a factorial arrangement 3 • 4, split plot. S...