Abstract—Field study was conducted to determine the post field soil fertility status responses of pawpaw (Carica papaya L.) var. homestead selection and sunrise-solo orchards to organo-mineral fertilizer (OMF) rates applied at 10, 20 40 t/ha where both the zero t/ha OMF and NPK 15:15:15 at 50 g/plant/month served as control. The result showed that all pawpaw orchards treated with OMF rates recorded significantly (p≤0.01) higher % P, % K, Na and % organic matter in soil compared to applied NPK which recorded lower Na. However, while orchards plated with sole pawpaw were higher in soil bulk density (SBD), orchards with homestead mixture were lower in SBD and significantly lower % organic matter compared to obtainable under sunrise crop mixture which recorded lower Na and Mg. In conclusion, as a result of loosening effect on soil particles, the homestead pawpaw probably due to more rooting activities as well as the addition of organic fertilizer to soils both had significant influence leading to lower SBD. Keywords—Carica papaya (L), growth and yield, organo- mineral fertilizer, soil fertility status. I. INTRODUCTION USTAINABILITY in organic farming encompasses not just conservation of non-renewable resources (soil, energy, minerals) but also issues of environmental and social sustainability [1]. Intercropping systems using biological methods of soil amendments including use of organic fertilizers are some of the other ways of sustainable agriculture [2] However also, organic farming methods with aid of organic fertilizers are characterized by quality of composting materials used and other aspects of biological pest control [1]. Positive effect of organic manure on pawpaw growth and yield [3] and ability to bind soils together absorb water and release nutrients steadily for vegetable crops [4] have been reported. The influence of organic matter on soil biological and physical properties is well documented as it affects crop growth and yields either directly by supplying nutrients or indirectly by modifying soil physical properties [5]; [6], improve soil structures and water retentive capacity [7], increase infiltration rates [8] and decrease soil bulk density [9]. However, while high rate of nutrient release from fast decomposition occurs only when the organic substrate is rich in nutrients (low C:N and C:P ratios), the net nutrient release from organic matter is a function of decomposition ratios of O. O. Olubode is with the Department of Horticulture, Federal University of Agriculture, P.M.B. 2240, Abeokuta, Ogun State, Nigeria. (Corresponding author to provide phone: (+234)8038572707, fax: (+234)39243045, e-mail: oluomobode@gmail.com). organic matter fractions and uptake of nutrients by the growing biomass [10]. The application therefore of organic materials has a potential to increase plant yields to an extent above that based on the application of fertilizer equivalent nutrients [10]. The judicious use of composted organic fertilizers as sources of nutrient is essential to maintain soil health, improve efficiency of nutrients and obtain optimum crop yield. In this experiment, pawpaw cultivated with cucumber was supplied with Pace- setter OMF and NPK 15:15:15 fertilizers to determine the soil amendment influence on post cropping soil fertility status under intercropping systems. II. MATERIALS AND METHODS The experimental conduced in 2008 was located at the Federal University of Agriculture, Abeokuta, Ogun State, Nigeria (latitude 7 º 12′N, longitude 3 º 20′E at 100m above sea level). The site had been previously cultivated and fallowed for three years before the trials. The weather data (Fig. 1) described the pattern of rainfall, mean air (maximum and minimum) temperatures, and relative humidity for the experimental period for the area. The composite analysis result (Table I) of the soil sample described the soil used at the 0-15 and 16-30cm. Influence of OMF Application Rates on Post Field Soil Fertility Status under Pawpaw (Carica papaya L.) Varieties O. O. Olubode, I. O. O. Aiyelaagbe, and J. G. Bodunde S World Academy of Science, Engineering and Technology International Journal of Agricultural and Biosystems Engineering Vol:7, No:9, 2013 878 International Scholarly and Scientific Research & Innovation 7(9) 2013 scholar.waset.org/1307-6892/16673 International Science Index, Agricultural and Biosystems Engineering Vol:7, No:9, 2013 waset.org/Publication/16673