The ever-increasing population of many countries of the world has necessitated the development of intensive agriculture technologies to sustain food yield. Soil fertility maintenance is essential in achieving and maintaining high crop yields over a period of time. Fertilizer application has usually been the major means of supplying plant nutrients. Use of mineral fertilizers has proven to be more convenient than the use of organic fertilizers that have traditionally been used since pre- industrial age. The impact of increased use of mineral fertilizers has been high but the resulting soil physical degradation, and increased soil acidity level and soil nutrient imbalance have drawn the attention of researchers back to the use of manures that are also known as organic fertilizers.
Several organic materials have been reported as suitable soil amendments for increasing crop production. The potential of cow dung, poultry droppings, refuse compost and farmyard manure as suitable soil amendments in the tropics has been reported [1, 2, 3, 4]. Application of organic materials as fertilizers provides growth-regulating substances and improves the physical, chemical and microbial properties of the soil [5, 6, 7, 8]. Sole use of organic manures to sustain cropping has, however, been reported inadequate, as they are required in rather large quantities to meet crops ' nutrient requirements because of their relatively low nutrient content . Several field research reports have indicated that high and sustainable crop yields are only possible with integrated use of mineral fertilizers with organic manure [10, 11, 12, 13]. Complementary application of organic and inorganic fertilizers increases nutrient synchrony and reduces losses by converting inorganic nitrogen into organic forms . It is also important not only for enhancing the efficiency of the fertilizers, but
References: [17.] Broadbent FE The soil organic fraction. Advs. Agron. 1953; 5: 153-183. [18.] Bray AH and LT Kurtz Determination of Total, Organic and Available forms of Phosphorous in soils Agric. Bio. Sci. 2008; 3 (4): 712-715. [23.] Makinde EA, Agboola AA and FI Oluwatoyinbo The effects of organic and inorganic fertilizers on the growth and yield of maize in a maize-melon intercrop