G.J B.A.H.S., Vol.2 (2) 2013:7-11 ISSN: 2319 – 5584 7 COW DUNG MANAGEMENT ON THE CALCIUM AND MAGNESIUM CONTENT AND TOTAL MICROBIAL POPULATION IN THE NORTHERN GUINEA SAVANNA OF NIGERIA J. Tanimu 1 , E.O. Uyovbisere 2 , S.W.J. Lyocks 3 , and Y. Tanimu 4 1 Department of Soil Science and Land Resources Management, Federal University Wukari, Taraba State 2 Soil Science Department, Institute for Agricultural Research/Faculty of Agriculture, Ahmadu Bello University, Zaria 3 Samaru College of Agriculture, Division of Agricultural Colleges, Ahmadu Bello University, Zaria 4 Department of Biological Sciences, Ahmadu Bello University, Zaria Abstract The effect of time and duration of storage of cow dung on the calcium and magnesium content and total microbial population was investigated for two years in Samaru, Northern Guinea Savanna, Nigeria. The treatments were composed of 0, 4, 8 and 12 weeks of cow dung storage in the field after one month of composting and a control treatment. The results showed that, the use of cow dung immediately after composting in May (4 weeks) significantly (P < 0.05) released more of Ca and Mg, however after field storage the June (0 week) treatment appeared to be better. The total microbial population, immediately after composting showed bacterial and fungal populations to be more in the June (0 week) treatment, but if stored in the field before use the April (8 weeks) treatment gave a significantly (P < 0.05) higher population of the microbes. Keywords: calcium, cow dung management, magnesium, microbial population, Nigeria. Introduction According to Camberato et al., (1996) and Fulhage (2000) the nutrient content of manure varies widely with animal species, age, ration and feed consumption, as well as with different methods of storage, handling methods, housing type, temperature and moisture content, treatment and land application. Fulhage (2000) has shown that manure contains the three major plant nutrients, nitrogen, phosphorus and potassium (NPK), as well as many essential nutrients such as Ca, Mg, S, Zn, B, Cu, Mn etc. That, in addition to supplying plant nutrients, manure generally improves soil tilth, aeration, and water holding capacity of the soil and promotes growth of beneficial soil organisms. Manure applied in the proper amounts at the appropriate time can supply some, if not all, of the nutrient requirements of many crops. Although much work had been done in northern Nigeria during colonial period on the value of manure to various crops (Dennison, 1961) feces of the various groups of livestock have not been characterized according to their contents of plant nutrients (Kallah and Adamu, 1989). They further explained that, chemical composition can be used to compare different sources and/or forms of animal feces. They argued that, it is a fair index for estimating the kind and potential amount of fertilizer elements being recycled on application. Calcium and Mg are among the essential nutrient elements that play vital roles in the nutrition of the crop. Calcium is an essential part of the plant cell wall structure, provides for normal transport and retention of other elements as well as strength in the plant. It is also thought to counteract the effect of alkali salts and organic acids within a plant. Magnesium is part of the chlorophyll in all green plants and essential for photosynthesis. It also helps activate many plant enzymes needed for growth. There are not always enough of these nutrients in the soil for the plants to grow healthy. This is why farmers use fertilizers (organic and mineral) to add the nutrients to the soil. Although conserving nutrients is a very important aspect of manure management, it is mistaken to regard manure as just a vehicle for nutrients. Manure is also an important source of humus and has a beneficial long-term effect on the structure and carbon-economy of the soil. Moreover, farmyard manures contain hormones, vitamins, and anti-biotin, and their stimulating effects on root growth and on the growth of micro- organisms (yeast cultures) have been demonstrated experimentally (Sauerlandt and Tietjen, 1970). The microbial biomass constitutes the active fraction of soil organic matter (Paul and Voroney, 1984), whose fast turnover makes it important as a potential source of nutrients (Sparling, 1985). It is, thus, involved in the decomposition of organic materials and the cycling of nutrients in the soils (Moore et al., 2000). Frequently, it is used as an early indicator of changes in soil chemical and physical properties resulting from soil management and environmental stresses in agricultural ecosystems (Brookes, 1985; Jordan et al., 1995; Trasar-Cepedar et al., 1998). Soil Microbiologists (Fauci and Dick, 1994; Ndiaye et al., 2002) have used microbiological analyses of soils as indices of soil fertility and land use. Other researchers have used microbial population and ratios to assess the modification of the soil ecological environment brought about by land use changes (Mendes et al., 1999 and Ndiaye et al., 2002). The data on soil microorganisms in several tropical soils are very limited and grossly underestimated (Ayanaba and Sanders, 1981). Most of the available reports did not consider the effects of some soil properties, cropping history and system and waste disposal on the microbial population (Isirimah et al., 2006). In their study, crop residues and animal waste were incorporated into the soil for different land use which affected the rate of organic matter decomposition as indicated by the