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The need for an increased production of vegetables to meet the dietary vitamin requirements of the people had necessitated a research in the use of manure in improving the soil fertility for an improved yield and quality of amaranth. The research was conducted in Obasoto Farm (latitude 7°10'N and longitude 5°37'E) in Owo Local Government Area of Ondo State, Nigeria in the early and late seasons of 2007, 2008 and 2009. The experimental design was a randomized complete block with three treatments replicated three times. The three treatments were 0 kg/ha manure, 2t/ha organic compost and 200 kg/ha NPK 15-15-15. Amaranthus cruentus seeds obtained from the Ondo State Agricultural Development Project were raised in the nursery and transplanted at a spacing of 10 x 20 cm into 1 x 3 meter manually prepared beds. Each manure type was incorporated by ploughing it in while preparing the bed at 600 g organic compost and 60 g NPK 15-15-15 fertilizer per the 1 x 3 meter bed respectively. Pre-treatment and post planting soil samples were taken for laboratory soil analysis of soil chemical properties for a comparison of the assessment of the cumulative effects of organic compost and inorganic fertilizer in improving soil fertility over a period of three years. The organic matter increased by 23.3% and 0.6% in the second and third year respectively in the plot treated with organic compost, while there was no such increase trend in the plot treated with 200 kg NPK/ha. The organic matter content correlated positively with the yield and vitamin C content of amaranth.

Soil microorganism is important for the restoration, sustainability, balancing of soil ecosystem and organic matter transfer. The diversity of the microbial community in soil is closely related to the functions and structure of its surrounding ecosystem. The aim of this research work is principally on the identification of microbial population under different land use types in Akure, Nigeria. The land use types were oil palm, teak plantation, unclear forest, and cassava and sugar plantations. The soil samples were collected at depth of 0-15 cm, 15-30 cm and 30-75 cm on each land use area and were taken to the laboratory for microbial analysis. Microbial analysis was carried out using the dilution spread plates techniques of identification of microbial population. The bacteria isolates were identified by morphological and biochemical characterization using taxonomy scheme of Bergey ' s manual of determinative bacteriology. The fungal isolate were stained with lactophenol cotton blue and observed under the microscope for identification. The result showed that, there are 40 different species of bacteria and 10 fungal strains isolated from all the land use types. Some of the isolated bacterial species were from phylumactinobacter, bacteriodietes, firmicutes, proteobacter and that of fungi were representatives of phylum Ascomycota and Zycomycota. The data on bacteria and fungi were analyzed using ANOVA. The means of bacteria and fungi occurrence were separated using least significance difference at 5% level. It was found that the cassava land showed higher diversity of microbial population, this might be attributed to the effect of tillage on the land year by year which enhanced the free movement of air and encourages the availability of microbial population due to the presence of some microorganism in the tuber of cassava which had a great influence on soil organic matter contents via mineralization and decomposition.

The effects of various tillage systems on soil physical and chemical properties and the yield of seed yam were investigated and compared in a research conducted in Akure (Latitude 7 0 18'N and Longitude 5 0 15'E)-Nigeria in 2008 and 2009. Three tillage systems comprising ploughing plus harrowing, ploughing plus harrowing plus ridging and manual ridging were replicated three times in a randomized complete block experimental design. Healthy yam tubers weighing about 1 kg were cut into minisetts of about 25 g, treated with a mixture of wood ash and demosan fungicide and planted in nursery made of moist sawdust. The minisetts sprouted after three weeks and at four weeks, transplanted to the field prepared under the various tillage methods. 100 kg/ha NPK 15-15-15 were applied at eight weeks after transplanting the seed yam seedlings while soil physical and chemical properties were taken at five months and the harvesting of seed yam done at six months after transplanting the seedlings. Soil bulk density was significantly high with a correspondingly lower porosity in the ploughed plus harrowing plot while the least values were observed in the ploughing plus harrowing plus ridging plot. The organic matter, nitrogen, phosphorus, potassium and the cation exchange capacity were in the medium adequate range for good seed yam growth. Bulk density was a major factor that influenced seed yam performance with the ridged plots producing lower bulk density and higher tuber weight and yield. The tuber weight and yield were comparable in both the mechanically and manually ridged plots.