The Combine Effect of Grasscutter (Thryonomys swinderianus) Manure and NPK Fertilizer on Soil Properties, Growth and Yield of Carrot (Daucus carota)

The use of inorganic fertilizer to produce most vegetables in Ghana like carrot is in ascendency in Asante Mampong and its environs and its continuous use has a rippling effect on soil health and productivity and the high cost of these fertilizers is a challenge to most poor resourced farmers in Ghana. A field experiment was conducted during the major raining season in 2010 at the University of Education Winneba, Faculty of Agriculture Education research field at Mampong in the forest-transitional zone of Ghana on the Bediase series. The objective of the study was to evaluate the effect of grasscutter manure in combination with NPK fertilizer on soil physical and chemical properties, growth and yield of carrot. The treatments were 300 kgNPK/ha, combination of half rate NPK fertilizer and different rates of grasscutter manure (GM) thus; (5tGM1/ha+150 kgNPK, 7.5tGM2/ha+150 kgNPK and 10tGM3/ha+150 kgNPK/ha) and control (without amendment) and the experiment was laid out in a randomized complete block design with 3 replications. Results indicates that application of grasscutter manure in combination with NPK fertilizer significantly improved the soil physical conditions particularly, soil bulk density, total porosity, and gravimetric moisture content than the NPK alone and the control. Compared with the control, the treatment combinations significantly increased soil organic carbon, N, organic matter concentrations and exchangeable cations. Plant height, number of leaves, tap root length and root yield of treatment combinations were higher than NPK and the control. Also the treatment combinations significantly reduced nematode presence and number of roots deformed. For good soil health, grasscutter manure in combination with NPK would be better than either manure or NPK alone.