Impact of Integrated Application of Fertilizer and Compost on Soil Quality and Yield in Northern Ghana’s Cropping Systems.

Low crop productivity and declining soil quality are common characteristics of smallholder cropping systems in sub-Saharan Africa. Adoption of sustainable intensification management practices such as integrating mineral fertilizer with organic inputs (manure, compost), and maintaining crop residues can improve soil quality and nutrient use efficiency. Improved soil quality leads to increased soil biodiversity and soil carbon stock resulting in high crop productivity. A field study was set up in 2013 at Nyankpala in northern Ghana to assess how the application of organic and inorganic fertilizers affect soil health and yield of maize. The experiment was laid out in a randomized complete block design (RCBD) as a 2-way factorial treatment structure. The first factor consisted of two levels of a compound NPK fertilizer (30-30-30 and 60-60-60 kg NPK ha^-1), and control. The second factor consisted of three different levels of compost at 2, 4, and 6 Mg ha^-1 plus a control. Assessment was made on soil samples collected from the 0-15 cm depth. Parameters measured include yield (grain and stover), bulk density, SOC (soil organic C), total N, soil available P and N (NO₃-N and NH₄⁺) and phospholipid fatty acid (PLFA). Results indicated that application of compost significantly affected SOC accumulation. SOC increases with increasing rates of compost applied. However, compost application had no significant treatment effect on total N. Soil bulk density decreases at higher rates (4 and 6 Mg ha^-1 ) of compost applied. Application of 4 Mg ha^-1 of compost also yielded greater total PLFA (microbial biomass) abundance compared to the other treatments. Application of mineral fertilizer at higher rate (60-60-60 kg NPK ha^-1) significantly increased grain yield from 2013 to 2016.