Comparative effects of poultry and cow dung-based composts on soil pH, organic matter, and macronutrient dynamics in a tropical sandy loam

Luxuriant crop development, especially in leafy vegetables, is strongly influenced by soil pH, organic matter, and macronutrients (N, P, K, Ca, and Mg). However, tropical soils are often deficient in these fertility indicators due to repeated cultivation without proper soil management or restoration. To maintain adequate organic matter content and improve soil nutrient status, research into organic soil fertility restoration strategies has become essential, particularly since inorganic fertilizers are often expensive, scarce, hazardous, and environmentally unfriendly. Cow dung/sawdust (CDS) and poultry dung/sawdust (PDS) have been the primary composting materials used. Therefore, this study aimed to investigate the effects of CDS and PDS composting on their chemical properties, as well as their impact on selected soil chemical properties. The compost mixtures were separately prepared and composted for 22 weeks at an ambient temperature of 24°C. Temperature changes were recorded fortnightly before watering. Samples from the compost heaps were chemically analyzed at the second and twenty-second weeks. Subsequently, the composts were incubated with soil at a rate of 30 t/ha for 16 weeks under room temperature. Soil pH, organic matter, and macronutrients (N, P, K, Ca, and Mg) were evaluated at 4, 8, 12, and 16 weeks of incubation. Temperature profiles showed higher readings in the CDS heap, suggesting faster composting. At 22 weeks, both composts showed improved chemical properties, with CDS recording higher values across most parameters. During incubation, soil pH, organic matter, N, P, and K increased steadily, indicating ongoing mineralization, whereas Ca and Mg contents declined. Both composts demonstrated potential to increase soil pH, organic matter, and macronutrient levels. However, PDS-treated soils showed greater mineralization of organic matter and macronutrients, making poultry dung/sawdust compost more effective for soil maintenance, fertility restoration, and sustainable crop production.