Impact of formulated organic fertilizers on soil physical and chemical properties in sandy loam soil of North-Eastern Nigeria

The excessive and sole use of inorganic fertilizers has led to soil nutrient depletion, acidification and loss of soil organic matter. Decreased organic matter content reduces the soil's ability to hold water and nutrients, which can lead to reduced crop yields. Organic fertilizers provide a slow release of nutrients to soil while at the same time improving soil health and reducing the risk of soil degradation. Hence, there is a need to investigate the impact of formulated organic fertilizers on soil physical and chemical properties in the study area. The study site is in the Teaching and Research Farm, Yobe State College of Agriculture, Science and Technology Gujba, Damaturu, Yobe State. Its geographic coordinates are 11.7461° N, 11.9608°. The study area is approximately twenty hectares while the size of land for the experiment was approximately two hectares. The soil analysis conducted revealed varying levels of nutrients. Nitrogen (N) ranged from 0.11 to 0.20 g/kg-1, indicating medium fertility. Phosphorus (P) levels ranged from 0.17 to 0.19 g/kg-1, indicating signifying low fertility, while potassium (K) varied from 0.46 to 0.89 g/kg-1, indicating high fertility. Copper (Cu) levels ranged from 0.67 to 0.85 g/kg-1, suggesting medium fertility. Zinc (Zn) ranged from 0.55 to 0.38 g/kg-1, indicating medium to low fertility, particularly in deeper soil layers. Iron (Fe) ranged from 0.53 to 0.01 g/kg-1, categorized as medium to low fertility. Manganese (Mn) ranged from 0.11 to 0.04 g/kg-1, showing low fertility levels insufficient for optimal agricultural production. Despite minor improvements post-application of organic fertilizer, overall fertility ratings remained largely unchanged. The study highlights the heterogeneous distribution of nutrients in the study area, emphasizing both strengths and deficiencies crucial for agricultural productivity.