Assessing combined effects of biochar concentrations and different fertilizer applications on physicochemical properties of a sandy loamy soil

Abstract

Biochar application in the soil is a major strategy for modifying or improving its physicochemical properties, while soil fertility can be boosted by fertilizer application. The process of soil amendment was explored to investigate the impact of combined biochar and fertilizer treatments on soil properties and yield of New Rice for Africa (NERICA 2) upland rice variety. A Randomized Complete Block Design experiment was conducted using three different fertilizer types, three different biochar concentrations, and two sets of control each, with zero biochar and zero fertilizer. The biochar levels were 0 t/ha, 5 t/ha, 10 t/ha, and 15 t/ha, while the fertilizer types were zero fertilizer, liquid organic fertilizer (LOF), solid fertilizer (NPK), and farmyard poultry manure (PM). A drip irrigation system with the completed layout captured the entire set-up, while soil properties were measured before soil treatment, post-season 1, and post-season 2. A significant increase in particle density from 3 3 3 3 2.51 g/cm³ to 2.56 g/cm³ was recorded while bulk density decreased from 1.42 g/cm³ to 1.41 g/cm³ , and soil textural classification remained relatively unchanged. Organic carbon, organic matter, nitrogen, phosphorus, potassium, cation exchange capacity, and base saturation increased from their respective pre-treatment values. Also, soil pH improved significantly from 6.38 to 6.37. There was a better improvement in soil properties, which resulted in increased paddy rice yield with an average value of 6.36 t/ha obtained using NPK with a biochar concentration of 15 t/ha (NPKB15) treatment. This is an equivalent of approximately 400% increase in yield compared to the zero fertilizer and zero biochar (FOBO) treatment yield of 1.14 t/ha. NPK fertilizer at a biochar concentration of 15 t/ha, gave the best result in the soil's physical and chemical properties and is recommended for rice production.