Effects of biochar and poultry manure on soil characteristics and the yield of radish

Studies on the effect of biochar and poultry manure on soil properties and radish productivity is rare, hence, field experiments were conducted over two years, 2015 and 2016, to evaluate the effects of biochar (B) and poultry manure (PM) on soil properties, leaf nutrient concentrations and root yield of radish (Raphanus sativus L.). Each year, the experiment consisted of 3 × 3 factorial combinations of biochar (0, 25 and 50 t ha−1) and poultry manure (0, 2.5 and 5.0 t ha−1). Application of B and PM alone, and in combination, improved soil physical and chemical properties, leaf nutrient concentrations and yield components of radish. In 2016, the application of B alone increased the soil pH and concentrations of organic matter, N, P, K, Ca and Mg, as well as leaf nutrient concentrations and yield of radish, but in 2015 it only increased soil pH and organic matter and not leaf nutrient concentrations and yield. In both years, the application of B significantly influenced the root length of the radish. In both years, there was a significant interaction effect of biochar and poultry manure (B × PM) and this was attributed to the ability of the B to increase the efficiency of the utilization of the nutrients in the PM. The combination of 50 t ha−1 B and 5 t ha−1 PM (B50 + PM5) resulted in the highest radish yield. Averaged over the two years, (B50 + PM5) increased the root weight of radish by 192, 250 and 257% compared with biochar alone at 50 t ha−1, biochar alone at 25 t ha−1 and no application of B or PM (control). Therefore, for a short season crop like radish the expected benefit of the biochar alone without the addition of poultry manure may not be achieved within the first year.