Particle Size of Biochar as Co-composted Fertilizer: Influence on Growth Performance of Lettuce and Concentration of Bioavailable Soil Nutrients under Salinity Stress Conditions

Abstract

This pot-based study investigated the influence of co-composted wood-derived biochar on lettuce growth performance under salinity and drought stress conditions. Biochar of two particle sizes; > 2 mm and < 1 mm were co-composted with the mixture (1:1 ratio of dry weight) of cow and poultry manures. Co-composted biochars were applied at 5% and 7% rates in soil. Control treatments included the amendment of mixture of biochar with manure in soil. Pots were subjected to slight drought (48-55% water filled pore space (WFPS) of soil) and non-drought conditions (60% WFPS) and under 0 and 1.3 dS m-1 salinity. Results revealed that plants growth performance was significantly better under treatments of co-composted biochar and no salt stress conditions, than when mixture of biochar and manure was applied to soil as non-composted fertilizer. Under no stress condition, small particle-sized co-composted biochar increased root biomass by 786.2% than the large particle-sized co-composted biochar at same application rate. As compared to large-sized co-composted biochar, small sized co-composted biochar at high application rates increased root biomass by 167 – 245% but not leaf biomass under both stress conditions. Small particle-sized co-composted biochar amendment also increased the phosphorus use efficiency (PUE) of lettuce leaves than large particle-sized co-composted biochar under no stress condition. The amendment of small-sized co-composted biochar also increased significantly the concentration of Olsen phosphorus in soil than the amendment of large-particle-sized co-composted biochar. In conclusion, amendment of small particle-sized co-composted biochar has the potential of attenuating salinity and drought stress in lettuce and promoting P cycling in soil.

Biochar-based compost: a bibliometric and visualization analysis

“…The combined co-application of biochar and compost to agricultural soils has been increasing in research trends, including the application of co-composted biochar as a final product from the addition of biochar to raw composting materials for plant growth and improved soil quality [ 24 ; 25 ], and for the treatment of soils polluted with inorganic and organic contaminants [ 26 ; 27 ]. The increased attention is due to the favorable physicochemical properties [ 28 ], and biological properties [ 29 ; 30 ].…”