Effects of Different Biochars and the Impact of Heavy Metals on Growth and Yield of Amaranthus at Zagyuri Irrigation Field Tamale, Ghana

Background and Objective: Vegetables are essential for human health, but in Northern, Ghana limited due to scarcity of water for irrigation. The study aims to determine the effects of different biochar wastewater filtrates on chlorophyll content, growth, yield parameters and heavy metal remediation of Amaranthus under pot cultivation in both rainy and dry seasons. Materials and Methods: The study employed a randomized complete block design with three replications. The treatment combinations consist of eight levels of treated wastewater, groundnut husk biochar produced in open field conditions, wastewater and pipe borne water, rice husk biochar and groundnut husk biochar both pyrolyzed at 400 and 600°C. The wastewater was prefiltered by corn cob biochar to reduce suspended solids and turbidity. The wastewater and pipe water were added as controls. Amaranthus (Amaranthus cruentus) was used as a test crop. Results: The studies revealed that high levels of contamination in the WW (wastewater) and soil reduced the vegetative growth parameters (leaf number, leaf area and chlorophyll content) of Amaranthus for both seasons even though the nutritional composition of the WW was observed to be higher than what was observed in the other irrigated source. Generally, filtrate from groundnut husk biochar pyrolyzed at 600°C resulted in the highest growth and yield parameters as well as reducing cadmium and lead in Amaranthus leaves for both rainy and dry seasons. Conclusion: This study recommended that the use of groundnut husk biochar(s) should be adopted in remediating wastewater to minimize the adverse effects of cadmium and lead on Amaranthus.