Effect of biochar application rates on soil properties and growth of Amaranthus caudatus

Abstract This study examined the impact of varying biochar application rates on soil characteristics and the growth of Amaranthus caudatus in Ghana. Corn cob biochar, produced at a temperature of 550 °C, was applied at different rates (0, 2.5, 5.0, 7.5, and 10.0 t/ha) in a Randomized Complete Block Design with three replications. The findings demonstrated a notable enhancement in soil characteristics as the biochar application rates increased. The soil pH rose from 5.45 in the control group to 6.16 with the application of 7.5 t/ha. The 10 t/ha rate resulted in a significant increase of up to 24.3% in organic carbon content. The 10 t/ha treatment resulted in a 60% rise in total nitrogen, whereas accessible phosphorus exhibited an 80% increase. The water retention ability was significantly enhanced, with the application of 7.5 t/ha resulting in the greatest increase (11.7% compared to 10.8% in the control). Biochar application had a favorable impact on plant growth metrics. The application of 10 t/ha resulted in the highest plant height, measuring 17.17 cm, which is a 100% increase compared to the control group. The 7.5 t/ha treatment had the highest number of leaves, with 11.54 leaves, representing a 15% increase compared to the control. The stem circumference also increased, with the application rate of 7.5 t/ha resulting in the widest stems measuring 21.1 mm. The application of biochar significantly increased the yield of fresh matter in Amaranthus caudatus. The 10 t/ha rate resulted in the highest yield of 1722 kg/ha, closely followed by the 7.5 t/ha rate with a yield of 1676 kg/ha. These rates showed yield increases of 183 and 176% respectively, compared to the control yield of 608 kg/ha. This study showcases the capacity of biochar to enhance soil fertility and increase crop yield in tropical soils when used as a soil supplement. The findings indicate that applying biochar at rates ranging from 7.5 to 10 t/ha could be the most effective in improving soil characteristics and promoting the growth of Amaranthus caudatus in comparable circumstances. The consequences of these discoveries are significant for the sustainable management of soil and the security of food in tropical countries.