Enhancing Growth Conditions for Maize and C.calothyrus via Functionalized and Cross-linked Cow-dung Biochar Application

Abstract

Water is a fundamental component in maintaining the plant posture, essential for photosynthesis, and protects the plant against temperature changes. Water scarcity is often linked to food insecurity, particularly in arid and semi-arid regions. Mulching mitigates water loss during plant growth. Mulching materials such as dry grass, hay, and sawdust have low water retention time, which informs the need to enhance the material’s water retention capability.  This can be enhanced via chemical functionalization and cross-linking of mulching materials. Large amounts of biogas slurry generated from cow dung during biogas production remain a persistent challenge for many biogas reactor operators, yet it is a potential source for agricultural use. Cow dung in this study was obtained from a cattle farm in Thika in Kiambu County. It was turned to biochar via gasification and then functionalized using phosphoric acid and subsequently, cross-linked with urea to make a hydrogel biochar mulch. The chemically modified biochar was tested for its degree of water retention by comparing the water retention of mulched and non-mulched maize and Calliandra calothyrsus trees. This was carried out in Makuyu ward, Maragua constituency in Murang’a County, a semi-arid area. Maize was grown for two seasons using a randomized block design, and growth and yield parameters were monitored periodically. The functionalized biochar yielded significantly higher weights (Fcal 2.74 in the second season compared to the first season). A significant change in width, length, and height was noted with (F_cal.1.2 (F_cal.7.0 , and (F_cal.8.5  respectively in the second season as compared to the first season. Based on these findings, the chemically modified hydrogel biochar was confirmed to have enhanced performance and has potential for improved agricultural performance if adopted for use in arid and semi-arid areas in Kenya.