Improving leaf chemical composition, yield, and fruit quality of Valencia orange trees through biochar soil application.

Biochar represents carbon rich material product obtained from pyrolyzing biomass and has been postulated to enhance soil health and agricultural productivity. This study examined the effect of amending the soil with biochar on yield as well as the physical and chemical properties of Valencia oranges. A control (no biochar) (T1), biochar applied at 2.0 (T2), 4.0 (T3), and 6.0 (T4) kg/tree/year were among the treatments used in a field experiment. Results showed that, when compared to control, biochar significantly (p < 0.05) increased leaf nutrient content in terms of N, P, K, and total chlorophyll content of leaves. The effect was strongest at the highest application rate of 6 kg/tree/year (T4). Biochar treatments also enhanced physical properties of fruit; the most marked improvements again being observed in T4. Yield was observed to increase progressively with increased biochar application rates. In the first year, yield increases over control were 52.9% in T2, 69.0% in T3, and 73.3% in T4. For T2, T3, and T4, the corresponding increases in the second season were 47.7%, 59.9%, and 67.9%. Biochar application also improved fruit chemical properties. Therefore, it was demonstrated that biochar could be utilized as a significant soil amendment to enhance Valencia orange production by increasing the soil's nutrient availability, increasing leaf chlorophyll content, fruit physical attributes, and ultimately fruit yield. In conclusion an application rate of biochar at the rate of 6 kg/tree/year is recommended for fulfilling the productivity of Valencia orange orchards.