Short-term effects of biochar and cake fertilizer on soil properties, plant growth, and fruit quality of Nanfeng tangerine

The acidic soil induces detrimental influences on citrus growth and development, which could be ameliorated using organic amendments, such as biochar and organic fertilizer. However, beneficial effects of biochar on fruit-bearing citrus orchards remain unknown. Here, we conducted a field experiment to compare the effects of biochar (B), cake fertilizer (CF), and their combined (B+CF) application on physicochemical attributes of soil, growth performance and fruit quality of Nanfeng tangerine during a one-year sampling period. Results revealed that soil pH, organic matter content, and available N and K concentrations were increased by B, CF, and B+CF applications. These applications also caused significant changes in microbial counts. Moreover, plant growth was largely improved by application of B and CF alone, and particularly by B+CF combination. This was further supported by the observation that the three applications increased leaf nutrient concentrations of Nanfeng tangerine. Additionally, fruit size and mastication characteristic were improved by B, CF, and B+CF applications. Increases in soluble sugars (fructose and glucose) and decline in citric acid content were observed in CF and B+CF treated fruits. Vitamin C content increased, and the highest value was recorded for the CF applied treatments. Overall, this investigation shows the potential and role of biochar with cake fertilizer in enhancing the growth and fruit quality of Nanfeng tangerine as well as an improvement of soil properties. This is a preliminary investigation of the phenomenon, and further studies may focus on field applications in long-term experiments.