Enhancing Soil Fertility of Apple Orchard through Biochar and Fertilizer Amendments: A Soil Aggregation Study

Abstract

The declining productivity of apple trees can be attributed to the adverse effects of unbalanced climatic conditions and dynamic soil properties. Addressing these challenges through sustainable agricultural practices is crucial to improving apple orchard productivity and ensuring a resilient agricultural system. To enhance the function of fragile ecosystem services, the addition of biochar at an appropriate rate along with chemical fertilizers (NPK) is considered an efficient approach for improving apple trees productivity. The treatments combinations were 0 t ha^-1 (Ck), 4 t ha^-1 (T1), 8 t ha^-1 (T2), 12 t ha^-1 (T3), 16 t ha^-1 (T4), and 20 t ha^-1 (T5). Our results demonstrated that, biochar addition rate in the T5 significantly increased macro-aggregates (WSAs > 0.25 mm), mean weight diameter (MWD) and therefore decreased micro-aggregates (WSAs < 0.25 mm) compare to the control. Soil organic carbon (SOC) and total nitrogen (T.N) in both the bulk soil and water stable aggregates (WSAs) showed similar and an increased trend with biochar addition rate. However, the trend of C:N ratio was in opposition with biochar addition rate for both the bulk soil and WSAs. Additionally, biochar addition rate (T5) significantly intensified partitioning proportion (%) of the SOC, and T.N in WSAs > 0.25 mm, and WSAs < 0.25 mm and therefore showed non significance differences for the others treatments. Such a partitioning proportion of the WSAs 0.5-0.25 mm were lower than the WSAs > 0.5 mm and WSAs < 0.25 mm. These results suggested that biochar addition rate (T5) with chemical fertilizer had a significant effect on the stability of aggregates associated SOC, T.N, and C:N ratio and it may also have a capability in optimizing partitioning proportion (%) of the SOC and T.N in WSAs > 0.25 mm. Thus, it is therefore suggested that biochar addition rate (T5) with chemical fertilizers is the best preference for the stability and optimization of the aggregate associated SOC and T.N which may enhance partitioning proportion (%) of the SOC and T.N in an apple growing soil.