A framework for evaluating benefits of organic fertilizer use in agriculture
Richard Culas, Muhuddin Rajin Anwar, Tek Maraseni
Abstract
Globally, 12 million hectares of agricultural soil are lost to degradation each year. Australia leads, with two-thirds of its agricultural land degraded, organic carbon content in heavily cultivated soils below 1 %, and a 2–3% annual decline in nitrogen (N) reserves. Research shows that organic fertilizers can restore degraded land and offer multiple environmental and financial benefits, yet organic farming adoption in Australia is under 10 %, mainly due to the lack of a framework to capture the full range of benefits. This study develops a framework to evaluate the economic viability of organic fertilizers. It analyses the use of biochar as an example for the organic fertilizers. Literature provides valuable insights into biochar's effects on soil health, carbon storage, and crop productivity. Whereas this study develops a framework to evaluate the long-term economic viability of all co-benefits from biochar application. Using the APSIM model, we then simulated the impact of biochar on soil health and farm productivity in wheat systems in Holbrook, NSW. Results indicate that (1) biochar improves soil structure, carbon storage, water, and nutrient retention, boosting productivity and profitability; (2) combining biochar with stubble retention enhances benefits compared to each practice alone; and (3) optimal biochar application rates vary by feedstock type, quantity, timing, method, soil, and crop type. The framework can be applied to other crops, both nationally and internationally, but requires APSIM model calibration for local topographic, edaphic, and climatic conditions. • Inorganic fertilizer use in Australia has been on increase over past 20 years. • Organic fertilizers can improve soil health, productivity and farm profitability. • A framework developed to evaluate the economic viability to use organic fertilizers. • APSIM simulations assessed the impacts of biochar use in wheat cropping system. • Optimal rates of biochar use can be decided by impacts and financial feasibility.