Phosphorus fertilizer application to crops is generally based on soil test P levels. However, the routine soil tests only measure the readily available P pool, which makes a small fraction of total soil P (<10%). We suspect that the contribution of inorganic and organic P to meet crop P demand is much more pronounced and only determining readily available P pool is not sufficient to develop P fertilizer recommendations. Furthermore, it is unclear how different P application rates or P sources have changed the soil P pools over the years to meet crop needs. The overarching goal is to refine the P fertilizer recommendations by a comprehensive overview of P needs of crops and P supplying capacity of soils.
The study includes soil sampling from different long term inorganic P fertilizer trials and sites receiving organic P application. Soil samples are being analyzed for total P, labile P, and non-labile P pools of soil. The experiment is also evaluating P saturation of soils under different P management scenarios.
Project Timeline: 2024 to 2025
Funding Source: Ohio Soybean Council
