They found that when soils were dry, very little diffusion occurred away from the site of application, and the P interactions with soil were negligible. This resulted in phosphorus remaining relatively unchanged and still in a plant-available form.
Another key finding was that granular sources resulted in higher amounts of available P compared with liquid P sources. However, when soils were wet, both granular and liquid P fertilizer experienced significantly more diffusion away from the application site and much more interaction with the soil. Consequently, when applied in wet soils, neither source differed in labile P.
These results show that there can be a distinct difference in how much P is soil available, based on which form is applied into dry and wet conditions. Keeping this research in mind can go a long way towards helping growers maximize their investment in P fertilizer.