A large amount of research has been done on phosphorus (P) dynamics in soils in the Eastern United States. However with differences in soil chemistry in the Western United States it is unknown how much of this information would apply. Currently we are working on several studies to investigate the changes in soil P during the growing season, and how much of the P supplied by biosolids is available to plants.
To investigate the changes in soil P over time 4 irrigated corn fields were sampled every two months during the growing season. The samples were then analyzed for 5 different forms of inorganic P and 9 forms of organic P. The data will then be analyzed to determine how soil P was moving between the different pools. A similar study was also conducted under dryland conditions for winter wheat.
A greenhouse study is also being conducted that is looking at how much P is taken up by sorghum sudan grass from different amendments (3 biosolids, raw manure, and composted manure) at varying rates of application. We are comparing the uptake of P from these 3 amendments to unfertilized soil, and soil fertilized with inorganic P. The plants are being harvested approximately every 21 days. The soil and plant samples are then analyzed to look at the changes in P concentrations.
This research is being funded by Metro Wastewater Reclamation District and Littleton Englewood Wastewater Treatment Plant.