Content and potential availability of selected nutrients in field-applied sugar beet factory lime

Factory lime generated during sugar beet processing contains phosphorus (P). Factory lime collected from seven sugar beet factories in North Dakota and Minnesota had P concentrations ranging from 3470 to 7043 mg P kg^-1. Soil collected from two field trials one and two growing seasons after factory lime application was analyzed for pH changes and soil-test P (STP). At one site, soil pH increased after both growing seasons, as did STP, indicating a continued release of P as the factory lime dissolved and reacted with the soil. At the second site, increased soil pH and STP were evident after one growing season, but a few months later the pH had no further change and STP decreased. The data suggest factory lime has the potential to supply P to a growing crop, but actual proportion of P available from the factory lime could not be quantified from these experiments.