Availability of phosphorus in calcium silicate slag

Significant yield increases of sugarcane and rice have been observed in the Everglades Agricultural Area of Florida from application of soluble silicon as calcium silicate slag. Although calcium silicate slag contains trace quantities of P, significant quantities of P can be applied using commercial rates of slag. This may be of concern to both the agronomists responsible for determining P fertilization rates for these crops and to land managers attempting to limit the application of P in this region. The objective of our research was to determine the biological availability of P applied as calcium silicate slag. Two sugarcane studies and two rice studies were conducted on a Terra Ceia muck (Euic, hyperthermic Typic Medisaprist), Pahokee muck (Euic, hyperthermic Lithic Medisaprist), and a Okeelanta muck (sandy or sandy‐skeletal, siliceous, euic hyperthermic Terric Medisaprist) at five locations for one to three years each. Calcium silicate slag was applied at rates ranging from 0 to 20 Mg ha‐1. F...