Effect of Sulfur and Molasses Added to Phosphate Rock on Solubility and Phytoavailability of Phosphorus on Young Orange Tree.

Effect of added sulfur on phosphate rock solubility and

phytoavailability of phosphorus to citrus plants

De Oliveira, L.M.^, R.S. Mylavarapu, G. Means and F. Bortolozo

¹Soil and Water Sciences Department, IFAS University of Florida, Gainesville-FL 32611 (USA); e-mail: letuziamo@ufl.edu

 

Healthy root systems are critical to plant growth and productivity for ensuring optimum yields and quality. Root characteristics such as mass and distribution may significantly be affected among other aspects by the volume, pH and drainage in container grown plants along with nutrient sources and amendment combinations. A greenhouse study was conducted to determine the effects of 5-0-7 fertilizer blend (F), Agricultural Carbon Source (ACS), and elemental sulfur (S) added in combinations on plant and root growth compared to control using 3-month old citrus (var. Hamlin) as test plants grown in standard container media mix in 57 liter pots. The treatments were applied every two weeks for a total of five applications. Root samples were collected starting 2^nd application for four times and analyzed for the nutrients. The root mass started differentiating after the first 4 weeks and by the 10^th week, the root growth has stabilized with the highest root mass recorded in plants that received any S followed by F with and without ACS. Evidently, gradual acidification with S application aided slow release of P from the rock phosphate, a typical ingredient in any container media mix. While the presence of ACS along with S generally improved the root mass, ACS was not found to be necessarily critical in these container media mix. This is possibly because of adequate organic matter in the media mixes. 

Keywords: root mass, elemental sulfur, container media mix, rock phosphate