Phosphates

Rock phosphate is the raw material used to manufacture ICL phosphate fertilizers. The rock phosphate comes from the fossilized remains of ancient marine life found in rock deposits, which is mined. This rock phosphate is processed to create water-soluble compounds that make the phosphorus available to plants as a nutrient.

In the manufacturing process, the phosphate rock is treated with sulfuric acid to produce SSP or phosphoric acid to produce TSP. SSP has less P content, but contains also sulfur and calcium, making it an excellent source of three plant nutrients. The presence of both sulfur (S) and calcium in SSP can offer an agronomic advantage where both nutrients are deficient. TSP has the highest P content of P fertilizers that don’t contain nitrogen (N), and also contains 15% calcium (Ca), providing an additional plant nutrient.

Phosphorus helps early plant health and root growth and plays a role in seed germination to ensure plants use water efficiently. Phosphorus provides the energy a plant needs to grow.

Small leaves take on a reddish-purple tint; leaf tips look burnt and older leaves become almost black. Stunted growth and poor rooting are also observed when P is deficient. Since phosphorus is mobile within the plant, deficiency symptoms appear on lower and older leaves first.

There is a process called phosphorus fixation which involves making the phosphorus unavailable to the plants. When P fertilizer is applied to the soil, it becomes less soluble in soil because it transforms to forms that are an inherent part of the soil. The degree of fixation is regulated mainly by soil pH. Maximum phosphorus availability occurs between a soil pH of 5.5 and 7.2. Below this level, insoluble compounds of iron, aluminum and manganese phosphates are formed. At a pH above 7.2, calcium phosphates form as less soluble compounds.