TYPE OF IRON
After examining the chart to the right, it may seem most appealing to use the iron fertilizer with the highest percentage of Fe, but that is not necessarily the case. Let’s break it down and figure out which iron fertilizers are best for plant and turf health.
IRON SULFATES (FERROUS SULFATE, FERRIC SULFATE)
Iron sulfates are some of the more commonly used granular iron fertilizers in the market. Many iron sulfate fertilizers contain ferrous iron sulfate which is more readily available for the plant than ferric sulfate fertilizers (which are dependent on soil pH). For example, if the soil is alkaline, the iron sulfate in the iron fertilizer will convert to an unavailable form of iron. It’s more beneficial to apply ferrous iron over ferric iron fertilizers. Staining may occur on concrete if not swept away after application, especially during wet conditions.
IRON SUCRATE (FERRIC SUCRATE)
Another well-known granular iron fertilizer, iron sucrate is produced by combining iron oxide with sugars. This type of iron has limited water solubility so it is less prone to staining. This fertilizer is desirable for areas that have large potential staining areas. Compared to iron sulfates, iron sucrates are less prone to staining when quickly swept off concrete.
IRON OXIDES (FERROUS OXIDE, FERRIC OXIDE)
Iron oxides present some of the highest percentages of iron. It may seem logical to choose any one of these as an iron source for turf, however iron oxide is completely unavailable for plant uptake above a pH of 6.0.