Properly Using Slow-Release, Sulfur-Coated Fertilizer
On Your Lawn

Spring has sprung in this part of Texas-or so many people believe! Tomato and pepper plants have been planted, fruit trees are in full bloom and folks are anxious to re-sod lawns and fertilize everything that's living.

From now until April 1- NEVER de?thatch your St. Augustine lawn. Instead, trim it back to 1/2 to 1/3 its current height. (This could be called scalping but that term is more hostile than trimming.) Do not collect the dead clippings. Let them remain as a source of organic material and, eventually, recycled fertilizer. Our landfills don't need any more grass-filled plastic bags occupying much needed and diminishing space. (Hybrid Bermuda turfs can be de-thatched if needed.)

On April 1-after you have probably mowed your grass twice (although you may have mowed the lawn weeds numerous times!), apply a slow-release fertilizer, such as 19-5-9, 20-7-7, 21-7-14, 25-3-5 or 22-3-3, 20-5-10, and 15-5-10. Why use a slow-release or sulfur?coated fertilizer instead of just regular fertilizer? Slow-release or sulfur-coated fertilizer is controlled-release fertilizer made possible by coating nitrogen and other plant nutrients with molten sulfur in varying thicknesses to allow turf feeding for 10 weeks. Regular, fast-release fertilizer doesn't last much longer than 30 days.

Nutrients of slow-release fertilizer become available when the coating degrades to expose them or when nutrients diffuse through small pores in the coating. If all sulfur-coated fertilizer particles were identical, the release of nutrients would occur at the same time for each particle. Fortunately, coatings are not the same on all particles.

Particles with thin or imperfect spots in the coating, which are covered by the sealant, have quick to moderate release rates. The longest delay in release comes from the thicker-coated particles with no imperfections. Thus, it is the variability in the particles that provides the sustained release of nutrients from slow-release or sulfur-coated fertilizer.

The exact feeding duration of slow-release or sulfur-coated fertilizer depends on the dissolution rate of the product. The 7-day dissolution rate is a laboratory measurement of the percentage of nutrients that go into solution when a sulfur-coated fertilizer sample is placed in 100 degree F. water for 7 days. It is used to indicate the relative rate of nutrient release. As the coating thickness increases, the dissolution rate decreases. Basically, 1/2 of the nutrients in slow-release or sulfur?coated fertilizer release is in the first month, and the remaining 50 percent is released over the next 6 weeks.

As temperature increases, the release rate increases. Release rate is not greatly affected by soil water, soil pH or microbial activity. Slow-release or sulfur?coated fertilizer lasts longer, so fewer applications are needed to maintain uniform quality turf. Use of slow-release or sulfur-coated fertilizer reduces the risk of fertilizer burn and decreases the loss of nitrogen through leaching and volatilization (changes to gas). Fewer applications and decreased nutrient loss means greater product efficiency, which more than justifies the higher cost of slow?release fertilizer. The sulfur of slow?release or sulfur?coated fertilizer remains after it is oxidized to the sulfate form. The oxidization from sulfur-coated fertilizers falls between the fairly rapid oxidization of powdered sulfur and the slow oxidization of granular sulfur.

So why should you use slow-release or sulfur-coated fertilizer on your lawn? It has the following advantages:

1) It makes more nitrogen available as a nutrient to the plant.

2) It resists leaching or washing through the soil into the water supply.

3) It decreases the risk of fertilizer burn associated with heavy
applications of conventional fertilizers.

4) It minimizes surge growth and reduces excessive clipping production
when mowing. This, in turn, eliminates the necessity of bagging
clippings if mowing occurs every 5 to 7 days.

5) It releases independently of microbial and bacterial action.

6) It offers controlled-release feeding for 10 weeks.

7) It provides sulfur as a plant nutrient.

8) It stimulates a more drought tolerant grass which only requires one
thorough watering once a week.

9) It reduces the occurrence of brown patch fungus. Excessive
amounts of fast-release fertilizer stimulate lush grass growth which
predisposes turf to brown patch fungus.

On or around July 15-if the greenness of the lawn is fading and the area is not in the grip of a severe drought, make a second application of slow-release or sulfur-coated fertilizer. Since the first application was made on April 1, and because the fertilizer only lasts 10 weeks, your turf will be out of nutrients by then. The July 15 fertilization will last for another 10 weeks or until the first of October. This will be the ideal time to apply the winterizer fertilizer ratio of 3-1-2 (15-5-10, 18-6-12) or 4-1-2 (20-5-10, 16-4-8). Slow?release or sulfur?coated fertilizer SHOULD NOT be used for fall feeding because grass needs immediate availability and uptake of nutrient elements so that the winterization can occur. Besides, the grass will be dormant in less than the 10 weeks that the slow-release fertilizer types would be coming available.

So, there is your lawn maintenance outline which will insure beautiful green grass with a minimum amount of effort and resources.