In the case of lime, winter application is fine

Q. My soil test results say to add urea and sulfur. Can I add both at the same time? Can I still do it this late?

Becky from Cortland

A. Great question! In general, you can apply either lime (to raise the pH) or sulfur (to lower the pH) this late in the year. It takes both of these substances up to one year (and sometime longer) to change the pH of the soil.

In the case of lime, winter application is fine. The most important factor is contact with the soil. Our generally wet soils in the winter allow for contact with the soil and get the process working.

Those of you using wood in the fireplace can use your wood ashes for lime (only if recommended based on a soil test). Be careful of over-application.

When it comes to sulfur, we are dealing with a completely different situation. First, we recommend “elemental sulfur” or “soil sulfur” or a related name for the product you should purchase. We used to recommend aluminum sulfate, but not anymore. Soil sulfur comes in the form of pellets, powder or granules.

Sulfur does not work in the same manner as lime. Sulfur requires soil bacteria to aid in the conversion to sulfuric acid, thus lowering the pH of the soil. These bacteria are most active when the soil temperature is above 55‚∞degrees. Also, the effect of some of the sulfur is lost when the sulfur sits in saturated soil. Thus, winter is not the best time to apply.

Your best bet is to have the powder form of sulfur and wait until spring to apply the product. It will still take time for the pH change to happen.

When it comes to fertilizer, your best bet is to wait until it is time to incorporate the fertilizer. This is either at tilling or planting in spring.

If the soil test calls for nitrogen (in this case in the form of urea), the best time for applying nitrogen in a home garden is at planting and during the time of plant growth. A rule of thumb is to not apply a liming product and nitrogen fertilizer at the same time. If you need both, you should apply them at least a few weeks apart with at least one rain event between the applications.

To learn more about changing the pH of your soil, go to: http://go.osu.edu/changeph

Eric Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County. Call the office hotline at 330-533-5538 from 9 a.m. to noon Mondays and Thursdays to submit your questions.