Granulated Sulfur

Question from Robin:
Hi. I have a problem and I need some advice.

I spread granulated sulfur on the top of heavy clay soil. Hindsight shows me this is not optimum, and I would like your opinion on my options. I want to establish vegetables on the site. And I had wanted to do it ASAP.

The garden is 10 x 15 feet and I spread most of a 5 lb box of sulfur “lentils.”

The following is a list of options I have thought through. I would like your opinion and suggestions.

Scrape it off and start over. (e.g. Amend with gypsum and compost.) -Removal poses safety and disposal problems. I would need advice on the best way to go about this

Till it in

• I worry that this might throw sulfur out of the garden area, endangering the dogs. (I’ve never used a tiller) I burned my hand on the dust so I’m a bit nervous.
• It will burn any earthworms under there.
• It may burn the roots of garden plants

Till it in, cover with 6” Agromend, and plant my veggies.

• any chance I can get away with this? It will still probably kill earthworms, but would the plants survive?

Scrape it off, save it, till the soil and apply properly at appropriate depth. After tilling in the sulfur, cover with 6” agromend and plant veggies.

• I feel this would be the best way if I want to grow veggies this summer, but I wouldn’t know what to save it in. Again I would need some safety advice.

The most sensible and least desirable option that I have come up with:

• Till it in, leave it till fall or next year, then establish my garden.  I’m unemployed and this was my chance to make a break from the office retrace. I want to sell at farmer’s markets to get myself known, and eventually open a nursery. This is a long time dream. I don’t want to go back to an office.

Corollary question:

Green humb carries an adorable garden boot, but will I need industrial type chemical resistant boots if I walk in this stuff? I haven’t yet stepped into the garden.

Answer from Pat:
As explained below, I don’t advocate that gardeners use soil sulfur but despite that, a five-pound box of granulated sulfur spread over a space that is ten by fifteen feet in size and then dug into the ground is not going to do any huge amount of harm. The correct proportion of soil sulfur to garden soil (if one were to add it) is 5 pounds for 1,000 square feet twice a year. (This is supposed to bring down the base of calcium in the soil and raise magnesium.) It would do more harm to the environment for you to scrape it off and dump it. I doubt also that it is going to kill earthworms since you are digging it into soil that I presume you already know is alkaline. Add plenty of organic matter into the ground and as mulch on top and you’ll get any number of earthworms. Also, once you have combined the sulfur with the soil, the alkalinity in the soil will neutralize the acid in the sulfur. That is a backwards way of saying the whole point of adding soil sulfur is to create a less alkaline condition in the soil. Your best option since you’ve already spread the sulfur is to dig it into the top foot or more of the ground. It will gradually combine with the soil over the years as you dig and amend your garden soil with organic matter twice a year prior to seasonal planting spring and fall. You could, however, rake it up and dig it into the ground in another part of the garden where you are not planning to plant seeds, but I really don’t think this is necessary.

You mention that you don’t use a tiller but amending the soil includes first spreading on the amendments and then using a garden fork or a garden spade and turning the soil over to combine ingredients into it. One does not need a tiller to do this, one just needs a sharp spade or garden fork and strength like I once had and don’t have any longer. Or you need a willing workman to do the job for you. Either that or become a “No Dig” gardener, but in that case never use anything like soil sulfur that has to be combined with soil in order to work.

Companies make granulated sulfur because it is considered safer for the environment than liquid sulfur which is a by product of some industries. Soil sulfur is a mined product, a natural mined element that comes from the earth. Sulfur is acid, not alkaline, and sometimes farmers add it to soil to try to correct problems with alkalinity. Soil sulfur differs from dusting sulfur. Dusting sulfur is one of the most ancient garden products. It has been used by mankind for thousands of years for dusting onto plants to kill some insects and plant diseases, such as mildew and blight. (American Indians dusted sulfur onto plants long before the white man discovered the New World.) Soil sulfur is sold by some nurseries as an acidifier for alkaline soils.

Despite all this, I do not advocate the use of soil sulfur by the home gardener for the purpose of acidifying soil. Instead, I have always felt the best way to acidify garden soil when necessary is to work in acid organic soil amendments, such as wood shavings. The main reason that I don’t recommend the use of soil sulfur for soil acidification is not so much because it’s dangerous, but more because it doesn’t work. In order to have soil sulfur work one would have to work it into the soil so that it is evenly distributed and so each grain of sulfur actually contacts individual particles of alkaline soil and then it also takes time to work, so you would have to keep it up twice a year. For example, simply spreading sulfur on top of the ground around camellias and azaleas and hydrangeas and then watering it in, as some gardeners have done, won’t work because sulfur doesn’t water into the ground that way.

You should also be careful not to breath sulfur into your lungs and you should use protected clothing, including gloves, when handling it. Also, soil sulfur can sometimes inhibit seeds from sprouting rather like corn gluten meal does but this action won’t last forever. It’s temporary.

Please refer to the pages at the beginning of my book for ways to treat alkaline soil, such as clay and for ways in which you can improve clay soil and make it drain better. Yes, gypsum is a harmless and helpful addition if your clay soil is compacted due to its alkalinity. (Please refer to other discussions about gypsum on this site.) Also, there is no better way to make clay soil drain than mixing in a layer of well-composted organic matter and keeping it up throughout the years.