QUESTION: I am researching the purchase of a diesel vehicle and have learned about the uses of biodiesel fuels. Are you aware of any places where this fuel is available to the general public in the Atlanta area?

ANSWER: I am aware only that the Georgia Building Authority has reportedly been using B20 (blended biodiesel fuel) for two years in downtown Atlanta. They also make it available to other Georgia state agencies.

- John Goodrum
UGA agricultural engineer

QUESTION: What effect will adding inorganic nitrogen have on the rate of organic matter breakdown in a newly constructed compost pile with a C:N ratio of 75:1?

ANSWER: First of all, how do you know you have a ratio of 75:1? If it's truly 75:1, the ratio needs to be brought down to 30:1 or thereabouts. What happens with composting is that the microorganisms usually have plenty of carbohydrates for eating but lack nitrogen for reproduction and energy use. Without the N, they just don't function well, and the whole process slows down. The usual rule of thumb: for three large bags of leaves, use about 1 cup of ammonium nitrate. The nitrogen will just reduce the ratio to where it should be for best composting.

- Wayne McLaurin
UGA horticulturist

QUESTION: Could you please tell me how to receive the special box needed to send a soil sample for analysis? Then where exactly should the sample be mailed and how much does it cost?

ANSWER: Most samples must be submitted through the county office of the UGA Extension Service. Each County Extension office has soil sample supplies and information on the UGA lab services, sample submission and fees. They can provide proper sampling and submission instructions and in most cases will return the results along with applicable recommendations. For a list of Georgia county extension offices, go to the County Name Listing web site.

- UGA Soil, Plant, and Water Analysis Lab

QUESTION: Just for aesthetic reasons, I'd like to have clear ice cubes and don't understand why I can't. Water's clear. How do I make ice clear?

ANSWER: To make ice clear, boil the water and let it cool slightly. Then pour it into ice cube trays and let it cool some more. Then freeze. I don't know the exact temperatures the water should cool to at each step.

- Connie Crawley
UGA nutritionist

QUESTION: We have a small creek that runs behind our suburban home. With the possibility of water restrictions looming again this summer, I'm wondering if there is any danger in using this creek water, which probably includes runoff from yards and subdivision storm drains, to irrigate our family vegetable garden?

ANSWER: You can use it, but with extreme caution. If the stream is fast-flowing -- flowing at a good rate -- it will probably be usable. If it's sluggish, as it would be during a drought, anything coming from runoff would be concentrated, and I wouldn't use it then. Also, irrigate from it in the middle of the week -- people tend to put out pesticides on the weekend. And right after a rain, when the runoff is greatest, don't use it as an irrigation source.

- Wayne McLaurin
UGA horticulturist

QUESTION: I have a question or two, regarding mosquito dunks. Are these safe to treat water in a reservoir, approximately 6,000 gals, which is used for drinking water? If not, what is?

ANSWER: None of the products containing Bti, which is the active ingredient in mosquito dunks, are registered for use in potable water. The only registered product for use in drinking water is Agnique MMF, a larvicide that forms a very thin film on the water's surface, preventing mosquito larvae from being able to breathe and thus suffocating them. For further information, consult the Agnique MMF Web site. If it's possible to screen the reservoir so adult mosquitoes can't get in to deposit eggs, that's a reliable and effective way to produce long-term mosquito control. Mosquito fish, also known as Gambusia, can be placed in potable water containers such as cisterns, water troughs, water tanks, stock ponds, etc. These small fish are voracious and avidly consume mosquito larvae. Bti products, which can be bought as dunks, briquettes and granules, provide sustained activity against mosquito larvae when applied to standing water such as flooded ditches, marshes, pools, lily ponds, etc. For further information, check out "Controlling Mosquitoes Around Our Homes and Neighborhoods," by Elmer Gray and Ray Noblet, at the UGA Entomology Web site.

- Nancy Hinkle
UGA entomologist

QUESTION: I read something about recycling Christmas trees last year that said since the birds have a hard time looking for bushy homes in the winter, if you had forest area behind you to take your tree out and stand it up. I did that last year, and when I took this year's tree out to stand beside it, I noticed several nests in the old tree. My question is, does putting this tree out hurt any of the other trees, as far as bugs and other tree ills?

ANSWER: Since Christmas trees are grown outside to begin with, I believe a Christmas tree would pose no problem to other trees outdoors.

- Orville Lindstrom
UGA horticulturist

QUESTION: Deer are eating things this year that they've never touched before, such as Boston ferns, impatiens and even green tomatoes. Is there a shortage of their natural food, or too many deer?

ANSWER: My suspicion is that it's still very dry in the woods. Spring growth was limited this year, and if my woods are any indicator, their food sources are very reduced. Our deer are very thin and eating pumpkin rinds...they must be hungry.

- Paul Thomas
UGA horticulturist