# RESEARCHING MAINTENANCE

Seed calculations I remember seeing a formula that enables you to calculate the pounds of seed needed per 1,000 square feet based on the germination, seed purity, etc., using the numbers on the seed tag. Can you provide me with the formula? - Via the internet

Seeding-rate recommendations are created with the assumption that you're using pure seed, all of which will germinate. However, virtually all commercial seed is less than 100-percent pure. Germination percentages vary, but also will be less than 100 percent. It's possible that these variables can be significant enough to noticeably affect the seedling stand if you don't adjust your rates accordingly.

## Related Topics

What you need to calculate is pure-live seed (PLS). Do this by multiplying the percent purity by the percent germination. Both of these figures are available on the seed tag. The result is the percent PLS.

Then divide the recommended seeding rate by the PLS to get the amount you actually need to sow to achieve the recommended seeding rate.

For example: - Recommended seeding rate = 8 pounds per 1,000 square feet

- Percent germination (from seed tag) of your seed = 90%

- Percent purity (from seed tag) = 95%

- PLS = 90% x 95% = .855

As you can see, if you simply applied 8 pounds of seed out of the bag, you'd only be achieving 85 percent of target rate. Dividing the desired rate by PLS reveals the actual rate you should use.

8 pounds ö .855 = 9.4 pounds

Some seed is pure enough that adjusting for PLS won't make a substantial difference. But some seed has even lower PLS than the example shown here, so it's definitely worth performing a quick calculation.

"Exotic" spark plugs Is there any advantage to using "high-end" spark plugs made out of special metals or with split electrodes? - Via the internet

For automotive engines, platinum, gold and split-electrode (such as Split-Fire brand) spark plugs have been marketed with promises of better performance, better gas mileage and longer engine life. Do these relatively expensive plugs - often \$5 or more - provide any tangible benefit to your equipment?

Robert Sokol, an Automotive Service Excellence master technician, explains that because of the fouling tendency of 2-stroke engines, it could be extremely detrimental to experiment with exotic plugs in such equipment. But what about 4-stroke engines?

Both platinum and gold better resist corrosion and wear, and, so the theory goes, should therefore last much longer than normal plugs. The problem, according to Sokol, is that the amount of platinum or gold used in spark plugs is tiny. If it is contaminated, such as with oil, the plugs will immediately foul and cause your engine to miss.

Exotic-metal plugs are factory equipment in many automobiles because their engines have pollution equipment that will keep the impurities off the spark plug. However, warns Sokol, small engines are not so equipped. Gold or platinum plugs in any small engine are a waste of money and will end up performing worse than a normal plug.

Plugs with split electrodes are based on the concept that you'll get a more reliable spark with two sharp electrodes, rather than one, from which sparks can jump. Does this work? Yes and no. According to Sokol, when you install a set of split plugs, you might notice a difference. (However, in many cases, this is simply because your old plugs were worn and needed replacing anyway.)

The problem, Sokol explains, is that the sharp edge will quickly wear off the electrode. Once this happens, split plugs perform just like normal plugs. How long will it take for the sharpness to wear off? According to Sokol, in a mower or other power equipment, it may be less than 20 hours. Do split electrodes help performance, engine life and fuel economy in small engines? Not significantly.

Keep in mind that if engine manufacturers thought their product would perform better with a split plugs, they would probably recommend their use. They do not, according to Sokol, who suggests always following the manufacturer's recommendation for spark plugs.

Ripped off! I recently had my entire trailer, with equipment, stolen (we were too tired to unload everything, so we left it in the trailer overnight). Is there any registry or tracking system to help recover stolen equipment? - Via the internet

Equipment theft is, as all commercial operators know, a serious problem. The best approach is to eliminate opportunities for thieves to take your property by securing your equipment at all times and to carry adequate insurance. Once equipment is stolen, there's little chance of seeing it again, which is true of most stolen goods.

One problem is that stolen power equipment isn't the type of thing to reappear in a way that can be tracked. For example, how often do you see pawn shops carrying mowers? So even if some sort of registry existed, it would rarely do any good because the equipment has to be located before it can be traced back to its rightful owner.

I have heard of operators who hide identification information on or in their equipment, such is inside of hollow handle bars on mowers. Again, however, you've got to find the equipment before you can put such a tactic to use.

At the least, you should have a record of serial numbers and physical descriptions so that you can submit the information in reports to police and your insurance company. Plus, in the unlikely event that stolen equipment is recovered, you'll need a positive way to identify it as yours, which means having an ID number.

Any readers who've successfully recovered stolen equipment are invited to share their strategies with us.

The use of copper-containing fungicides is widespread throughout the golf world. Because the mobility of copper within the soil profile is limited, it accumulates at the soil surface and root zone. Is it possible that concentrations could eventually reach levels that adversely affect the growth of turfgrass?

To test that possibility, researchers Mike Faust and Dr. Nick Christians at Iowa State University conducted studies with `Pencross' creeping bentgrass grown in silica and calcareous sand media. They added various levels of copper to the growing media and then measured the effects on bentgrass growth, including plant-tissue copper concentrations, clipping weights and root mass.

The effect on roots was not dependent on media type. The dry root mass of plants grown in each sand medium declined significantly with the addition of copper, with both dropping 50 to 60 percent at the highest concentrations.

The effect on grass-clipping production, unlike root mass, varied by medium type. It was not significant for grasses growing in calcareous sand (which had an initial pH of 7.3). However, grass plants growing in silica sand, with an initial pH of 6.8, did exhibit significant decreases.

Interestingly, the concentration of copper in the roots of plants grown in the silica sand was 34 percent greater than those in the calcareous sand. This apparently was due to the fact that copper becomes more available for plant uptake as pH decreases. The copper itself is what caused the pH of the silica sand media to decline - from 6.8 to 5.4 at the highest copper concentrations. By contrast, for the calcareous sand media, the pH of the control was 7.3 and the lowest pH attained with copper additions was 7.2. The researchers note that effect of copper is buffered by a reaction with calcium carbonate in the calcareous soil, reducing its ability to lower soil pH.

Does this mean that superintendents should be wary of using copper-based fungicides? Fortunately, no. Christians notes that the copper concentrations simulated in this study were extremely high and unlikely to ever result from real-world fungicide use. This is good news, because copper fungicides have long been vital fungicidal tools for turf managers. Now, superintendents wondering if copper accumulations could be harming their bentgrass can breathe easier.

Have you ever wondered how plant roots "know" to grow down instead of up? Most plants that have been laid sideways or upside down right themselves by responding to gravity and resuming downward root growth and upward shoot growth. Of course, if they didn't they would have a shortened existence. But how do they know which way is up?

While much genetic research in plants focuses on genes that allow organisms to grow larger fruits or fend off disease and insects, new research indicates that certain plant-specific genes can explain some aspects of root growth, including which direction they grow. Researchers at the Whitehead Institute for Biomedical Research, (Cambridge, Mass.), have isolated a gene in the plant Arabidopsis thaliana that controls root growth. Specifically, the gene controls the ability of roots to respond to gravity by acting as a pump that distributes a hormone that controls root growth. They found that Arabidopsis plants containing the gene displayed normal downward root growth. Plants that did not contain the gene lost their ability to grow downward.

These findings raise the possibility that herbicide manufacturers may be able to develop classes of compounds whose active ingredients act only on plant-specific genes with minimal non-target effects. This also could save substantial money and time in the development of new, effective herbicides.

## Interactive Products

### Equipment Blue Book

#### Used Equipment Valuation Guide

Riding mowers, lawn tractors, snow throwers, golf carts

### Repair Manuals

#### CLYMER Repair Manuals

Chain saws, riding mowers, trimmers, tractors