When I was in second grade, I won a third-place ribbon in my hometown science fair for an embarrassingly rudimentary experiment. I took a set of basic cacti (those little round ones with the short needles) and planted them in various substances (soil, sand, clay probably), compared the results over time, and described my findings on a big, fancy poster.

As best as I can recall, my “research” showed that cactus will pretty much grow anywhere. I suspect I got the ribbon for the poster, but my parents beamed with pride, as only parents can, confident they had a Nobel Prize winner in the family.

Forty years later, my research hasn’t become any more sophisticated, but the object of my curiosity is still plants. Now I’m interested in how certain changes in the planting medium affect what grows in my vegetable garden. In addition, the prolonged wet weather earlier this month, which left some vegetables oversaturated, also gave me an opportunity to see what happens when plants get too much of a good thing.

As an average vegetable gardener, most of what I know has come from year-in, year-out experience as my own garden has responded to various weather cycles and other changes in its environment. The most instructive developments have been those that have affected only a portion of the garden, so that the results can be compared through simple observation.

For example, I could easily discern the effects of overwatering on the tomato plants in one portion of my garden where the soil level is lower and the drainage slower. These two facts about that part of my garden are not really noticeable until we get a lot of rain, and I found it very instructive to stand outside the fence right after one of the many downpours and make mental notes about the location of standing water.

Even if you start with a perfectly level garden plot, the soil can get out of kilter through tilling. At some point, I will need to haul in some dirt and fill in those low spots. In the mean time, several puny tomato plants, victims of the deluge, are there to remind me where the problems are.

Similarly, I am still seeing the clear benefits of supplemental manure that I put on part of the garden last year. The plants in and near the area where I amended the soil are bigger, bushier and several shades greener than those growing elsewhere.

It is inadvisable to place even composted manure directly on an already-planted garden because of the risk of nitrogen burn. Tomatoes in particular can be easily pushed over the nitrogen edge. In cases of extreme overfeeding, you’ll see “burning” on the leaves of the plant; in most cases overfed plants produce a lot of vegetation and little fruit.

In any case, the safest way to add manure to the garden during the growing season is with manure “tea,” which is manure in a diluted, pourable form. I was reminded of this by Chris Hamill after I put out my call for gardening tips a few weeks ago. For a large garden, he suggests preparing the tea in a 55-gallon drum, but 5-gallon buckets would work for a small space. Always use livestock manure, not that of household pets.

Chris offers the following instructions: “The manure tea is a way of getting a lot of trace minerals, soluble nitrogen and humic acid to plants. Most commercial greenhouses and large-scale growers have a feeding program of soluble fertilizer that is mixed into water delivered to plants. Manure tea serves the same function. Manure used must be well composted. Fresh manure will deliver excessive amounts of urea to the water and smells really bad. Even the composted manure will have a certain ‘tang.’

“Note that any compost will deliver nitrogen and a range of trace minerals to water. Maybe ‘compost tea’ is the better rubric. Use a gunny sack or other cloth bag : Fill the bag with your compost. Steep. Like any tea, yours will increase in concentration with time. It is generally recommended to remove the ‘teabag’ within 24 hours. Also, as with other teabags, you may reuse yours, expecting weaker results the second time. And, if you overdo it, dilute with pure water.”