Building Great Soil (cont)
By: Warren Schultz
By April in Texas, the soil has been worked, and the first crop is growing. But it's not too late to improve the soil with organic matter. "The best way to do that is with mulch," says John Dromgoole. "What's most important here is to make sure that the garden will perform well going into the extreme heat of the summer. A 4-inch layer of mulch drops our soil temperature from 105°F to 80°F--just like that." At the same time, it contributes organic matter and nutrients to the soil as it decomposes. Regardless of where you garden, you can still improve soil even once you're growing in it.
"For a mulch, we want something that lies flat and stays tight on the soil," Dromgoole says. "If it's loose, it creates a good habitat for pillbugs and slugs and other pests." Coastal Bermuda grass hay has always been a popular choice for mulch in Texas, "but we don't recommend it anymore," Dromgoole says, "because we found some that was contaminated with a broadleaf herbicide. If you use it on your vegetable garden, the production gradually decreases. Instead, we recommend pine needles. They do have kind of an open habit, but if you apply them in May, once the plants are established, the pillbugs and slugs can't do as much damage."
Mulch and compost burn up quickly in the hot Texas summers, but Dromgoole has found a way to make his compost go a long way: build a little dam of earth around each plant, then put compost in the little basin created by the dam. That helps to save water, too, by focusing it where it should be. And whenever you water, you're constantly feeding with a compost tea.
Dromgoole also relies on regular applications of greensand, a mineral fertilizer, to toughen up the plants. "We've found that applications of greensand are very important. The available potassium in it increases hardiness of plants going into the heat of summer. I apply a full cup per [mature] plant, and it's very beneficial."
If you're going to add only one amendment, make it kelp meal, says Bill Wolf, president of the board of directors of the Organic Materials Review Institute. "Kelp or seaweed is a great source of trace minerals and growth elements. Just apply 1 pound per 100 square feet at any time during the growing season," he says. Adding seaweed triggers an increase in microbial activity and fuels the decay cycle of organic matter in the soil. It doesn't take much to get things cooking.
According to Wolf, there is one overlooked ingredient in soil health. "The most important fertility component in your soil--more important than anything you can buy--is air. Air is the driving force in stimulating soil life. Microorganisms, earthworms, biotic activity, all rely on a good supply of air."
That's the reason for the standard caution against working the soil too early in the year. Tilling wet soil will destroy its structure, compact the soil, and squeeze out the air. "When you compress the air out of the soil, you kill everything in it. So treat your soil gently," Wolf advises. "Don't overtill, and don't even walk on it when it's wet."
By mulching, cover cropping, and composting, you can work on the soil all season long. You don't have to break your back at the start of the year trying to get it all done right then. In fact, you can tend your soil through the season, just as you tend your plants.