(ARA) - Good, healthy soil provides plants with the right amount of nutrients, water and air to thrive. Understanding the characteristics of soil will help you improve your soils' health and the overall health of your garden. One indicator of healthy soil is the number of earthworms it supports. When a lot of organic matter is present, earthworms abound. Healthy soil also is bursting with microorganisms breaking down organic matter into a usable form by plants. But that's difficult to see.

"Know your soil," recommends Julian Wesley, botanical supervisor for Boerner Botanical Gardens, Hales Corners, Wis. "Have your soil tested for the pH and levels of nitrogen, potassium and phosphorus."

You can determine the quality of your soil with some simple tests that indicate its structure, pH level and fertility. Armed with these basics, you can amend the soil appropriately and look forward to producing beautiful plants and flowers and a bountiful vegetable garden.

Soil Structure

Soil structure is determined by the amount of sand, silt, clay and organic matter it contains. The size and characteristic of each particle affects the soil's ability to hold air, water and nutrients. Humus is the organic component of soil. It is the remains of once-living organisms, mostly plants. The ideal soil for gardening contains a mixture of all four items.

Sand, the largest particle, allows air and water to infiltrate the soil and drain well. But sandy soils also lack the ability to hold moisture and nutrients. As a result, they tend to dry out quickly and require more fertilization.

Silty soils usually occur in flood plains and readily hold water. When dry, these soils become powdery and difficult to rewet. Silty soils hold more nutrients and water than sandy ones.

Clayey soils readily retain water and are easily compacted. Clay soils require more time to dry out in spring and may puddle. These soils also easily hold most nutrients.

The addition of organic matter will generally improve poor soils. Organic matter improves sandy soils by retaining moisture and nutrients, and improves the drainage and aeration of silty and clayey soils.

"Add lots of compost," recommends home gardener, Ruth Alt, Glendale, Wis. "And use mulch that will decompose into compost. But don't forget to replace the nitrogen, which is drawn out of the soil by the decomposing mulch."

Natural organic fertilizers, which come from biological materials, provide organic matter as well as nutrients to soil, including the nitrogen lost to decomposing mulch. Milorganite, for example, is a natural organic fertilizer that contains a high amount of organic matter - up to 40 percent carbon. "It serves as a fertilizer and soil conditioner with its high organic matter content," explains Mike Archer, market development and research coordinator at Milorganite. "It's especially good for high clay and sandy soils."

Proper pH

"The most important thing to do when you begin gardening is to test and then amend the soil to bring it up to the proper pH level," recommends Alt.

A soil's pH value indicates the acid or alkaline level and can affect the availability of some nutrients to plants. The ideal pH level for fertile soil is 7.0, which is considered neutral. For most edible plants, a pH range of 5.5 to 7.5 is good. Amendments can be added to bring the soil closer to neutral, but organic matter, especially compost, tends to neutralize soil over time.

To test the pH of your soil, use a do-it-yourself pH kit available at garden centers, or send a soil sample to your local county extension agent. Home kits also may test fertility by measuring the relative amount of nitrogen, potassium and phosphorus. University extension laboratories will test soil for a small fee and may provide a more extensive analysis and recommendations. A soil's pH can change over time and should be checked every three to four years.

Fertility

How well soil supports plant life determines its fertility. Three basic nutrients are essential to plants: nitrogen, phosphorus and potassium.

"Nitrogen, phosphorus and potassium are the most critical nutrients for optimum plant growth," explains Archer. "They are often the most limiting nutrients in most soil." Additional micronutrients also are essential for proper plant growth, but only in small amounts.

What is NPK?

On packages of fertilizer you'll find the N-P-K ratio - nitrogen (N), phosphorus (P) and potassium (K). Potassium also is referred to as potash - K is its chemical symbol.

"N-P-K is the amount of macro nutrients in the fertilizer by weight. It's guaranteed by law," explains Archer. "For example: If the N is 6, the product contains 6 percent nitrogen by weight. In a 40-pound bag of Milorganite, that's 2.4 pounds of nitrogen."

Nitrogen (N) is vital for healthy leaf and stem growth. It is the prominent nutrient in fertilizers designed to stimulate foliage growth. It promotes quick growth and dark green foliage. Too much nitrogen can cause plants to become leggy. Too little will stunt growth.

"Another nitrogen feature to watch for in fertilizers is the amount of 'slow release' or 'water insoluble' nitrogen," explains Archer. "These two sources of nitrogen are available to the plant over a longer period of time than those in water-soluble forms."

Phosphorus (P) promotes strong root growth and aids flowering, fruit and seed production. This nutrient is especially important to vegetable gardens, fruit trees, bulbs and newly planted bare root plants. Phosphorus must be placed near the roots where the plant can use it.

Potassium (K) is a word derived from potash (chemical symbol K). In the past, this nutrient was applied to gardens in the form of wood ashes. It is necessary for flower and fruit production. It also is responsible for healthy growth, resistance to disease and cold, and aids plants in utilizing other nutrients.

The Benefits of Natural Organic Fertilizer

Fertilizers replace nutrients that have been used up from the soil. Whether you use a natural organic fertilizer or a synthetic chemical fertilizer is a personal preference. Although each has benefits, natural organic fertilizers may provide your garden with a bit more of what it needs.

"The two most important things for a successful garden are compost and a natural organic fertilizer," advises Alt. "Both make the soil easier to work with and more environmentally friendly to plants."

"There are lots of good natural organic fertilizers available. There's no reason to use something that isn't natural." continues Alt. "I use Milorganite for environmental reasons."

Natural organic fertilizers provide nutrients and encourage microorganisms to thrive. The organic materials turn into humus as microorganisms in the soil break them down. Synthetic fertilizers tend to deplete organic matter in the soil, which leads to a more compacted soil. It also may interrupt the ecology of the soil with its quick release of nutrients. Beneficial microorganisms can be harmed, while harmful microorganisms may be encouraged.

"A slow release fertilizer, like Milorganite, is good," explains Dennis Lukaszewski, urban agriculture program coordinator for the University Extension Milwaukee County. "It encourages microbial activity in the soil."

Nutrients from natural organic fertilizers are released into the soil lover a longer period of time at a rate the plants can use. The rapid release of nutrients from synthetic fertilizers may cause run-off and groundwater concerns.

"A slow release of nutrients, especially nitrogen, is beneficial to plants," explains Archer. "Plants that receive a quick shot of nitrogen grow too quickly, increasing their susceptibility to disease. Top-heavy plants may grow at the expense of root growth and may impede their ability to set flowers and fruit."

A slow-release natural organic fertilizer may take a little longer to show results, but you won't need to fertilize as often. You'll save time because they require less frequent application than their chemical counterparts.

There are many benefits to natural organic fertilizers, like Milorganite, that home gardeners will certainly appreciate. But Lukaszewski puts it best, "You can't mess up with Milorganite." How can you dispute someone who used this natural organic fertilizer to grow 100 varieties of tomatoes last season - a total of 1,000 tomato plants?

Courtesy of ARA Content, www.aracontent.com, e-mail: info@aracontent.com

Home