What’s the Value of Organic?

The Bay Gardener by Dr. Francis Gouin

Depends on how you define it

I am frequently asked if I am an organic gardener, based on my reputation for having been heavily involved in composting and compost utilization research since 1972. My answer is yes and no.

The importance of organic matter in soils and the use of compost to improve and maintain soil productivity is not thoroughly appreciated. In my gardening practices, I use a combination of compost and chemical fertilizers and minimize restricted-use pesticides as much as I can.

Based on my many years of research in plant nutrition, I know that plants do not make distinctions in getting their nitrogen, phosphorus, potassium, calcium, magnesium, iron, copper and molybdenum. Whether it’s released by the decomposition of organic matter or from the fertilizer bag means nothing to them. Nutrients are nutrients.

But there are things compost does that chemical fertilizers cannot do. One is to improve soil conditions so that nutrients can be absorbed better. Two is to improve the physical conditions of soils, resulting in better root distribution. Three is to improve water-holding capacity, making plants more drought tolerant. Four is to supply important and essential trace elements not available in most commercial fertilizers.

In the early 1980s, the University of Maryland hosted the annual meeting of the National Composting Council. In preparation, my colleague and I grew cantaloupes in a commercially fertilized sandy soil very low in organic matter and in a similar soil that had been amended with four cubic yards of compost per 1,000 square feet. Both areas received the same amount of commercial fertilizer.

During a break in the meetings, we served the cantaloupes on separate platters and watched the unsuspecting attendees to see if there was a response. By the end of the break, it was evident that the cantaloupes grown in the compost-amended soil and fertilized with commercial fertilizers won hands-down. They tasted sweeter and out-yielded the commercially fertilized plots without compost.

However, a few years later a graduate student conducted a two-year study of the taste, quality and yield of snap beans grown in soils containing four percent organic matter using either commercial fertilizer or organic fertilizer. After repeating the trials twice yearly for two consecutive years, we found no differences in taste, quality or mineral and protein concentration between the two growing methods. The only real difference was that the commercially fertilized treatments produced higher yields.

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Cutting Tree Roots

Q I have two trees in the front yard. I do not know what kind, but they are about eight feet high with trunks about a foot wide. The problem is the roots are growing above ground. One is growing along the driveway toward the house. Can I cut the roots without damaging the trees?

–Tim Steeley: [email protected]

A I do not know of any trees that are only eight feet tall with trunks 12 inches in diameter. A tree can survive from having lost 50 percent of its roots. It will regenerate new roots. You will simply slow down the growth.