Farmers and gardeners have been urged for years to purchase soil miracle compounds, often called soil activators or conditioners, which are claimed to provide some beneficial effect. Concern about the validity of these "magical" materials, and a lack of scientific data to suport any opinions, prompted a coordinated study by soil scientists from agricultural experment stations of the Department of Agriculture throughout the southeastern United States.

Researchers representing Louisiana, Alabama and Texas selected two of these products -- Medina and Supernate -- and evaluated them on crops of regional importance.

The results of all tests were summarized as follows in a research report by Dr. Edward P. Dunigan, professor of soil microbiology, and Dr. Olen D. Curtis, agronomy specialist, of Louisiana State University:

"1) Based on laboratory analysis, Medina and Supernate contained plant nutrients that were already common to soils. Amounts of these elements that would be added to the soil, based on manufacturers' recommendations, were very low in relation to crop nutrient requirements.

"2) Application of these products at recommended rates did not alter the number or activity of microorganisms that were naturally present in soils. The microorganism population in the products was considered to be too low for the products to be regarded as soil or plant inoculants.

"3) The severity of cotton root rot was not reduced in greenhouse tests or in well-designed field trials where plots were of reasonable size for plant or yield evaluation.

"4) Yields of grain sorghum, cotton, oats or Bermuda grass forage, soybeans, rice, peanuts or tomatoes were not significantly increased with the recommended rates of Medina or Supernate. Where yields of succeeding crops were obtained, there was no indication of a delayed benefit."

There are many of these "magical" soil activators or conditioners for sale, the research report said. How does one spot them?

The products are claimed to provide mysterious benefits by unlocking soil nutrients. Often these materials will originate from some unusual natural product.

The product has no guarantee for nitrogen, phosphorus or potassium, thereby avoiding the regulations of the state fertilizer laws.

Results from unbiased sources are generally played down and claims are supported by testimonials from users of the product.

Discovery of the product is said to be so recent that agricultural experment stations and cooperative extension service personnel have not heard about it yet, or refuse to conduct research on it.

How can the farmer or gardener determine whether a product is legitimate? Study specific claims the manffacturer makes, the report says. If these appear to be too good to be true, they probably are just that -- not true.