This is a good question with no simple answer. What constituents a fertile soil, and what constituents nutrient value have to be defined. The use of the word nutrient is not specific since it can include elements, sometimes referred to as minerals, as well as substances, such as proteins, carbohydrates, sugars, vitamins, etc. In this discussion, the focus will be on the elements (minerals).

Soil fertility status is generally correlated with crop yield, low on infertile soils, high on fertile. Would the compact alkaline sands of Saudi Arabia, when adequately fertilized and irrigated, producing some of the highest wheat yields in the world, be considered fertile soils; while some of the most productive soils in the world, high in both organic matter and colloidal content, producing low crop yields due to the lost of both structure and tilth because tilled when wet, be then classed as infertile soils? In his book, Robert Parnes takes 190 pages to describe how to establish and maintain a fertile soil (Parnes, 1990).

Applying these same organic materials can improve the soil’s physical properties, increasing water-holding capacity, improving soil structure, tilth and degree of aeration, properties that can add to the soil’s fertility status. Overdosing a mineral soil with these same organic materials, however, will significantly change the physical and chemical properties of the soil that then requires a different set of management practices to sustain its fertility status. High (>10%) organic matter content soils are much more difficult to manage that mineral soils of lower organic matter content.

Another danger is that failing to either compost or sterilize animal manures can increase the risk for the occurrence of salmonella and E. coli bacterial illnesses, particularly when applied to soils used to grow vegetable crops. It should also be remembered that composting an organic material results in the loss of organic components, making the composted material considerably higher in elemental content than what was in the original material.

Elements are not evenly distributed among soil types, reflecting what existed in the parent materials that were weathered to form the soil. During the weathering process, some elements are leached from the soil profile or washed away by erosion. Soil water pH and texture are also factors relating back to the parent material and character of the weathering process (Jones, 2003). The only way to add elements not initially in the parent materials, and/or those lost due to leaching and erosion, is to add them using an outside source in the form of either chemical fertilizers or organic materials. It is impossible to replace these elements by just recycling crop residues or assuming their presence to be in dropped manure from gazing animals.

In order to be root absorbed, an element must be in ionic form in the soil solution.  The idea that an elemental ion being derived from an organic source is more likely to be root absorbed than that from an inorganic source does make scientific sense. Also, an element adsorbed on the surface of a solid substance, whether inorganic or organic, will not be absorbed directly by the plant root, although in physical contact with the root. How the plant root absorbs these element ions from the soil solution is not fully understood. There are two theories, both requiring energy derived from root respiration. Therefore, the root must be functioning in an aerobic (oxygen present) environment for ion absorption to take place. The message here is that the origin of an element taken into the plant is not influenced by whether it came from an organic or inorganic source.

The suggestion that an organically produced plant product has higher nutrient value than that same product inorganically produced can not be easily verified since there are many interacting factors that can influence the nutrient value.

For example, weather conditions can have a far greater impact on product quality than whether the plant is being grown under an organic- or inorganic-based system. A good example of this weather effect is blossom-end rot, a physiological disorder, commonly occurring in tomato and pepper fruits. The disorder is due to a calcium deficiency occurring at the blossom end of a developing fruit, resulting in a cellular breakdown. Sufficient calcium in the soil and plant will not completely ensure that blossom-end rot will not occur since the triggering mechanism is moisture stress occurring at the time a fruit is being initially formed. Root absorption and translocation of calcium within the plant is reduced when the plant is in a water-stress condition. The number of fruits affected will be lessened when calcium is at the sufficiency level within the plant and when the period of moisture stress is short. A foliar application of calcium will not reduce the occurrence of this disorder, whether the calcium source is an organic or inorganic form.

Long periods of drought, or even when with only short periods of rain, will significantly change the elemental content of the soil solution since leaching does not occur, and the upward movement of water by evaporation from the soil surface, brings elements from the lower soil profile into the surface soil. These accumulating elements will impact plant growth, yield, and product quality, either favorably or unfavorably, depending on the element and its concentration in the soil solution existing in the surface soil. The use of either inorganic fertilizers or organic materials will not affect this accumulating process; however monitoring the soil by means of a soil test can determine what element or elements need to be left out of an applied fertilizer, easily done with a chemical fertilizer source, not possible using an organic source material.

Some elements found in animal and human tissues have their source from ingested dust and drinking water. When leaded gasoline was in use, lead content in blood and bone tissue could identify residence or working environment, low in those living and working in rural communities, high in those living and working in urban areas, the highest concentration occurring for those in areas with high vehicular traffic. A noted British actress, following a doctor’s recommendation, regularly took bone meal as a calcium supplement. Failing in health, she sought medical advice to determine the cause. Searching medical texts, she concluded that her symptoms fit those of lead poisoning. She found that the bone meal supplement she was taking came from bones of cows grazing on pastures downwind of a lead-smelting mill. Lead in airborne ingested dust and that deposited as particulate matter on the leaf surfaces of the forage plants being grazed, accumulated in the bone marrow of the grazing animals.

One should search out what exists upwind to determine what elements may be in airborne dust particles emanating from power and industrial plants, emissions from crop fields, unpaved roads, etc. Elements found in air particulate matter when ingested define what is referred to as one’s body burden.

In many areas, the major source for both calcium and magnesium is from drinking water. Drinking relatively “pure” water, low in ion content, is corrosive, easily dissolving what it comes in contact, absorbing elements from bodily tissues when passing through the gut.

When the relationship between fluoride and the incidence of tooth decay was discovered, fluoride-containing toothpaste was marketed and the addition of fluoride to public drinking water supplies initiated. Since iodine is not evenly distributed in soils and drinking water, iodine added to table salt in order to prevent goiters. In many parts of the world, soils lacking certain trace elements essential to plants are being added to fertilizers to prevent deficiencies as well as a means for supplying these elements to grazing animals that require the same element. For humans, including in the diet a wide a variety of foods from many different sources is the best way to ensure trace element sufficiency, not by taking trace element supplements that may contain elements not needed or not present in sufficient concentration to prevent insufficiency.

Agricultural Handbook No. 8 (Watt, 1988) lists the composition values for many foods and food products, the handbook being considered the “bible” for such values. Another source of these values for crops and foods can be found on numerous internet websites. The elemental content of many commonly consumed food and food products is fairly well fixed, particularly for fruits, seeds, and nuts; therefore, not easily altered by crop production procedures, whether organically or inorganically based. Some foods and food products are recommended for inclusion in the diet since they are considered good sources for a particular element or group of elements. Some of the essential trace elements reflect their presence in the soil, whose plant uptake is based on the physical and chemical properties of the soil as well as the genetic characteristics of the plant itself. Some plants are known for their ability to accumulate certain elements, even when growing in soils that are relatively low in concentration for that element (Pais and Jones, 1977; Jones, 2003). Some non-essential plant trace elements will accumulate in a plant that can have significant effects on animal and human health when consumed (Pais and Jones, 1997). Some soil types are avoided for growing certain plants because of their accumulating ability of an element considered undesirable for human consumption, cadmium accumulation in sunflower seed being a good example.

State and Federal Laws define what can be designated as organically-grown. To the consumer, organically-grow carries with it the connotation that such a designated food product is superior to that same product grown using a chemically-based production system. Most of what identifies an organically-grown food product is determined by what chemicals are used for pest control and source of essential plant elements. For the organic grower, finding organic or natural source materials, balanced in their elemental content, is the greatest challenge, nitrogen being the major element in this category since its rate of application has the greatest effect on both plant growth and product yield. Plants that are nitrogen deficient are low yielding as well as generating poor product quality. Nitrogen is also that element whose supply affects the protein content of produced product.

In summary, the relationship between soil fertility and plant/plant product nutrient value is complex. Neither an organic, or inorganic-based growing method will result in a significant difference in crop yield and product quality as along as there is elemental balance. There is considerably greater chance for elemental imbalance to occur when using an organically-based crop production system than for an inorganic chemically based due to the wide variation in elemental content in most organic materials. Soil type, weather conditions, and crop genetic characteristics play more significant roles in what elements and at what concentration they are found in the plant and plant products than that due to whether grown in an organically, or inorganically-based system. For many elements, their concentration found in animal and human tissues is determined by what exists in ingested dust and drinking water, rather than what foods are eaten. Food and food products vary considerably in their elemental content; therefore a diet based on selections from all major food groups is the best way to ensure a balanced elemental intake.

J. Benton Jones, Jr. has a PhD in Agronomy and is the author of several books including Hydropopnics: A Practical Guide for the Soilless Grower and Tomato Plant Culture. It is available at www.crcpress.com. Dr. Jones may be contacted at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it . Dr. Jones has written extensively on hydroponic growing and has been outdoor vegetable gardening employing sub-irrigation hydroponic growing systems (see: http://www.grosystems.com/), and using domestic water for making his nutrient solution.

Jones, J. Benton, Jr. 2003.  Agronomic Handbook: Management of Crops, Soils, and their Fertility.  CRC Press, Boca Raton, Florida.

Pais, I, and J. Benton Jones, Jr. 1997.  The Handbook of Trace Elements.  St. Lucie Press, Boca Raton, Florida.

Parnes, Robert.  1990.  Fertile Soil. agAcess, Davis, California.

Watt, Bernice K.  1988. Composition of Foods: Raw, Processes, and Prepared.  Agricultural Handbook No. 8.  Government Printing Office, Washington, DC.