Reader asks, I regularly prepare many of my main meals using vegetables from the brassica family (e.g., broccoli, cauliflower, Brussels sprouts, cabbage, and kale) which I accent and flavor by adding garlic, onions, or mustard. Given the nature of my diet, shouldn’t I be getting enough sulfur from what I’m eating? Why would I need to take organic sulfur?
Radical changes in the way that agricultural land is cultivated and fertilized have led to a severe reduction of essential nutrients such as sulfur in our soil and, ultimately, our food supply.
In the distant past, farmland was traditionally fertilized using livestock manure that is naturally rich in nutrients and organic matter. Farmers rotated crops and allowed fields to remain unplanted. This time-honored regimen enables organic matter to decompose into various nutrients that get recycled into the soil.
Nowadays, it is not uncommon for home gardeners and commercial farmers to be using either NPK (sodium-phosphorus-potassium) or chemical fertilizers such as ammonium nitrate to speed up the growing process and increase yields. These manmade fertilizers provide only enough minerals to sustain basic plant life and don’t replenish other trace minerals found in manure that are necessary for optimal health. Moreover, the deployment of popular pesticides such as Roundup chelate (remove) minerals from the soil.
In 2004 the University of Texas at Austin’s Department of Chemistry and Biochemistry published a landmark study where a team of researchers led by Donald Davis determined that between 1950 and 1999, there was a decline in the amount of protein, calcium, phosphorus, iron, riboflavin, and vitamin C in 43 different fruits and vegetables. The Organic Consumers Association have cited another study which found that between 1975 and 1997 that average calcium levels in 12 fresh vegetables dropped 27 percent; iron levels 37 percent; vitamin A levels 21 percent, and vitamin C levels 30 percent.
GRACE Communications Foundation develops strategies to increase public awareness of the critical environmental and public health issues created by the current industrial food system. A soil quality article posted on the Foundation’s website describes the changes that have taken place over several generations:
Today’s large-scale industrial farms depend on synthetic, manmade chemical fertilizers to support high-intensity monocrop systems. Unfortunately, synthetic fertilizers are often over-applied to cropland. In fact, it’s estimated that only about half of all fertilizers are actually absorbed by plants; the remaining chemicals pollute the atmosphere, soils and waterways.
In the above report, the Foundation noted that over-fertilization causes soils to leach out minerals such as calcium, magnesium, and potassium.
Ammonium-based fertilizers and their effect on soil pH
Nitrogen enables plants to produce healthy, green leaves. While nitrogen is the most abundant gas in the atmosphere, plants have a difficult time absorbing it fully when it is in this natural form.
As described on the Plant & Soil Sciences eLibrary web page entitled, “Soils – Part 8: Characteristics of Fertilizer Materials,” ammonium nitrate is a dry granular material that is made by reacting nitric acid with anhydrous ammonia. Easy to make and inexpensive, ammonium nitrate makes nitrogen bioavailable to plants, which accounts for why it has been widely used as a fertilizer since the 1940s. Ammonium nitrate is applied as a plant fertilizer for acidic soil, while ammonium sulphate is used on alkaline soil.
In recent years, urea that is made by reacting ammonia with carbon dioxide has begun to supplant the use of ammonium nitrate, as the former is less expensive and easier to store and maintain.
As noted in a University of Minnesota | Extension post entitled, “Soil test interpretations and fertilizer management for lawns, turf, gardens and landscape plants,”
Soil pH is a measure of soil acidity. A pH of 7 is neutral, a pH below 7 is acid, and a pH above 7 is alkaline… Soil pH is an important chemical property because it affects the availability of nutrients to plants and the activity of microorganisms in the soil.
According to a report published by Cornell University’s Cooperative Extension of Suffolk County that was entitled, “HOW DOES SOIL pH AFFECT FERTILIZERS AND FERTILITY,”
Any fertilizer that contains ammonium or produces ammonium can reduce the pH… If the pH is 5, about 54% of applied fertilizer may be unavailable to plants… If soils are below pH 5, then availability of boron, molybdenum and sulfur is reduced, and nutrient uptake and foliage production are lowered by a third or more, regardless of N fertilization.
Finally, as outlined in a Scientific American article entitled, “Dirt Poor: Have Fruits and Vegetables Become Less Nutritious?”
The key to healthier produce is healthier soil. Alternating fields between growing seasons to give land time to restore would be one important step. Also, foregoing pesticides and (chemical) fertilizers in favor of organic growing methods is good for the soil, the produce and its consumers.
Dirt Poor: Have Fruits and Vegetables Become Less Nutritious?
Grace Communications Foundation
Ammonium Nitrate Fertilizer: How To Use Ammonium Nitrate In Gardens
By Bonnie L. Grant | GardeningKnowHow
Difference Between Ammonium Nitrate and Ammonium Sulphate
Source: Difference Between
Soils – Part 8: Characteristics of Fertilizer Materials
Plant & Soil Sciences eLibrary
[This lesson, as well as the other nine lessons in the Soils series, is taken from the “Soils Home Study Course,” published in 1999 by the University of Nebraska Cooperative Extension]
University of Minnesota | Extension
Soil test interpretations and fertilizer management for lawns, turf, gardens and landscape plants
Carl J. Rosen, Peter M. Bierman and Roger D. Eliason
HOW DOES SOIL pH AFFECT FERTILIZERS AND FERTILITY
Cornell University | Cooperative Extension of Suffolk County
The Atmosphere | Rice.edu