» Danger to Soil Organisms from Using Commercial Fertilizer

Danger to Soil Organisms from Using Commercial Fertilizer

Q. Jim, I listened to your discussion on YouTube w/ LDS Prepper on the 5-6 reasons that some other “organic” grower wouldn’t use the Mittleider method, along with several others.  I have one important question on the Mittleider system that I haven’t found an answer to yet – wondering if you could just answer it for me. QUESTION:  I’ve been told by a few soil experts that, at a certain point, as the count on the chemical fertilizer (NPK) goes up, it starts to kill the micro-organisms in the soil.  For this reason I have tried to use a 13-13-13, and still had some decent success.  What I would like more detail (and scientific evidence on) is at what point do standard chemical fertilizers kill off the micro-organisms?  Can you provide any information on that?   Thanks,   Ted
A. Thanks for asking Ted. Your soil experts are correct in their assertion that too much chemical fertilizer can hurt and even kill soil organisms, just as it can hurt and kill your garden plants.  The reason for this is something called “salinity”.  Most fertilizer compounds are “salts”, and too much salt in the soil reverses the osmotic process by which nutrients are drawn from the soil into the plants, and instead pulls the moisture out of the plants and kills them. However, what they are not telling you (or perhaps are not even aware of or thinking about) is that everything in this world is chemical. “Plants cannot tell the difference between nitrogen from a leaf and nitrogen from a fertilizer bag” – J. I. Rodale  The same holds true for the other 12 nutrients essential to plant growth.  The point is that “chemical fertilizers” are the same, whether from compost or from a commercially produced bag. The question that needs a good answer then, is how much fertilizer is being applied to the soil. The Mittleider system of growing applies 1/2 OUNCE per running foot of a balanced mixture of 10 water-soluble mineral compounds to the soil in the growing area of an 18″-wide soil bed or Grow-Box (only 18% of the total garden area), and does it several times throughout the growing season (a separate application of mostly calcium 2 or 3 times per season does not cause salinity).  The typical family garden likely receives 10-12 feedings in a growing season.  Because the total actual salt content of the Weekly Feed fertilizer is about 47%, a 30′-long garden bed would receive 5.28# of fertilizer salts per year, properly balanced between all of the essential plant nutrients, and applied as the plants need it throughout their growth cycle. An organic garden, on the other hand, typically receives 2-3″ of organic material, such as horse manure or other compost, and it is applied all at once before the crop is planted.  Also, most often the compost is applied to the entire garden area, including the aisles and periphery.  For the moment let’s just consider the effect of the compost applied to the actual growing area of the plants. Loamy-clay soil 12″ deep in a soil-bed will weigh somewhere between 3,000# and 3,500#.  Let’s assume that compost weighs 1/3 as much as soil.  Therefore, 2 1/2″ of compost spread over this 18″ X 30′ bed would weigh something in the neighborhood of 250#.  If compost contains 1% each of N, P, and K, as is generally claimed. and the other 10 nutrients are represented in lower amounts, would it be fair to assume that total fertilier salts would be 5%-6%?  This would indicate that the garden soil in that bed would receive between 12.5# and 15# of fertilizer salts, applied all at once at the beginning when the seeds or plants are tiny, weak, and most vulnerable to being hurt or killed with too much salt. So, which growing method poses the greater danger to garden plants and beneficial soil organisms from the application of too much salt to the soil – the Mittleider Method with its 5.28# of salts applied evenly over 4-5 months, or the organic method with its 12.5#-15# applied all at once at the beginning?  And let’s not forget that the organic gardener applied compost/manure to the entire garden!  That multiplies the amount of fertilizer salts by 5 1/2 times, for a total of fertilizer salts in the organic garden of 68# to 82#! If the foregoing explanation has not put your concerns to rest, perhaps the following will help complete the job for you.  A few years ago, in response to accusations from a couple of college educated “soil experts” that the Mittleider Method was killing soil organisms, hurting the plants, leaching into the ground water, and likely hurting humans and the environment, we hired the BYU Soil Lab in Provo, Utah, and the Stukenholtz Soil Lab in Twin Falls, Idaho. They instructed and supervised us in running a comprehensive set of soil tests on 3 Mittleider gardens – a 5-year garden, a 10-year garden, and a 20-year garden, specifically to determine the validity of the charges leveled against Mittleider Gardening.  The results evidenced that NONE of the accusations were true, in any of the Mittleider gardens, and I have a copy of those results, in the event anyone doubts what I’m saying. Let me know if there is anything else I can do to assist you,