Humphrey D-
In my experience offgassing of ammonia N is an indicator of Sulfur deficiency, or an imbalanced S:N ratio. Methionine, cysteine, homocysteine, and taurine are the 4 common sulfur-containing amino acids. Soil organisms need adequate S to synthesize these. It's analogous to the C:N ratio: if there is excess Carbon in relation to Nitrogen, C will be offgassed as CO2 rather than incorporated into stable humus. If there is excess N in relation to C, ammonia will be offgassed, and this is especially true when S is deficient.
If the goal is to incorporate N into humus and as ammonium NH4+ on cation exchange sites, and to stabilize soil Carbon levels, all three elements must be available and in balance. (as a side note, isn't it strange that the people railing about carbon sequestration are unaware of the importance of S to stabilize Carbon?)
I was not aware that Steve Solomon was recommending up to 800 lbs/acre of N. To me that is dangerously high and wasteful. I have never recommend more than 200 lbs/acre of added N, and my general recommendation is 100 lbs per acre. Any further N needed should be readily supplied by breakdown of existing organic matter or by microbial fixing of atmospheric N during the growing season.
The problem I see here is not taking the existing soil N reserves into account. The usual assumption is that soil organic matter SOM (as stable humus) contains 5%N by weight. If the soil has 5% organic matter, the top 2 million pounds of soil would theoretically contain 100 thousand pounds of organic matter and 5 thousand pounds of N.
Sphagnum peat moss is rather low in N, averaging 0.4 to 1.6%N source but many other sources of organic matter are much higher. A metric ton (1000 kg) of peat moss at 1%N will contain 10 kg of N. With a C:N ratio of 58:1 pure peat would need another 19 kg of N per 1000kg to achieve a 20:1 C:N ratio. This is assuming that only peat is being used and there are no other sources of N present or added to the mix and no N fixing activity by microbes. This is also assuming that one is planning to beak down (e.g. compost) all of the peat rapidly. Otherwise a 40:1 or 50:1 ratio of C:N should work fine.
I have not used chelated minerals mostly because I've never felt the need for them and also because of the expense. Soil biology chelates minerals quite well as they are absorbed by and made a part of the bodies of the microbes etc. In addition it is my understanding that most plants have the ability to absorb mineral nutrients in ionic form from the soil solution or from exchange sites. Probably the only reason I could see for using chelated minerals would be as a foliar or root drench if the crop had a serious deficiency because the needed mineral was not present in adequate amounts in the soil, and there was no other practical method of getting it to the plant in time to save the crop.
I don't understand the reluctance to use sulfates because of the "very high P". P is not usually soluble as it reacts so quickly with any available cation, and if Ca is present in proper amounts P will likely be found as Calcium phosphate forms. In high Ca soils I will often recommend a Sulfur level equal to the "ideal" Phosphorus level just to keep the P more available.
I covered my thoughts on the paste test in my previous post in this thread; I'll only add that Zn is not very soluble in plain water at pH7.
I've heard about huge amounts of P reserves showing up on total digest tests (e.g. aqua regia), while showing as deficient on "standard" soil tests, from Hugh Lovel and several others. While I believe that could be the case if a Morgan or Ammonium Acetate test was used, I don't see it happening with an M3 test at pH 2.5. The Mehlich 3 extractant is made up of acetic acid, ammonium nitrate, ammonium fluoride, nitric acid and EDTA-H4. The M3 test was developed to extract the maximum amount of P possible short of a complete digest.
The Ideal Soil chart limits on secondary and micro elements are only there for a caution; there is no reason they cannot be exceeded if the technician sees reason to do so. They may need to be considerably higher in calcareous and high pH soils.
Recently I made recommendations for a limestone soil from the Bahamas with a pH of 7.9. The M3 test showed 11,925 ppm Ca, the AA8.2 test 1106 ppm Ca. M3 estimated CEC was 66.10 meq, AA8.2 was 7.31 meq. If the AA8.2 CEC estimate was used one could easily end up with many elements deficient because the excessive Ca would overwhelm them. What I ended up recommending was to raise the numbers to 234ppm K, 117ppm Fe, 59ppm Mn, 11.7ppm Cu, 23.4ppm Zn, and 3ppm B, which would be about right for a soil with a CEC of 15 meq. Any high-pH calcareous soil will also need a good level of microbial activity.
At the time Steve Solomon wrote The Intelligent Gardener he had never written a single soil Rx and followed through on it. His entire practical experience came from using an Rx I wrote for him after telling him which test to get and sending him to an Australian lab to have it done. His knowledge base on balancing minerals came from reading the 2010 edition of The Ideal Soil and whatever else he picked up online. The same goes for his co-author Erica Reinheimer: her entire experience came from applying the recommendations she hired me to write for her California garden. I wouldn't rely on anything either of them speculated about during the production of their book.
