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bit north of London, UK | v interesting essay for first thing on a frosty sat morn..
Couple of questions / comments if i may..
You said < The fact is most four-year agronomy students receive very little plant physiology, microbiology, and true science. To quote a very close friend of mine,” We have segregated and specialized ourselves into ignorance”. >
So very true and bears repeating / pinning on the office wall
Quote
< Nitrogen: First of all you need to know there are two forms of nitrogen, Ammonia and Nitrate forms. Both are needed at differing stages of a plants life. Nitrate is needed when the plant needs to stay in the growth stage or vegetative. Ammonia is the form which is needed for seed production. This doesn’t mean we cannot grow crops with ammonia (urea) but it would make more sense to use the right material. Nitrogen is one element that will be nitrate and ammonia, and will switch back and forth with just a simple issue as temperature change. Remember that nitrogen is the only element that will move into the plant without any other element. >
I would disagree with most of this.
Yes nitrate N will enter the plant without help, but ammonium N crosses root wall with a carrier mechanism.
Nitrate N uptake is unregulated, and this poses problems in high N input ag where N is broadcast... in fact i view broadcast ammonium nitrate or urea as the devils N. As nitrate N floods in reaching levels potentially dangerous to the plant, all the plant can do is grow (TOO!) fast and soft up top, with the root system having to play catchup.
In UK wheat acres might get 200 lbs actual N, all broadcast, and applied in 2 or 3 splits. When not spreading N, the farmer is all spring and summer spraying growth regulators and fungicides to keep the crop standing and clean...meanwhile all the soil mass is subject to artificially high and or fluctuating levels of nitrate...whose negative feedback is tripping up any natural supply the soil might have had to offer.
We dont have anhydrous here, but at least when knifed in bands, a lot of soil is unaffected by the addition of the N, and natural N fixing can carry on. Regardless of the chaos going on around the anhydrous site.
Knifed in / banded / spoke-wheeled liquid urea/AMS mixes.....now you are talking. Yes i know its a lot more volume / work. But the soil is worth it.
Re the environment / sustainability... any unused broadcast N is mostly going to end up as nitrate in ground or river water, regardless of what N form was initially used.
Here i use liquid AMS on high calcium high pH clay, dont use or need chlormequat et al (PGR), and about half the fungicide i used to use/ my neighbours use. I apply 80% of intended N req as the AMS, intending to top up broadcast AN for the final 20% if needed (or overspray 20% liquid urea)...last two years we have had such spring / summer drought that this late top up has not been needed.
hmm drought / water management (ps i know you guys think in uk it is always raining...not so in the east...we are 23inch/yr long term..last year 20feb - 18 june not quite 1 inch rain total plus dew here..the year before not much better...we are saved by generally deep clay based soil / moderate temp)
boron probably / potassium definitely positivly implicated in plant water management / drought proofing. Here it is looking like we have under appreciated potassium. Interested how you have arrived at opposite conclusion. Or am i being obtuse, and the point is that with enough cover crop / crop residue / compost flying about then a large enough reserve of labile K can be maintained to dispense with most/all the bought in KCl/SO4 ??
Calcium / Potassium / Magnesium interactions and ratios...esp the 7:1 ratio Ca/Mg...what we would like and what we can afford / is practical might be two or three different things. Like the farm Jeff (you i assume) grew up on, we are calcareous clay also. Keserite is not cheap. Small bits of parent rock chalk mixed in the soil WILL re-establish a given Ca level regardless of how much MG and K sulphate we apply.
Lunch is calling. Thanks for the read.
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Fertilizer recomendations?? Soil Tests
