Excellent point Red-sort of. That will cut down on some demand for N2. Potash and phosphate are still necessary. Most modern producers are guided by soil samples for nutrient requirements.
Rocket no matter crop is chosen it will impact little on phosphate and potash demand. It will only reduce nitrogen use if the legume option is chosen. Yields removed with legumes are less than corn on a per hectare basis but the nutrient loadings of P (~15% more) and K (~20% more) are higher in soy than corn.
And then of course there are farmers (like myself) that have actually doubled up on P and K purchases to avoid future price rises and achieve tax deductions as well. I have topped up my potassium levels across the whole farm with significantly surplus to basal needs and have saved roughly $150/t off future needs in doing so. Similarly with superphosphate I haved saved $100/t off future needs. And those savings will grow as prices continue to rise. Those units are stored in my soils waiting to be converted to grain in time. Its a complex picture but no matter what angle you try to come from it is bullish. There is no way any farmer will risk a nutrient deficiency with grain prices this high ...
If ever there was an asset bubble needed at this point in time. It is in the capacity of agriculture to produce more. Bet against that and I'd be sure to bet you are playing on the wrong side of the market. Friday night in Chicago town highlighted that ...