Lots of people worry about nitrogen getting tied up by wood chips. This is a temporary problem at worst.
But some say that the amount of potassium imported in a sheet mulch will lock up phosphorus by unbalancing the soil. That might be a harder problem to solve.
Is this true?
And how does one do yearly soil tests to make sure all the ratios are right and everything is balanced when the sheet mulch IS the soil? I imagine that sending a clump of half decomposed wood chips and manure to a lab would not get very accurate results, if any.
Hau, Gilbert, I have never seen a problem with potassium locking up phosphorus in a soil system. Usually it is calcium in soil that will cause deficiency of potassium and or phosphorus.
If you have managed to get enough of either into a sheet mulch, you have really done something. Usually potassium is added by using green sand or granite meal as an amendment. While Phosphorus is added by amending with bone meal or rock phosphate. The main forms of both are not prone to interaction, but can be bound by different chemical processes.
This is a great resource for understanding these processes. Land recources