Over-application of poultry litter to fields across my region has resulted in extremely high phosphorus levels. Could this impact the availability of other nutrients?

Yes. Phosphorus is adsorbed to soil minerals in a stronger fashion than sulfur, so excessive phosphorus reduces sulfur efficiency as more sulfur is displaced via leaching. The organic phosphorus in litter may also reduce zinc availability.

Is ammonium sulfate good for pecan trees in Texas? If so, how much?

As a matter of fact, ammonium sulfate is recommended more than other nitrogen sources on high pH soils (common in Texas) because of its acidifying effect. It temporarily increases the availability of micronutrients, such as iron and