Serrano Creek Soil Amendments

To the contrary, the presence of mushrooms means that the soil has active fungi.  As the fungi populations grow, they are making nutrients available for your plants.  This is the natural system.  Remember that the purpose of compost is to bring life to your soil, and bacterial and fungal growth are the building blocks.  Just let them be, as this is a important stage in the life cycle of fungi.  In a few days, they collpase and will add to the health of the soil.

Typically a 50% reduction in water usage is normal.  Using compost on the surface prevents evaporation from the soil, and this alone can be half of your water usage.  Additionally compost allows more water to soak into the soil rather than washing off.  Lastly the roots will grow further out from the plant, finding the water they need.  No sprinkler system is perfect, and running the sprinkler for additional time to get that dry spot is expensive.

Ideally, you should mimic how nature builds healthy soils.  The last few times I was at the rental yard, I didn't see nature renting a rotiller.  Instead she (is that ok to say?) places organic matter on the surface, and uses a host of microorganisms to work it into the soils.  Rototilling actually is more disruptive than good, because each strata of your soil has specific microorganisms that work at that level.  

The traditional method was to dig a hole twice the root ball and then backfill with 50% compost and 50% native soil.  What has been found is that using this method, the roots never grow outward. Instead they stay in the hole you dug circling around.  This result is that the  plant / tree is prone to drought becuase the root are so close to the trunk, as well as easily blown over during winds. 

Go ahead and dig your hole, but add your compost on the surface, not in the hole.  The effect is that the plant will put more effort into growing a strong root system, and in the long run be healthier and stronger.