Until you have attempted to dig a hole in Hardpan you can only visualize it in an abstract sense how hard it is, concrete would be about right. Trees do not live in these hills, of this I am sure because the hardpan is so solid that without machines breaking through there is no way for them to obtain the nutrients and moisture to survive the summers. The hardpan is formed over millions of years by minerals being washed down during winter rains and having the right composition to bond with each other. The hardpan on our parcel varied in depth from 2-3 feet below the surface and varying thicknesses of 1 to 3 feet thick. The grapes need deeper soil than exists above the hardpan layer to succeed, they also need drainage or the roots will set in water and rot. Nothing, including water, will penetrate the hardpan layer, which meant something had to be done to break it up.

The most common way for a farmer to break up the hardpan is to hire a D-10 or larger Cat with a 7 feet deep ripping shank to rip the ground in two directions. This breaks the hardpan into chunks and does some mixing of the soils. One of the other problems that we faced was several layers on differing soil types from sand, to pure solid red clay that was impervious to water. If these layers were not mixed the plants have a tendency not to push roots across the boundary layer between the soil types and again will not deep root.

Having some experience with hardpan, I knew that if I wanted a special quality vineyard something more than the standard practice of ripping was in order. The University of California at Davis published a guide on dealing with hardpan in existing vineyards. The ripping only of vineyards sometimes leads to the hardpan reforming after several years and again blocking root development. The University recommended digging trenches thru the hardpan between the rows of the existing vineyard. The roots then would move into the trench and down deep. I also found an article about using this practice in new vineyards at Arciero Winery, in Paso Robles. I traveled there and met the farm manager who was nice enough to give me a tour and show me the results they have seen in the plant development compared with non-trenched vineyards.

The results seemed astounding, four year old plants in the trenched fields were more than twice the diameter of non-trenched fields. I was sold, the problem was cost. Renting a machine capable of doing this work would be more than $200.00 per hour and doing our forty acres would take more than 1,000 hours. We decided the only answer was to purchase a used excavator and I would learn to operate it.