Since we began farming in Chiles Valley in 1974, we were confronted with serious erosion issues. Especially difficult were and still are our hillsides, which had been cleared around 1870 and fallen into disrepair. There the soils belong to the Bressa Dibble complex with slopes between 10% and 25%. Even on the Valley floor which consists of Tehama silky clay loam we had some serious erosion problems. The first approach we took consisted in simply mowing the volunteer cover that came up during the winter months and consisted of mustard, filaree and other non native grasses. Within a year we began to see two problems: one was star thistle and the other was twig borers. The latter thrived in the prunings that were lying on top of the cover crop which were not plowed under anymore. Very quickly we returned to conventional farming with clean cultivation.
Repeated erosion damage on some hillsides led to the next trial. Every fall we would seed an erosion control mix on all hillsides and all roadways. The mix consists of 5% Zorro fescue, 13% Crimson clover, 18% Blando broom, and 61% barley. The results were very good except during years with early and heavy rain, which at times washed out the soil and all of the small grassy plants. It became clear that we needed to find a more permanent solution. In cooperation with Phil Blake from U.S.D.A. and Dr. Robert Bugg from U.C. Davis, we developed a long term plan to seed permanent cover crops in all our vineyards. We began in 1996 with the following mixture: 30% Mokelumne fescue, 30% Idaho fescue, 30% California barley, and 10% Pine blue grass. Then we added 5 pounds of Three Week fescue. The ground was prepared in this way. We sprinkler irrigated and later cultivated all germinated seeds under. We repeated this and then seeded every other row at the rate of about 20 pounds per acre. The stand has developed very well and is managed in the following way. It is mowed once a year in early June. Under the wire we clean with weedeaters and shovels.
After four years we see some non-natives invade; including barclover, oats, vetch morning glory, and a few broad leaves such as prickly lettuce. We also see vigor reduction because of moisture loss as well as crop reduction. How much reduction is difficult to say.
In 1998 we continued planting the native mix on two hillsides, seeding every row as opposed to every other. There we could not irrigate with sprinklers and the natives came up in much smaller numbers. So far the mix of natives and non-natives seems to be doing well.
All sites show the need for more intensive clean up under the wire in order to reduce competition between vines and weeds. This fall we will continue the cover crop planting but will substantially reduce the amount of California Barley since it is the most aggressive consumer of moisture.