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Stories from the valley

Protecting Water Quality before the crop starts growing

Contributed by Tim Johnson

It’s early in the wine grape growing calendar. The leaves are just starting to unfurl and we won’t see the first blooms for more than a month. The tiny clusters will come sometime in June. While farming has definite seasons, watching out for water quality is important year–round.

This is the time of year we apply herbicides to keep the weeds down in the vineyard. In generations past we would have disced the soil to keep the weeds down. It worked great but erosion was a problem. Spring rains would pick up the top soil and it would find its way into the creeks.

About 15 years ago, we changed that practice and now plant native grass and clover cover crop in the vineyard rows which we mow three to four times a year.

In addition to keeping the soil in place, the cover crop also help keep our crop sprays in place. Rather than spray everything, we strip spray just under the vines – where the mower can’t get. The grass filters capture any over spray.

These native cover crops also provide forage for bees and other insects while the clover provides a portion of the nitrogen needed by the vines. We only apply fertilizer after a leaf analysis (actually the stem is what gets sent to the lab) shows that nutrients are needed. On average, about every three to five years.

Drip irrigation during the growing season controls run off and it’s a big improvement from the old overhead sprinklers originally installed.

All of these management practices, in place well before the first zinfandel bunches start to show up, help ensure both clean water and a healthy crop.