On Sunday night, my wife and I watched the film “Interstellar”, in which the Earth is losing its ability to feed its population due to climate change. In the first few minutes of the movie, a monster dust storm overtakes the protaganist’s farm and coats everything in powdery soil. On Monday morning, we got our own real-life dust storm that arrived thanks to dry 50 mph winds that pummeled the bone dry landscape of northern California. You could actually see it on the satellite imagery, a 300 mile long cloud that extended roughly from Winters to Bakersfield.
On our farm, we had seen the forecast for strong winds several days prior, so we were able to plan around it. We harvested what we could on Friday and Saturday, anticipating difficult working conditions as well as potential crop damage. And of course, we worked overtime to get as much of the farm irrigated as possible.
Dry wind is the most damaging weather phenomena we face at Terra Firma. It can be either hot or cold, but it is the low humidity and sheer force of the wind that does the damage — sucking the moisture out of the leaves and leaving them too limp to harvest. Of course it has the same effect on human beings, which is why we try to avoid doing much work on the most brutally windy days. We gave most of the harvest crew the day off on Monday in advance. That turned out to be a great decision, since by 9 am there was a constant stream of dust blowing across the farm and the winds were howling.
Monday windstorms make planning for the CSA box difficult. Once the wind stops, the plants generally recover overnight, allowing us to harvest them. But wind damage on the leaves of crops isn’t always apparent within a day — sometimes it can take 2-3 days to show up. We might go out and harvest nice looking leaves of Kale, for example, the day after the wind, only to have them turn brown or yellow a few days later — in your refrigerators. This week’s windstorm made the decision easy: the wind continued through the night and into Tuesday. (The Arugula in the boxes we delivery Wednesday was picked very early Monday before the wind started.)
So the Diablo winds are bad enough on their own, but if they come before we get a decent rain, they create the duststorms. A majority of crop fields in the Central Valley have been harvested by now, so fields are being tilled, orchards are being harvested and irrigation has ended for most summer crops. And with the drought causing water restrictions for many farmers, thousands of acres have been fallowed and haven’t seen any water all this season. With just a few green fields left in a sea of brown, there are millions of acres of bone-dry farmland just waiting to have the topsoil blown away. This was about the worst-possible time for a big wind.
Some people hear the term “No-Till farming” and think this might be the solution. But here in the Central Valley, the difference between untilled and tilled soil in October — six months into our dry season — is really not very different. Growing cover crops is one way to prevent soil erosion from wind, but it requires quite a bit of irrigation to get a cover crop established in late summer here. Most years, we plant about 20 acres of cover crops in late summer, but with the drought raging it has not seemed appropriate.
Most of our cover crops at Terra Firma get planted in late fall to protect the ground from rain in the winter. But these cover crops are intended to be dry-farmed — or more appropriately, rain-fed. In a dry winter last year’s, we don’t have enough water available to irrigate both the vegetables and more than a small acreage of cover crops. So I wait until we get at least a half inch of rain before I plant any cover. If it doesn’t come by Thanksgiving, then it’s simply “too late”. That’s what happened last year.
One frequent “victim” of the dry north winds is our strawberry patch. Last spring the plants and berries were severely damaged by a wind event during our harvest season, but they are even more vulnerable in the fall just after planting, when the plants are still small. This year I decided to experiment with building a windbreak to protect them: a 700 ft. long fence of 6 foot high shade cloth. Anecdotally, this should have provided about 60 feet of protection behind the fence.
This week’s windstorm was a pretty good test of the windbreak. While it did protect the first 4 beds of berries directly downwind of the fence 100%, the prophylactic affect ended there. Just a few feet further away from the windbreak, the plants were almost entirely defoliated (Most of the berry plants will survive and grow back, eventually coming into production in the spring as they always do.) Given that the field is 250 feet wide, that was an underwhelming result. To protect the entire field, we would need a windbreak every 20 feet. Ten windbreaks, at a cost of $2000 each. Strawberries are a valuable crop, but not that valuable. And other crops that are vulnerable to wind certainly don’t warrant the expense.
Over the long run, our primary protection from weather events like this week’s Diablo wind is diversification. We will continue to grow and harvest dozens of crops in (relatively) small amounts that limits our exposure to the risk of losing all our income at once. And when we see them coming on the weather forecast, we’ll batten down the hatches and try to weather the storm.