During the numerous winter storms of 2019, much of our farm was covered with lush green plants grown specifically to protect the soil from wind and rain. Cover crops, as they are know, are a core component of our organic farming practices as well as our major source of nitrogen fertilizer — which they pull from their air and “fix” in their roots.
By naturally covering the soil this way, we greatly reduce erosion and runoff from our fields. The ground absorbs more of the rain that does fall, and dries out more slowly and evenly when it stops raining.
But these same benefits can become liabilities in a year like this one. A fallow field left bare for the winter might dry out enough to plant in just a few days between rainstorms, where a field with a cover crop takes over a week. And the longer you wait to “kill” a cover crop before turning it into the soil, the taller and more lush it grows. All of that lush growth needs to decompose before you can plant into it. Most years this takes 2-3 weeks, but when it’s cold and rainy it takes longer.
At Terra Firma we usually plan to start killing our cover crop in mid-February. We use sheep to do this, as they eat most of the above-ground vegetation and convert it into manure. That makes it easier for us to incorporate the residue into the ground, and allows us to plant the fields by mid-March. But this year, thanks to the rain, we are way behind schedule.
Each year we leave a certain number of acres “uncovered” — fallow — for vegetable planting during the winter, but it’s always a guessing game because of the weather. As ecologically-minded farmers, we don’t want to leave too many fields bare. At the same time, we have economic concerns. We want to be able to plant at least once a month during the winter so we have things like spinach, lettuce, carrots and kale for your boxes in the spring.
When making these plans, though, we never assume that the rain will be as persistent and as long-lasting as it has been this year. February was a complete shut-out for us; we weren’t able to get any cover cropped fields prepared. Over the past weekend we finally were able to start turning some under, but with the rain that’s coming, the residue will likely just sit there and possibly even start growing again from the roots.
Sometimes Mother Nature has a hidden message though. Some of the crops we would normally be planting in late March — sweet corn, green beans, summer squash — would be miserable now if we had been able to plant them. They would likely be stunted by the cold and wet weather anyway.
And the benefits that we will receive from this overly-wet winter will likely last for years: a big surge in the ground water tables, an especially abundant infusion of fertility into our soil, and a solid end to the drought that still lingered in some parts of California (although not here).
Still, when it comes time to make decisions about winter cover crops in the coming years, 2019 will stand as a reminder to leave just a few more acres fallow…just in case.