“The cover crop we grow with winter rain becomes the water-holding soil organic matter that gets us through our long, dry summers.”
This phrase is a staple of every farm tour and school visit that comes to Petty Ranch. But how does the winter cover become summer’s mulch? By mowing.
Our cover crop usually includes annual grains, which die back during the summer. Winter’s green blanket of barley turns into a golden yellow mat of straw over the summer. This shades and cools the soil, retains moisture, and inhibits dust.
How do we know the optimal time to mow? Confession time: We don’t.
It isn’t really possible to know the perfect time without knowing exactly what still lies ahead in terms of rain and weather. Without a time machine, we are out of luck.
But perfection is overrated. Farmers are often ruled by practical considerations. Do we need to allow a harvest crew to pick? Are gophers getting out of control while hidden by the greenery? Are the winter’s fig prunings brittle enough to chop nicely?
Most importantly: If it is time to water the trees, it is time for the cover crop to stop using water.
Cover crops do great things for the soil, but they do use water. That is why we like to grow them during the rainy season. When we stop getting water for free it is time to cut the cover crops off. Literally. Sadly, it looks like most of the rain for the season is now behind us. (After only 7.5 inches, making my prediction from December 4 more accurate than I would have liked.)
We started an irrigation cycle this morning that will run through Friday. Once it is completed, it will be time to start mowing.
Last winter’s rains were wonderful and sorely needed. But it was easy to forget that they were about average. News coverage focused on Northern California’s record rains and the drama at Oroville Dam. But for those of us in Ventura and Santa Barbara Counties, the drought didn’t go away… it just paused. Groundwater and lake levels are not much different than a year ago. Soil salinity is inching back up. We had was a nice break, but break time’s over. The drought is back; indeed it never left.
The odds of a reprieve this year seem slim. As I write this on December 4 we see no rainfall ahead; only a week of howling Santa Ana winds and single digit humidity. It is probable that we will see no measurable rainfall until after New Year’s Day. My estimate is that we are going to be short 10 inches of rainfall for the season.
I’d love to think this pessimism is misplaced. I look forward to spreading this winter’s covercrop so we can make the best possible use of the whatever rainfall we get. I hope we will have the chance to take our well offline for some badly needed maintenance, but we need a good rain event to allow a break in our irrigation schedule. We shall see.
The drought continues.
There seems to be a fair amount of interest these days in edible cover crops. We’ve experimented with a few, most notably sugar beets. (Read about them here !) And some we know are edible but aren’t practical to eat, like barley. Finding a cover crop that is both effective and marketable has been a challenge.
We’re taking another stab at it with daikon radishes. We’ve been very pleased so far. They grow very rapidly, and seem to be able to out-compete weeds. The deep tap roots are great for getting down into the soil, and they are reputed to give some nematicidal effect once they have been turned under.
Quick growth also makes them well suited for a market crop. Other crops we have tried as covers need 100 days or more to reach maturity. Inevitably, they will get trampled in the course of orchard operations during such a long period. Daikon radishes only need about 45 days. With a little planning, we can work around that time frame in the fig orchard. (Lemons or avocados might be a different story.)
This week we will start to make daikon radishes available to our customers. Like any cover crop, we don’t expect to harvest all of it. A cover crop exists to feed the soil, not the people. But we’re looking forward to being able to add a little variety to our program.
Erosion and soil loss are history’s leading farmland killers, so we are always looking for ways to keep our soil right where we want it.
These pictures show a ditch stabilization project that we are undertaking with California Bio-Worm, a Santa Paula based startup. Elmo Iadevaia and his team have been great partners!
The next step is to backfill the wattles with compost. This will encourage root growth from the avocados and anchor a cover crop of mint to stabilize the bank.
A little more reconstruction of this ditch will widen it to slow the water, reducing erosion and improving infiltration into the soil.
We will also experiment with growing vegetables and cuttings directly into the soil filled wattles. But that is another story!
Here’s a quick look at our stand of buckwheat, our first stab at a summer covercrop for soil remediation and enrichment. Part of this area will shortly be replanted to Meyer lemons. Another part of this area will serve as our trial bed for the purple artichokes mentioned a few weeks back. The rest will rotate through some late squash, a winter cover (favas?) and another crop of buckwheat before being replanted next summer.
The rows of buckwheat reflect the hose and sprinkler arrangement for the citrus that will be planted here. The thin areas are the drive rows that will pass between the rows of trees at maturity. Remnants of the winter covercrop of rye are still holding on, despite 10 weeks without water before the new hoses and buckwheat went in. This block also has a little mustard and vetch that survived from the winter covercrop as well. This is a testimony to the water holding properties of a clay soil. Unfortunately, it is too heavy for the citrus trees. We hope that the intensive covercrop program (along with the intensive mechanical ripping, manure and gypsum) will bring this soil back to top form. It is pretty popular with bees. How many can you spot?