Week of weeds: Day 3.

Rose clover (Trifolium hirtum) is an annual herb that is often included in cover crop mixtures for vineyards, not in the least because as a legume it has the ability to fix nitrogen.  With a tap root that can extend up to 78 inches in depth, rose clover is a valuable cover crop to sew in hillside vineyards that have problems with soil erosion. A native of Europe, rose clover often out-competes native clovers, however, it seems to be happily growing alongside a lot of hop clover, white clover and a tiny bit of crimson clover in Vinoland.
I don't think I have ever seen as much rose clover as I have seen this spring, it's everywhere. And not just on the slope above the homestead.

Spring is almost sprung.

The past couple of days have been spectacular weather-wise. It is amazing how winter has just suddenly disappeared. Sure we could get nasty frosts through April here in Napa, but for all intents and purposes, winter is over.
My daffodils are all but finished and my tulips, short-lived at the best of times, are about 75% done. My irises have just started blooming. A large Valley Oak, (Quercus lobata), to the north of the house has large, swollen buds and even a few immature leaves. Spring doesn't even officially begin until tomorrow.
Nicest of all the early spring surprises around here, for me, is the recurrence of my cover crop from three years ago. My field peas, (Pisum sativum), are dotting the vineyard with their happy, purple and lilac flowers. The sub-clovers I planted last autumn don't seem to be making an appearance just yet. Thank goodness for the self-seeding prowess, and nitrogen fixing capacity, of these little legumes. The peas were easy on the eye as I pruned today. My babies look so pretty.
Of course V2's early mowing protocol, (with her never resting jaws), will mean there will be less self-seeding next year!

Roll me over in the clover.

If you had visited the Napa Valley as recently as 5 or 6 years ago, you would have noticed the absence of any vegetation in the vineyards except for the foliage of the vines themselves. Thankfully that's changed. The majority of farmers have now adopted a 'no-till' policy, choosing to plant cover crops or allow native vegetation to proliferate. Even a vineyard floor covered in dandelions would be preferable to a 'scorched earth' approach to farming.
This year I chose to plant a clover mix in our vineyard. Clovers are legumes, belonging to the Fabaceae family, and so are capable of fixing nitrogen from the air. Through a symbiotic association with bacteria from the genus Rhizobium, they convert nitrogen gas (N2) in the atmosphere to ammonium (NH3) that can be readily used by crops. Because rhizobia occur naturally at low levels in most soils, the bacteria must be present on the legume seed at planting, hence the uniform look of the seed in my photograph. They are coated with everything they need to perform this amazing feat of alchemy.
There are arguments for and against the planting of cover crops. On the pro side; they are very beneficial to overall soil health, add organic matter to soil, retard soil erosion and provide shelter for beneficial predatory insects, amongst other things. Naysayers fear; competiton for available groundwater, too much nitrogen fixation (that could result in too much vigour), and the over-wintering of problematic insects...but seeing as I am a proponent of cover cropping, and it's my blog, I'm not going to dwell on the negatives. There is a lot more to this subject than just tossing out a few seeds and calling it good. Cover crop management is quite complex and is a science in itself, but the positive aspects of this practice are to me incontestable. Besides, it was a great day to be outdoors. The weather was fantastic (84F) and V2 accompanied me as I worked...or at least I think she did, if the huge shadow of her large ears just to my side was anything to go by.