As I write this, I’m listening to the sound of falling rain outside. After an incredibly dry and warm October – and after a heartbreaking fire season – our rainy season has finally arrived! What a relief!
Our small sheep operation depends on the grass that Mother Nature grows for us for about nine months of the year. Ours is a rain-fed system – the grass our sheep graze through the winter and spring starts growing with the first real rain of autumn. And this year’s first rain was late! What else would we expect from 2020?!
Fortunately, we take a conservative approach to grazing management – we always try to save enough of our spring grass to tide us through the uncertainty of fall germination. But we do need that germinating rain – ewes that can get by on last year’s dry grass in late October need the nutrition of green grass come February. By the time our sheep start lambing in late February, they’ll need nearly twice the quality and quantity of green grass that they need now. Producing milk to feed hungry lambs takes the best grass our rangeland pastures can grow!
That’s why if you’re around a grass geek like me (or just about any other rancher, really), you’ll hear talk about a germinating rain. Usually, we need at least three-quarters of an inch of rain to get the grass started, followed by another decent storm in 7-10 days. The median germination date in my part of the Sierra foothills, at least in the last 40 years, has been October 20 – that means that the germinating rain arrives before October 20 half the time, and later than that date the other half. This year, obviously, we were late – by more than three weeks.
As you can probably tell, I’m grateful for this rain – but a germinating rain deep into November is not ideal. First, we’re rapidly approaching the winter solstice. The shorter days mean we don’t have enough sunlight to stimulate significant grass growth. Our rangeland forages will germinate, but they won’t grow much until the days start growing longer in February. An earlier germination means we’ll have enough sunlight to grow more grass.
Soil temperature also plays a role in forage growth. With shorter days, colder storms, and freezing morning temperatures, the temperature of our soils in the top six inches will drop significantly in late November and early December. My dad says we usually get our coldest mornings of the year in the first two weeks of December – and I suspect the soil responds accordingly. The colder soil, in turn, compounds the slow growth caused by shorter days. At some point after Thanksgiving – at least in most years – our newly germinated fall grass will go dormant. In other words, the green grass we have next Thursday will have to sustain our sheep until growth picks up again in late winter.
I realize that this is more grass minutiae than a normal person would care to read about, but as a rancher, it can often be all-consuming. As my family will attest, I grow increasingly grumpy the longer I have to wait for the fall rains to begin. They know that for me, fall doesn’t officially begin until I have to wear a raincoat when I leave the house in the morning. And now, thankfully, our rainy season has begun!