Last week, the Nevada Irrigation District ended our irrigation season – as they typically do in mid-October. Except for a brief vacation in June, and a handful of other days since April 15, this week marks the first time in six months that my day hasn’t started with firing up the Honda ATV and dragging our K-Line sprinklers across our irrigated pasture. Part of me is enjoying the freedom of being able to sleep in a little longer, or to go for a walk before work.
But the other part of me is waiting – waiting for the rain to start. As the days grow shorter and (eventually, I hope) cooler, the forages in our irrigated pasture will slow their growth and eventually go dormant until next spring. We rely on rainfed rangelands to grow grass for our sheep in the fall, winter and early spring. Without any rain (yet), we’ll put the sheep on last year’s dry grass. Since this forage is less nutritious, we’ll have to supplement the ewes’ diet with extra protein until we get a germinating rain and enough new grass growth.
I’ve realized over the years that many folks don’t know what irrigated pasture actually is – or rangeland, for that matter. Let’s start with irrigated pasture. More than simply adding water to grassland, good irrigated pasture is planted to improved, mostly perennial, forage varieties – grasses like orchardgrass and tall fescue, and legumes like white clover and birdsfoot trefoil. We apply water based on the demands of the plants and the soil – quantified as evapotranspiration (or ETo). Our pastures get watered for a 24-hour period every 10-14 days (in practice, this means we water the same part of the pasture every 10-14 days; we move water to a new zone every day). Properly managed, these pastures are highly productive – one acre of irrigated pasture can support five of our ewes for six months.
On the other hand, my sheepherder definition of rangeland is any landscape that is too hot, too cold, too dry, too steep, too something to grow a cultivated crop. The rangelands that we graze can’t be irrigated – there’s simply no cost-effective way to get water to them. Consequently, we graze what Mother Nature grows – in our part of the Sierra Foothills, she grows mostly annual grasses and broadleaf plants (called forbs) that were introduced to California when the Spanish arrived over 400 years ago. Some of our grazing land still grows native grasses and forbs – including California’s official state grass, purple needlegrass (Stipa pulchra) – which we try to encourage through our grazing practices. In an average year, our rangelands will grow enough grass on three acres to feed one of our sheep for a year.
Both types of grazing land support other values, as well! Growing plants sequester carbon through the process of photosynthesis. We see a variety of grassland birds on our pastures as well as our rangelands. This year, we supported a thriving population of tree frogs in our irrigated pastures – which didn’t escape the notice of our local great blue herons!
But irrigation season has ended, and now we wait. We’ve stockpiled enough irrigated forage to feed the sheep through the end of breeding season on November 9. And we’ve stockpiled enough of last year’s rangeland forage to feed the sheep through January. But at some point, Mother Nature needs to do her part! We need rain!