In general, the Kerr Center horticulture program is pretty sparing with irrigation. When we do use water, we try to work it so that a little goes a long way. In high summer, when crops are most in need of a drink and water conservation is also most critical, conservation practices stand out.
The most obvious trick for getting the most bang out of your water bucket is to use drip irrigation. Especially when combined with mulching, this can keep harvests going through hot and dry spells.
Sprinklers are normally in the forbidden zone from a water conservation standpoint, but even they can have their uses. As Luke Freeman explained a few summers back, “Though we don’t normally irrigate with sprinklers, we’ve been putting sprinklers out on our sorghum-sudangrass cover crop to provide the soil moisture to keep it growing.”
“This is an especially critical stage in the growth of our summer green fallow. The sorghum-sudangrass will regrow after it is grazed or mowed mid-season as long as there is enough moisture in the soil. And because we rely on this summer cover crop to provide a lot of biomass that becomes soil organic matter, we need that second growth out of the sorghum-sudangrass. Without the regrowth, we’re missing out on soil fertility and weed suppression.”
“Another reason we are irrigating our green fallow plots is that we want to get the most out of our compost tea applications. By irrigating with sprinklers before and after spraying compost tea, we are providing moist surfaces for the compost tea microbes to land on; and we are ensuring that a good amount of compost tea soaks into the soil to inoculate our soil with beneficial microbes. For a fall or spring compost tea application, this would not be as critical – but extreme heat and drought call for extra measures.”
Here are some additional resources on irrigation from the Kerr Center’s horticulture library:
The demonstrations and trials described in these reports relied on drip irrigation and summer cover crops: