Dealing with troublesome Boron soils.
Soils with a level of Boron of 1 ppm or more can be very limiting as
most plants hate soil levels of Boron above 2 ppm. Sensitive plants
start having problems at 1ppm. High Boron soils occur in many
spots in California, sometimes in spots you'd never guess without a
soil analysis. High boron soils can be associated with serpentine
soils, such as south of San Luis Obispo, arid areas such as
the west side of the San Joaquin Valley and Coachella
Valley or mountainous areas like the Mt. Pinos area.
The common treatment for high Boron soils is to leach out the Boron.
This is increasingly a problem though as no one wants that boron on
there site. So moving the Boron from your site to someone else's is
a option in many causes. Also many times the water also has high
Boron. You can try to make it less available by adding gypsum
or playing with the pH. I'm not much of a fan of either. I do
not think soil amendments do much over time.
Mulch has helped by pushing the Boron down below root level. But how
much mulch can you find and how can you grow row crops with mulch?
Here's a list of Boron Tolerate plants that we have observed along
with some that a customer in the Lockwood Valley south of Mt. Pinos.
None of these are absolute and every site is different. But they
worked at a B of 3-5 ppm.
The hills around San Luis Obispo have between 2-10 ppm Boron.