Agriculture Reference
In-Depth Information
Sea salt is around 40% Sodium, depending on the moisture content.
26# / 0.40 Na = 65#
We need to add 65# sea salt or mineral salt.
Sodium Na+
ppm
Desired
Found
Deficit
39
26
-13
Add
65#
sea salt
or
96#
Chilean Nitrate of Soda
Na Base Saturation 1-5 %
1.0%
Another source of Sodium: Chilean Nitrate of Soda
Chilean nitrate of soda is a naturally occurring Sodium nitrate mineral deposit that
is mined in the high, dry deserts of Chile and Peru. It contains
16% soluble
Nitrogen
as nitrate NO
3
and
27% Sodium
by weight. Mined Sodium nitrate is
allowed for use under USDANOP rules as long as it does not supply more than
20% of the soil's annual nitrogen needs. If we used nitrate of soda to supply our
needed Sodium, we would need
26 / 0.27 Na =
96# Chilean nitrate
, which is 16%N and would supply 96 x 0.16 =
15# of readily available Nitrogen along with the 26# of Sodium.
Phosphorus P
The soil worksheet says that we need to add 78ppm or
156# elemental
Phosphorus
. In
Chapter 4
on Phosphorus, Sulfur, and Chlorine we determined
that
phosphate, P
2
O
5
, is 44% Phosphorus
by weight.
Florida clay phosphate
is 20% P
2
O
5
; 44% of 20% is:
0.20 x 0.44 = 0.088 or
9% actual P
Tennessee brown phosphate
is 23% P2O5; 44% of 30% is:
0.23 x 0.44 = 0.10 or
10% actual P
The choice we make will depend on the type of soil we are working with, our
proximity to the source, and the price at which it is available.As of 2013, the “rock”
phosphate
most commonly available in the US is Calphos
brand colloidal clay
phosphate from Florida, which we determined was 9% Phosphorus.
156 / 0.09 =
1733# of Calphos soft rock phosphate needed
.
1733 lbs/ac or kg/ha is a lot of phosphate rock.. Is it too much to add all at once?
No, because the readily available P2O5 is only 3%, so we are really applying only
60# of “available” P2O5.
