SO4 Sodic Soil Amelioration Calculator
Estimate a recommended SO4 Rate for sodic soil remediation using CEC and either sodium ppm or % Na. The calculator normalizes sodium to a % Na basis, then converts exchangeable sodium to an SO4 requirement.
Yearly application rates should be based on economic and operational considerations. In general, rates in excess of 600 lb/acre will not be practical for economic and logistical reasons. Rates in excess of 600 lb/acre can be split over multiple years.
Inputs
Derived counterpart
8.70% Na
Read-only value derived from the selected sodium input method.
% Na was derived from sodium ppm.
% Na used
8.70%
Exchangeable sodium
1.30 meq/100g
ESP
0.087
SO4 Needed to Achieve Desired Level
4,435 lb/acre
2.22 tons/acre
Based on normalized % Na and CEC, the calculator estimates exchangeable sodium and converts that into a recommended SO4 Rate using the built-in sodic soil amendment factor.
Calculation breakdown
▼
Calculation breakdown
▼% Na used
Source-of-truth sodium saturation
= 8.696%
Sodium (ppm)
Provided or derived from % Na and CEC
= 300 ppm
Sodium (meq/L)
300 ÷ 23
= 13.043 meq/L
Exchangeable sodium
15.0 × (8.696 ÷ 100)
= 1.304 meq/100g
ESP
8.696 ÷ 100
= 0.0870
Amendment factor
Exchangeable sodium × 1.7
= 2.217 tons/acre
SO4 Product Rate
2.217 × 2000
= 4,435 lb/acre
If CEC is 0 or less, the calculator returns a 0 recommendation.