Estimating likelihood of affected plants
If salt damage is suspected, it is recommended to send a diagnostic soil sample to NCDA&CS for testing. A diagnostic sample will provide you with additional information, such as the SS-I (Soluble Salt Index). By using the (ESP) Exchangeable Sodium Percent and SS-I from your diagnostic soil sample report, you can estimate the severity of crops affected.
Follow the ESP on the y-axis and the SS-I on the x-axis to estimate the likelihood of plants affected due to irrigation water with a high EC.
Leaching Salts
Gypsum (CaS04) can be used to help displace the Sodium ion in the soil. This does not happen overnight and works best when high-quality irrigation water or natural rainfall is applied to the soil after Gypsum is applied. Gypsum does not increase pH.
**Please do not apply Gypsum without calculating the proper rate by using one of the two documents linked below. Please reach out to your Extension agent if you need help with your calculation.
Soil Root Zone Salt Tolerance of Selected Crops
Various salt tolerance thresholds are listed in Table 2-34 of the National Irrigation Handbook. This table can be found on page 118.
