Why is salt historically used on asparagus plants?
Written by
Julia Anderson
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Salting the beds is related to the "weed suppression" aspect. This ancient technique, used in sandy soils, was employed by some farmers in the past. They discovered that sodium chloride would effectively kill shallow-rooted weeds with a hard surface crust without damaging the deep crowns of asparagus. It was effective only in well-drained areas, where rain would wash the salt away after application. I have come across some old farm journals that reference this practice, dating back to the 1800s.
Soil Degradation
- Sodium accumulation: Breaks down soil aggregates
- Reduced porosity: Creates surface crusting
- Nutrient lockup: Prevents potassium absorption
- Solution: Gypsum application for remediation
Biological Harm
- Microbe reduction: Kills beneficial mycorrhizae
- Earthworm decline: Disrupts soil aeration
- Enzyme inhibition: Slows organic matter decomposition
- Recovery: 2-3 years microbial rebuilding
Plant Stress
- Osmotic shock: Draws moisture from roots
- Chloride toxicity: Burns root tips
- Growth reduction: Stunts spear development
- Signs: Yellow fern tips and stunted growth
Modern cultivation techniques discourage salt, wanting too much sodium leached out. Although salt is applied in only small quantities year after year, over decades it invariably builds up to harmful concentrations. Crops can be appreciably affected in five years on ridges of contaminated land, for example. I have removed beds affected by salt damage using gypsum and deep leaching.
Organic alternatives provide a safer path to weed suppression. Apply 3 inches of straw mulch each season to block light and choke off weeds. For perennial intruders, consider landscape fabric between the rows. You can also use solarization during the summer months to naturally roast weed seeds. These methods protect the soil's life forms while combating weeds.
Rehabilitate salt-affected beds with gypsum applications. Drill 5 pounds of gypsum per 100 square feet before heavy irrigation. Sow a salt-tolerant cover crop of barley in the first season. Check soil conductivity every month until the sodium level drops into the normal range, as I've seen with the beds I've brought back using this 18-month method.
Keep your history to yourself. Too many gardeners take over from predecessors who didn't recognize the consequences of salt use. Show them how you read about how the yield from salted beds dropped 60 percent after 10 years. Teach them how to improve their organic practices to ensure good soil for subsequent generations to enjoy as their heritage. Your children's and grandchildren's asparagus deserves better than the salt.
Read the full article: When to Plant Asparagus: Essential Growing Guide
