Nutrient Management Research Database

This presentation covers the basics of managing soil fertility for pepper production.

Many details are included within the presentation, which deserves to be looked at in it's entirety. A summary of the highlights is presented below.

Nutrient Uptake

A bell pepper crop producing 50,000 lbs of fruit/ac can take up 200-260 lbs N per acre, 40-60 lbs P₂O₅ per acre, and 240-320 lbs K₂O per acre. Of this, 80-110 lbs N, 20-30 lbs P₂O_5, and 120-180 lbs K₂O is in the pepper fruit.

Phosphorus (P) Management

For California soils, Olsen-P (also known as bicarbonate P) is a useful measurement of plant available P.

Every 10^o F increase in soil temperature increase P availability by about 20%.

Olsen-P values less than 20 ppm will always show a yield response to P fertilization. Values between 20-40 ppm are likely to show a yield response, especially under colder conditions. Yield responses are unlikely when Olsen-P values are greater than 40 ppm.

Rates greater than 120-150 lbs P₂O₅ per acre are questionable regardless of soil test levels.

Nitrogen (N) Management

Crop N uptake varies by growth stage, from <1 lbs N per acre during early growth, 4-5 lbs N per acre during middle growth stages, and back to less than 3 lbs N per acre during fruit set.

Both residual soil N (remaining from previous years) and soil N mineralization should be considered when determining N application rates. N from mineralization can provide as much as 1 lb N per acre per day.

One inch of irrigation water can leaching as much as 20-30 lbs nitrate-N per acre out of the root zone.

Potassium (K) Management

Crop K uptake varies by growth stage, from <1 lbs K per acre during early growth, 4-7 lbs K per acre during middle growth stages, and back to less than 4 lbs K per acre during fruit set.

Pepper has moderately high K requirements, at 240-320 lbs K₂O per acre. Most of that K ends up in the fruit, and is transferred there from plant leaves.

Fields greater than 200 ppm exchangeable K do not require K fertilization, while levels less than 150 ppm should be fertilized. 

K fertilization is most effective during fruit set and early fruit development.

Crop Nutrient Monitoring

In season soil nitrate testing can aid in mid-season nutrient management. Nitrate-N concentrations greater than 20 ppm indicate that additional N application can be postponed.

Petiole testing values show current nutrient sufficiency, but cannot predict far into the future.

Deficiency Symptoms

Calcium deficiency symptoms are covered in-depth, and the picture guides are useful to help identify calcium deficiency.