Tree and Shrub Fertility Needs Colorado State University Extension Tri River Area Mesa Delta Montrose and Ouray Counties

Soil Test Levels (ppm)
Recommendations based on a soil test report (Ammonium Bicarbonate DPTA technique)

NO₃- N (nitrate nitrogen)

Level of sufficiency

Requirement ^[1]

0- 13 ppm

low to moderately low

Apply from 1 to 6 lbs N/1000 sq ft area

sufficient

> 50

excessive

0 Likely a drainage problem.

P (phosphorus) ^[2] & ^[4]

Level of sufficiency

Requirement: P₂O₅/1000 sq ft area

0- 6 ppm

very low

No more than 1 lb

sufficient ^[3]

K (potassium) ^[2]

Level of sufficiency

Requirement: K₂0/1000 sq ft

0- 60 ppm

very low

up to 8.5 lbs

61- 120

low

up to 5 lbs

120- 150

medium low

up to 1.75 lb

> 151

sufficient

Fe (iron) ^[2]

Level of sufficiency

Fe recommendation/1000 sq ft area

< 5 ppm

very low

1 lb/1000 sq ft

5- 10

low

0.5 lb/1000 sq ft

> 10

sufficient

^[1] Do not apply Nitrogen to newly planted trees and shrubs; apply to established trees and shrubs only.

^[4]The extraction method used to determine the P in the sample needs to considered with using this fertility chart. Conversion information based on the extraction method used is provided at Phosphorus_analysis_techniques.html

^[2] Must be applied and worked into the soil prior to planting.