Placed on the Internet Tuesday, September 21, 2004 22:54
Soil Test Levels (ppm)
Recommendations based on a soil test report (Ammonium Bicarbonate DPTA technique)
| Soil Test Levels (ppm) |
Percentage of Organic Matter Present |
||
| NO3-N (nitrate nitrogen) [1] | 0 - 1 % |
1.1 - 2.0 % |
> 2.1 % |
| 1 ppm = 0.05 lb. N/1000 sq. ft |
Lbs. Nitrogen to add per 1000 sq. ft area |
||
| 0 - 6 ppm |
5 |
4 |
3 |
| 7 - 18 |
4 |
3 |
2 |
| 19 - 24 |
3 |
2 |
1 |
| 25 - 30 |
2 |
2 |
1 |
| 31 - 36 |
2 |
1 |
1 |
| 37 - 42 |
1 |
1 |
0 |
| > 42 |
0 |
0 |
0 |
| P
(phosphorus)
[2] & [9] 1 ppm P = 0.1 lb. P205/1000 sq. ft |
Level of sufficiency |
Lb. P205/1000 sq. ft |
| 0 - 3 ppm |
very low |
5 |
| 4 - 7 |
low |
4 |
| 8 - 11 |
medium low |
3 |
| 12 - 14 |
moderate |
1 |
| > 14 |
sufficient |
0 |
| K
(potassium) 3 1 ppm K = 0.06 lb. K20/1000 sq. ft |
Level of sufficiency | Lb. K20/1000 sq. ft |
| 0 - 60 ppm |
very low |
3 |
| 61 - 120 |
low |
2 |
| 121 - 181 |
medium low |
1 |
| > 181 |
sufficient |
0 |
| Fe (iron) 3 |
Level of sufficiency 4 |
Lb. Fe chelate/1000 sq. ft 5 |
| 0 - 5.0 ppm |
low |
1 |
| 5.0 - 10.0 6 |
moderate - high |
0 for non-Fe sensitive crops |
| > 10 |
sufficient for all crops 7 |
0 |
| Zn
(zinc) 1 lb. Zn = 2.48 lb. ZnSO4 |
Level of sufficiency | Lb. ZnSO4/1000 sq. ft area 8 |
| 0 - 0.9 ppm |
Low |
0.6 pounds ZnSO4/1000 sq. ft |
| 1.0 - 1.5 |
moderate |
0.3 pounds ZnSO4/1000 sq. ft |
1 Nitrogen can be surface applied and watered in. Nitrogen will need to be added each year.
2 Phosphorus and potassium should be worked into the soil prior to planting.
3 If liquid is used apply according to label directions.
4 Low levels of available iron may indicate over watering, poor soil preparation, excessive phosphorus levels, or soil compaction.
5 Iron chelate (Sequestrene 138Fe) should be incorporated into the soil if available.
6 Fe-sensitive plants need higher levels of Fe in the soil.
7 An over-application of iron can cause other micronutrient disorders.
9 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
WebMaster
Dr. Curtis E. Swift, Area Extension Agent, Horticulture
Colorado State Extension
2775 US Hwy 50, Grand Junction, CO. 81503
voice: 970-244-1834
fax: 970-244-1700