2015 Soil Analysis

General · 06 Mar 2023

In 2015, Emily Townsend had a soil sample (5 in deep) tested by the University of Delaware Cooperative Extension Soil Testing Lab. A summary of the results follows.

Lead

The concentration of lead (Pb) was measured at 33 parts per million in the garden soil. Per the report,

Soil lead concentration is at background level and well below the recommended limit of 400 parts per million in the soil.

To minimize exposure to any lead present, follow good hygiene practices during and after handling the soil.

pH

The garden soil had pH 5.0 (acidic).

Maintain a soil pH of 6.5 or higher to reduce availability of any lead present. To raise soil pH to the desired level, apply 100 lbs of ground limestone per 1000 square feet. Monitor soil nutrient levels as good fertility will minimize the uptake of lead by plants.

If growing acid loving plants (e.g., blueberries, azaleas), raising soil pH to 6.5 may result in poor plant growth. You may wish to maintain a lower soil pH but follow other mentioned practices to minimize exposure to any lead present.

Nutrient Composition

The report provides “index values,” where 100 indicates “optimal” and values above that are “excessive.” The garden soil indices were:

*Element*	*Name*	*Index*	*Level*
P	Phosphorus	6	Low
K	Potassium	56	Medium
Mg	Magnesium	94	Optimal
Ca	Calcium	62	Optimal

The report also provides a bar chart for at-a-glance interpretation:

         ┏━━━━━━┥LOW┝━━━━━━┥MEDIUM┝━━━━━┥OPTIMAL┝━━━━┥EXCESS┝━━┓
P index  ┫*** 6                                                ┃
K index  ┫********************** 56                            ┃
Mg index ┫************************************* 94             ┃
Ca index ┫************************ 62                          ┃
         ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛

Compositions of a few more elements were also reported in units of “pounds per acre” as follows (sulfate is a source of sulfur, S):

*Element*	*Name*	*Amount*
B	Boron	0.7
Mn	Manganese	35.6
Zn	Zinc	4.2
S/SO₄	Sulfur/-ate	36.0

Miscellaneous Data

3.9% organic matter
5.8% phosphorus saturation
54.9% base saturation
8.0 mg per 100 g cation exchange capacity (CEC)
Buffer pH 7.55

Fertilizer Program

The report closes with the following recommendation:

Apply 75 lbs ground limestone per 1000 square feet and work in by spading, plowing, or tilling.
Apply 4 lbs triple superphosphate (0-46-0) per 1000 square feet and work in to the top 4 to 6 inches of the soil by spading, plowing, or tilling.
Apply 20 lbs 5-10-5 or equivalent water soluble fertilizer to the soil surface and rake in just before planting.

Action Taken

Lime was spread on all plots based on the report’s recommendations.