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If you have any questions about soil nutrients contact Dr. Clain Jones. If you think plant growth issues may be related to pesticide (e.g., herbicide residual in compost), please contact Noelle Orloff (994-6297) or Dr. Tim Seipel (994-4783) for assistance.

 Soil testing

  • Best done in early spring.
  • Remove mulch or thatch before taking the sample (0-6 inches deep). Use soil sampling auger (borrow from local Extension office) or bulb planter. Be sure tools used to sample aren't contaminated by storage near fertilizers.
  • Collect and mix 10 samples for each 1000 sq. feet of area of interest (e.g., lawn separate from vegetable garden).
  • Take a pint sized subsample of the mixed samples.
  • Keep below 40°F and overnight ship, or immediately dry at 110-120°F, or freeze for drying at 110-120°F later.
  • Send to a lab and request pH, organic matter, electrical conductivity (EC = salts), nitrogen (N), phosphorus (specify Olsen P method), and potassium (K). You can add texture (or do that on your own), and micronutrients if you suspect iron, or other deficiency or excess. Sulfur (S) soil tests are not a good indication of sulfur availability for plants, i.e. don't do soil test for sulfur.

Visit our Soil Sampling website for more information.

Approximate NPK added by 4000 lbs ≈ 1 inch material/1000 sq. ft.
Material N P2O5 K2O
Manure compost1 40 15 40
Yard compost2 58 8 12
Green/food compost3 15 9 30
Dead leaves4 40 9 18
Dead pine needles 18 4.8 1.2
Alfalfa pellets 120 40 80
Annual vegetable harvest lb/1000 sq. ft5 2.3 0.5 2.7

Sources:

1. MSU, 2. Maryland Urban compost LeafGro and SmartLeaf, 3. Waste Resources Action Programme of Wales  4. Heckman and Kluchinski 1996, 5. Univ. Mass., Michigan State, Oregon State, Morris et al. 2007

 

Approximate NPK of soil amendments, as % of weight (the 'grade' listed on fertilizers).
Material N P2O5 K2O
Manure compost 0.01 0.0037 0.01
Yard compost 0.0145 0.002 0.003
Green/food compost 0.0037 0.002 0.0075
Dead leaves 0.01 0.0023 0.0046
Dead pine needles 0.0045 0.0012 0.0003
Alfalfa pellets 3 1 2
Bone meal 3.5 17 0
Blood meal 12 0 0
Brewery grain (wet) 0.9 0.5 0.05
Canola meal 6 3 1
Wood ash (unleached) 0 1.25 2
Coffee grounds (dry) 2 0.36 0.67
Urea (chemical fertilizer) 46 0 0
Worm castings highly variable and its not about NPK