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  • From: "TradingPostPaul" <tradingpost@riseup.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Calculating nutrients available from a cover crop
  • Date: Thu, 17 Aug 2006 17:33:25 -0600


Calculating nutrients available from a cover crop
http://www.ncsu.edu/sustainable/cover/table2_3.html
Sustainable Practices for Vegetable Production in the South
Dr. Mary Peet, NCSU

1. Harvest the above-ground part of the cover crop from a 1 square foot
section of the field, dry it, and weigh it. In a conventional oven, the
sample should be dried at 112 degrees F for 2 to 5 days.
2. To find biomas in pounds of dry matter per acre, multiply dry weight x
43,560
3. Calculate N content of the cover crop per acre according to the
following formulas:
Rye: N = .0174 X biomass - 17.4
Hairy vetch: N = .0368 X biomass - 3.1
Crimson clover: N = .0183 X biomass + 13.8
Austrian winter pea N = .0362 X biomass - 9.2
Caley peas: N = .0383 X biomass - 6.1
Subterranean clover: N = .0252 X biomass + 2.9
4. For legumes, on average, pounds of potassium (k) = pounds of nitrogen
(N), and pounds of phosphorus (P) = 10 percent pounds N.
EXAMPLE - A one square foot plot in a field of rye was cut to the ground
shortly before the rye was to be turned under.
The rye was dried in the oven and weighed. It weighed .12 pounds.
Biomass (lbs dry matter/acre) = .12 x 43,560 = 5227.2 lbs/acre
Nitrogen = .0174 (5227.2) - 17.4 = 73.6 lb N available / acre
Potassium (K) - approximately 73 pounds per acre
Phosphorus (P) = approximately 7.3 pounds per acre.





  • [Livingontheland] Calculating nutrients available from a cover crop, TradingPostPaul, 08/17/2006

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