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Nitrogen Deposition Study – Fertilizer Treatments

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In use from 2010-01-01

Abstract

The LTER Nitrogen Deposition Study was established in 2001 to examine the effects of increased nitrogen deposition on successional and forested communities. Nitrogen fertilizer is applied annually at three different levels to plots adjacent to Mid-successional (SF), Coniferous Forest (CF) and Deciduous Forest (DF) treatments of the LTER Main Cropping System Experiment (MCSE). Since 2010*, these plots are preferentially fertilized with ammonium nitrate (NH4NO3)† at the following rates:

  • One-fold fertilization (1F) = 1 g Nitrogen (N) m-2 yr-1= 10 kg N ha-1 yr-1
  • Three-fold fertilization (3F) = 3 g N m-2 yr-1 = 30 kg N ha-1 yr-1
  • Ten-fold fertilization (10F in DF only) = 10 g N m-2 yr-1 = 100 kg N ha-1 yr-1

The 1F plots are 100 m2 (10m x 10 m) each, with the exception of CF3 which is 6 m2 (2m x 3 m). The annual application rate is 10 kg N ha-1 as an ammonium nitrate (NH4NO3)† solution, equivalent to 100 g (6 g on CF3) N per plot. N is applied in 3 doses of 3.33 kg N ha--1each diluted to 4 L (2 L on CF3). The three doses are evenly spaced from April through November (after spring thaw through litterfall) and are preferentially applied to all deposition plots on the same day.

The 3F plots are 4 m2 (2m x 2m) each. The annual application rate is 30 kg N ha-1 added in 3 doses of 10 kg N ha-1 each diluted to 2 L per plot.

The 10F plots were added to the DF treatment only in 2007 and are 4 m2 (2m x 2m) each. The annual application rate is 100 kg N ha-1 added in 3 doses of 2 L per plot.

See the Detailed Fertilization Log for specifics on fertilization dates and type of fertilizer applied.

Protocol

Preparation of fertilization solutions

  1. Weigh 8 bags of 98 g NH4NO3 (34% N) for 1F, 1 bag of 5.9 g NH4NO3 (34% N) for 1F in CF3, 9 bags of 11.8 g of NH4NO3 (34% N) for 3F, and 3 bags of 39.3 g.NH4NO3 (34% N) for 10F
  2. Mix fertilizer with water in 4L flasks with stir bars on stir plate. Add fertilizer slowly to allow it to dissolve.
  3. Pour solutions into 4L sprayers and carboys for spraying or transport to the field.
  4. Fill the containers for 1F plots to 4L and the containers for CF3-1F and all 3F and 10F plots to 2L.

Spraying the plots

  1. Use a 4L hand sprayer to apply the fertilizer solutions to all 1F, 3F, and 10F plots.
  2. Divide the 1F plots (10x10 m) into quadrants and apply 1 liter of solution to each.
  3. In the CF3-1F, 3F and 10F plots, apply the 2 liters of solution evenly across the plot.

Exceptions

†When ammonium nitrate is not available, urea (46% N) is used instead and is applied at the same N rates. The 1F plots receive 72.5 g urea mixed with 4L water, except CF3 which receives 4.3 g urea mixed with 2L water. The 3F plots receive 8.7 g Urea/application mixed with 2L water, and the 10F plots receive 29 g urea mixed with 2L water. See the Detailed Fertilization Log for type of fertilizer used for each application.

*From 2001 through 2009, an erroneous fertilizer level was applied at 10 times the appropriate level. So, during those years the 1F plot received nitrogen at a rate of 100 kg/ha/yr, 3F received 300 kg/ha/yr, and 10F received 1000 kg/ha/yr. See retired protocol: https://lter.kbs.msu.edu/protocols/107

Date modified: Thursday, Jan 04 2024

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