MCSE Poplar N Fertilization Study


In use from 2010-05-01 to 2018-04-01


Microplots were established in the northern 15 meters of each Poplar treatment (T5) replicate plot (R1-R6) of the LTER Main Cropping System Experiment (MCSE) in 2010, coincident with planting of NM-6 (Populus nigra x populus maximowiczii) in 2009, to examine the effects of nitrogen fertilization on poplar growth and production. Six different microplot treatments (N1-N6; see figure below), varying in N fertilizer application rates and frequency, were randomly assigned to individual microplots in each replicate (see table below). Although six treatments were originally intended, only five treatments (N1-N5) were fully executed:

  • N1 = 0 lbs N/acre
  • N2 = 50 lbs N/acre; applied once in 2011
  • N3 = 100 lbs N/acre; applied once in 2011
  • N4 = 50 lbs N/acre; applied annually 2011-2017
  • N5 = 100 lbs N/acre; applied annually 2011-2017
  • N6 = 100 lbs N/acre; applied once in the year prior to harvest; but did not occur, so N6 = 0 lbs N/acre

Poplar cuttings were planted May 12-13, 2009 at a density of 1,089 trees/acre (8 feet between rows and 5 feet between trees), spot replanted April 15-19, 2010, and harvested March 8-18, 2018.


The northern 15 meters of all T5 replicate plots was subdivided into six different 14.6 m x 15 m microplots (see diagram below). Fertilizer treatments were randomly assigned to individual microplots within each T5 replicate (see table below) and received their respective fertilizer treatments in late spring/early summer, starting in 2011 and ending in 2017; CAN-27 (27% ammonium nitrate) was used in 2011-2012 and ammonium sulfate (21-0-0-4) was used in 2013-2017. Search the KBS Aglog for further details.

Six trees in the middle of the center two rows (n=12) of each microplot were marked with numbered plastic tags (see diagram below) for measurement identification (id = 1-12). Basal stem diameter of each of these trees was measured at 15 cm above the soil surface before the first fertilizer application and annually in early winter thereafter.

Poplar leaves were sampled during the peak of the growing season (~ mid-July) on a near annual basis to measure nutrient concentrations. Five recently mature leaves were collected from the new branch growth of three randomly selected measurement trees in each microplot. Leaves were composited by microplot, dried and ground, and subsamples were analyzed for total carbon and nitrogen content and were sent to MSU Plant and Soil Nutrient Lab for comprehensive nutrient analysis.

Date modified: Wednesday, Dec 06 2023



    12/6/2023: JSchuette edited to past tense and actual procedures followed

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