The purpose of this experiment is to measure the effect of soil nitrogen availability on the growth rates of different species of plants. The experiment took place within a fenced area at Cedar Creek. The ground had been covered with a plastic tarp to help control weeds. The experiment looked at 8 different species planted in 5-gallon pots in seven soil types corresponding to nitrogen levels between 100 and 1500 ppm total soil nitrogen. For further information on soil construction, see soil details. The eight species were assigned a letter code. The species and their codes are:
A - Agrostis scabra
B - Poa pratensis
C - Sorghastrum nutans
D - Solidago nemoralis
E - Solidago rigida
F - Aster azureus
G - Berteroa incana
H - Schizachyrium scoparium
There were nine replicates of each soil type and species for a total of 504 pots. Replicates 1 - 6 were sown at low density about 20 plants/pot. Replicates 7 - 9 were sown at high density about 100 plants/pot. Replicates 1 - 6 were collected in three stages. For replicates 1 - 3 all three stages were collected during the 1985 field season. For replicates 4 - 6 two stages were collected in 1985 and one was collected in 1986. Replicates 7 - 9 were collected in two stages. For replicate 7 both stages were collected in 1985 and for replicates 8 and 9 one stage was collected in 1985 and one stage in 1986. See CALENDAR.DOC for times of planting and harvesting.