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Methods for Experiment 023 -

Animal Sampling Methods

Small mammal trapping in E023 is the same as that in E001.

Field Operations: Fencing

The plots in experiment C023 are enclosed by a fence to exclude mammalian herbivores. Galvanized welded-wire hardware cloth with 6mm x 6mm openings was buried to a depth of 84cm. Additional hardware cloth extends 60cm above the ground, and poultry netting extends to 1.8m above the ground.

Field Operations: Fertilization

Fertilizer is mixed and spread by hand twice a year, once in early May and once in late June. Each plot gets the fertilizer mixture specified by its fertilizer treatment code.

Field Operations: Mammal Trapping

Small mammals are trapped as often as possible to keep the resident population low. A list of the number and kind of mammals taken from each field is in the small mammal documentation file. Pocket gophers are trapped out of the fields as soon as they appear. Gopher mounds are then removed and vegetation is unburied.

Microplot Fertilization Treatments

The "microplot" fertilization treatments are used in experiments 1, 2, 4, 8, 9, 11, 23, 25, and 52. Experiments 5, 6, 28, 36,53,97, 98 and 100 are conducted within plots that are fertilized and should be treated as part of the fertilized plot. There are nine treatment levels, assigned a letter A through I. This is also equivalent to the numeric labels 1 to 9. Treatment levels A through H differ in the amount of NH4NO3 added. Treatment I is a true control and receives no nutrients. The nutrients are applied twice a year, once in early May and once in late June. An exception is experiment 25 where time of application is experimentally manipulated. Not all experiments use all possible treatments. Nutrients are given in g/m2 for each fertilization; plot area and treatments used follow the nutrient lists. Treatment A to H receive the following base nutrients:

Rate Volume Element
10 g/m2 150 ml P2O5 (0-46-0)
10 g/m2 150 ml K2O (0-0-61)
20 g/m2 200 ml CaCO3 (lime)
15m2 200 ml MgSO4 (Epsom Salts)
0.0625 ml/m2 trace mineral solution in 1 ml to 10 ml sand
 

The description for making trace mineral sand is at the end of this section. The amount of NH4NO3 fertilizer added at the different treatment levels is:

Treatment Rate Volume
A 0.0 g/m2 0 ml
B 1.5 g/m2 25 ml
C 3.0 g/m2 50 ml
D 5.0 g/m2 90 ml
E 8.0 g/m2 140 ml
F 14.0 g/m2 250 ml
G 25.0 g/m2 445 ml
H 40.0 g/m2 710 ml
I 0.0 g/m2 0 ml
 

These rates are added twice a year. Actual annual N addition is calculated as: 0.34%N * rate (g/m2) * 2 times/year The trace mineral stock solutions are made by adding the following grams of reagent to 1000 ml of water: CuSO4*5H2O 9.8 g ZnSO4*7H2O 22.0 g or ZnCl2 10.5 g CoCl2*6H2O 10.0 g MnCl2*4H2O 180.0 g Na2MoO4*2H2O 6.3 g H3BO3 6.0 g The trace metal solution is made by combining 120ml of each stock solution, adding 67.2g of citric acid dissolved in deionized water and adding deionized water to bring the volume to a total of 2 liters. The working solution is then autoclaved to chelate the trace metals. The size of the plots and treatments used for each experiment are:

Experiment Treatments Plot size (m2)
Experiment 1 except Field D A thru I 16
Experiment 1 Field D A thru I 6
Experiment 2 A thru I 16
Experiment 4 E, G, I 1000
Experiment 8 C, F, H, I 16
Experiment 9 C, F, H, I 16
Experiment 11 E, G, I 16
Experiment 24 E, G, I 16
Experiment 25 E, G, I 5.25
Experiment 52 A, C, F, G 25
 

Microplot Fertilization Treatments

Some changes and/or additions occur from year to year for some experiments. These changes are listed below. Unless specific experiments are mentioned, these differences apply to all experiments in a category.

In 1982, 30ml of each stock solution was combined with 16.8g citric acid, brought to a total volume of 1 liter, and autoclaved to dissolve. 1.5ml of this solution was added to 30ml of silica sand, mixed and dried.

In 1983, 60ml of each stock solution was combined with 25g of EDTA brought to 1 liter, and autoclaved to dissolve. 1ml of this solution was added to 10ml of sand and added to each plot.

In 1984, 60ml of each stock solution was combined with 25g of citric acid and brought to 1 liter.

In 1985, the first fertilization for experiments 1 and 2,
Treatment F received an extra 23 g/m2 of CaCO3
Treatment G received an extra 118.5 g/m2 of CaCO3
Treatment H received an extra 132.5 g/m2 of CaCO3

In 1985, between fertilizations for experiments 1 and 2,
Treatment G received 137.5 g/m2 of CaCO3
Treatment H received 206.25 g/m2 of CaCO3

In 1985, the second fertilization for experiments 1 and 2,
Treatment F received an extra 23.0 g/m2 of CaCO3
Treatment G received an extra 252.7 g/m2 of CaCO3
Treatment H received an extra 441.1 g/m2 of CaCO3

In 1985, the first fertilization for experiment 4,
Treatment E received no CaCO3
Treatment G received an extra 45.5 g/m2 of CaCO3

In 1985, both fertilizations for experiments 8, 9, and 11,
Treatment F received an extra 23 g/m2 of CaCO3
Treatment G received an extra 43.5 g/m2 of CaCO3
Treatment H received an extra 57.5 g/m2 of CaCO3

In 1989, lime was added to adjust pH to the following treatments in the spring:

In the fall of 1989, each plot receiving treatments B, C, D, E, F, G and H in field D of experiment 1, received 1067g of lime to adjust pH.

Sampling Problems in C023

Plot I1, subplots 1 and 3 sustained some gopher damage but were clipped September 23, 1985.
Plot E1, subplots 1, 2, 14 and 15 sustained gopher damage but were clipped September 23, 1985.
Plot E2 subplots 4, 5, 6, 7 and 8 sustained gopher damage but were clipped August 14, 1985.
Plot G2, subplots 15 and 16 sustained gopher damage but were clipped August 21,1985.

Treatment layout : trmte23

Field Identification Experiment Number Treatment Nitrogen Treatment Ammonium Nitrate (34-0-0) addition (g/m2/yr) Plot Number Subplot Number
C23E51611
C23E51612
C23E51613
C23E51614
C23$
 

Vegetation Sampling Methods

Sampling of E023 was done in 1985. Each plot was sampled by clipping 0.2m x 0.5m quadrats (subplots) every two weeks during the growing season.