Three-way ANOVA?

#1
Hello,

I am testing the effects of treatment to control the population of a soil nematode. So I selected 10 fields (location) and used my treatment on each of them (each field also had a control). I also counted the nematode population 4 times in each field.

How should I analyze it? a three-way ANOVA or something different?

Thank you so much!
 

Miner

TS Contributor
#2
This is a split plot design (first developed in agriculture!). The field locations form the whole plots and the treatment/control form the subplots. Counting the population 4 times are repeats.
 
#3
Hi miner, thank you so much for helping. I read about split-plot but I am not sure if that is the case here.

A little bit more detail on the experiment:

The trial tests the effect of a winter cover crop on suppressing the population of a canola nematode. 15 fields with different initial levels of the nematode were selected (5 high; 5 moderate; 5 low) and in each of these fields, the cover crop and control (clean field) were planted side by side in 3 replications for each field. Canola was planted after the winter cover crop in June.

We evaluated the nematode population 4 times in every single plot to see the possible effects of the cover crop on the nematode population. Sampling times were pre-cover crop, after cover crop/pre canola, mid canola and after canola.

Is it a split-plot or RBD? Also, do you think we should treat the sampling time as a factor and run a 3-way ANOVA? Any other suggestions would be very appreciated.

AgGuy
 

Miner

TS Contributor
#4
This does change it somewhat. It now appears to be a split plot repeated measures design. The whole plot is the starting level of nematode and has 5 replicates. The subplot is the cover crop/control and has 3 replicates. The repeated measures are the 4 times in which the nematode population was counted.