Hi r-sig-mixed-models


I am a new user of R and have a practical problem with an experiment on 
vegetable production carried over time with rotation

Objective:To evaluate fertilizer reduction strategies for improving nutrient use 
efficiency in urban vegetable production systems
Two experiments were conducted. 
Experiment
-       The experiments were carried at two Site D and Site K.
-       Four and six representatives’ plots were selected at Site D and Site K., 
respectively for to closely monitor gardener’s crop management and fertilization 
practices. Like control
At Site K
-       Nine plots were considered at each site for studying the effect of 
fertilization reduction. 

-        3 treatments T100, T70, T0 were considered (a total of 3 plots receive 
a given treatment). T100: farmer normal practice, T70: 70% of the amount of 
fertilizer applied in T100; T0: Unfertilized plots. But at K, because yields 
declined rapidly in the T0 treatment it was decided to apply fertilizer for the 
3rd and 7th cycles the same rate as for T100. 

-       The experiment followed a randomized design where 3 treatments (referred 
as T100, T70 and T0) representing 3 fertilizer management strategies were laid 
out. 

-       At site K, the experiment run for 1 year with a continuous lettuce crop. 
Eight (8) cycles of lettuce crop. At the beginning and before growing the next 
crop soil samples were collected at three depths (A, B, C) and analysed for pH, 
exchangeable ions and conductivity. Also before each growing cycle the treatment 
were applied again.
 
At site D
-       At site D, two complete crop rotations were monitored, over a period of 
2 years. For Year 1 the rotation was composed of succession of 
tomato-cabbage-lettuce-carrot.For Year 2 the rotation was composed of succession 
of tomato-lettuce-cabbage-carrot
-       Yield were estimated and soil sampling and parameters estimation 
followed the same procedure.
 
Need of analysis
- Compare for each treatment the values measured for the soil parameters at the 
beginning and end of the study.
- See interaction treatment and depth effect
- See the time effect and carryover effect
 
 
Any assistance with R script??




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