Interpreting output from sum constrast model

Question

I have a question following the great response @DaveArmstrong answered in this topic about sum contrast coding.

To first introduce my problem, have a model to account for species richness which is:

model = glmmTMB(richness~ season + scale(year)*soil_type + (1|plot/place), 
             family = "poisson", data = data, 
             contrasts = list(soil_type= "contr.sum"))

• richness are count data.
• season and soil_type are categorical variables, but I treat season with a basic treatment contrast. I only applied sum contrast on soil_type.
• year is the time (scaled), so a quantitative variable.
• plot and place are random effects.

My issue is that I can't understand the output, and especially:

• What does in this case the intercept represent? Since season is coded with treatment contrast and soil_type with sum coding? Is this even coherent to do?
• How can I find the estimate of the last level of my factor soil_type since the output doesn't plot it?

Here's below the output of my model:

> summary(model)
 Family: poisson  ( log )
Formula:          richness ~ season + scale(year) * occ_sol_mix + (1 | plot/place)
Data: data

     AIC      BIC   logLik deviance df.resid 
 30805.1  30916.5 -15385.5  30771.1     5171 

Random effects:

Conditional model:
 Groups         Name        Variance Std.Dev.
 station:maille (Intercept) 0.18499  0.4301  
 maille         (Intercept) 0.03717  0.1928  
Number of obs: 5188, groups:  station:maille, 1366; maille, 175

Conditional model:
                           Estimate Std. Error z value Pr(>|z|)    
(Intercept)                2.389147   0.022763  104.96  < 2e-16 ***
seasonspring        0.097723   0.007769   12.58  < 2e-16 ***
scale(year)              -0.047237   0.005340   -8.85  < 2e-16 ***
soil_type1              -0.829020   0.029872  -27.75  < 2e-16 ***
soil_type2              -0.056194   0.053894   -1.04 0.297095    
soil_type3               0.394487   0.056035    7.04 1.92e-12 ***
soil_type4               0.484181   0.029935   16.17  < 2e-16 ***
soil_type5              -0.226980   0.052702   -4.31 1.66e-05 ***
soil_type6              -0.334582   0.030146  -11.10  < 2e-16 ***
scale(year):soil_type1 -0.047871   0.011518   -4.16 3.24e-05 ***
scale(year):soil_type2 -0.018347   0.017078   -1.07 0.282680    
scale(year):soil_type3 -0.003713   0.014529   -0.26 0.798287    
scale(year):soil_type4 -0.023846   0.007869   -3.03 0.002443 ** 
scale(year):soil_type5  0.056602   0.017220    3.29 0.001013 ** 
scale(year):soil_type6  0.036098   0.009743    3.70 0.000212 ***
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Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1