data <- scan(what = list(source="",block=0,yrsaccum=0,chlor=0), multi.line=F)
   Urea 1 2 3.8  Urea 1 5 5.3  Urea 1 8 5.9 
   Urea 2 2 3.9  Urea 2 5 5.4  Urea 2 8 4.3 
   Ammsul 1 2 5.2  Ammsul 1 5 5.6  Ammsul 1 8 5.4 
   Ammsul 2 2 6.0  Ammsul 2 5 6.1  Ammsul 2 8 6.2 
   IBDU 1 2 6.0  IBDU 1 5 5.6  IBDU 1 8 7.8 
   IBDU 2 2 7.0  IBDU 2 5 6.4  IBDU 2 8 7.8 
   UreaSC 1 2 6.8  UreaSC 1 5 8.6  UreaSC 1 8 8.5 
   UreaSC 2 2 7.9  UreaSC 2 5 8.6  UreaSC 2 8 8.4 

data

table142   <- data.frame(data)
rm(data)

table142$source         <- as.factor(table142$source)
table142$block         <- as.factor(table142$block)
table142$yrsaccum   <- as.factor(table142$yrsaccum)



 # gives mostly the same information as Proc Mixed

library(lme4)
library(lmerTest)

table142.lme1  <- lmer(chlor ~ source +(1|block) +(1|source:block) +yrsaccum +source:yrsaccum, data = table142)

summary(table142.lme1)

anova(table142.lme1)

lsmeans(table142.lme1)

difflsmeans(table142.lme1)