3 files changed, 21 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index 0b8af1d..4e7e1ab 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ pfm*\.tar.gz
 pfm\.Rcheck
 pkg/ChangeLog
 test.R
+README.html
diff --git a/README.md b/README.md
index 4cf12c3..04ac11f 100644
--- a/README.md
+++ b/README.md
@@ -30,7 +30,11 @@ library(devtools)
 install_github("jranke/pfm", subdir = "pkg", quick = TRUE)
 ```
 
-To read in and analyse a cwa file:
+## Use
+
+# Analyse TOXSWA output
+
+Read in and analyse a cwa file:
 
 
 ```r
@@ -73,3 +77,18 @@ print(example_cwa)
 ## Event statistics for threshold 100 
 ## No events found
 ```
+
+# Calculate PEC soil
+
+Simple PEC soil calculation for an application rate of 100 g/ha and
+25% interception, assuming complete mixing into 5 cm and a soil bulk
+density of 1.5 kg/L, output in mg/kg:
+
+
+```r
+PEC_soil(100, int = 0.25)
+```
+
+```
+## [1] 0.1
+```
diff --git a/figure/unnamed-chunk-3-1.png b/figure/unnamed-chunk-3-1.png
index 176aa58..6adc605 100644
--- a/figure/unnamed-chunk-3-1.png
+++ b/figure/unnamed-chunk-3-1.png