known-differences-between-june-2011-version-and-june-2016-version.md

+In principle SimRoot is backward compatible, i.e. the new executable can simulate old input files. However, the results will not always be the same because of bug fixes. Here is a list of known issues that can cause differences in the simulation output between newer and older versions. 
+
+1. v2011.6 has stemdw zero when carbon model is not enabled. 
+2. rootLength2Base is wrong in v2011.6, and correct in current version. This has influence on secondary growht, and thereby on many other things. Quick Fix: remove the if condition on line 76 in geometry.cpp (for getting lf in the constructor of rootlength2base). 
+3. When unequal branching along the root axis is used (as is in lupin), v2011.6  has too early timing. This can be fixed by changing at line 137 of file Rootbranching.cpp this:
+```
+		branchingFrequency->get((Time)(timeLastBranch-parentRootCreationTime),spatialShift);
+```
+to:
+```
+		Time gpatposition(timeLastBranch);
+		parentRootLength->getTime(offsetLastBranch,gpatposition,timeLastBranch-4,timeLastBranch);
+		branchingFrequency->get(gpatposition-pSB->getStartTime(),spatialShift);
+```
+
+4. BarberCushman simulates less P uptake in the new version (in test 3% less). Known changes:
+* competition was not done correctly. This does not seem to matter much in the end. Maybe in specific cases it does. 
+in v1 line 123 of NutrientUptake.cpp reads
+```
+				Ci-= ((u/volume)/b).value;
+```
+but should read
+```
+				Ci-= ((uptake/volume)/b).value;
+```
+* Some minor changes with respect to Ja (do not seem to effect results much)
+
+* difference seems mostly be caused to the corrections in the way roothairs are handled. 
+