Question
Why / how does compost buffer against pH change? My students are struggling with the actual chemistry of what is happening and I can not find an answer. So far we have discussed carbonate ions (source?), negative charge of clay/humus complex (but how is base buffered?), and magic (suggested out of frustration by one group of students). Thanks
Answer
There are so many buffering systems in a pile of dung-phosphate and ammonia come to mind immediately. There will be a host of organic acid buffers (lactate, caproate, etc), each with their own buffering ranges based on their dissociation constants. Also, the inorganic buffers mentioned above, pluc carbonate, as you mentioned (dissolved CO2 in water will form a carbonate-bicarb buffer). Hope that helps. Curious, how did this interest come about?<BR>robert.vieth@uconn.edu
http://vrd.askvrd.org/services/answerschema.xml
