Monitoring cation exchange capacity (CEC) during manure composting

Cation exchange capacity (CEC) was monitored during two manure composting p rocesses. In the first process, cattle/swine manure was composted with stra w (MS-composting). In the second process, cattle/swine manure was composted with peat and straw (MP-composting). One week of composting in a continuou sly operating drum composter was followed by composting in experimental hea ps. The evolution of CEC during composting was studied by means of CECdm pr ofiles (CEC in dry matter as a function of composting time). CECdm profiles of MS-composting were at a lower level than CECdm profiles of MP-compostin g, and the increase in CECdm was smaller in MP-composting than in MS-compos ting CECdm profiles provide a means to describe and compare the evolution o f CECdm during manure composting, and to predict the evolution of CECdm dur ing similar manure composting. The effects of composting on the number of c ation exchange sites were studied using CECdm_ref profiles (CEC in mass-bal anced dry matter as a function of composting time). Composting increased th e number of cation exchange sites during the two manure composting processe s, more so during MS-composting than during MP-composting. In addition, it was shown in this study that the use of a value basis is more informative t han the use of a percentage basis when comparisons are to be made between c omposting processes or periods.