Agriculture Reference
In-Depth Information
Figure 3. TG-DTA curves of humic acids extracted from unamended soil (C 0 ) at the start of the
experiment and amended consecutively for 30 yrs with cow manure (CM) and crop-residues (CR).
C ONCLUSION
This long-term field experiment highlighted how both the amount and quality of organic
matter of agricultural soils can be affected by management and amendment practices such as
crop-rotation and amendment with different kinds of organic materials (manure and crop-
residues). Conventional farming caused, in the long run, a loss of soil organic C. The addition
of crop residues, on the contrary, significantly reduced this loss, whereas the addition of
manure preserved the initial level of soil organic C. However, the C loss mainly involved the
non humic fraction, since the amount of humic C increased in all the treatments including the
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