In one field trial comparing no-till and conventional tillage, soil samples taken after 15 years without liming revealed that the pH of the upper 15 cm was lower on the no-till plot than on the conventional plot. Which of the following most likely accounts for this difference?
A) Plowing mixes the surface soil more thoroughly.
B) Al3+ ions are tied up by the organic matter thereby releasing H+ ions.
C) Acidifying effects of nitrogen-containing fertilizers.
D) Earthworms were more active in the no-till plot.
E) Organic decomposition produced more organic acids in the no-till plot.
C
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