In One Field Trial Comparing No-Till and Conventional Tillage,soil Samples

question 38

Multiple Choice

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)organic decomposition produced more organic acids in the no-till plot
• B)earthworms were more active in the no-till plot
• C)acidifying effects of nitrogen-containing fertilizers
• D)Al³⁺ ions are tied up by the organic matter thereby releasing H⁺ ions
• E)plowing mixes the surface soil more thoroughly

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