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Verbal·Information and Ideas·Command of Evidence
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AuthorsLocationCropCrop yield with tilling (kilograms per hectare)Crop yield with no tilling (kilograms per hectare)
T.K. Das and colleaguesIndiamaize2,7604,040
Igor Bogunovic and colleaguesCroatiamaize8,5536,065
Vinicius Brown and colleaguesBrazilsoybeans3,0702,270
Adrian Gracia-Romero and colleaguesZimbabwemaize2,4202,990
A student argues that tilling — the practice of mechanically turning and breaking up soil before planting — consistently improves crop yields. The student contends that disturbing the soil aerates it, improves water infiltration, and reduces weed competition, all of which should benefit plant growth. To evaluate this claim, the student compiled data from multiple studies comparing crop yields in tilled and untilled plots across different crops and geographic regions, as shown in the table.
Which choice best describes data from the table that weaken the student’s claim?
A
There are some studies, such as the study by T.K. Das and colleagues, that have found crop yields to be lower with tilling than without it.
B
The finding that tilling is associated with an increase in crop yield has not been replicated outside of Croatia.
C
The study by Bogunovic and colleagues actually found that tilling was associated with a decrease in crop yield rather than an increase.
D
Vinicius Brown and colleagues reported a crop yield of 3,070 kilograms per hectare when no tilling was used but a yield of only 2,270 kilograms per hectare when tilling was used.