Which of the following is a true statement about chemical constraints in different agroecological areas of the tropics?
A) Highest phosphorus fixation occurs in semiarid areas.
B) Low CEC is most prevalent in acid savannas.
C) Acidity without Al toxicity is highest in the humid tropics.
D) Aluminum toxicity is most widespread in semiarid areas.
E) The proportion of saline soils in the humid tropics is greater than in other regions.
Question 2
Which of the following has not been an effect of the intensified agriculture of the past 40 years?
A) reduced need to cultivate fragile lands to produce the food required by the world
B) imbalanced human nutrition due to decreased production of edible legume crops
C) increased use of chemical pesticides
D) increased micronutrient levels in the soil
E) decreased biological diversity in soil systems
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