Soil Orders

Quiz

Question

Question 8: Mr. Shortz just purchased some land in Hawaii containing Oxisols. If he applied and incorporated 100 tons (approximately 3 inches) of biosolids on top of soil annually over 30 years, do you think the organic matter added would last longer or shorter in the soil as compared to the Mollisol in southeastern Colorado‏? (Hint: Compare the upper soil of the Mollisol to the Oxisol)

To review this concept click on the links: Soil Genesis and Development Lessons 5.6 and 5.10

Longer

No, the organic matter addition to an Oxisol probably won?t last as long as in a Mollisol. In highly weathered tropical soils there is a lot of water and high temperatures. Thus, soil microbial activity is accelerated as compared to a Mollisol. The organic matter added will be decayed rapidly and the nutrients released will be absorbed by growing plants. This is the reason we don?t see dark surface horizons present in Oxisols as compared to Mollisols.

Shorter

The organic matter addition to an Oxisol probably won?t last as long as in a Mollisol. In highly weathered tropical soils, the soil is affected by high temperatures and lots of water from rainfall. Thus, soil microbial activity is accelerated as compared to a Mollisol. The organic matter added will be decayed rapidly and the nutrients released will be absorbed by growing plants. This is the reason we do not see dark surface horizons present in Oxisols as compared to Mollisols.

Looks Good! The organic matter addition to an Oxisol probably won?t last as long as in a Mollisol. In highly weathered tropical soils, the soil is affected by high temperatures and lots of water from rainfall. Thus, soil microbial activity is accelerated as compared to a Mollisol. The organic matter added will be decayed rapidly and the nutrients released will be absorbed by growing plants. This is the reason we do not see dark surface horizons present in Oxisols as compared to Mollisols.

Question

Question 9: Which soil order, an Oxisol or Mollisol, would most likely benefit from organic matter (i.e., biosolids) addition?

To review this concept click on the links: Soil Genesis and Development Lessons 5.6 and 5.10

Oxisol

The Oxisol would most likely benefit from biosolids addition. There seems to be little, if any, organic matter present in the soil surface in an Oxisol as compared to a Mollisol (See question 6). Organic matter, upon decay, releases nutrients necessary for plant growth.

Mollisol

No, the Oxisol would most likely benefit from biosolids addition. There seems to be little, if any, organic matter present in the soil surface in an Oxisol as compared to a Mollisol (See question 6). Organic matter, upon decay, releases nutrients necessary for plant growth.

Looks Good! The Oxisol would most likely benefit from biosolids addition. There seems to be little, if any, organic matter present in the soil surface in an Oxisol as compared to a Mollisol (See question 6). Organic matter, upon decay, releases nutrients necessary for plant growth.

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