P-test-2

Quiz on Phosphorus Name ________________________

(20) 1. Define how one would maximize the availability of phosphorus in rock phosphate by listing the conditions mandatory for the use of rock phosphate as a fertilizer.

a. _____________________________________________________________________________________

b. _____________________________________________________________________________________

c. _____________________________________________________________________________________

d. _____________________________________________________________________________________

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(15) Define the following terms:

a. Superphosphate________________________________________________________________________

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b. Phosphorus mobility in plants_____________________________________________________________

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c. Colloidal rock phosphate _________________________________________________________________

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(15) 3. Comment on the value of the following materials as phosphorus fertilizers.

a. Animal residues or by-products ____________________________________________________________

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b. Plant residues or by-products _____________________________________________________________

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c. Naturally occurring rocks and minerals ______________________________________________________

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(18) 4. Explain why all of the phosphorus fertilization of a crop must be at planting of a crop, whereas nitrogen fertilization of a crop is most efficient if the nitrogen fertilizers are applied in several applications during the growing season of the crop.

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(24) 5.Indicate the importance of Phosphorus Fixation in organic agriculture by responding to the following inquiries.

a. Definition of phosphorus fixation __________________________________________________________

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b. Benefits of phosphorus fixation in soil fertility _______________________________________________

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c. Detriments of phosphorus fixation in soil fertility ____________________________________________

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(2) 6.Describe one mechanism through which additions of organic matter to soil increase the available of phosphorus in soil.

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(2) 7. How does liming of an acid soil improve phosphorus nutrition of crops with or without phopsphorus fertilization?

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(2) 8. Why should the acidity of a soil to which rock phosphate is supplied as a fertilizer be at pH 5.5?

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(2) 9. Why does colloidal rock phosphate have a lower value as an organic fertilizer than ordinary rock phosphate?

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