Exam 2 Questions - Soil Fertility Management | SOCR 350, Exams of Soil Mechanics and Foundations

Download Exam 2 Questions - Soil Fertility Management | SOCR 350 and more Exams Soil Mechanics and Foundations in PDF only on Docsity! Name_____________________________ Soil Fertility Management SOCR 350 / Exam 2 November 7, 2008 Circle the underlined correct answer(s) on multiple choice or write the answer in the blank where appropriate. The number in parenthesis indicates the points for each question. Show work on problems. GIVEN: 1% O.M. supplied 30 lb. N/A Legume contributions: Manure supplies 10 lb. N/T Alfalfa - 50 lb. N/A 2.7 x ppm = lb/A Ft. H2O Beans - 30 lb. N/A Alfalfa Grass - 30 lb. N/A ppm x 3.6 = lb. NO3-N/foot/acre ____________________________________________________________________________________ 1. (9) There are three environmentally “active” forms of P in the soil. They are listed below. Match the active form with the description (write the correct letter in the blank). Water soluble - P ________ Readily desorbed – P ________ Biologically available – P ________ A. Used to estimate the amount of P released from a soil that can be used by microbs in water bodies. B. P attached to soil particles that will desorb and move into water for microbial use. C. P that is in the soil solution that can move off a soil with runoff into water bodies. 2. (10) Below is the N cycle. Write the N transformation process (number) in the appropriate blank in the N cycle. A. Aminization B. Mineralization C. Immobilization D. Denitrification E. Teaching F. Ammonification G. None of the above 3. (4) Nitrate leaches in the soil and can adversely impact ground water quality. Does phosphorous (H2P04 - / HP04 = ) leach? Why? 7. (16) Which of the following factors in the P index risk assessment increase or decrease the final risk interpretation. (Circle correct answer) A. Application of manure to a soil with a low water infiltration. Increase or decrease B. Application of commercial inorganic P fertility. Increase or decrease C. Application of manure to a field that does not have tailwater that leaves your property. Increase or decrease D. Application of manure to a field that has a high amount of residue cover. Increase or decrease E. Injection of manure below the soil surface. Increase or decrease F. Application of manure to a soil with high P soil test levels. Increase or decrease G. Choose any of your answers above (a-f) and justify your answer based upon what you know about P management and the P cycle. 8. (10) Below is figure 4.16 from your notes. Answer the following question using this figure: A. What does the CO2 evaluation actually measure? B. Why is the “new NO3 - level” higher than the initial NO3 - level? C. If you add wheat straw to a soil next spring (C:N – 70:1), what will be the NO3 status in the soil in: 1. 20 days compared to before straw addition? 2. 90 days compared to before straw addition? 3. What drives the NO3 level during residue decomposition. 9. (14) Using the solubility diagram and the given chemical reactions (below), answer the following questions. Given: 1. AlPO4 ● 2H2O + H2O <-----> Al (OH)3 + H + + H2PO4 - 2. HPO4 2- + H + <-----> H2PO4 - 3. CaHPO4 ● 2H2O + CO2(g) + H2O <-----> CaCO3 + HPO4 2- + 2H + + H2O 4. CaHPO4 ● 2H2O + H + <-----> Ca 2+ + H2PO4 - + H2O 5. None of the above a. What would be the first stable reaction product formed in the soil if you added APP (ammonium polyphosphate) fertilizer to the following soils: Soil A Soil B pH = 5.2 pH = 7.5 Answer: __________________ Answer: __________________ b. You have a soil that has a pH of 4.0. You add enough lime to the soil to change the pH by 1.5 units. 1. The final pH of the soil will be _______________.