Agronomy 375 Exam Archive
Exam 1 Spring 1999

Note: There are 15 questions. One bonus question is also included at the end of the exam. A total of 100 points is possible. Best wishes for your success !

  1. (7 pts.) How can a crop producer measure the efficiency of crop input use in a crop production system (how does he/she know how near optimum they are with the input mix)? Please explain.
  2. (7 pts.) Is management to optimize crop input use efficiency (as referred to in question 1 above) profitable and consistent with good environmental stewardship and sustainability? Please explain. (Assume crop management for the long run (greater than 5 years).
  3. (5 pts.) Give an example of a positive interaction among inputs in a crop production system. Include a brief explanation of how this interaction can contribute to the attainment of maximum economic yield.
  4. (5 pts.) Describe the difference between a primary symptom and a secondary symptom in diagnosing a crop problem. Give an example of each.
    1. (6 pts.) What major considerations should be kept in mind to determine where within-field soil samples should be collected to accurately represent P and K levels as a basis for routine fertilizer recommendations ? These factors may be used alone when not on a grid sampling pattern or they may be used to add more precision to grid sampling in areas where this greater precision is called for (i.e. to help interpret otherwise unexplained variation in yield within areas of a field).
    2. (4 pts.) What soil sampling depth(s) is/are to be used for the routine determination of P and K soil test levels as a basis for P and K fertilizer recommendations for corn and soybean production?
  6. (4 pts.) Describe GPS, GIS, and VRT and integrate them into one example which illustrates their use in working toward the achievement of Maximum Economic Yield.
  7. (8 pts.) How might Fall "zone" tillage and/or residue management (e.g. a set of three coulters tilling a band 7 inches wide over each row and/or "trash whippers" in front of each row) affect the suitability of a no - till planting system for corn after corn on a poorly drained central Indiana soil. Please explain.
  8. (5 pts) List five problems associated with poor soil drainage in a corn production environment in Indiana.
  9. (8 pts.) Economic goals (also called Critical Levels) for P and K soil testing / fertilizer recommendations are targeted in such a way that there is a 10 to 40 percent probability of a positive crop yield response to P or K fertilizer at even higher levels than the economic goal (Critical Level). Please explain this apparent contradiction. Why not simply add P and K fertilizer up to a level which is never limiting to yield?
    1. (4 pts.) Given the following information, calculate the percent residue cover remaining after planting (please show your work). 
                                                                   Residue Cover Remaining

		Corn residue after harvest                            85%
		Fall straight point chisel plow                       50%		
		Overwintering at this northern Indiana location       90%
		Field cultivator in Spring (15 inch sweeps)           80%
		Planter with 13 wave coulters                         70%
    2. (3 pts.) Describe the "Line Transect" method for measuring actual soil surface residue cover remaining after a series of field operations.
  11. (10 pts.) Describe two early - growing season differences in the physical properties and of the upper soil profile (e.g. top few inches) under a no-till and a conventionally plowed field in a poorly-drained central Indiana soil.

    Explain why these differences exist and note how they influence early root development by corn or soybean plants?
  12. (10 pts.) How are crop residue (previous crop), soil drainage, slope, and latitude related to the successful adaptation of a tillage and planting system for corn production in Indiana? (Please be thorough in explaining your answer).
  13. (4 pts.) Note four visible soil or crop symptoms of soil compaction.
  14. (6 pts.) Herbicides are commonly used for the chemical control of weeds in crop systems. However, crop systems also generally include cultural and mechanical controls for weeds as well. Briefly give an example of each (one cultural and one mechanical) of these weed control components for a corn or soybean production system.
  15. (4 pts.)
    1. To what depth (inches) should a PPI herbicide be uniformly incorporated to optimize herbicide effect for corn and soybean production?
    2. What is the general relationship between depth of tillage and the depth of herbicide incorporation for PPI herbicides applied by nozzles in front of a tandem disc?

BONUS (5 pts.) How might a system change from moldboard plowing (followed by conventional spring tillage and planting) to no-till planting influence the costs that a farmer might face and the net income that the farmer might realize? What should be the primary economic basis for making a tillage/planting change in a corn and soybean production system? Please explain thoroughly.

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