AGRONOMY 375 EXAM III December 15, points possible

Transcription

1 AGRONOMY 375 EXAM III December 15, points possible Name There are 15 questions plus a Bonus question. Each question requires a short answer. Please be thorough yet concise and show your work where calculations are involved. 4 pts. 1. Briefly describe four factors which contribute to increased yield and / or profit potential for corn planted early (e.g. April 20 vs. May 5) in central Indiana. a) b) c) d) 2. A portion of a row is uncovered to check planter calibration in the field. The following distances are recorded between successive seeds in this row segment. Row width is 30 inches. Please show your work. 8 inches 5 inches 7 inches 8 inches 2 inches 2 pts. a) The actual seeding rate for this row segment is seeds/acre 2 pts. b) What level of standard deviation (from uniform spacing) is presented in this row segment? 2 pts. c) What yield loss (if any) due to poor precision is likely at this level of planting precision?

2 2 bushels per acre. 10 pts. 3. Describe each of the following for commercial dent corn: a) V stage of the plant in the following picture. Note that the collar of the leaf with thumb-shaped tip is visible while that of the next leaf up is not. b) The number of the node which is at the top of the first elongated internode visible when splitting the base of a corn stalk. c) Visible indicator that a plant has reached R2. d) Visible indicator that a plant has reached R3. e) Visible indicator that a plant has reached R5. 4 pts. 4. For a medium texture soil at field capacity approximately how much water (inches) is plant-available per foot of rooting depth? 6 pts. 5. Compare the drought tolerance of soybean yield to that of corn yield. Provide at least two reasons for the greater yield stability of the most drought-tolerant crop.

3 3 6 pts. 6. a) What is the optimum seeding date for Soft Red Winter Wheat in the Midwestern U.S.? ( Note: Your answer should apply equally well to any location in this Soft Red Winter Wheat producing area.) 4 pts. b) Please give two reasons for this seeding date goal. 8 pts. 7. a) What is the optimum established stand density goal for Soft Red Winter Wheat in Indiana? plants / square foot b) How many inches of row length comprise one square foot of area where row width is 9 inches? inches of row length / square foot 8. The following pertain to a proposed crop of Indiana wheat; Yield goal = 90 bushels per acre Previous crop = soybeans (Please show your work.) 3 pts. a) What total N rate is appropriate to recommend (please show your work)? 3 pts. b) What maintenance P2O5 rate should be applied per acre? 3 pts. c) What maintenance K2O rate should be applied per acre? Lbs. N / Acre Lbs. P2O5 / Acre Lbs. K2O / Acre

4 4 4 pts. 9. At what wheat developmental stage(s) should topdress N be applied in the Spring? 4 pts Why topdress wheat at this/these stage(s)? Please be specific and provide two reasons for this timing. a) b) 4 pts. 10. Note the appropriate maintenance P2O5 and K2O rates for 65 bushel per acre soybeans. (Please show your work). Lbs. P2O5 / Acre Lbs. K2O / Acre 11. Compare a Maturity Group II vs. a Maturity Group IV indeterminate soybean variety with respect to each of the following (assume both are planted on the same day at the same location in central Indiana, in the same row width and at the same population). 2 pts. a) Flowering date of Maturity Group II vs that of Maturity Group IV. 2 pts. b) Mature plant height of Maturity Group II vs that of Maturity Group IV. 7 pts. 12. How can a producer know if they have optimized soybean row width with regard to accomplishing optimum light harvest and removing that as a factor potentially limiting to yield? Please explain your answer.

5 5 4 pts. 13. a) If shooting for a non-limiting established/harvest stand what would be an approximate recommended target goal per acre and per foot of row for each of the following row widths? 6 Inch Row Width plants per acre plants per foot of row 15 Inch Row Width plants per acre plants per foot of row 4 pts. b) Soybeans have a very strong ability to compensate over a wide range of plant populations so optimal seeding rate recommendations may vary with conditions. Note two factors that may affect what is the optimal seeding rate for a given situation. a) b) 8 pts. 14. Note a quantifiable characteristic which uniquely indicates that a soybean plant is at each of the following; a) R 2 growth stage? b) R 3 growth stage? c) R 5 growth stage? d) R 6 growth stage? 4 pts. 15. Assume a hoop with diameter 30 inches has been used to estimate stand counts in a drilled soybean field. The average plant density in the area surrounded by the hoop was 18. What is the estimated stand density for this field? (Please show your work). Plants / Acre

6 6 5 pts. BONUS. What is the developmental stage of the soybean plant pictured at center below? Note that one unifoliolate and one trifoliolate leaf node have leaves with margins no longer touching while the second trifoliolate leaf node has leaves with margins still touching. HAVE A BLESSED AND MERRY CHRISTMAS! CONGRATULATIONS TO THE GRADUATES!