In addition, crop management practices (e.g. soil fertility management, plant population, planting date, weed control, etc.) had not been developed as a system which was sufficiently productive to gain the full expression of single cross hybrid yield potential.
Application of N as ammonia only, allows for maximum security from loss as ammonia reacts with soil moisture to produce ammonium (NH4+), a cation which is held by a soil's exchange sites. Fall N application is not recommended unless a soil has a C.E.C. of at least 10 meq / 100 grams as a means of assuring adequate capacity to retain Fall applied ammonium.
At temperatures below 50 F (particularly at more northern latitudes where temperatures generally remain low once this threshold is passed), and in the presence of a chemical nitrification inhibitor such as N - Serve, the conversion of ammonium (NH4+) to nitrite (NO2-) (and ultimately to nitrate (NO3-) is slowed sufficiently to lessen the potential for N loss to acceptable levels.
182 Lbs N/Acre
- 10 Lbs N/Acre starter at planting
172 Lbs N/Acre as side dressed N
(1 seed / 8 in.) ( 12 in. / ft.) (17,424 ft. / acre) = 26,136 seeds/ acre
|4 - 8 = 4||16||Sum of squares of differences / r - 1 = 30 / 4 = 7.5 = S2|
|11 - 8 = 3||9|
|7 - 8 = 1||1|
|10 - 8 = 2||4||S = 2.74 inches|
|8 - 8 = 0||0|
2.74 - 2.0 = 0.74 inches of standard deviation greater than 2.
( 0.74 ) (3 bushels yield penalty per inch standard deviation greater than 2) = 2.2 bushels per acre
To calculate the preventable dollar loss for comparison with treatment cost;
(175 bushels) (0.50 infested) (0.75 control) (0.044 yield loss) ($3.00 per bushel) = $8.66 / acre preventable dollar loss.
This compares with a treatment cost of $11 / acre, so treatment is not well advised.
BONUS (5 pts.) Part I.
Part II. PSNT is most reliable on high organic matter (particularly on muck) soils or where high rates of manure have been applied as this technique predicts how much N is being released through mineralization from organic sources.