Ammonium Sulfate and Ammonium Sulfate Nitrate Application on White Potatoes

Rotation: White potatoes, wheat/double-cropped soybeans, grain corn and single crop soybeans.
Note: The experiment is set up so each crop will be evaluated each year.

Example of a Rotation Cycle: No-till and zoned tilled grain corn, no-till and minimum tilled soybeans, conventional tilled (chisel plowing/discing) white potatoes planted into the continuous no-till and minimum tilled strips, no-till/minimum tilled wheat/double-cropped soybeans.

Fertility Program: All major and minor soil nutrients will be maintained at a U of MD recommended maximum nutrient management level.

1. Check, Grain crops no nitrogen. Potato crop to receive a modest amount of N(54 lbs/a), applied preplant.
2. Grain crops urea, N(130 lbs/a) applied preplant. Potatoes, N applied 3 times (preplant, 1^st sidedress @ emergence, 2^nd sidedress @ hilling).**
3. Grain crops 130 lbs N/a. AMS(150 lbs/a) blended with Urea(214 lbs/a) applied preplant. White Potatoes, N applied 3 times (preplant, 1^st sidedress @ emergence, 2^nd sidedress @ hilling).** Potatoes AMS applied preplant and @ emergence. No AMS at hilling.
4. Grain crops 130 lbs N/a. Ammonium Sulfate Nitrate (ASN – 26-0-0-14) applied preplant at 257 lbs/a + Urea at 137 lbs/a. White potatoes, N applied 2 times (preplant, 2^nd sidedress @ hilling).**

**White potato fertilization fertilizer sources used in study: nitrogen & calcium(ammonium nitrate (34-0-0), ammonium sulfate (21-0-0-24) and calcium nitrate (15-0-0-19(Ca)), phosphorous (0-46-0) & potassium (0-0-60).

Four Treatments will be evaluated in study
Treatment 1. Total fertility 54-100-55-55(Ca) broadcast and tilled into soil by chisel plowing/discing (54-100-55-55(Ca).
Fertilizer Sources: Nitrogen & calcium (ammonium nitrate 34-0-0 and calcium nitrate 15-0-0-19(Ca)), phosphorous 0-46-0 & potassium 0-0-60

Treatment 2. Total fertility 179-100-120-55(Ca)
a. Broadcast and tilled into soil by chisel plowing/discing (54-100-55)
b. 1^st sidedress, cultivated into soil while potatoes are covered up (69-0-65-36(Ca)
c. 2^nd sidedress, cultivated into soil while potatoes are hilled (57-0-0-19(Ca)).

Treatment 3. Total fertility 179-100-120-78(S)-55(Ca)
a. Broadcast and tilled into soil by chisel plowing/discing (54-100-55-43(S)).
b. 1^st sidedress, cultivated into soil while potatoes are covered up (74-0-65-35(S)-36(Ca)).
c. 2^nd sidedress, cultivated into soil while potatoes are hilled (51-0-0-19(Ca)

Treatment 4. Total fertility 179-100-120-78(S)-55(Ca)
a. Broadcast and tilled into soil by chisel plowing/discing (54-100-55-43(S)).
b. 1^st sidedress, cultivated into soil while potatoes are covered up (68-0-65-28(S)-36(Ca)).
c. 2^nd sidedress, cultivated into soil while potatoes are hilled (57-0-0-7(S)-19(Ca).

Duration of Study: 3 years beginning Spring 2009.