To Side-Dress or Not to Side-Dress (apologies to the Bard of Avon) Dave Franzen, PhD Professor Soil Science Extension Soil Specialist, NDSU, Fargo

Nitrogen Fantasy Land- -Apply N fertilizer any way at any time -Yield increases -Quality increases -Profit increases

Nitrogen Reality Land- -Source matters -Timing matters -Yield can increase (or not) -Quality may improve (or not) -Profit may increase (or not)

Factors influencing rate of transformation- NH4+ → NO2- → NO3- ‘Slow’ ‘Fast’ Nitrosomonas spp Nitrobacter spp Factors influencing rate of transformation- Moisture (moist, not saturated) Temperature- max ~ 80F, min 32F pH- favored by pH > 7 slowed by pH < 6

Once nitrate is in the soil, it can be taken up by plants and microbes, or it could be leached below rooting depth temporarily, semi-permanently, or permanently; or it could be further transformed under anaerobic (low oxygen) conditions through denitrification.

Most anions are not held by soil (NO3-, Cl-, SO4-2)

Corn N timeline Day 1 Day 45 Day 80 Day 120 Most susceptible Period of greatest uptake Application Day 1 Day 45 Day 80 Day 120 Most susceptible period for N loss

Nitrification inhibitors- N-Serve® /Instinct® nitrapyrin (2-chloro-6-[trichloromethyl] pyridine) DCD, dicyandiamide (~ 67% N) Ammonium thiosulfate (some activity, not much)

Fall N, Touchton et al., 1978 N-Serve 24, Illinois Spring N, Touchton et al., 1978 N-Serve 24, Illinois

Instinct II® is a new formulation of Nitrapyrin that can be mixed with ammonium fertilizers and can stay on the soil surface without incorporation. The formulation is microencapsulated nitrapyrin. That means that nitrapyrin release is slow compared to nitrapyrin for ammonia.

NP-nitrapyrin ENP- Instinct DCD Ammonium thiosulfate

DCD- a nitrification inhibitor Found in AgrotainPlus (Agrotain, Int.) SuperU (Agrotain, Int.) Guardian DF (Conklin) Guardian DL (Conklin) Others….. Needs to be added at <1% of total N content of fertilizer needing protection. Best commercial product is about 1.2%

ESN- Agrium Images from Agrium ESN website

How ESN works (Agrium website)

Date of Sampling Date of ESN Burial 10/11 10/25 % urea remaining Urea in ESN remaining after field burial, Casselton, N.D., fall 2013. Ransom, unpublished data, North Dakota State University † Values followed by the same letter are not significantly different from each other at P<0.05 level of probability.   Date of Sampling Date of ESN Burial 10/11 10/25 % urea remaining 10/25/2013 89 a† na 11/08/2013 84 a 96 a 04/29/2014 55 bc 65 b 05/13/2014 50 c 59 bc 05/27/2014 37 d 45 cd 06/10/2014 38 d

North Dakota and Minnesota as affected by source of N (ESN and urea) Spring wheat protein and yield at three sites in the Red River Valley of North Dakota and Minnesota as affected by source of N (ESN and urea) and Instinct, 200 lb. N/acre applied, spring, 2015. Ransom, unpublished data, NDSU     Treatment Protein, % Yield, bushels/acre Check 13.2 50.9 ESN 14.3 70.4 Urea 13.9 71.6 75% ESN:25% Urea 14.4 69.7 50% ESN:50% Urea 14.5 70.8 Urea+ Instinct 70.1 LSD (0.05) 0.7 7.3

An ESN blend before or at planting may also delay N release later into the season. Results from Montana and South Dakota are mixed. MT results indicate little gain from ESN over urea, but they are in a dry environment. South Dakota results showed increase in grain protein with use of ESN.

Best fit for ESN- Spring wheat/Durum- in soil Corn as a blend in preplant to keep plant healthy until side-dress Maybe a 4 part urea/1 part ESN blend Enough ESN to carry N into late grain fill season for higher protein.

Region/Soil Category Preplant N rate $3 corn/40 cent N Less soil test and previous crop credit West-River 149 Eastern ND Long-term no-till 179 High clay >160 bu/a 222 High clay <160 bu/a 150* Medium texture > 160 bu/a 208 Medium texture < 160 bu/a Irrigated anywhere

How about west? Wheat? Row Crops??

How to determine side-dress rate? Ground-based active-sensors are best Greenseeker (Trimble) Holland Crop Circle Sensor (Holland Scientific)

Algorithms are available for corn and are based on soil texture, region, and tillage. Important to apply side-dress from V5-V8. Later can be too late for full effect.

Distance sensor to application point = block of variable rate fertilizer applied Sensor setup for field applicator (Feel free to draw your own- this is why I didn’t get straight A’s in grade school- had to take art. Sensor is at the front at the right, application point is at the left (supposed to be a boom or tool bar) distance of sensing is from sensor to boom as the unit moves through the field.

Example field- 160 acres Use zone sampling to direct the initial N-rate to field- Usually about ½ anticipated total N requirement When fertilizer N is applied preplant, and about half the needed N should be applied preplant so the corn stays healthy until side-dress, within variety and within soil category (high clay high productivity, medium texture high productivity, etc). Farmers should not split a planter with varieties when using this system. In some area of the field, a high rate of N, maybe 200 pounds N per acre should be applied, width of applicator, maybe 100 feet long. This is the N sufficient area. This is the standard to base the side-dress later on. Apply about 200 lb N to a small reference area

Example field- 160 acres When applicator enters the field to apply side-dress application, the reference area serves as the INSEY that is the maximum yield supported by any N rate Uploaded into controller are: -Algorithm for soil category -Any over-rides of 0 rate -Efficiency factor (0.2 to 0.6) When the applicator enters the field to side-dress N, the controller needs the right algorithm, it needs growing degree days from planting to today, it needs an efficiency estimate (usually 0.6 unless there is reason to suspect it might be less). The applicator senses the N sufficient area first. If the N sufficient area is the yellowest area in the field, there is a major S deficiency, and a S application should be made, then come back a week later and side-dress the N. Reference area previously highly fertilized with N

Reference Yield Yield Reference INSEY INSEY By running the sensor over the N sufficient area, the highest yield possible in that variety in that soil category for that year is established for any rate of N. Reference INSEY INSEY

Reference Yield Yield Field Yield estimate Reference INSEY INSEY If the readings (INSEY) is within 5% of the N sufficient reading, no N is applied because yield has been maximized for N rate. If the INSEY is less than 5% less than N sufficient reading, the controller estimates the yield difference is nothing is done using the algorithm. Reference INSEY INSEY in field INSEY

Reference Yield Yield Field Yield estimate Reference INSEY INSEY The yield difference is the basis for the N rate calculation within the controller. Reference INSEY INSEY in field INSEY

Corn yield difference in pounds per acre. X 1.25 % N in corn grain divided by efficiency factor 0.6 = N rate Reference Yield Yield Field Yield estimate Corn yield X 1.25% N in grain (relatively constant) divided by the N application efficiency factor that you put into the system, usually 0.6 for coulter UAN or anhydrous ammonia application. Reference INSEY INSEY in field INSEY

Example- Reference yield predicted- 160 bushels In-field yield estimated- 100 bushels difference = 60 bushels X 56 lb grain/bushel = 3360 pounds X 0.0125 = 42 lb N 42 /0.6 efficiency factor = 70 lb N at that location.

Total Known Available N, pounds per acre* Western Sunflower N rate, long-term no-till, oil-seed   Sunflower Seed Price $ per pound N cost, $ per pound 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 Total Known Available N, pounds per acre* 0.09 126 77 31 0.12 150 115 43 0.15 135 106 50 22 0.18 101 78 54 9 0.21 140 119 98 58 38 19 0.24 132 113 95 60 0.27 142 125 109 93 62 121 92 * Total known available N includes soil test N to 2 feet, previous crop credit and fertilizer amendment N rate.

There were several sites where 0 N plots had less than 40% oil. This is only possible with high N subsoil All of these sites were 1st year sunflower, or sunflower grown with at least a 5 year gap between the sunflower crop and another deep-rooted crop.

Consider for 1st year sunflower or many years in between sunflower crops-

Pioneer- 8 state similar protocol 2 sites per state Objective- determine best side-dress predictive tools for the NC region- results into Encirca Program Missouri Minnesota Illinois Nebraska Iowa Wisconsin Indiana North Dakota

2014- rained all through May and into June Protocol was to apply side-dress V9- too late for us. Corn suffered until side-dress- hurt yields.

Amenia, 7/10, week after side-dress. Check plot

TREATMENT YIELD Check 70.9 40 pp 108.5 80 pp 131.3 120 pp 152.9 160 pp 152.1 200 pp 168.3* 240 pp 152.6 280 pp 167.2* 40 pp 40 sd 136.2 40 pp 80 sd 147.0 40 pp 120 sd 156.1 40 pp 160 sd 150.5 40 pp 200 sd 169.4* 40 pp 240 sd 157.8 80 pp 80 sd 165.7* 80 pp 160 sd 176* LSD 5% 24.5 Amenia 2014

Durbin 2014 Check 34.0 40 pp 58.1 80 pp 76.7 120 pp 93.6 160 pp 106.2* TREATMENT YIELD Check 34.0 40 pp 58.1 80 pp 76.7 120 pp 93.6 160 pp 106.2* 200 pp 102.6 240 pp 91.8 280 pp 103.3 40 pp 40 sd 73.9 40 pp 80 sd 40 pp 120 sd 100.1 40 pp 160 sd 106.0* 40 pp 200 sd 96.3 40 pp 240 sd 89.0 80 pp 80 sd 102.4 80 pp 160 sd 104.3* LSD 5% 29.5 Durbin 2014

2015- rained all May. Side-dress applied V5-V6. Amenia Durbin

Amenia 2015 Treatment Yield, bushels per acre Check 81 40 pp 118 80 pp 142 120 pp 160 160 pp 161 200 pp 180* 240 pp 159 280 pp 178* 40/40 153 40/80 177* 40/120 40/160 175* 40/200 165 40/240 80/80 80/160 183* LSD 31 Amenia 2015

Durbin 2015 Treatment Yield, bushels per acre Check 67 40 pp 123 80 pp 172* 120 pp 147 160 pp 165 200 pp 171* 240 pp 185* 280 pp 139 40/40 131 40/80 166 40/120 173* 40/160 158 40/200 40/240 140 80/80 80/160 159 LSD 28 Durbin 2015

Proper timing propelled Durbin yields over 180 bu/a for the first time. Need enough N to keep the corn healthy, and apply the N by V8.

Summary Keeping N available to crops may be a problem in sandier soils or in clay soils if spring into early summer period is wet. Proper nitrification inhibitors can help ESN can help Side-dress can help if enough N is applied early to keep the crop healthy until side-dress

Summary It is still the best recommendation to apply N to short-season crops like wheat preplant near or at seeding. High rainfall may make top-dress supplements up to early jointing profitable. The active-optical sensor strategy can help make the decision to apply extra N easier.