University of Nebraska, USDA-ARS Project

Collaborative Research with USDA-ARS, University of Nebraska

Collaborative Research USDA-ARS, AMES, Iowa

World Nitrogen Use Efficiency for Cereal Production is 33%,
Agronomy Journal 91:357

Yield level and Nitrogen response are Independent (corn and wheat) J. Prec. Agriculture 12:508-518

2005 Evan Brandes Cooperation

Corn Trial conducted jointly with Dennis Francis and Jim Schepers, USDA-ARS, University of Nebraska, Lincoln, NE. Corn trial located near Shelton, NE. Harvested in October, 2003

Summary 2003: Using the maximum yield Nitrogen Fertilization Optimization Algorithm (NFOA), grain yields were increased by 4 bu/ac when compared to the 80-85 N split (treatment 10 versus 4). For treatment 10 and treatment 4, 80 lb of N /ac was applied at a fixed rate preplant. When topdress N was applied on June 17, 2003, fixed rates were applied in treatments 2, 3, and 4. Treatments 7-11 received topdress N applied using the variable N rate applicator (illustrated below) capable of sensing and treating each corn plant individually. Grain yields were increased by 4 bu/ac for treatment 10 when compared to treatment 4, using 42 less lb N/ac. As a result, the nitrogen use efficiencies of this treatment were 10% better than the split N treatment (treatment 10 vs 4, 40% NUE, and 30% NUE, respectively).

Corn OFIT Trial, MSEA site, USDA-ARS				Planted:
2003				Harvest:
Treatment	Preplant Rate	Sidedress Rate	N Rate	Total N Rate	Grain Yield	NUE
		10 to 12 leaf stage	Pre+topdress
	lb N/ac	lb N/ac	lb N/ac	lb N/ac	bu/ac	%
1	0	0	0	0	118
2	0	89	89	89	165	37
3	0	161	161	161	170	23
4	80	85	165	165	193	30
5	80	0	80	80	180	53
6	160	0	160	160	181	27
7	0	RI-NFOA	0+37	37	141	41
8	80	RI-NFOA 60 % NUE	80+25	105	177	41
9	0	MY-NFOA	0+64	69	165	42
10	80	MY-NFOA	80+43	123	197	40
11	80	RI-NFOA 40% NUE	80+61	141	175	28
SED					11	13

Replications	4			NDVI N Rich	0.513	RI = 1.2
Soil N applied at the base of each corn plant				NDVI Check	0.448

RI NFOA -nitrogen fertilization optimization algorithm (based on the response index)
MY MFOA - nitrogen fertilization optimization algorith (based on maximum yield)
Damaged Plots (Application Error, removed from analysis & entered as missing data) 101, 102, 103, 104, 105, 308

Corn OFIT Trial, MSEA site, USDA-ARS

Planted: April 29, 2002
Harvest: September 24, 2002

Treatment	Preplant Rate	Sidedress Rate	Total N Rate	Grain Yield	NUE	Std. Dev.
		8 to 12 leaf stage
	lb N/ac	lb N/ac	lb N/ac	bu/ac		bu/ac
1	0	0	0	107.9	0	15
2	0	70	70	118.2	10.3	21
3	0	140	140	115.1	3.6	21
4	70	70	140	128.3	10.2	15
5	70	0	70	124.1	16.2	14
6	140	0	140	123.8	7.95	10
7	0	RI NFOA (23)	23	105.9	0	22
8	70	RI NFOA (23)	93	130.6	17	15
9	0	flat RI NFOA (22)	22	94.3	0	33
10	70	flat RI NFOA (22)	92	129.1	16	6

*one of the check plots was lost due to harvest error
NFOA - nitrogen fertilization optimization algorithm (N applied to each plant)
flat NFOA - average N rate determined from treatments 7 and 8, applied uniformly to treatments 9 and 10.
Treatment 4 topdress applied 2 weeks later.

Replications 4
Days from planting to sensing

Soil N applied at the base of each corn plant, June 11, 2002
4/29/2002

Treatment 4 (sidedress application date delayed)
6/11/2002

Border rows for treatments 7 and 8 received flat rates (25 kg/ha)
Center 2 rows of treatments 7 and 8 were fertilized by-2-plants

Evan Brandes (bran@cconline.net), Central City, NE, April 7, 2005
308 940-0202

Paul Gangwish, Shelton, NE April 8, 2005

Dr. Jim Schepers inspects one of the many variable N rate trials conducted near Shelton Nebraska at the USDA-ARS MSEA site (June 22, 2004). Dr. Schepers was the first scientist to establish Nitrogen Reference Strips for calibrating in-season fertilizer applications.

By-plant determination of NDVI using the GreenSeeker sensor near Shelton, NE

David Smith (NTech Industries) and Kent Martin prepare to collect by-plant sensor readings near Shelton, NE using a GreenSeeker sensor and a shaft encoding device that writes distance to the same file where NDVI readings are collected. This allows for accurate determination of average NDVI on a by-plant basis.

Corn OFIT Trial, MSEA site, USDA-ARS

Planting date:
Harvest date:
Preplant N Fertilization:
Topdress N fertilization: June 11, 2002

Treatment	Preplant Rate	Sidedress Rate	Total N Rate	Grain Yield	Std. Dev.
		8 to 12 leaf stage
	lb N/ac	lb N/ac	lb N/ac	bu/ac	bu/ac
1	0	0	0	107.9*	15
2	0	70	70	118.2	21
3	0	140	140	115.1	21
4	70	70	140	128.3	15
5	70	0	70	124.1	14
6	140	0	140	123.8	10
7	0	NFOA (23)	23	105.9	22
8	70	NFOA (23)	93	130.6	15
9	0	flat NFOA (22)	22	94.3	33
10	70	flat NFOA (22)	92	129.1	6
				SED = 12.4
*one of the check plots was lost due to harvest error, and this mean is likely overestimated (based on the other 3 values)

Summary 2002:
1. Applied N increased yields by more than 22 bushels/acre
2. OSU-NU NFOA (trt 8) produced equivalent yields using 47 less lbs N/ac Preplant 70 + Fixed 70 (trt 4)
3. When no N was applied Preplant, by-plant N rates increased yields by 11.6 bu/ac (7 versus 9) compared to flat N rates
4. When 70 lb N was applied preplant, by-plant N rates had equal yields (8 vs 10) compared to flat N rates
5. Nitrogen applied mid-season to plots receiving no preplant N could did not result in equivalent yields when compared to all N applied preplant and/or split applied (early season N stress should be avoided).

Dr. Jagadeesh Mosali applies fixed N rates in a collaborative corn trial with Dr. Dennis Francis and Dr. Jim Schepers (MSEA site, near Shelton, NE), June 11, 2002