Planning Session for Improving NUE in Corn and Wheat

Corn Research

1. Mexico Sensor Results 2002-2003

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: 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

Kevin Raun, Corn-Soybeans-Wheat Rotation

IMG_1064.MOV

Figure 1. Relationship between corn by-plant dry yields and NDVI sensor measurements multiplied times plant height at 6 locations, 2003.

Can By-Plant yield levels be predicted at early stages of growth? Figures 1 and 2 suggest that this can indeed take place in corn.

Figure 2. Relationship between wet yield and by-plant NDVI sensor readings taken at V7, V8, and V10 stages in corn.

By row differences in corn color as a function of N deficiency, Mead, Nebraska

Paul Hodgen (B.S., and M.S. Oklahoma State University), and current Ph.D. student at the University of Nebraska operates one of the variable N rate applicators developed for corn near Shelton, NE (June 17, 2003).

Corn, V5, Efaw OK, 2003

Do corn roots overlap when plants are more than 7 inches apart? When corn plants were excavated from a corn field to a depth of 2 feet, few rooting cylinders overlapped, unless plants were less than 7 inches apart. Over 70% of the root mass was found to exist within a 6 inch diameter of the stalk, further supporting by-plant variable N application in corn.

After excavation and complete root washing, corn plants were placed in the exact same location as from the slide above. Root systems from these plants were then thoroughly evaluated. Unless the plants were within 6 inches of each other, the 70% by-plant root mass (exists within a 6 inch radius of the stalk) did not overlap with bordering plants. Thus treatment of each plant or every 2 plants within 6 inches makes a lot of sense in corn since N can be accurately placed within the 70% root mass.

2004 Variable N Rate Applicator for Corn, June 1, 2004. Brian Arnall operates this reconfigured unit that senses and applies variable N rates, by plant. Visible in the pictures are the sensors that travel 3 feet above the row, and the drop down nozzle systems (3 per cluster).

Perkins, OK Corn OFIT trials managed by Kyle Freeman & Brenda Tubana. This trial sensed on June 4, 2004, had a response index of 1.34.

Brenda Tubana, Roger Teal, and Jason Taylor inspect the CORN OFIT trial at the Efaw Experiment Station.

Corn trials at the EFAW experiment station, June 2004.