Locations Efaw Lake Carl Blackwell Haskell Years2005, 2006 Objectives: 1)To determine the minimum preplant N fertilizer needed to achieve maximum yield if sidedress N fertilizer is applied later in the season. 2) To determine how late sidedress N can be applied without decreasing grain yields. Effect of Delayed Nitrogen Fertilization on Corn Grain Yields

TreatmentPreplant N fertilizer application Sidedress N fertilizer application N rate (kg ha -1 ) Growth stage V V6 6090V V VT 90180VT 1090 V V VT 1345 V V6

Grain yield as a function of N application timing LCB, 2005 SED = 0.6

Grain yield as a function of N application timing LCB, 2006 SED = 2.0

NUE as a function of N application timing LCB, 2005

NUE as a function of N application timing LCB, 2006

Conclusions  Grain yields decreased when no preplant N was applied and sidedress N was delayed until VT  Recommend preplant N followed by N application at or before V10.  Window of opportunity for mid-season N application: V6 – V10.  Grain yields decreased when no preplant N was applied and sidedress N was delayed until VT  Recommend preplant N followed by N application at or before V10.  Window of opportunity for mid-season N application: V6 – V10.

Location Lake Carl Blackwell Years2006 Objectives: 1) To establish the amount of nitrogen accumulated in corn over the entire growing season under different levels of N fertilizer. Aboveground N Accumulation as Function of Time in Corn

Nitrogen Uptake of Corn at Different Growth Stages at Lake Carl Blackwell, 2006.

Summary  Maximum N uptake occurred at growth stages V12 from treatments receiving N fertilizer.  N uptake continued to increase until VT in plots receiving no fertilizer N.  Maximum N uptake occurred at growth stages V12 from treatments receiving N fertilizer.  N uptake continued to increase until VT in plots receiving no fertilizer N.

Locations Lake Carl Blackwell Efaw Years2005, 2006 Objectives: 1) To determine corn grain yield reduction as a function of interplant competition arising from delayed emergence. 2) To evaluate yield levels associated with 3 plant sequences, with and without delayed emergence. Effect of Delayed Emergence on Corn Grain Yields

Treatment Delay in planting N rate, kg ha -1 1 All 3 plants planted on the same day Middle plant planted 2 days late 56 4 Middle plant planted 5 days late 56 5 Middle plant planted 8 days late 56 6 Middle plant planted 12 days late 56 7 All 3 plants planted on the same day Middle plant planted 2 days late Middle plant planted 5 days late Middle plant planted 8 days late Middle plant planted 12 days late 168 XXXXOXXXXXXXXOXXXXXXXXOXXXXXXXXOXXXXXXXXOXXXXXXXXOXXXXXXXXOXXXXXXXXOXXXXXXXXOXXXXXXXXOXXXX

X O X

Conclusions Delayed emergence reduces corn grain yields Greater than 5 days delay - significant yield reduction (homogeneity of plant stands) There was a linear reduction in yield with each day of delayed planting Plants delayed by 2,5, and 8 days continued to compete with border plants. By 12 days these plants competed less with border plants. Delayed emergence reduces corn grain yields Greater than 5 days delay - significant yield reduction (homogeneity of plant stands) There was a linear reduction in yield with each day of delayed planting Plants delayed by 2,5, and 8 days continued to compete with border plants. By 12 days these plants competed less with border plants.

Effect of Altered Nitrogen Distribution on Corn Grain Yield LocationsLake Carl Blackwell Efaw Years2005, 2006 Objectives To determine the application resolution at which N competition influences corn grain yield 1) To determine the application resolution at which N competition influences corn grain yield 2)To determine the N application resolution at which corn grain yields are maximized. 2)To determine the N application resolution at which corn grain yields are maximized.

Treatment Structure TrtPlant Distance (cm) Preplant N kg ha -1 Sidedress* N Distribution Application Scenario 1180Check, 0 Preplant and Sidedress N 21845By-plant 31845Every 2 plants 41845Every 3 plants 51845Middle of the row 61845Distributed in the entire row 71845Check, 0 Sidedress N 8110Check, 0 Preplant and Sidedress N 91145By-plant Every 2 plants 11 45Every 3 plants Middle of the row Distributed in the entire row 14110Check, 0 Sidedress N * 62 kg ha -1 for dryland and 123 kg ha -1 for irrigated

Sidedress N Distribution Scenarios Distributed in the Entire Row Center Plant of the Row By-Plant

Grain Yield at LCB, 2005 and 2006 TrtDistance, cm ScenarioTotal N Appiled Kg ha -1 Grain Yield, Mg ha By-plant Every 2 plants Every 3 plants Middle row Distributed By-plant Every 2 plants Every 3 plants Middle row Distributed

Grain Yield at Efaw, 2005 and 2006 TrtDistance, cm ScenarioTotal N Appiled Kg ha -1 Grain Yield, Mg ha By-plant Every 2 plants Every 3 plants Middle row Distributed By-plant Every 2 plants Every 3 plants Middle row Distributed

Evaluating Nitrogen Competition Across Rows in Corn LocationsLake Carl Blackwell Years2005, 2006 Objective To evaluate alternate row N placement on corn grain yield.

Treatment Structure TrtSidedress N Applied kg ha -1 Row Sequence ( )

Grain Yield, 2005 and 2006 TrtSidedress N Applied kg ha -1 Row Sequence ( ) Grain Yield, Mg ha

Figure 1. Grain yield of corn plants where sidedress N fertilizer was applied in the first 3 rows only, First 3 Rows FertilizedLast 2, 0-N

Figure 2. Grain yield of corn plants where sidedress N fertilizer was applied in the first 3 rows only, First 3 Rows Fertilized Last 2 Rows, 0-N

Effect of Nitrogen Fertilizer Rate and Placement on Corn Grain Yield LocationsLake Carl Blackwell Haskell Year2006 Objectives 1) To evaluate the use of directed stream application at the base of the plant using UAN versus dribble surface bands applied in the middle of the row. 2) To evaluate the use of directed stream application at the base of the plant, and by-plant using UAN versus dribble surface bands applied in the middle of the row.

Treatment Structure TrtPre-plant kg ha-1 Sidedress (V8-V10) kg ha -1 Method 14020By plant at base 24020By row at base 34020DSB at center 440 By plant at base 540 By row at base 640 DSB at center 74080By plant at base 84080By row at base 94080DSB at center By plant at base By row at base DSB at center

Corn grain yield at LCB and Haskell, 2005 and 2006 TrtTotal N Applied kg ha -1 MethodGrain Yield, Mg ha -1 Lake Carl Blackwell Haskell By plant at base By row at base DSB at center By plant at base By row at base DSB at center By plant at base By row at base DSB at center By plant at base By row at base DSB at center

Corn NUE% at LCB and Haskell, 2005 and Trt Total N Applied kg ha -1 MethodGrain NUE% Lake Carl Blackwell Haskell By plant at base By row at base DSB at center By plant at base By row at base DSB at center By plant at base By row at base DSB at center By plant at base By row at base DSB at center

CORN OFIT LocationsLake Carl Blackwell Efaw Perkins Year2004, 2005, 2006 Objectives 1) To determine the nitrogen fertilization optimization algorithm that will be used to estimate N rate for optimum corn growth. 2) To determine optimum resolution to treat field spatial variability in corn.

Treatment Structure TRT Preplant N kg ha -1 Mid-Season Sidedress Rate kg ha -1 Resolution m RICV- NFOA RICV-NFOA Flat RICV-NFOA RICV-NFOA RI-NFOA RI-NFOA0.34

Results TreatmentPreplant kg ha -1 Sidedress Grain Yield Mg ha -1 Nitrogen Use Efficiency % Check Common Flat Rate RICV RICV flat RI Common Flat Rate versus Algorithms at Efaw site from With Preplant Nitrogen

Results TreatmentSidedress kg ha -1 Grain Yield Mg ha -1 Nitrogen Use Efficiency % Check Common Flat Rate RICV RICV flat RI Common Flat Rates versus Algorithms at Efaw site from Without Preplant Nitrogen

Results AlgorithmResolution m 2 Total N Applied Kg ha-1 Grain Yield Mg ha -1 Nitrogen Use Efficiency % Check RICV-NFOA RICV-NFOAflat RICV-NFOA RI-NFOA RICV- versus RI-NFOA at Efaw from With Preplant N

Results TRTDescriptionTotal N Applied kg ha -1 Grain Yield Mg ha -1 NUE, % 1Check *CFR-topdress *CFR-topdress *CFR-split *CFR-preplant *CFR-preplant RICV-NFOA RICV-NFOA Flat RICV-NFOA Flat RICV-NFOA RICV-NFOA RI-NFOA RI-NFOA On-average * CFR : Common Flat Rate

Summary  NUE was generally higher when mid- season N rates were generated by NFOA compared with flat farmer rates.  Increased NUE was attributed to the lower N rates applied.  NUE was generally higher when mid- season N rates were generated by NFOA compared with flat farmer rates.  Increased NUE was attributed to the lower N rates applied.

Summary  Use of RI NFOA resulted in a higher increase in NUE than RICV NFOA.  There was limited benefit of treating spatial variability at the high resolution (0.34 m 2, RICV algorithm).  NFOA approaches didn’t project high N rates that did not affect increased yields.  Use of RI NFOA resulted in a higher increase in NUE than RICV NFOA.  There was limited benefit of treating spatial variability at the high resolution (0.34 m 2, RICV algorithm).  NFOA approaches didn’t project high N rates that did not affect increased yields.