Abstract
Nitrogen placement options for improved N efficiency are limited in ridge‐tillage systems where primary and secondary tillage for fertilizer incorporation is absent. Studies were conducted for 3 yr on a Webster clay loam (fine‐loamy, mixed, mesic Typic Haplaquoll) in southern Minnesota to determine the effect of placement and time of N application on corn ( Zea mays L.) production and postharvest residual soil nitrate (RSN) and to evaluate the spoke‐wheel injector for precise placement of urea‐ammonium nitrate solution (UAN, 28‐0‐0) for corn after soybean [ Glycine max (L.) Merr.] in a ridge‐tillage system. Nitrogen as UAN was either band‐applied on the ridge, broadcast, or point injected into the ridge (PINJ‐R) or valley (PINJ‐V) and was compared with anhydrous ammonia (AA) injected into the valley (INJ‐V). Single preplant and pre‐emergence applications were compared with split applications where 30 to 40% was applied preemergence and 60 to 70% was applied at the V7 and V16 growth stages. Leaf N concentration at the Rl stage and whole plant dry matter and N concentration at the R2 stage were generally enhanced by single preemergence applications compared with split applications and by PINJ‐R compared with the PINJ‐V treatment. Grain yield, total N uptake, and net economic return were generally optimized by point injecting UAN and the injection of preplant AA compared with band and broadcast applications of UAN. Split applications did not produce higher yields, N uptake, or net economic return than single preemergence injected applications of N. However, RSN was highest with the V16 application of UAN under these nonirrigated conditions. Three‐year average grain yield and net economic return were highest with the preemergence PINJ‐R treatment. These results suggest that a single preemergence spoke‐wheel application of UAN into the ridge or preplant AA in the valleys can be successfully used to optimize N management and corn production following soybean in a ridge‐tillage system. Nitrogen efficiency will be enhanced and ammonia volatilization will be reduced with these application methods. Research Question Economically profitable and environmentally sound corn production in conservation tillage systems requires excellent N management. Placement options are often limited, however, if no primary or secondary tillage is conducted. The objectives of this study were to: (i) determine the effect of placement and time of N application on corn production and residual soil nitrate (RSN) levels, (ii) evaluate band vs. broadcast and single vs. split applications of N, and (iii) evaluate the spoke‐wheel injector as a tool for precise placement of urea‐ammonium nitrate (UAN) solution for corn following soybean in a ridge‐tillage system. Literature Summary Many studies have cited reduced corn yields and significant volatilization losses of ammonia when urea containing fertilizers, e.g. UAN, are applied to the soil surface and not incorporated in conservation tillage systems. These negative effects are most prevalent in no‐till continuous corn, but also occur in other tillage systems where incorporation is not practiced. The spoke‐wheel injector developed in the late 1980s in Iowa gives greater timing and placement flexibility for N application in conservation tillage systems. Few studies have compared a wide range of N application methods and timing options, especially for corn after soybean in a ridge‐tillage system. Study Description A 3‐yr study was conducted on a Webster clay loam at the University of Minnesota Southern Experiment Station at Waseca. Nitrogen as UAN was either band‐applied on the ridge, broadcast, or point injected into the ridge (PINJ‐R) or valley (PINJ‐V) and was compared with anhydrous ammonia (AA) injected in the valleys. Single preplant and preemergence applications were compared with split applications where 30 to 40% of the N was applied preemergence and 60 to 70% was applied at the V7 and V16 growth stages. Leaf N at silking, whole plant dry matter and N concentration at the blister stage, grain yield, total N uptake, and RSN measurements were taken each year to evaluate the treatments. Applied Questions Were corn grain yields and net economic return to N affected by N placement? Highest yield and net economic return were obtained with the PINJ‐R treatment and were followed closely by preplant AA and preemergence PINJ‐V when applied at the 100‐lb N rate (Table ). Surface application of UAN either in an 8 to 10‐in. band on the row or broadcast resulted in slightly lower yields, N uptake, and net economic return. Were corn grain yields and net economic return to N affected by timing of N application? Split applications consisting of 30 to 40 lb N/acre band‐applied preemergence and sidedress applications of 60 to 70 lb N/acre as either AA or UAN at the V7 or V16 growth stages did not produce greater yields or net economic return to N than single, preemergence injected applications of N on this clay loam soil (Table ). Applying a portion of the N at the V16 stage resulted in the greatest RSN values in the 0 to 3 ft. profile, thereby suggesting a greater potential for postharvest leaching of nitrate. Were mid‐season leaf and whole‐plant measurements helpful in assessing the end‐of‐season performance of the N application methods? Many of the placement and timing effects measured at the silking and blister stages did not occurr with respect to grain yield. Apparently, conditions in this corn‐soybean system were conducive for some late‐season uptake of N and corn growth after onset of the reproductive stage to offset many of the mid‐season concerns. Was the spoke‐wheel injector an acceptable tool for applying UAN to this conservation tillage system? The spoke‐wheel injector performed well and offered great flexibility in the timing and placement of UAN. Corn plants were not damaged. High N‐use‐effciency was obtained with this application method. Based on our experiences, the spoke‐wheel injector should perform satisfactorily in a variety of tillage systems. Recommendations Nitrogen management and corn production after soybean can be optimized by a single preemergence, spoke‐injection of UAN directly into the ridge or preplant AA in a ridge‐tillage system. These application methods will enhance N eficiency and reduce ammonia volatilization commonly found with nonincorporated, surface application of UAN. Three‐yr average corn grain yield and net economic return to N as influenced bv N rate, source, and application time and method. Nitrogen Application Net Grain economic Rate Source Time Methof yield return to N lbN/acre lb/acre $/acre 0 Control ‐‐ ‐‐ 114.9 ‐‐ 100 AA PP INJ‐V 154.7 84 60 UAN PE B‐R 138.1 43 100 UAN PE B‐R 150.8 66 140 UAN PE B‐R 160.6 81 100 UAN PE BDCT 147.7 58 100 UAN PE PINJ‐R 161.4 94 100 UAN PE PINJ‐V 155.3 77 30 + 70 UAN/AA PE + SD (V7) B‐R/INJ‐V 155.3 77 30 + 70 UAN/UAN PE + SD (V7) B‐R/PINJ‐V 153.4 64 30 + 70 UAN/UAN PE + SD (V16) B‐R/PINJ‐V 153.4 64 30 + 50 UAN/UAN PE + SD(V16) B‐R/PINJ‐V 148.7 57 30 + 70 = 30 l
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Claims 20
Claim · model-written summary
Single preemergence applications enhanced Leaf N concentration compared with split applications.
- Taxon
- corn
Zea mays subsp. mayst0 - Treatment
- single preemergence applicationse0
- Outcome
- Leaf N concentratione0
- Direction
- enhancede0
- Comparator
- split applicationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf N concentration at the Rl stage and whole plant dry matter and N concentration at the R2 stage were generally enhanced by single preemergence applications compared with split applications and by PINJ‐R compared with the PINJ‐V treatment.”
t0“Corn”
Claim · model-written summary
Single preemergence applications enhanced whole plant dry matter and N concentration compared with split applications.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- single preemergence applicationse0
- Outcome
- whole plant dry matter and N concentratione0
- Direction
- enhancede0
- Comparator
- split applicationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf N concentration at the Rl stage and whole plant dry matter and N concentration at the R2 stage were generally enhanced by single preemergence applications compared with split applications and by PINJ‐R compared with the PINJ‐V treatment.”
t0“Corn”
Claim · model-written summary
PINJ-R enhanced Leaf N concentration compared with PINJ-V.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- PINJ‐Re0
- Outcome
- Leaf N concentratione0
- Direction
- enhancede0
- Comparator
- PINJ‐Ve0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf N concentration at the Rl stage and whole plant dry matter and N concentration at the R2 stage were generally enhanced by single preemergence applications compared with split applications and by PINJ‐R compared with the PINJ‐V treatment.”
t0“Corn”
Claim · model-written summary
PINJ-R enhanced whole plant dry matter and N concentration compared with PINJ-V.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- PINJ‐Re0
- Outcome
- whole plant dry matter and N concentratione0
- Direction
- enhancede0
- Comparator
- PINJ‐Ve0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf N concentration at the Rl stage and whole plant dry matter and N concentration at the R2 stage were generally enhanced by single preemergence applications compared with split applications and by PINJ‐R compared with the PINJ‐V treatment.”
t0“Corn”
Claim · model-written summary
Point-injected UAN and preplant AA optimized Grain yield compared with surface UAN applications.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- point injecting UAN and the injection of preplant AAe0
- Outcome
- Grain yielde0
- Direction
- optimizede0
- Comparator
- band and broadcast applications of UANe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain yield, total N uptake, and net economic return were generally optimized by point injecting UAN and the injection of preplant AA compared with band and broadcast applications of UAN.”
t0“Corn”
Claim · model-written summary
Point-injected UAN and preplant AA optimized total N uptake compared with surface UAN applications.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- point injecting UAN and the injection of preplant AAe0
- Outcome
- total N uptakee0
- Direction
- optimizede0
- Comparator
- band and broadcast applications of UANe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain yield, total N uptake, and net economic return were generally optimized by point injecting UAN and the injection of preplant AA compared with band and broadcast applications of UAN.”
t0“Corn”
Claim · model-written summary
Point-injected UAN and preplant AA optimized net economic return compared with surface UAN applications.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- point injecting UAN and the injection of preplant AAe0
- Outcome
- net economic returne0
- Direction
- optimizede0
- Comparator
- band and broadcast applications of UANe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain yield, total N uptake, and net economic return were generally optimized by point injecting UAN and the injection of preplant AA compared with band and broadcast applications of UAN.”
t0“Corn”
Claim · model-written summary
Split applications did not improve yields over single preemergence injection.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- Split applicationse0
- Outcome
- yieldse0
- Direction
- did not produce highere0
- Comparator
- single preemergence injected applications of Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Split applications did not produce higher yields, N uptake, or net economic return than single preemergence injected applications of N.”
t0“Corn”
Claim · model-written summary
Split applications did not improve N uptake over single preemergence injection.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- Split applicationse0
- Outcome
- N uptakee0
- Direction
- did not produce highere0
- Comparator
- single preemergence injected applications of Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Split applications did not produce higher yields, N uptake, or net economic return than single preemergence injected applications of N.”
t0“Corn”
Claim · model-written summary
Split applications did not improve net economic return over single preemergence injection.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- Split applicationse0
- Outcome
- net economic returne0
- Direction
- did not produce highere0
- Comparator
- single preemergence injected applications of Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Split applications did not produce higher yields, N uptake, or net economic return than single preemergence injected applications of N.”
t0“Corn”
Claim · model-written summary
Residual soil nitrate was highest after V16 UAN application.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- V16 application of UANe0
- Outcome
- RSNe0
- Direction
- higheste0
- Qualifier
- nonirrigated conditionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“However, RSN was highest with the V16 application of UAN under these nonirrigated conditions.”
t0“Corn”
Claim · model-written summary
Three-year average grain yield was highest with preemergence PINJ-R.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- preemergence PINJ‐R treatmente0
- Outcome
- grain yielde0
- Direction
- higheste0
- Qualifier
- Three‐year averagee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Three‐year average grain yield and net economic return were highest with the preemergence PINJ‐R treatment.”
t0“Corn”
Claim · model-written summary
Three-year average net economic return was highest with preemergence PINJ-R.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- preemergence PINJ‐R treatmente0
- Outcome
- net economic returne0
- Direction
- higheste0
- Qualifier
- Three‐year averagee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Three‐year average grain yield and net economic return were highest with the preemergence PINJ‐R treatment.”
t0“Corn”
Claim · model-written summary
Many midseason placement and timing effects did not persist in grain yield.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- placement and timinge0
- Outcome
- grain yielde0
- Direction
- did not occurre0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Many of the placement and timing effects measured at the silking and blister stages did not occurr with respect to grain yield.”
t0“Corn”
Claim · model-written summary
The spoke-wheel injector performed well and allowed flexible UAN timing and placement.
- Taxon
- cornZea mays subsp. mayst0
- Outcome
- performed welle0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The spoke‐wheel injector performed well and offered great flexibility in the timing and placement of UAN.”
t0“Corn”
Claim · model-written summary
The spoke-wheel injector did not damage corn plants.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- this application methode0
- Outcome
- Corn plants were not damagede0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Corn plants were not damaged. High N‐use‐effciency was obtained with this application method.”
Claim · model-written summary
The spoke-wheel application achieved high nitrogen use efficiency.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- this application methode0
- Outcome
- N‐use‐effciencye0
- Direction
- Highe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Corn plants were not damaged. High N‐use‐effciency was obtained with this application method.”
Claim · model-written summary
The authors recommend single preemergence spoke‐wheel application of UAN into the ridge for corn nitrogen management after soybean.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- single preemergence spoke‐wheel application of UAN into the ridgee0
- Outcome
- optimize N management and corn productione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These results suggest that a single preemergence spoke‐wheel application of UAN into the ridge or preplant AA in the valleys can be successfully used to optimize N management and corn production following soybean in a ridge‐tillage system.”
Claim · model-written summary
The authors recommend preplant AA in the valleys for corn nitrogen management after soybean.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- preplant AA in the valleyse0
- Outcome
- optimize N management and corn productione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These results suggest that a single preemergence spoke‐wheel application of UAN into the ridge or preplant AA in the valleys can be successfully used to optimize N management and corn production following soybean in a ridge‐tillage system.”
Claim · model-written summary
The authors expect these methods to enhance nitrogen efficiency and reduce ammonia volatilization.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- these application methodse0
- Outcome
- Nitrogen efficiency will be enhanced and ammonia volatilization will be reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen efficiency will be enhanced and ammonia volatilization will be reduced with these application methods.”
t0“Corn”
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Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.