Abstract
Weather uncertainty and soil spatial variability impact nitrogen (N) cycling and corn (Zea mays L.) growth, making accurate N predictions a challenge. Field studies were conducted in Lansing, Michigan, to evaluate a computer model (i.e., Adapt-N), a preseason year-based model (i.e., maximum return to N [MRTN]), and a crop sensor model (i.e., active canopy sensor with algorithm) for recommending corn N rates. To determine site-specific economic optimum N rates (EONR), five N rates were also applied (0, 33%, 66%, 133%, and 166% of the suggested MRTN) as starter + sidedress (SD) at V4. In a wet year (i.e., 2015), Adapt-N increased V8 SD N rates 35 kg N ha−1 relative to the MRTN V4 SD N application. Although the greater rate of N may have provided additional yield protection, no statistical yield differences were observed between the two models. The MRTN model increased partial factor productivity (PFP) 20% relative to Adapt-N. Limited expression of V8 corn N deficiency reduced crop sensor total N rates (21–56 kg N ha−1) and yield (0.82–1.05 Mg ha−1) relative to other models. In a drier year (i.e., 2016), N demand was reduced (EONR 64 kg N ha−1 less than 2015), resulting in similar corn response to all three models. Despite differences in actual corn N rate recommendations, all three models resulted in similar economic net returns across study years.Abbreviations: EONR, economic optimum nitrogen rate; MRTN, Maximum Return to Nitrogen; NUE, nitrogen-use efficiency; PFP, partial factor productivity; SBNRC, sensor-based nitrogen rate calculator; SD, side-dress
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Claims 8
Claim · model-written summary
Adapt-N raised V8 sidedress nitrogen rates by 35 kg N ha−1 in wet 2015.
- Taxon
- corn
Zea mays subsp. mayst0 - Outcome
- V8 SD N ratese0
- Direction
- increasede0
- Value
- 35 kg N ha−1e0
- Comparator
- MRTN V4 SD N applicatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In a wet year (i.e., 2015), Adapt-N increased V8 SD N rates 35 kg N ha−1 relative to the MRTN V4 SD N application”
t0“corn”
Claim · model-written summary
Yield did not differ statistically between Adapt-N and MRTN.
- Taxon
- cornZea mays subsp. mayst0
- Outcome
- yield differencese0
- Direction
- no statisticale0
- Comparator
- MRTNe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no statistical yield differences were observed between the two models”
e1“Adapt-N increased V8 SD N rates 35 kg N ha−1 relative to the MRTN V4 SD N application”
t0“corn”
Claim · model-written summary
MRTN increased partial factor productivity by 20% relative to Adapt-N.
- Taxon
- cornZea mays subsp. mayst0
- Outcome
- partial factor productivitye0
- Direction
- increasede0
- Value
- 20%e0
- Comparator
- Adapt-Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The MRTN model increased partial factor productivity (PFP) 20% relative to Adapt-N”
t0“corn”
Claim · model-written summary
The sensor model reduced total nitrogen rates by 21–56 kg N ha−1 compared with other models.
- Taxon
- cornZea mays subsp. mayse0
- Outcome
- crop sensor total N ratese0
- Direction
- reducede0
- Value
- 21–56 kg N ha−1e0
- Comparator
- other modelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Limited expression of V8 corn N deficiency reduced crop sensor total N rates (21–56 kg N ha−1) and yield (0.82–1.05 Mg ha−1) relative to other models”
Claim · model-written summary
The sensor model reduced yield by 0.82–1.05 Mg ha−1 compared with other models.
- Taxon
- cornZea mays subsp. mayse0
- Outcome
- yielde0
- Direction
- reducede0
- Value
- 0.82–1.05 Mg ha−1e0
- Comparator
- other modelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Limited expression of V8 corn N deficiency reduced crop sensor total N rates (21–56 kg N ha−1) and yield (0.82–1.05 Mg ha−1) relative to other models”
Claim · model-written summary
Drier 2016 had an EONR 64 kg N ha−1 below 2015.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In a drier year (i.e., 2016), N demand was reduced (EONR 64 kg N ha−1 less than 2015)”
t0“corn”
Claim · model-written summary
Corn responded similarly to all three models in 2016.
- Taxon
- cornZea mays subsp. mayse0
- Outcome
- corn responsee0
- Direction
- similare0
- Comparator
- all three modelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“resulting in similar corn response to all three models”
Claim · model-written summary
All three models gave similar economic net returns across years.
- Taxon
- cornZea mays subsp. mayst0
- Outcome
- economic net returnse0
- Direction
- similare0
- Comparator
- all three modelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“all three models resulted in similar economic net returns across study years”
t0“corn”