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- Title
Predicting Economic Optimal Nitrogen Rate with the Anaerobic Potentially Mineralizable Nitrogen Test.
- Authors
Clark, Jason D.; Fernández, Fabián G.; Veum, Kristen S.; Camberato, James J.; Carter, Paul R.; Ferguson, Richard B.; Franzen, David W.; Kaiser, Daniel E.; Kitchen, Newell R.; Laboski, Carrie A. M.; Nafziger, Emerson D.; Rosen, Carl J.; Sawyer, John E.; Shanahan, John F.
- Abstract
Estimates of mineralizable N with the anaerobic potentially mineralizable N (PMNan) test could improve predictions of corn (Zea mays L.) economic optimal N rate (EONR). A study across eight US midwestern states was conducted to quantify the predictability of EONR for single and split N applications by PMNan. Treatment factors included different soil sample timings (pre-plant and V5 development stage), planting N rates (0 and 180 kg N ha-1), and incubation lengths (7, 14, and 28 d) with and without initial soil NH4--N included with PMNan. Soil was sampled (0-30 cm depth) before planting and N application and at V5 where 0 or 180 kg N ha-1 were applied at planting. Evaluating across all soils, PMNan was a weak predictor of EONR (R² ≤ 0.08; RMSE, ≥67 kg N ha-1), but the predictability improved (15%) when soils were grouped by texture. Using PMNan and initial soil NH4--N as separate explanatory variables improved EONR predictability (11-20%) in fine-textured soils only. Delaying PMNan sampling from pre-plant to V5 regardless of N fertilization improved EONR predictability by 25% in only coarse-textured soils. Increasing PMNan incubations beyond 7 d modestly improved EONR predictability (R² increased ≤0.18, and RMSE was reduced ≤7 kg N ha-1). Alone, PMNan predicts EONR poorly, and the improvements from partitioning soils by texture and including initial soil NH4--N were relatively low (R² ≤ 0.33; RMSE ≥ 68 kg N ha-1) compared with other tools for N fertilizer recommendations.
- Subjects
NITROGEN fertilizers; FERTILIZERS; SOIL texture; CORN; SOIL sampling; NITROGEN; SOILS
- Publication
Agronomy Journal, 2019, Vol 111, Issue 6, p3329
- ISSN
0002-1962
- Publication type
Article
- DOI
10.2134/agronj2019.03.0224