Abstract
Abstract Field average based recommendations have been a common practice for recommending the major crop nutrients nitrogen (N) and phosphorus (P). The problem is yield will not be the same from year to year with application of the same amount of recommended rate of fertilizer. The objectives of this study were to demonstrate how recommendations generated using nutrient response experiments were dynamic; and to assess the relative contribution of temporal variability, N and P fertilizers on winter wheat grain yield and N concentration. Twelve factorial combinations of four N (0, 56, 112, and 168 kg ha−1) and three P (0, 14.5, and 29 kg P ha−1) rates were evaluated in a randomized complete block design with three replications at Perkins, Oklahoma. To address the first objective, ANOVA and orthogonal polynomial contrasts were used. To address the second objective, a ten predictor variable multiple linear regression model with two quantitative variables and their interaction (N, P and N×P) and seven-year variables was evaluated and a reduced model containing seven variables was generated. Wheat grain yield showed three distinct responses to N rates: Linear, quadratic and no response. These individual year data show that it is not always appropriate to use results of nutrient response experiments to estimate next year's N fertilizer requirement due to apparent temporal variability in the results. Wheat only responded to P during the first two years of the study. The reduced model from the regression analysis revealed that most of the variability in grain yield was accounted for by five individual indicator years and N only. High variability across years in grain yield and fertilizer (N and P) response, even between years of similar grain yield, is an indication of a given season's production dependence on factors other than N and P.
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Claims 5
Claim · model-written summary
Wheat grain yield had linear, quadratic and absent responses to nitrogen across years.
- Taxon
- Wheat
Triticum aestivume0 - Treatment
- N ratese0
- Outcome
- grain yielde0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Wheat grain yield showed three distinct responses to N rates: Linear, quadratic and no response.”
Claim · model-written summary
Wheat responded to phosphorus only in the first two study years.
- Taxon
- WheatTriticum aestivume0
- Outcome
- responded to Pe0
- Qualifier
- first two years of the studye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Wheat only responded to P during the first two years of the study.”
Claim · model-written summary
Five year indicators and nitrogen accounted for most grain yield variability in the reduced model.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- Ne0
- Outcome
- variability in grain yielde0
- Qualifier
- five individual indicator years and N onlye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The reduced model from the regression analysis revealed that most of the variability in grain yield was accounted for by five individual indicator years and N only.”
t0“winter wheat”
Claim · model-written summary
The authors caution that nutrient response experiments may not predict next-year nitrogen needs.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- estimate next year's N fertilizer requiremente0
- Qualifier
- apparent temporal variability in the resultse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it is not always appropriate to use results of nutrient response experiments to estimate next year's N fertilizer requirement due to apparent temporal variability in the results.”
t0“winter wheat”
Claim · model-written summary
Yearly variation in yield and fertilizer response indicated dependence on factors beyond nitrogen and phosphorus.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- production dependence on factors other than N and Pe0
- Setting
- across yearse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“High variability across years in grain yield and fertilizer (N and P) response, even between years of similar grain yield, is an indication of a given season's production dependence on factors other than N and P.”
t0“winter wheat”