Browsing by Author "Carpenter, Jonathan"

Now showing 1 - 6 of 6
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    Active optical sensor measurements and weather variables for predicting winter wheat yield
    (Agronomy Journal, 2021) Aula, Lawrence; Omara, Peter; Nambi, Eva; Oyebiyi, Fikayo B.; Dhillon, Jagmandeep; Eickhoff, Elizabeth; Carpenter, Jonathan; Raun, William R.
    Accurate winter wheat (Triticum aestivum L.) grain yield prediction is vital for improving N management decisions. Currently, most N optimization algorithms use in-season estimated yield (INSEY) as a sole variable for predicting grain yield potential (YP). Although evidence suggests that this works, the yield prediction accuracy could be further improved by including other predictors in the model. The objective of this work was to evaluate INSEY, pre-plant N rate, total rainfall, and average air temperature from September to December as predictors of winter wheat YP. An 8- yr (2012–2019) data set for grain yield was obtained from Experiment 502, Lahoma, OK. The experiment was designed as a randomized complete block with four replications and N applied at 0, 45, 67, 90, and 112 kg ha–1.Weather data was obtained from the OklahomaMesonet (http://mesonet.org). The data were analyzed using R statistical computing platform. The best model was selected using least absolute shrinkage and selection operator. Root mean square error (RMSE) was obtained using k-fold cross-validation. The model selection algorithm produced the full model as the best model for yield prediction with an R2 of .79 and RMSE of 0.54 Mg ha–1. The best one-variable model – as expected – used INSEY as the predictor and had the highest RMSE of 0.72 Mg ha–1 and an R2 of .62. Mid-season YP prediction accuracy could be improved by including pre-plant N rate, mean air temperature, and total rainfall from September to December in a model already containing INSEY.
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    Biochar Application in Combination with Inorganic Nitrogen Improves Maize Grain Yield, Nitrogen Uptake, and Use E ciency in Temperate Soils
    (Agronomy, 2020) Omara, Peter; Aula, Lawrence; Oyebiyi, Fikayo B.; Eickho, Elizabeth M.; Carpenter, Jonathan; Raun, William R.
    Biochar (B) has shown promise in improving crop productivity. However, its interaction with inorganic nitrogen (N) in temperate soils is not well-studied. The objective of this paper was to compare the e ect of fertilizer N-biochar-combinations (NBC) and N fertilizer (NF) on maize (Zea mays L.) grain yield, N uptake, and N use e ciency (NUE). Trials were conducted in 2018 and 2019 at Efaw and Lake Carl Blackwell (LCB) in Oklahoma, USA. A randomized complete block design with three replications and ten treatments consisting of 50, 100, and 150 kg N ha􀀀1 and 5, 10, and 15 Mg B ha􀀀1 was used. At LCB, yield, N uptake, and NUE under NBC increased by 25%, 28%, and 46%, respectively compared to NF. At Efaw, yield, N uptake, and NUE decreased under NBC by 5%, 7%, and 19%, respectively, compared to NF. Generally, results showed a significant response to NBC at 10 Mg B ha􀀀1. While results were inconsistent across locations, the significant response to NBC was evident at LCB with sandy loam soil but not Efaw with silty clay loam. Biochar application with inorganic N could improve N use and the yield of maize cultivated on sandy soils with poor physical and chemical properties.
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    Evaluation of Sorghum Emergence and Grain Yield Response to Seeding Density and Plant Spacing Attained Using the OSU Hand Planter
    (Communications in Soil Science and Plant Analysis, 2021) Nambi, Eva; Aula, Lawrence; Oyebiyi, Fikayo B.; Eickhoff, Elizabeth M.; Omara, Peter; Carpenter, Jonathan; Raun, William R.
    Plant spacing and density are important metrics in crop production because they impact the plant’s ability to utilize resources and attain full yield potential. Planting sorghum (Sorghum bicolor (L.) Moench) in a more narrow spacing brings about phytochrome-mediated responses, where plants develop narrow leaves, long stems, fewer roots, and this is linked to competition that plants develop for nutrients like nitrogen (N). The Oklahoma State University hand planter (OSU-HP) can improve plant homogeneity and midseason placement of N. However, this crop production tool alongside other agronomic practices have not been adequately evaluated for improving sorghum grain yields. The objective of this work was to evaluate the response of sorghum to planting methods, the number of seeds per hole, within row spacing, and N rate. A randomized complete block design with 13 treatments replicated 3 times was used in this study. The treatments included different combinations of 3 planting methods (John Deere [JD], OSU-HP, and stick planter [check]), 3 within-row spacings (10, 30, and 60 cm), 3 different number of seeds per hole (1, 3, and 6) and 3 N rates (0, 30 and 60 kg ha−1). Average grain yield with 3 seeds per hole was at least 18% higher than the yield range of 0.7 to 4.6 Mg ha−1 achieved with 1 or 6 seeds per hole. This study demonstrated that the production of sorghum using sound agronomic practices could improve yield.
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    Improving winter wheat grain yield and nitrogen use efficiency using nitrogen application time and rate
    (Agrosystems, Geosciences & Environment, 2021) Aula, Lawrence; Omara, Peter; Oyebiyi, Fikayo B.; Eickhoff, Elizabeth; Carpenter, Jonathan; Nambi, Eva; Fornah, Alimamy; Raun, William R.
    Preplant nitrogen (N) application, which involves placing nutrients in the soil before seeding, has been an integral part of crop production systems for decades. Some producers are known to apply N at least 21 d before planting. This may increase N loss and lower grain yield. This study evaluated the effect of timing and rate of N application on winter wheat (Triticum aestivum L.) grain yield and N use efficiency (NUE). An experiment with a factorial arrangement of treatments was set up in a randomized complete block design with three replications. Treatments included four N rates (0, 45, 90, and 135 kg ha–1) with each applied 7 or 30 d before planting, and at Feekes 5 (FK5). Grain N was analyzed using LECO CN dry combustion analyzer. The difference method [Grain N from (fertilized plot – check plot)]/N applied was used to compute NUE. Nitrogen application rate significantly affected grain yield (P ≤ .01). Although the rate may be temporally and spatially variable, approximately 90 kg N ha–1 was required to obtain yields that differ markedly from the check. Midseason applied N (FK5) had similar yields to preplant applied N in two of four siteyears and significantly increased yield at one site in 2020. Out of two sites, the timing of N application had a substantial effect on NUE in both years (P ≤ 0.11). In this case, NUE was increased by as much as 9.5% for midseason applied N compared to 30 d before planting N application time.
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    No-tillage Improves Winter Wheat (Triticum Aestivum L.) Grain Nitrogen Use Efficiency
    (Communications in Soil Science and Plant Analysis,, 2019) Omara, Peter; Aula, Lawrence; Oyebiyi, Fikayo; Nambi, Eva; Dhillon, Jagmandeep S.; Carpenter, Jonathan; Raun, William R
    Tillage practices are among the factors that affect soil quality as well as use efficiency of fertilizer nitrogen (N). Data consisting of 24-site-years from two long-term experiments 222 (E222) located in Stillwater and 502 (E502) located in Lahoma, Oklahoma were used in this study. Treatments included pre-plant N rates of 0, 45, 90, and 135 kg N ha−1 at E222 and 0, 22.5, 45, 67, 90 and 112 kg N ha−1 at E502. The objective was to evaluate the influence of no-tillage (NT) on grain N uptake and N use efficiency (NUE) of winter wheat (Triticum aestivum L.) relative to conventional tillage (CT). Generally, results indicated significantly higher grain N uptake and NUE under NT relative to CT. However, single-degree-of-freedom contrast at individual N rate indicated inconsistency in grain N uptake and NUE between experimental locations. Under both tillage practices, grain N uptake increased with N rate while NUE decreased as N rate increased. Overall, NUE and grain N uptake was 23% and 7.5% higher under NT compared to CT, respectively. Therefore, winter wheat farmers in the United States Central Great Plains currently practicing CT could improve the efficiency of the surface-applied fertilizer N and farm profitability by adopting NT.
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    Variability in Winter Wheat (Triticum aestivum L.) Grain Yield Response to Nitrogen Fertilization in Long-Term Experiments
    (Communications in Soil Science and Plant Analysis, 2020) Omara, Peter; Aula, Lawrence; Dhillon, Jagmandeep S.; Oyebiyi, Fikayo; Eickhoff, Elizabeth M.; Nambi, Eva; Fornah, Alimamy; Carpenter, Jonathan; Raun, William
    Crop nitrogen (N) use is always affected by the variability in production environment. Dataset (2001 to 2014) from long-term winter wheat (Triticum aestivum L.) experiments at Lahoma and Stillwater, Oklahoma was used. Both experiments have a randomized complete block design with four replications, and fertilizer N was applied as urea pre-plant. Responsiveness of grain yield to maximum fertilizer N rate (112 kg ha−1 – Lahoma; 135 kg ha−1 – Stillwater) was compared with that from check plot (0 kg ha−1). The objective was to determine the relative influence of environment, management, and variety on winter wheat grain yield. The combined analysis of variance indicated that the main effect of year, treatment, location, and variety accounted for 29.3%, 21.2%, 3.1%, and 22.6%, respectively of the variance terms. Over the study period, the nonresponsiveness of winter wheat to fertilizer N accounted for 29% and 23% of grain yield at Lahoma and Stillwater, respectively where yield at maximum N rate did not significantly differ from check plot. This highlights the importance of random changes in a crop production environment and its influence in dictating the response to applied N fertilizer. Nitrogen fertilizer losses could be reduced by adopting in-season variable N application techniques.