Calculating socially optimal nitrogen (N) fertilization rates for sustainable N management in China

Efficient N management practices usually involve many potential strategies, but always involve choosing the correct amount of N and the coupling of N management to efficient water management. Nitrogen management strategies are integral parts of improved production practices recommended by land-grant universities such as the Institute of Food and Agricultural Sciences, Univ. of Florida. This paper, which draws heavily on research and experience in Florida, outlines the concepts and technologies for managing vegetable N fertilization to minimize negative impacts on the environment.

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Transforming Unmanned Aerial Vehicle (UAV) and Multispectral Sensor into a Practical Decision Support System for Precision Nitrogen Management in Corn

Remote Sensing ◽

10.3390/rs12101597 ◽

2020 ◽

Vol 12 (10) ◽

pp. 1597

Author(s):

Laura J. Thompson ◽

Laila A. Puntel

Keyword(s):

Decision Support ◽

High Resolution ◽

Decision Support System ◽

Support System ◽

Critical Issue ◽

N Fertilization ◽

Sensor Data ◽

N Application ◽

High Resolution Imagery ◽

N Management

Determining the optimal nitrogen (N) rate in corn remains a critical issue, mainly due to unaccounted spatial (e.g., soil properties) and temporal (e.g., weather) variability. Unmanned aerial vehicles (UAVs) equipped with multispectral sensors may provide opportunities to improve N management by the timely informing of spatially variable, in-season N applications. Here, we developed a practical decision support system (DSS) to translate spatial field characteristics and normalized difference red edge (NDRE) values into an in-season N application recommendation. On-farm strip-trials were established at three sites over two years to compare farmer’s traditional N management to a split-application N management guided by our UAV sensor-based DSS. The proposed systems increased nitrogen use efficiency 18.3 ± 6.1 kg grain kg N−1 by reducing N rates by 31 ± 6.3 kg N ha−1 with no yield differences compared to the farmers’ traditional management. We identify five avenues for further improvement of the proposed DSS: definition of the initial base N rate, estimation of inputs for sensor algorithms, management zone delineation, high-resolution image normalization approach, and the threshold for triggering N application. Two virtual reference (VR) methods were compared with the high N (HN) reference strip method for normalizing high-resolution sensor data. The VR methods resulted in significantly lower sufficiency index values than those generated by the HN reference, resulting in N fertilization recommendations that were 31.4 ± 10.3 kg ha−1 higher than the HN reference N fertilization recommendation. The use of small HN reference blocks in contrasting management zones may be more appropriate to translate field-scale, high-resolution imagery into in-season N recommendations. In view of a growing interest in using UAVs in commercial fields and the need to improve crop NUE, further work is needed to refine approaches for translating imagery into in-season N recommendations.

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Shelf-Life of Bunched Carrots as Affected by Nitrogen Fertilization and Leaf Presence

Agronomy ◽

10.3390/agronomy10121982 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1982

Author(s):

Anita Ierna ◽

Rosario Paolo Mauro ◽

Cherubino Leonardi ◽

Francesco Giuffrida

Keyword(s):

Shelf Life ◽

Nitrogen Fertilization ◽

Reducing Sugars ◽

Growing Season ◽

N Fertilization ◽

Fresh Weight ◽

Total Polyphenols ◽

Fertilization Rates ◽

N Dose ◽

Nitrates Content

Nitrogen (N) fertilization is essential for adequate earliness and the commercial attractiveness of carrots, but its excess could generate fast decay during postharvest, mostly in bunched carrots exhibiting their highly perishable leaves. A field experiment was conducted over the 2016–2017 growing season to address the effects of two N fertilization rates (120 and 240 kg N ha−1, hereafter N120 and N240, respectively) and leaf presence/absence (leaf+ and leaf−) on physicochemical and compositional traits of carrots cv. ‘Dordogne’, after storage at 4.0 ± 0.5 °C, 95–96% relative humidity (RH) for 0, 3, 6, 12, and 24 days (hereafter S0–S24). Before storage, carrots were arranged in bunches and packaged in common low-density polyethylene (LDPE) pouches (thickness 95 μm), 54 × 24 cm size, with 16 holes of 5 mm size. N240 carrots compared to N120 showed higher cumulative weight loss (CWL) and firmness reduction, with differences at S24 equal to 108 vs. 41 g kg−1 fresh weight (FW) and 13.3 vs. 14.5 N, respectively. N240 compared to N120 increased also the color deviation (ΔE*ab, +126%) and nitrates content (+93%) of carrots and slowed down their temporal increase of total polyphenols and antioxidant activity. Leaf+ carrots compared to leaf boosted CWL and firmness reduction, with differences at S24 equal to 90 vs. 58 g kg−1 FW and 12 vs. 17 N, respectively. In addition, leaf presence increased reducing sugars (+17%) and decreased nitrates (−24%) contents. This research has shown the possibility of improving the desirable quality and shelf-life of carrots by halving the N dose commonly supplied by growers and marketing bunched carrots within 12 days from the start of storage.

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Variability for Nitrogen Management in Genetically-Distant Maize (Zea mays L.) Lines: Impact of Post-Silking Nitrogen Limiting Conditions

Agronomy ◽

10.3390/agronomy8120309 ◽

2018 ◽

Vol 8 (12) ◽

pp. 309 ◽

Cited By ~ 1

Author(s):

Isabelle Quilleré ◽

Céline Dargel-Graffin ◽

Peter J. Lea ◽

Bertrand Hirel

Keyword(s):

N Uptake ◽

Predictive Marker ◽

N Fertilization ◽

High Yield ◽

N Content ◽

Whole Plant ◽

Large Level ◽

N Remobilization ◽

N Management ◽

The Impact

The impact of nitrogen (N)-limiting conditions after silking on kernel yield (KY)-related traits and whole plant N management was investigated using fifteen maize lines representative of plant genetic diversity in Europe and America. A large level of genetic variability of these traits was observed in the different lines when post-silking fertilization of N was strongly reduced. Under such N-fertilization conditions, four different groups of lines were identified on the basis of KY and kernel N content. Although the pattern of N management, including N uptake and N use was variable in the four groups of lines, a number of them were able to maintain both a high yield and a high kernel N content by increasing shoot N remobilization. No obvious relationship between the genetic background of the lines and their mode of N management was found. When N was limiting after silking, N remobilization appeared to be a good predictive marker for identifying maize lines that were able to maintain a high yield and a high kernel N content irrespective of their female flowering date. The use of N remobilization as a trait to select maize genotypes adapted to low N input is discussed.

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Tuber growth and biomass partitioning of two potato cultivars grown under different n fertilization rates with and without irrigation

American Journal of Potato Research ◽

10.1007/bf02874766 ◽

2001 ◽

Vol 78 (2) ◽

pp. 109-117 ◽

Cited By ~ 24

Author(s):

G. Bélanger ◽

J. R. Walsh ◽

J. E. Richards ◽

P. H. Milbum ◽

N. Ziadi

Keyword(s):

N Fertilization ◽

Biomass Partitioning ◽

Potato Cultivars ◽

Tuber Growth ◽

Fertilization Rates

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Management of nitrogen fertilization in maize cultivated in succession to black oats in a temperate climate

Comunicata Scientiae ◽

10.14295/cs.v9i2.2585 ◽

2018 ◽

Vol 9 (2) ◽

pp. 202-210

Author(s):

Ricardo Henrique Ribeiro ◽

Marcos Renan Besen ◽

Samuel Luiz Fioreze ◽

Jonatas Thiago Piva

Keyword(s):

Management Strategies ◽

N Fertilization ◽

Temperate Climate ◽

Early Developmental Stage ◽

Early Application ◽

N Application ◽

Drought Period ◽

Growing Seasons ◽

Productive Potential ◽

N Management

The objective of this study was to verify early nitrogen (N) fertilization on maize cultivated in succession to black oats. We conducted three experiments, relating to the 2012/13, 2013/14, and 2014/15 growing seasons, at UFSC-Curitibanos, in a randomized complete block experimental design, with four treatments and four replicates. The treatments were N management strategies in which the amount of N applied to maize was split into pre-sowing, at sowing, and topdressing times: (T1) control with no N application; (T2) 2/3 - 1/3 - 0; (T3) 1/3 - 1/3 - 1/3; and (T4) 0 - 1/3 - 2/3. The biometrics and productive potential parameters of the crop were evaluated. Application of N, regardless of the treatment, increased the yield. In 2012/13, there were no significant differences between the ways in which the N application was split, although they produced a higher yield than the control, resulting in a mean yield of 5,008 kg ha-1. In 2013/14, T2 was similar to T3 and T4, resulting in a yield of 9,858 kg ha-1; in 2014/15, T3 and T4 were similar, with a mean yield of 12,466 kg ha-1, while T2 resulted in a lower yield of 10,487 kg ha-1. When 2/3 of the N is applied pre-sowing, it is only effective when it is associated with the occurrence of a drought period at an early developmental stage of the plants. In adequate rainfall conditions, the early application of N fertilization is only effective when combined with a further 1/3 of the amount of N at sowing, and later as a topdressing.

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Nitrogen and Potassium Requirements for Field-grown Areca and Mexican Fan Palms

HortScience ◽

10.21273/hortsci.50.10.1567 ◽

2015 ◽

Vol 50 (10) ◽

pp. 1567-1571

Author(s):

Timothy K. Broschat

Keyword(s):

United States ◽

Southeastern United States ◽

Calcareous Soils ◽

N Fertilization ◽

Fill Soil ◽

Fertilization Rates ◽

Application Rates ◽

Field Nursery ◽

Nursery Production ◽

K Deficiency

Potassium (K) deficiency is a widespread problem in palms growing in sandy or calcareous soils in southeastern United States. Its symptoms are highly conspicuous, reduce palm aesthetic appeal, are difficult to correct, and can be exacerbated by nitrogen (N) fertilization. The objective of this study was to determine the optimum fertilization rates and ratio for N and K in areca palm [Dypsis lutescens (H. Wendl.) Beentje & J. Dransf. and Mexican fan palm (Washingtonia robusta H. Wendl.) growing in a calcareous sandy fill soil. Both species had their highest quality when fertilized with 12.2 g·m−2 N and 12.2 g·m−2 K from controlled-release (2–3 month release) sources every 3 months. Actual N and K application rates were better predictors of palm quality than N:K ratio at the highest fertilization rates that would be recommended for field nursery production. However, at lower application rates more typical of those used for landscape palm maintenance, palm quality improved as the N:K application ratio was decreased.

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Foliar Calcium Corrects a Deficiency Causing Green Fruit Drop in ‘Draper’ Highbush Blueberry (Vaccinium corymbosum L.)

Agriculture ◽

10.3390/agriculture9030063 ◽

2019 ◽

Vol 9 (3) ◽

pp. 63 ◽

Cited By ~ 2

Author(s):

Eric Gerbrandt ◽

Charles Mouritzen ◽

Mark Sweeney

Keyword(s):

Vaccinium Corymbosum ◽

N Fertilization ◽

Climatic Conditions ◽

Economic Losses ◽

Highbush Blueberry ◽

High Concentration ◽

Physiological Disorder ◽

Fertilization Rates ◽

Green Fruit ◽

Fruit Drop

‘Draper’ northern highbush blueberry (Vaccinium corymbosum L.) is a widely-planted mid-season cultivar with excellent fruit quality. Under the climatic conditions of Southwestern British Columbia, Canada, and Northwestern Washington, USA, it expresses a physiological disorder causing spontaneous green fruit drop (GFD) of up to half of the developing crop just prior to onset of the fruit coloring phenophase. Reduction of economic losses due to GFD required identification of the cause of this disorder and development of an agronomic solution that would reduce fruit drop. In 2014, two initial experiments were conducted to compare three foliar Ca products under a range of N fertilization rates. In 2015 and 2016, three locations were used in a first step to optimizing rates and timings of foliar Ca application. Initial experiments determined that higher N fertilization rates exacerbate GFD but that foliar Ca corrects the condition. Multi-site, multi-year trials identified key rates and timings for foliar Ca application to provide an agronomic solution for commercial growers. These trials identified an acute fruit Ca deficiency as the cause of GFD, and that foliar calcium applied frequently at high concentration from mid-bloom onward can be effective in reducing GFD, often to negligible levels. This condition has now been reported in several production regions around the world.

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Optimal Nitrogen Practice in Winter Wheat-Summer Maize Rotation Affecting the Fates of 15N-Labeled Fertilizer

Agronomy ◽

10.3390/agronomy10040521 ◽

2020 ◽

Vol 10 (4) ◽

pp. 521

Author(s):

Haiyan Liang ◽

Pengfei Shen ◽

Xiangze Kong ◽

Yuncheng Liao ◽

Yang Liu ◽

...

Keyword(s):

Crop Yield ◽

N Uptake ◽

N Fertilization ◽

Nitrogen Recovery ◽

Shaanxi Province ◽

Recovery Efficiency ◽

N Losses ◽

Nitrogen Recovery Efficiency ◽

Potential Losses ◽

N Management

Lower nitrogen recovery efficiency (NRE) and negative environmental impacts caused by excessive nitrogen (N) fertilization threaten the sustainability of agriculture. Efficient and appropriate fertilization practices are extremely important to achieve higher crop yield with minimum N loss. A field microplot experiment was conducted in a wheat-maize rotation system in Shaanxi province, at North China Plain, using the 15N isotope tracer technique to qualify the different annual N managements in terms of crop yield, NRE, N distribution in plant-soil, and N losses to optimize the N management. The experiment included four N treatments: conventional practice with 510 kg ha−1 annually in four applications (N1), and three optimized N treatments, reducing N rate to 420 kg ha−1, adjusting topdressing fertilizer times and using slow-release fertilizer (SRF) (N2, N3, N4). The results showed that the grain yield and N uptake did not differ significantly among treatments. N from fertilizer taken up (Ndff) by wheat was not affected by N management; however, in maize, Ndff performed differently. Optimized treatments significantly decreased the Ndff as compared to N1 treatment. Furthermore, NRE of wheat and annual nitrogen recovery efficiency (annual NRE) did not differ among treatments in 2016 but significantly increased in 2017 compared to N1. Annual NRE in 2017 was similar to that obtained for wheat. For maize, optimized N managements decreased the NRE in N3 and N4 treatments of two years. Potential losses in wheat were also similar amongst treatments, but in maize, N3 and N4 had lower residual N in the soil’s top 60 cm but resulted in higher potential losses than N1 and N2. Overall, our results demonstrate that applying 420 kg N ha−1 annually in three applications and combining SRF and urea are effective to sustain crop yield, improve the efficiency of N usage by maize, and reduce N losses in this region.

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Nitrate reductase activity in leaves and stems of tanner grass (Brachiaria radicans Napper)

Scientia Agricola ◽

10.1590/s0103-90162004000600012 ◽

2004 ◽

Vol 61 (6) ◽

pp. 640-648 ◽

Cited By ~ 14

Author(s):

Jairo Osvaldo Cazetta ◽

Luciana Cristine Vasques Villela

Keyword(s):

Nitrate Reductase ◽

Plant Development ◽

Nitrate Reductase Activity ◽

Reductase Activity ◽

N Fertilization ◽

Fresh Weight ◽

N Supply ◽

N Management ◽

Triton X

Tanner grass (Brachiaria radicans Napper) is a forage plant that is adapted to well-drained soils or wetlands, and responds well to nitrogen (N) fertilization. The assimilation of N involves the nitrate reductase (NR) enzyme, and its activity seems to be dependent on N supply. Molybdenum (Mo) is also important because it is a cofactor of NR. In this study, the variables of an in vivo assay were optimized for measuring nitrate reductase activity (NRA) in the leaves and stem tissues. This method was used to evaluate NO3- metabolism in plants fertilized with NaNO3, NH4Cl or urea, in association with or without application of H2MoO4, aiming to provide guidelines for N management of this species. The best conditions to determine NRA involved the incubation of 300 mg of tissues in a medium composed of 200 mmol dm3 phosphate buffer (pH 7.4), 60 mmol dm3 KNO3, 10 cm³ dm3 n-butanol, 0.1 cm³ dm3 detergent (triton-X-100®), under vacuum and in the dark for a period of 60 to 100 minutes. Leaves showed NRA levels two to three times higher than stems. Although there were some interactions between treatments, stem fresh weight and NRA were not affected by N sources. Plants fertilized with NaNO3 showed the best growth and NRA values when compared with NH4Cl and urea, which had, respectively, the lowest and intermediate scores. The application of Mo in the absence of N improved NRA and did not affect leaf and stalk growth. In the presence of N, the Mo levels applied limited leaf NRA and plant development.

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