Nitrogen Use Efficiency Definitions of Today and Tomorrow

Crop production has a large impact on the nitrogen (N) cycle, with consequences to climate, environment, and public health. Designing better N management will require indicators that accurately reflect the complexities of N cycling and provide biological meaning. Nitrogen use efficiency (NUE) is an established metric used to benchmark N management. There are numerous approaches to calculate NUE, but it is difficult to find an authoritative resource that collates the various NUE indices and systematically identifies their assets and shortcomings. Furthermore, there is reason to question the usefulness of many traditional NUE formulations, and to consider factors to improve the conceptualization of NUE for future use. As a resource for agricultural researchers and students, here we present a comprehensive list of NUE indices and discuss their functions, strengths, and limitations. We also suggest several factors—which are currently ignored in traditional NUE indices—that will improve the conceptualization of NUE, such as: accounting for a wider range of soil N forms, considering how plants mediate their response to the soil N status, including the below-ground/root N pools, capturing the synchrony between available N and plant N demand, blending agronomic performance with ecosystem functioning, and affirming the biological meaning of NUE.

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Assessment of Fertilizer Management Strategies Aiming to Increase Nitrogen Use Efficiency of Wheat Grown Under Conservation Agriculture

Agronomy ◽

10.3390/agronomy8120304 ◽

2018 ◽

Vol 8 (12) ◽

pp. 304 ◽

Cited By ~ 1

Author(s):

Jesús Santillano-Cázares ◽

Fidel Núñez-Ramírez ◽

Cristina Ruíz-Alvarado ◽

María Cárdenas-Castañeda ◽

Iván Ortiz-Monasterio

Keyword(s):

Nitrogen Use Efficiency ◽

Crop Production ◽

Management Practices ◽

Production Systems ◽

Conservation Agriculture ◽

Fertilizer Application ◽

Nitrogen Use ◽

Agronomic Efficiency ◽

Use Efficiency ◽

N Management

Sustainable crop production systems can be attained by using inputs efficiently and nitrogen use efficiency (NUE) parameters are indirect measurements of sustainability of production systems. The objective of this study was to investigate the effect of selected nitrogen (N) management treatments on wheat yields, grain and straw N concentration, and NUE parameters, under conservation agriculture (CA). The present study was conducted at the International Maize and Wheat Improvement Center (CIMMYT), in northwest, Mexico. Seventeen treatments were tested which included urea sources, timing, and methods of fertilizer application. Orthogonal contrasts were used to compare groups of treatments and correlation and regression analyses were used to look at the relationships between wheat yields and NUE parameters. Contrasts run to compare wheat yields or agronomic efficiency of N (AEN) performed similarly. Sources of urea or timing of fertilizer application had a significant effect on yields or AEN (p > 0.050). However, methods of application resulted in a highly significant (p < 0.0001) difference on wheat yields and agronomic efficiency of N. NUE parameters recorded in this study were average but the productivity associated to NUE levels was high. Results in this study indicate that wheat grew under non-critically limiting N supply levels, suggesting that N mineralization and reduced N losses from the soil under CA contributed to this favorable nutritional condition, thus minimizing the importance of N management practices under stable, mature CA systems.

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Nitrogen Use Efficiency in Parent vs. Hybrid Canola under Varying Nitrogen Availabilities

Plants ◽

10.3390/plants10112364 ◽

2021 ◽

Vol 10 (11) ◽

pp. 2364

Author(s):

Shanay T. Williams ◽

Sally Vail ◽

Melissa M. Arcand

Keyword(s):

Nitrogen Use Efficiency ◽

N Uptake ◽

N Cycling ◽

Utilization Efficiency ◽

Ammonium Oxidation ◽

Soil N ◽

Nitrogen Use ◽

Leaf Stage ◽

Below Ground ◽

Use Efficiency

Improving nitrogen use efficiency (NUE) is essential for sustainable agriculture, especially in high-N-demanding crops such as canola (Brassica napus). While advancements in above-ground agronomic practices have improved NUE, research on soil and below-ground processes are limited. Plant NUE—and its components, N uptake efficiency (NUpE), and N utilization efficiency (NUtE)—can be further improved by exploring crop variety and soil N cycling. Canola parental genotypes (NAM-0 and NAM-17) and hybrids (H151857 and H151816) were grown on a dark brown chernozem in Saskatchewan, Canada. Soil and plant samples were collected at the 5–6 leaf stage and flowering, and seeds were collected at harvest maturity. Soil N cycling varied with phenotypic stage, with higher potential ammonium oxidation rates at the 5–6 leaf stage and higher urease activity at flowering. Seed N uptake was higher under higher urea-N rates, while the converse was true for NUE metrics. Hybrids had higher yield, seed N uptake, NUtE, and NUE, with higher NUE potentially owing to higher NUtE at flowering, which led to higher yield and seed N allocation. Soil N cycling and soil N concentrations correlated for improved canola NUE, revealing below-ground breeding targets. Future studies should consider multiple root characteristics, including rhizosphere microbial N cycling, root exudates, and root system architecture, to determine the below-ground dynamics of plant NUE.

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Effect of in-season application methods of fertilizer nitrogen on grain yield and nitrogen use efficiency in maize

Canadian Journal of Soil Science ◽

10.4141/s03-052 ◽

2004 ◽

Vol 84 (2) ◽

pp. 169-176 ◽

Cited By ~ 8

Author(s):

B. L. Ma ◽

M. Li ◽

L. M. Dwyer ◽

G. Stewart

Keyword(s):

Grain Yield ◽

Nitrogen Use Efficiency ◽

Dry Matter ◽

Foliar Spray ◽

Soil N ◽

Nitrogen Use ◽

N Application ◽

Maize Hybrids ◽

Use Efficiency ◽

Application Methods

Little information is available comparing agronomic performance and nitrogen use efficiency (NUE) for N application methods such as foliar spray, soil application, and ear injection in maize (Zea mays L.). The objective of this study was to investigate the effects of various N application methods on total stover dry matter, grain yield, and NUE of maize hybrids using a 15N-labeling approach. A field experiment was conducted on a Dalhousie clay loam in Ottawa and a Guelph loam in Guelph for 2 yr (1999 and 2000). Three N application methods were tested on two maize hybrids, Pioneer 3893 and Pioneer 38P06 Bt. At planting, 60 kg N ha-1 as ammonium nitrate was applied to all treatments. In addition, 6.5 kg N ha-1 and 13.5 kg N ha-1 as 15N-labeled urea were applied to either foliage (Treatment I) or soil (Treatment II) at V6 and V12 stages, respectively. In Treatment III, 20 kg N ha-1 as 15N-labeled urea was injected into space between ear and husks at silking. The results showed that compared with soil N application neither foliar spray nor injection through ear affected grain yield or stover dry matter. The NUE values ranged from 12 to 76% for N fertilizer applied at V6 a nd V12 stages, or at silking for all treatments. There was no interaction of hybrid × N application methods on any variables measured with the only exception that for soil N application, grain NUE in Pioneer 38P06 Bt was significant higher than in Pioneer 3893. The difference in total N and NUE of grain and stover between soil N application and foliar N spray was inconsistent. However, NUE was substantially higher for N injection through the ear than for foliar or soil application without differential responses between the two hybrids. Nitrogen injection through the ear at silking might have altered N redistribution within the plant and improved NUE. Hence, it can potentially enhance grain protein content. Foliar N spray is not advocated for maize production in Ontario. Key words: Maize, Zea mays, nitrogen application methods, nitrogen-15, yield, nitrogen use efficiency

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Synthesis of Climate, Soil Factors, and Nitrogen Management Practices Affecting the Responses of Wheat Productivity and Nitrogen Use Efficiency to Nitrogen Fertilizer in China

Sustainability ◽

10.3390/su10103533 ◽

2018 ◽

Vol 10 (10) ◽

pp. 3533 ◽

Cited By ~ 1

Author(s):

Yunqi Wang ◽

Jiapeng Yang ◽

Rui Zhang ◽

Zhikuan Jia

Keyword(s):

Nitrogen Use Efficiency ◽

Management Practices ◽

Wheat Yield ◽

Soil Factors ◽

Nitrogen Use ◽

N Application ◽

Average Annual Temperature ◽

Coated Urea ◽

Use Efficiency ◽

N Management

The reported effects of nitrogen (N) fertilizer on wheat yield and nitrogen use efficiency (NUE) vary greatly, due to differences in climate, soil factors, and N management practices in different regions of China. We collected literature published during 1950–2017 that reported the yield and NUE for wheat in China, under N application and control treatments, and analyzed the data therein. A significant increase in yield was observed with N application, and varied with climate, soil factors, and N management practices in different regions. A larger increase in yield was observed under an average annual temperature of 13–15 °C, an average annual precipitation of >800 mm, respectively. Greater yield-increasing effects were observed in soil with a coarse soil texture, lower soil total N, available N, and a soil pH of ≤7 and >8, respectively. In Northwest China, the yield increase was greater under multiple coated urea applications after anthesis, while the higher NUE was observed under single coated urea application before anthesis. In North China, the yield and NUE were greater under multiple coated urea applications before anthesis. In South China, the yield and NUE were greater under multiple N applications. Consequently, to improve wheat yield and NUE, site-specific N management practices should be adopted.

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The role of Plant Growth Promoting Bacteria in improving nitrogen use efficiency for sustainable crop production: a focus on wheat

AIMS Microbiology ◽

10.3934/microbiol.2017.3.413 ◽

2017 ◽

Vol 3 (3) ◽

pp. 413-434 ◽

Cited By ~ 24

Author(s):

Nilde Antonella Di Benedetto ◽

◽

Maria Rosaria Corbo ◽

Daniela Campaniello ◽

Mariagrazia Pia Cataldi ◽

...

Keyword(s):

Plant Growth ◽

Nitrogen Use Efficiency ◽

Crop Production ◽

Plant Growth Promoting Bacteria ◽

Nitrogen Use ◽

Sustainable Crop Production ◽

Plant Growth Promoting ◽

Use Efficiency ◽

Growth Promoting

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Review on Improving Nitrogen Use Efficiency for Cereal Crop Production

International Journal of Forestry and Horticulture ◽

10.20431/2454-9487.0603002 ◽

2020 ◽

Vol 6 (3) ◽

Keyword(s):

Nitrogen Use Efficiency ◽

Crop Production ◽

Cereal Crop ◽

Nitrogen Use ◽

Use Efficiency

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Review of Active Optical Sensors for Improving Winter Wheat Nitrogen Use Efficiency

Agronomy ◽

10.3390/agronomy10081157 ◽

2020 ◽

Vol 10 (8) ◽

pp. 1157

Author(s):

Lawrence Aula ◽

Peter Omara ◽

Eva Nambi ◽

Fikayo B. Oyebiyi ◽

William R. Raun

Keyword(s):

Winter Wheat ◽

Grain Yield ◽

Optical Sensors ◽

Nitrogen Use Efficiency ◽

Optical Sensor ◽

Management Practices ◽

N Uptake ◽

Nitrogen Use ◽

Use Efficiency ◽

N Management

Improvement of nitrogen use efficiency (NUE) via active optical sensors has gained attention in recent decades, with the focus of optimizing nitrogen (N) input while simultaneously sustaining crop yields. To the authors’ knowledge, a comprehensive review of the literature on how optical sensors have impacted winter wheat (Triticum aestivum L.) NUE and grain yield has not yet been performed. This work reviewed and documented the extent to which the use of optical sensors has impacted winter wheat NUE and yield. Two N management approaches were evaluated; optical sensor and conventional methods. The study included 26 peer-reviewed articles with data on NUE and grain yield. In articles without NUE values but in which grain N was included, the difference method was employed to compute NUE based on grain N uptake. Using optical sensors resulted in an average NUE of 42% (±2.8% standard error). This approach improved NUE by approximately 10.4% (±2.3%) when compared to the conventional method. Grain yield was similar for both approaches of N management. Optical sensors could save as much as 53 (±16) kg N ha−1. This gain alone may not be adequate for increased adoption, and further refinement of the optical sensor robustness, possibly by including weather variables alongside sound agronomic management practices, may be necessary.

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Crop Mass and N Status as Prerequisite Covariables for Unraveling Nitrogen Use Efficiency across Genotype-by-Environment-by-Management Scenarios: A Review

Plants ◽

10.3390/plants9101309 ◽

2020 ◽

Vol 9 (10) ◽

pp. 1309 ◽

Cited By ~ 2

Author(s):

Gilles Lemaire ◽

Ignacio Ciampitti

Keyword(s):

Growth Rate ◽

Plant Growth ◽

Nitrogen Use Efficiency ◽

Soil N ◽

Nitrogen Use ◽

Genotype By Environment ◽

N Supply ◽

Fertilizer Application Rate ◽

Use Efficiency ◽

N Status

Due to the asymptotic nature of the crop yield response curve to fertilizer N supply, the nitrogen use efficiency (NUE, yield per unit of fertilizer applied) of crops declines as the crop N nutrition becomes less limiting. Therefore, it is difficult to directly compare the NUE of crops according to genotype-by-environment-by-management interactions in the absence of any indication of crop N status. The determination of the nitrogen nutrition index (NNI) allows the estimation of crop N status independently of the N fertilizer application rate. Moreover, the theory of N dilution in crops indicates clearly that crop N uptake is coregulated by (i) soil N availability and (ii) plant growth rate capacity. Thus, according to genotype-by-environment-by-management interactions leading to variation in potential plant growth capacity, N demand for a given soil N supply condition would be different; consequently, the NUE of the crop would be dissimilar. We demonstrate that NUE depends on the crop potential growth rate and N status defined by the crop NNI. Thus, providing proper context to NUE changes needs to be achieved by considering comparisons with similar crop mass and NNI to avoid any misinterpretation. The latter needs to be considered not only when analyzing genotype-by-environment-by-management interactions for NUE but for other resource use efficiency inputs such as water use efficiency (colimitation N–water) under field conditions.

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