Editorial

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Open AccessEditorial

Towards a Better Understanding of Agronomic Efficiency of Nitrogen: Assessment and Improvement Strategies

by Francesco Montemurro and Mariangela Diacono

Agronomy 2016, 6(2), 31; https://doi.org/10.3390/agronomy6020031 - 10 May 2016

Cited by 31 | Viewed by 4732

Agronomic N-use efficiency is the basis for economic and environmental efficiency, and an effective agro-ecosystem management practice, improving nutrient use efficiency, is a crucial challenge for a more sustainable production of horticultural, industrial and cereal crops. However, discrepancy between theory and practice still [...] Read more.

Agronomic N-use efficiency is the basis for economic and environmental efficiency, and an effective agro-ecosystem management practice, improving nutrient use efficiency, is a crucial challenge for a more sustainable production of horticultural, industrial and cereal crops. However, discrepancy between theory and practice still exists, coming from large gaps in knowledge on net-N immobilization/mineralization rates in agro-ecosystems, as well as on the effects of indigenous and applied N to crop response. A more thorough understanding of these topics is essential to improve N management in agricultural systems. To this end, the present Special Issue collects research findings dealing with different aspects of agronomic efficiency of N in different agro-ecosystems, and environmental impact derived from fertilization management practices. In particular, the Special Issue contains selected papers, which concern a wide range of topics, including analyzing tools, options of management, calculation equation and modeling approaches. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

Research

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Open AccessArticle

Little Potential of Spring Wheat Genotypes as a Strategy to Reduce Nitrogen Leaching in Central Europe

by Juan Manuel Herrera, Christos Noulas, Peter Stamp and Didier Pellet

Agronomy 2016, 6(2), 29; https://doi.org/10.3390/agronomy6020029 - 09 May 2016

Cited by 7 | Viewed by 4163

Abstract

Nitrogen (N) losses negatively impact groundwater quality. Spring wheat genotypes varying in N-fertilizer recovery were studied (by using lysimeters) for their potential to minimize NO₃-N leaching during spring and summer, over a three-year period. Additionally, we examined to what extent root [...] Read more.

Nitrogen (N) losses negatively impact groundwater quality. Spring wheat genotypes varying in N-fertilizer recovery were studied (by using lysimeters) for their potential to minimize NO₃-N leaching during spring and summer, over a three-year period. Additionally, we examined to what extent root growth and NO₃-N leaching explain the well-known difference found between apparent and isotopic N recovery. The genotypes were grown under low (2 g m⁻²) and high (27 g m⁻²) N fertilizer supply. On average, the apparent and isotopic recoveries of N fertilizer by wheat were 43% and 51%, respectively. The three genotypes varied in fertilizer N recovery but not in NO₃-N leaching, which only accounted for 15% of the applied N fertilizer. The differences in N uptake, fertilizer N recovery and root growth among the genotypes were not associated with the leached NO₃-N because root growth and N uptake were not well synchronized with NO₃-N leaching. Already at stem elongation 70% to 98% of the season-long NO₃-N leaching had already taken place. Thus, the ability to minimize in-season NO₃-N leaching by using spring wheat genotypes with higher fertilizer N recovery was limited because maximum N leaching occurred in the early crop season. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

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1031 KiB

Open AccessFeature PaperArticle

Assessing Nitrogen Use Efficiency and Nitrogen Loss in a Forage-Based System Using a Modeling Approach

by Chiara Piccini, Claudia Di Bene, Roberta Farina, Bruno Pennelli and Rosario Napoli

Agronomy 2016, 6(2), 23; https://doi.org/10.3390/agronomy6020023 - 12 Apr 2016

Cited by 13 | Viewed by 5661

Abstract

In intensive agriculture, N supply often exceeds crop requirements, even in nitrate vulnerable zones (NVZ). In farmland, the N surplus gives rise to NO₃⁻ leaching and consequent groundwater pollution. The present study aimed at proposing measures to reduce N leaching and [...] Read more.

In intensive agriculture, N supply often exceeds crop requirements, even in nitrate vulnerable zones (NVZ). In farmland, the N surplus gives rise to NO₃⁻ leaching and consequent groundwater pollution. The present study aimed at proposing measures to reduce N leaching and hence improve N efficiency in a buffalo livestock farm located in the NVZ of Latina plain (Central Italy). The farm was cultivated with forage crops in a double annual crop rotation: Italian ryegrass (Lolium multiflorum Lam.) in winter and silage corn (Zea mays L.) in summer. Mineral and organic fertilizers were supplied to both crops. The annual N budget and soil solution NO₃-N concentrations were evaluated using a modeling approach. The performance of the WinEPIC model in simulating the response of the NO₃-N concentration in percolation to the N application rate was assessed and validated by field measurements of the NO₃-N concentration in the soil solution. Three scenarios were proposed to identify the best practice to minimize the environmental impact of N application without significant yield loss. Also, recommendations of best practices in N fertilization and animal manure spreading were given. This study thus provides useful preliminary information for decision-making in agriculture/environmental policies. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

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213 KiB

Open AccessArticle

A Simple and Reasonable Calculation Equation of Balanced Fertilization

by Shenwu Lv, Xuemei Wang and Gangcai Liu

Agronomy 2015, 5(2), 180-187; https://doi.org/10.3390/agronomy5020180 - 25 May 2015

Cited by 8 | Viewed by 5831

Abstract

Reasonable fertilization is a primary concern for agronomy scientists and farmers. However, there is still no satisfying calculation formula to guide farmer’s fertilizing. Five kinds of indices were tested in more than 500 field plots successively, and more than 50 pieces of long-term [...] Read more.

Reasonable fertilization is a primary concern for agronomy scientists and farmers. However, there is still no satisfying calculation formula to guide farmer’s fertilizing. Five kinds of indices were tested in more than 500 field plots successively, and more than 50 pieces of long-term and short-term fertilizer field test data acquired by others were analyzed. Quick-acting fertilizers should be applied for balanced fertilization if the soil-available nutrient content is within the normal range. Through rigorous derivation and validation by a multi-year continuous ¹⁵N tracer field test, it is obtained that, total soil exogenous N = total output N − total recovery N + soil profit or lost N; utilization efficiency of fertilizer N = (output N − exogenous N) ÷ balanced application amount of N fertilizer. Optimal balanced utilization efficiency of fertilizer N, P, K = total recovery efficiency, and soil nutrient net amount = total amount after test − total amount before test. Equation application parameters were collected from more than 50 tests, which is more applicable than collecting from a single test. When soil-available nutrient content is excessively low or excessively high, adjusting this should be based on balanced fertilization to properly increase or reduce the fertilization rate. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

376 KiB

Open AccessArticle

Nitrogen Fertilizer Sources and Application Timing Affects Wheat and Inter-Seeded Red Clover Yields on Claypan Soils

by Kelly A. Nelson, Peter P. Motavalli and Manjula Nathan

Agronomy 2014, 4(4), 497-513; https://doi.org/10.3390/agronomy4040497 - 11 Nov 2014

Cited by 11 | Viewed by 7832

Abstract

Controlled-release N fertilizer, such as polymer-coated urea (PCU), may be a fall N management option for wheat (Triticum aestivum L.) grown in poorly-drained claypan soils. Field research evaluated (1) urea release from fall-applied PCU in 2006 and 2007; (2) broadcast fall-spring split [...] Read more.

Controlled-release N fertilizer, such as polymer-coated urea (PCU), may be a fall N management option for wheat (Triticum aestivum L.) grown in poorly-drained claypan soils. Field research evaluated (1) urea release from fall-applied PCU in 2006 and 2007; (2) broadcast fall-spring split (25%:75%) of N sources; and (3) a single fall (100%) application of PCU, urea, urea plus NBPT (N-(n-butyl) thiophosphoric triamide] (U + NBPT), ammonium nitrate (AN), or urea ammonium nitrate (UAN) at 0, 56, 84, and 112 kg·N·ha⁻¹ on wheat yield, wheat biomass, N uptake by wheat, and frost-seeded red clover (FSC) (Trifolium pratense L.) forage yield (2004–2007). PCU applied in fall released less than 30% urea by February. Urea released from PCU by harvest was 60% and 85% in 2006 and 2007, respectively. In poorly-drained soils, wheat yields ranked PCU > AN > U + NBPT > urea ≥ UAN over the rates evaluated for fall-only application. PCU was a viable fall-applied N source, with yields similar to or greater than urea or U + NBPT split-applied. Split-N applications of AN, urea, UAN, and U + NBPT generally resulted in greater wheat yields than a fall application. Enhanced efficiency fertilizers provide farmers with flexible options for maintaining high yielding production systems. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

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Review

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Open AccessReview

Emerging and Established Technologies to Increase Nitrogen Use Efficiency of Cereals

by Juan M. Herrera, Gerardo Rubio, Lilia Levy Häner, Jorge A. Delgado, Carlos A. Lucho-Constantino, Samira Islas-Valdez and Didier Pellet

Agronomy 2016, 6(2), 25; https://doi.org/10.3390/agronomy6020025 - 19 Apr 2016

Cited by 74 | Viewed by 13136

Abstract

Nitrogen (N) fertilizers are one of the most expensive inputs in agricultural settings. Additionally, the loss of N increases costs, contributes to soil acidification, and causes off-site pollution of the air, groundwater and waterways. This study reviews current knowledge about technologies for N [...] Read more.

Nitrogen (N) fertilizers are one of the most expensive inputs in agricultural settings. Additionally, the loss of N increases costs, contributes to soil acidification, and causes off-site pollution of the air, groundwater and waterways. This study reviews current knowledge about technologies for N fertilization with potential to increase N use efficiency and reduce its negative effects on the environment. Classic inorganic sources such as urea and ammonium sulfate are the major sources utilized, while controlled N release fertilizers have not been significantly adopted for cereals and oil crops. Microorganisms, with the exception of Rhizobium sp. in soybeans, are also not widely used nowadays (e.g., plant growth-promoting bacteria and cynobacteria). The interest in implementing new N fertilization knowledge is stimulating the development of sensors to diagnose the N status and decision support systems for integrating several variables to optimize sources, rates and methods of application. Among potential new technologies we identified the incipient development of nanofertilizers, nutrient formulations to coat seeds, and recycled nutrients. Furthermore, increasing concern about the environmental consequences of N may facilitate the implementation of innovations outside the farm such as more effective regulations to guide N fertilization and methods to manufacture N fertilizers that are more energy-efficient and less CO₂ equivalent emitting. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

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Open AccessReview

Review of Alternative Management Options of Vegetable Crop Residues to Reduce Nitrate Leaching in Intensive Vegetable Rotations

by Laura Agneessens, Jeroen De Waele and Stefaan De Neve

Agronomy 2014, 4(4), 529-555; https://doi.org/10.3390/agronomy4040529 - 02 Dec 2014

Cited by 42 | Viewed by 9978

Abstract

Vegetable crop residues take a particular position relative to arable crops due to often large amounts of biomass with a N content up to 200 kg N ha⁻¹left behind on the field. An important amount of vegetable crops are harvested during [...] Read more.

Vegetable crop residues take a particular position relative to arable crops due to often large amounts of biomass with a N content up to 200 kg N ha⁻¹left behind on the field. An important amount of vegetable crops are harvested during late autumn and despite decreasing soil temperatures during autumn, high rates of N mineralization and nitrification still occur. Vegetable crop residues may lead to considerable N losses through leaching during winter and pose a threat to meeting water quality objectives. However, at the same time vegetable crop residues are a vital link in closing the nutrient and organic matter cycle of soils. Appropriate and sustainable management is needed to harness the full potential of vegetable crop residues. Two fundamentally different crop residue management strategies to reduce N losses during winter in intensive vegetable rotations are reviewed, namely (i) on-field management options and modifications to crop rotations and (ii) removal of crop residues, followed by a useful and profitable application. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

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Other

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Open AccessTechnical Note

A Calculation Tool for Analyzing Nitrogen Use Efficiency in Annual and Perennial Crops

by Martin Weih

Agronomy 2014, 4(4), 470-477; https://doi.org/10.3390/agronomy4040470 - 05 Nov 2014

Cited by 23 | Viewed by 17918

Abstract

Assessment of crop nitrogen use efficiency (NUE) is important in agricultural research. Various approaches exist to analyze NUE. A recently proposed NUE concept is further developed and a calculation tool for practical use presented. A critical component in the NUE concept is the [...] Read more.

Assessment of crop nitrogen use efficiency (NUE) is important in agricultural research. Various approaches exist to analyze NUE. A recently proposed NUE concept is further developed and a calculation tool for practical use presented. A critical component in the NUE concept is the plants’ mean nitrogen (N) content during the main growth period (N’). The N’ is delimited by the critical crop phenology stages initiating and terminating accelerated crop N uptake. Especially when experimental treatments and/or crop cultivars cause great variation in phenology, it is often not feasible to perform destructive plant harvests at the critical phenology stages for all treatments and cultivars, which may result in inaccurate estimates of N’ and, ultimately, the NUE components N uptake efficiency and yield-specific N efficiency. A method is proposed to accurately calculate the crop N contents at the relevant critical phenology stages even when sampling is made at other time points. The only requirements are two separate destructive plant harvests performed within the main growth period, together with the time points for the critical phenology events. The method was exemplified using data from wheat and the perennial energy crop Salix, and an electronic calculation tool for the various NUE components is provided. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

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