Research

Open AccessArticle

Artefacts in Field Trial Research—Lateral Ammonia Fluxes Confound Fertiliser Plot Experiments

by

Karin S. Levin

,

Felizitas Winkhart

,

Kurt-Jürgen Hülsbergen

,

Hans Jürgen Reents

and

Karl Auerswald

Agriculture 2023, 13(8), 1617; https://doi.org/10.3390/agriculture13081617 - 16 Aug 2023

Viewed by 431

Abstract

Agricultural ammonia (NH₃) emissions can have serious environmental impacts, lower fertiliser nitrogen-use efficiencies, and cause economic losses. NH₃ losses may not only occur directly from organic fertilisers such as biogas digestates when applied to crops, the crops themselves may also [...] Read more.

Agricultural ammonia (NH₃) emissions can have serious environmental impacts, lower fertiliser nitrogen-use efficiencies, and cause economic losses. NH₃ losses may not only occur directly from organic fertilisers such as biogas digestates when applied to crops, the crops themselves may also be a source of ammonia emissions. Wheat yields from 14 years of an organic small plot fertiliser trial fertilised with biogas digestate were analysed to determine if there was significant lateral N transfer between plots. A simple NH₃ loss/gain model was developed to calculate possible N gains and losses via NH₃ volatilisation from the applied digestate. This model was tested using NH₃ volatilisation measurements. In addition, ¹⁵N isotope measurements of crop biomass were used to analyse plant N uptake. While digestate fertilisation increased wheat yields, yield patterns indicated that NH₃ emissions from plots fertilised with biogas digestate affected yields in neighbouring unfertilised plots. Measurements of ammonia losses and gains in the field validated our modelling results, showing that 55% of digestate NH₄⁺-N was volatilised. ¹⁵N isotope analysis indicated that crops took up as much as 30 kg ha⁻¹ NH₃-N volatilised from digestate, and that plots closer to fertilised plots took up more of this NH₃-N than crops further away from fertilised plots. Our results imply that neither the results from the fertilised plots nor from the unfertilised plots are without bias. To avoid inadvertently introducing artefacts into fertiliser field trials, plot sizes need to be increased and treatments situated further apart. Full article

(This article belongs to the Special Issue Nitrogen Fertilization in Crop Production)

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Open AccessFeature PaperArticle

Soil Moisture and Temperature Effects on Granule Dissolution and Urease Activity of Urea with and without Inhibitors—An Incubation Study

by

Kang Ni

and

Andreas Siegfried Pacholski

Agriculture 2022, 12(12), 2037; https://doi.org/10.3390/agriculture12122037 - 28 Nov 2022

Viewed by 1236

Abstract

Urea granule dissolution in soil and soil urease activity are essential parameters for the accurate prediction of nitrogen dynamics after urea application, but both are scarcely studied. The response of urease activity to temperature is unclear under the addition of urease or nitrification [...] Read more.

Urea granule dissolution in soil and soil urease activity are essential parameters for the accurate prediction of nitrogen dynamics after urea application, but both are scarcely studied. The response of urease activity to temperature is unclear under the addition of urease or nitrification inhibitors. In this study, we conducted laboratory incubation trials using glass jars with 100 g soil to quantify urea granule dissolution. Urease activity after urease and nitrification inhibitor addition were investigated in plastic bottles (5 g soil) under different temperatures. Inhibitor N-(2-nitrophenyl) phosphoric triamide (2-NPT), and a mixture of dicyandiamide and 1 H-1,2,4-triazol (DCD/HZ) were tested as urease and nitrification inhibitors separately and in combination. The dynamics of urease activity was fitted with Michaelis–Menten kinetics combined with the Van’t Hoff equation. At low soil moisture contents close to air-dry conditions (4–8% w/w water content), soil moisture was the dominant factor, but at higher soil moisture contents (28% and 48% w/w), temperature controlled the dissolution process. Dissolution could take several days or even longer at very dry soil conditions, while it was completed between a few hours and 24 h at high soil moisture levels. Urea with urease inhibitor formulation dissolved significantly slower at a moisture level of 28% (w/w). In the studied soil, urease activity varied between 2.9 and 54.4 mg NH₄⁺-N kg⁻¹ h⁻¹. Across all urea concentrations, the addition of urease inhibitor 2-NPT significantly reduced urease activity. The relationship between urease activity and urea addition rate could be accurately described with Michaelis–Menten kinetics, and urease inhibitor addition reduced the temperature sensitivity of urease activity by 7%, while the nitrification inhibitor increased it by 4%. Parameter estimates and process characterization for urea granule dissolution and urea hydrolysis in this study are meaningful for and helpful in agricultural practice and the model simulation of soil nitrogen dynamics. Full article

(This article belongs to the Special Issue Nitrogen Fertilization in Crop Production)

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Open AccessEditor’s ChoiceArticle

Acidification Effects on In Situ Ammonia Emissions and Cereal Yields Depending on Slurry Type and Application Method

by

Christian Wagner

,

Tavs Nyord

,

Annette Vibeke Vestergaard

,

Sasha Daniel Hafner

and

Andreas Siegfried Pacholski

Agriculture 2021, 11(11), 1053; https://doi.org/10.3390/agriculture11111053 - 27 Oct 2021

Cited by 13 | Viewed by 2180

Abstract

Field application of organic slurries contributes considerably to emissions of ammonia (NH₃) which causes sever environmental damage and can result in lower nitrogen (N) fertilizer efficiency. In recent years, field acidification systems have been introduced to reduce such NH₃ emissions. [...] Read more.

Field application of organic slurries contributes considerably to emissions of ammonia (NH₃) which causes sever environmental damage and can result in lower nitrogen (N) fertilizer efficiency. In recent years, field acidification systems have been introduced to reduce such NH₃ emissions. However, combined field data on ammonia emissions and N use efficiency of acidified slurries, in particular by practical acidification systems, are scarce. Here, we present for the first time a simultaneous in situ assessment of the effects of acidification of five different organic slurries with a commercial acidifications system combined with different application techniques. The analysis was performed in randomized plot trials in winter wheat and spring barley after two applications to each crop (before tillering and after flag leave emergence) in year 2014 in Denmark. Slurry types included cattle slurry, mink slurry, pig slurry, anaerobic digestate, and the liquid phase of anaerobic digestate. Tested application techniques were trail hose application with and without slurry acidification in winter wheat and slurry injection and incorporation compared to trail hose application with and without acidification in spring barley. Slurries were applied on 9 m × 9 m plots separated by buffer areas of the same dimension. Ammonia emission was determined by a combination of semi-quantitative acid traps scaled by absolute emissions obtained from Draeger Tube Method dynamic chamber measurements. Experimental results were analysed by mixed effects models and HSD post hoc test (p < 0.05). Significant and almost quantitative NH₃ emission reduction compared to trail hose application was observed in the barley trial by slurry incorporation of acidified slurry (89% reduction) and closed slot injection (96% reduction), while incorporation alone decreased emissions by 60%. In the two applications to winter wheat, compared to trail hose application of non-acidified slurry, acidification reduced NH₃ emissions by 61% and 67% in cattle slurry, in anaerobic digestate by 45% and 57% and liquid phase of anaerobic digestate by 58%, respectively. Similar effects but on a lower emission level were observed in mink slurry, while acidification showed almost no effect in pig slurry. Acidifying animal manure with a commercial system was confirmed to consistently reduce NH₃ emissions of most slurry types, and emission reductions were similar as from experimental acidification systems. However, failure to reduce ammonia emissions in pig slurry hint to technical limitations of such systems. Winter wheat and spring barley yields were only partly significantly increased by use of ammonia emission mitigation measures, while there were significant positive effects on apparent nitrogen use efficiency (+17–28%). The assessment of the agronomic effects of acidification requires further investigations. Full article

(This article belongs to the Special Issue Nitrogen Fertilization in Crop Production)

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Open AccessArticle

Sugar Beet Root Yield and Quality with Leaf Seasonal Dynamics in Relation to Planting Densities and Nitrogen Fertilization

by

Ivana Varga

,

Zdenko Lončarić

,

Suzana Kristek

,

Antonela Markulj Kulundžić

,

Andrijana Rebekić

and

Manda Antunović

Agriculture 2021, 11(5), 407; https://doi.org/10.3390/agriculture11050407 - 02 May 2021

Cited by 8 | Viewed by 2816

Abstract

This study aimed to analyze the seasonal dynamics of sugar beet leaf and root yield and quality in different plant populations and the nitrogen fertilization rate. The field trials were set as four different planting densities (60,000 to 140,000 plants ha⁻¹) [...] Read more.

This study aimed to analyze the seasonal dynamics of sugar beet leaf and root yield and quality in different plant populations and the nitrogen fertilization rate. The field trials were set as four different planting densities (60,000 to 140,000 plants ha⁻¹) and three different spring nitrogen fertilization rates: no fertilization, pre-sowing (45 kg ha⁻¹ N), and pre-sowing with top dressing (99 kg ha⁻¹ N in 2014 and 85.5 kg ha⁻¹ N in 2015. The changes of leaf growth were done measuring leaf area (LA), leaf area index (LAI), specific leaf area (SLA), and leaf area ratio (LAR). The highest LAI in 2014 was determined on 30 July at 140,000 plants ha⁻¹ (9.35 m² m⁻¹) and in 2015 on 20 June at 100,000 plants ha⁻¹ (4.83 m² m⁻²). In both years, the SLA and LAR was highest at the end of May. In relation to plant density, higher plant densities had on average the highest root yield, sucrose content, and white sugar yield. In both years, pre-sowing with top dressing spring nitrogen fertilization resulted in the highest root (95.0 t ha⁻¹) and white sugar yield (11.4 t ha⁻¹), whereas the highest sucrose content was after pre-sowing fertilization (14.9%). Full article

(This article belongs to the Special Issue Nitrogen Fertilization in Crop Production)

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Graphical abstract

Open AccessArticle

Effect of Nitrogen Fertilization on the Dynamics of Concentration and Uptake of Selected Microelements in the Biomass of Miscanthus x giganteus

by

,

,

,

and

Agriculture 2021, 11(4), 360; https://doi.org/10.3390/agriculture11040360 - 16 Apr 2021

Cited by 1 | Viewed by 1830

Abstract

This paper presents the effects of nitrogen (N) fertilization on the concentration of selected micronutrients as an important issue in reducing combustion-induced air pollution. We studied the effects of the dose of 60 kg ha⁻¹ N in different terms of biomass sampling [...] Read more.

This paper presents the effects of nitrogen (N) fertilization on the concentration of selected micronutrients as an important issue in reducing combustion-induced air pollution. We studied the effects of the dose of 60 kg ha⁻¹ N in different terms of biomass sampling on the concentration and uptake of iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) in the dry matter of the underground and aerial parts of Miscanthus x giganteus in the years 2014–2016. The order of microelement concentrations (mg kg⁻¹) in rhizomes and the aboveground parts of plants was as follows: Fe > Mn > Zn > Cu. N fertilization had no significant effect on the concentrations of the selected microelements in the Mischanthus biomass (except for the Mn concentration in the stems and Cu in the leaves). The results indicated that the quality of the combustion biomass did not worsen under nitrogen fertilization. During the whole vegetation period, the iron concentration increased in the rhizomes and decreased for Zn and Cu. In the aboveground parts of the plant, the concentrations of all tested elements decreased. In turn, the uptake of Fe, Mn, Zn, and Cu (except for Fe in the stems) by rhizomes and the aboveground parts of Mischanthus depended significantly on the N fertilization. Full article

(This article belongs to the Special Issue Nitrogen Fertilization in Crop Production)

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Open AccessArticle

An Assessment of the Site-Specific Nutrient Management (SSNM) Strategy for Irrigated Rice in Asia

by

Divina Gracia P. Rodriguez

Agriculture 2020, 10(11), 559; https://doi.org/10.3390/agriculture10110559 - 19 Nov 2020

Cited by 12 | Viewed by 4338

Abstract

The site-specific nutrient management (SSNM) strategy provides guidelines for effective nitrogen, phosphorus and potassium management to help farmers make better decisions on fertilizer input and output levels in rice (Oryza sativa) production. The SSNM fertilizer recommendations are based on the yield [...] Read more.

The site-specific nutrient management (SSNM) strategy provides guidelines for effective nitrogen, phosphorus and potassium management to help farmers make better decisions on fertilizer input and output levels in rice (Oryza sativa) production. The SSNM fertilizer recommendations are based on the yield goal approach, which has been frequently cited in empirical studies. This study evaluates the assumptions underlying the SSNM strategy for rice in the top rice-producing countries around the world, including India, Indonesia, the Philippines, Thailand, and Vietnam. Using a generalized quadratic production function, I explore whether major nutrients are substitutes as inputs and if there are complementarities between inorganic fertilizer and soil organic matter (SOM). The results suggest the relationships among major nutrients vary across sites—some inputs are complements, some are substitutes, and some are independent. The SOM also significantly affects the nitrogen fertilizer uptake. I conclude by suggesting that the SSNM strategy can be made to be more adaptive to farmer’s fields if these relationships are accounted for in the fertilizer recommendation algorithm. Full article

(This article belongs to the Special Issue Nitrogen Fertilization in Crop Production)

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Open AccessArticle

Efficiency of Mineral Nitrogen Fertilization in Winter Wheat under Pannonian Climate Conditions

by

Gerhard Moitzi

,

Reinhard W. Neugschwandtner

,

Hans-Peter Kaul

and

Helmut Wagentristl

Agriculture 2020, 10(11), 541; https://doi.org/10.3390/agriculture10110541 - 11 Nov 2020

Cited by 11 | Viewed by 2198

Abstract

Improvements in nitrogen (N) use efficiency in crop production are important for addressing the triple challenges of food security, environmental degradation and climate change. The three fertilizers, calcium ammonium nitrate (CAN), urea (Urea) and stabilized urea (Urea_stab), were applied at a [...] Read more.

Improvements in nitrogen (N) use efficiency in crop production are important for addressing the triple challenges of food security, environmental degradation and climate change. The three fertilizers, calcium ammonium nitrate (CAN), urea (Urea) and stabilized urea (Urea_stab), were applied at a rate of 160 kg N ha⁻¹ with two or three splits to winter wheat (Triticum aestivum L.) in the Pannonian climate region of eastern Austria. On average, over all fertilization treatments, the grain yield (GY) increased by about a quarter and the grain N concentration (GNC) doubled compared to the control without fertilization. Consequently, the grain N yield (NY_GRAIN) was increased with N fertilization by 154%. The GY increased due to a higher grain density with no differences between N fertilizers but with a tendency of a higher grain yield with three compared to two splits. Three splits also slightly increased the GNC and consequently the NY_GRAIN of CAN and Urea_stab in one year. The removal of N fertilizer with the NY_GRAIN (N surplus) was higher than the amount of applied fertilizer. Fertilization decreased the N use efficiency (NUE), the N uptake efficiency (NUpE) and the N utilization efficiency (NUtE) but increased the soil mineral nitrate (NO₃-N) at harvest and the apparent N loss (ANL). Three compared to two applications resulted in a higher NO₃-N at harvest but also a lower N surplus due to partly higher NY_GRAIN. Consequently, the ANL was lower with three compared to two splits. Also, the NUpE and the apparent N recovery efficiency (ANRE) were higher with three splits. The best N treatment regarding highest above-ground biomass yield with lowest N surplus, N balance and ANL was the three-split treatment (50 CAN, 50 CAN, 60 liquid urea ammonium nitrate). Three splits can, under semi-arid conditions, be beneficial when aiming high-quality wheat for bread-making and also for reducing the N loss. Whereas, two splits are recommended when aiming only at high GY, e.g., for ethanol-wheat production. Full article

(This article belongs to the Special Issue Nitrogen Fertilization in Crop Production)

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Open AccessArticle

Does the Organ-Based N Dilution Curve Improve the Predictions of N Status in Winter Wheat?

by

Ke Zhang

,

Xue Wang

,

Xiaoling Wang

,

Syed Tahir Ata-Ul-Karim

,

,

,

and

Agriculture 2020, 10(11), 500; https://doi.org/10.3390/agriculture10110500 - 26 Oct 2020

Cited by 10 | Viewed by 1769

Abstract

Accurately summarizing Nitrogen (N) content as a prelude to optimal N fertilizer application is complicated during the vegetative growth period of all the crop species studied. The critical nitrogen (N) concentration (Nc) dilution curve is a stable diagnostic indicator, which performs plant critical [...] Read more.

Accurately summarizing Nitrogen (N) content as a prelude to optimal N fertilizer application is complicated during the vegetative growth period of all the crop species studied. The critical nitrogen (N) concentration (Nc) dilution curve is a stable diagnostic indicator, which performs plant critical N concentration trends as crop grows. This study developed efficient technologies for different organ-based (plant dry matters (PDM), leaf DM (LDM), stem DM (SDM), and leaf area index (LAI)) estimation of Nc curves to enrich the practical applications of precision N management strategies. Four winter wheat cultivars were planted with 10 different N treatments in Jiangsu province of eastern China. Results showed the SDM-based curve had a better performance than the PDM-based curve in N nutrition index (NNI) estimation, accumulated N deficit (AND) calculation, and N requirement (NR) determination. The regression coefficients ‘a’ and ‘b’ varied among the four critical N dilution models: Nc = 3.61 × LDM^–0.19, R² = 0.77; Nc = 2.50 × SDM^–0.44, R² = 0.89; Nc = 4.16 × PDM^–0.41, R² = 0.87; and Nc = 3.82 × LAI^–0.36, R² = 0.81. In later growth periods, the SDM-based curve was found to be a feasible indicator for calculating NNI, AND, and NR, relative to curves based on the other indicators. Meanwhile, the lower LAI-based curve coefficient variation values stated that leaf-related indicators were also a good choice for developing the N curve with high efficiency as compared to other biomass-based approaches. The SDM-based curve was the more reliable predictor of relative yield because of its low relative root mean square error in most of the growth stages. The curves developed in this study will provide diverse choices of indicators for establishing an integrated procedure of diagnosing wheat N status, and improving the accuracy and efficiency of wheat N fertilizer management. Full article

(This article belongs to the Special Issue Nitrogen Fertilization in Crop Production)

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