Effect of nitrogen source and rate on potato tuber external and internal physiological disorders

Athyna N. Cambouris1, Mervin St. Luce1, Noura Ziadi1, Bernie J. Zebarth2 and Isabelle Perron1

1Agriculture and Agri-Food Canada, 2560 Hochelaga Boulevard, Quebec City, QC, Canada, G1V 2J3, Noura.Ziadi@agr.gc.ca

2Agriculture and Agri-Food Canada, 850 Lincoln Road, PO Box 20280, Fredericton, NB, Canada, E3B 4Z


Potato (Solanum tuberosum L.) tuber quality is an important factor that can affect its market value. We investigated the impact of nitrogen (N) fertilizer source and rate on external and internal defects of potato tubers across five growing seasons (2008 – 2012) under irrigated conditions on sandy soils in Quebec, Canada. The treatments included an unfertilized control, and three N sources [ammonium nitrate (AN), ammonium sulphate (AS) and polymer-coated urea (PCU)] applied at four rates (60, 120, 200 and 280 kg N ha1). The PCU was applied 100% at planting and the AN and AS were applied 40% at planting and 60% at hilling. Yield of misshapen tubers was greater and there was a lower incidence of rhizoctonia at higher N rates. Conversely, common scab and brown spot were more prevalent at higher N rates. Yield of misshapen tubers and the presence of hollow heart were greater for AN and PCU than AS. There was also a greater occurrence of common scab for PCU as compared to AN and AS. Additionally, brown spot tended to be more prevalent when PCU was used. Our results suggest that while PCU may give similar potato tuber yields to AN and AS, there may be a slightly greater tendency for increased common scab when PCU is applied. Overall, this study showed that N fertilizer rate and source are important factors that can influence the occurrence of external and internal physiological disorders of potato tubers, and thus tuber marketability.

Effective use of nitrogen fertilisers for growing garlic

Luji Bo1,2,3,4, Yingpeng Zhang1,2,3,4,Yan Li1,2,3,4, 6, Jiafa Luo1, 5, Ming Sun1,2,3, Ziwen Zhong1, Yongping Jing1,2, 4

1 Institute of Agricultural Resources and Environment, Shandong Academy of Agricultural Sciences, No.202 North Industrial Road, Jinan, China, 250100

2Key Laboratory of Agro-Environment of Huang-Huai-Hai Plain, Ministry of Agriculture, No.202 North Industrial Road, Jinan, China, 250100

3Shandong Provincial Key Laboratory of Agricultural Non-Point Source Pollution Control and Prevention, No.202 North Industrial Road, Jinan, China, 250100

4Shandong Provincial Engineering Research Center of Environmental Protection Fertilizers, No.202 North Industrial Road, Jinan, China, 250100

5Ruakura Research Centre, AgResearch Limited, Private Bag 3123,Hamilton, New Zealand, 3240

6 Corresponding author:E-mail: nkyliyan@126.com


An experiment was conducted on garlic (Allium sativum L.) to investigate the effects of nitrogen management on yield, economic benefit and the soil apparent nutrient balance, in the region of Laiwu town in Shandong province, China. The treatments included control (no N fertiliser), urea at 300 kg/ha, urea at 240 kg/ha, combined urea and commercial organic fertilisers at 120 kg N /ha each, and controlled-release nitrogen fertiliser at 192 kg N /ha. Results showed no significant difference both for garlic bulb yield and economic benefits between the urea treatments at different N application rates. The effect of the combined use of urea and organic fertiliser was similar to that of the urea application at the same N application rate. However, garlic bulb yields in the treatment of controlled-release nitrogen fertiliser were significantly higher than in the other fertiliser treatments, even the N application rate was lower. The net income from garlic in the treatment of controlled release fertiliser was also significantly higher than those in the other treatments (P0.05). There was N surplus after the garlic growth season when urea was applied at 300 kg/ha, while there was N, P and K deficit when the controlled-release N fertiliser at 192 kg/ha was used to produce more garlic. It is suggested that use of controlled release N fertiliser combined with a supplement of other nutrients would be a sustainable strategy for fertiliser management in garlic production.

Optimal cattle manure application rate to maximise crop yield and minimise risk of N loss to the environment in a wheat-maize rotation cropping system

Yongping Jing1,2, Yan Li1,2,4, Yingpeng Zhang1,2, Jiafa Luo3, Luji Bo1,2, Ming Sun1, Ziwen Zhong1

1 Institute of Agricultural Resources and Environment, Shandong Academy of Agricultural Sciences, Jinan 250100, China

2 Key Laboratory of Agro-Environment in Huang-Huai-Hai Plain, Ministry of Agriculture, Jinan 250100, China

3AgResearch Research Ruakura, 10 Bisley Road, Hamilton 3240, New Zealand

4Corresponding author: nkyliyan@126.com


This paper examines the effect of cattle manure application rates on nitrate nitrogen (NO3-N) migration and accumulation in a farmland soil and investigates methods for appropriate manure use in order to reduce NO3pollution to the environment. A field experiment was conducted on a fluvo-aquic soil in a cropping area of Caoxian County in Shandong Province, China. The effect of cattle manure (with N concentration of 1.5%), at different application rates (0, 15000, 30000, 45000, 60000 and 75000 kg/ha/year), on vertical distribution of soil NO3-N, crop yields, and nitrogen use efficiency was determined in a winter wheat and summer maize rotation on farmland under natural rainfall conditions. The results showed that the NO3-N concentrations in the soil profile (0-100 cm) increased with the increase in application rate. When the rate was greater than 45000 kg/ha/year, soil NO3-N concentrations were significantly higher than those in the other treatments with lower application rates. The NO3-N levels in the 80–100 cm soil layers were several times higher than those of the surface soils at the later growing stage of the winter wheat in early summer, indicating that this NO3-N, which had migrated downward and accumulated in the deep soil would be prone to drain to groundwater during the summer rainfall season, as it would be below the root zone of the summer maize. A quadratic relationship between crop yields and cattle manure application rates was found. Wheat and maize silage yields were highest when cattle manure application rate was 45000 kg/ha/year, with the N use efficiencies of wheat and maize silage both being about 50%. We conclude that a cattle manure application rate of 45000 kg/ha/year (equivalent to 675 kg N/ha/year) is optimal for this wheat-maize rotation cropping system.

Influence of total soil nitrogen levels on dry matter production responses to nitrogen fertilisation of dairy pastures in New Zealand

Danilo F. Guinto1, Jeff D.Morton2 , Warwick Catto1

1 Ballance Agri-Nutrients Ltd, Private Bag 12 503, Tauranga, 3143, New Zealand, dguinto@ballance.co.nz; wcatto@ballance.co.nz

2 MortonAg, Hastings, New Zealand, Email: mortonag@vodafone.co.nz


To test whether topsoil (0-7.5 cm) total soil N levels influence pasture dry matter yield (DM) responses at various rates of N fertiliser, field experiments were conducted in spring 2013 and autumn 2014 at five locations in the North Island (Whangarei, Te Awamutu, Central Hawke’s Bay 1, Central Hawke’s Bay 2, and Taihape) and two locations in the South Island (Culverden and Te Anau) of New Zealand. At each site, N fertiliser at rates of 0, 25, 50, 75, 100 and 200 kg N/ha were applied and pasture DM production data collected. At a little more than half the measurement events, the response in pasture DM production was greater at lower total soil N than at higher total soil N levels with the other sites showing a similar pasture DM production response at both low and high soil total N levels. Thus, total soil N was partially successful in predicting DM response to N fertilisation.

Brown coal-urea blends for increasing nitrogen use efficiency and biomass yield

Biplob K. Saha1, Michael T. Rose2, Vanessa Wong3, Timothy R. Cavagnaro4 and Antonio F. Patti1*

1School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia
2NSW Department of Primary Industries, Wollongbar Primary Industries Institute, Wollongbar, NSW 2477, Australia
3School of Earth, Atmosphere & Environment, Monash University, Clayton, Victoria, 3800, Australia
4School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, South Australia, 5064, Australia

*Corresponding author. Email: tony.patti@monash.edu


Increasing crop yield by minimum application of nitrogenous fertilisers is becoming more important due to its detrimental effects on the environment. Addition of humic rich brown coal (BC) as an organic amendment can alter N cycling and its availability to crop plants. However, the effect of brown coal-urea (BCU) blends on the biomass yield and N uptake by plant needs to be studied. Therefore, a glasshouse pot trial study was conducted to assess the effects of BCU blends on the growth, biomass yield and N uptake by silver beet. Blending of urea with BC showed a promising impact on the behavior of N fertiliser in the soil system. Compared to urea, BCU blends increased biomass yield by 27% and 23% in both a neutral (pH 7.24) and acid (pH 5.4) soil, respectively. In addition, incorporation of BCU blends to soil generally suppressed N2O emissions by 29% compared to urea. Application of BCU blends in soil maintained significantly higher amounts of mineralisable N in soil compared to urea application only. Moreover, addition of BCU blends increased the N uptake by silver beet and organic carbon content of soil. The blends with higher BC had higher biomass yield, maximum N uptake and maintained higher mineral N in soil compared to the blends with lower BC. The overall results suggest that blending of urea with BC can significantly increase N availability and its uptake by silver beet. As a result better crop yield can be obtained due to increased fertiliser N use efficiency.

Urea-based fertilizer assessment in forage grass production in eastern Canada

Bernard Gagnon, Noura Ziadi, Gilles Bélanger, Gaétan Parent

Agriculture and Agri-Food Canada, 2560 Hochelaga Blvd, Quebec, QC, Canada, G1V 2J3, bernard.gagnon@agr.gc.ca


Nitrogen fertilization is essential for forage grass production but little information exists on the efficiency of different mineral N fertilizers available in eastern Canada. We assessed the benefits of using different urea-based fertilizers in timothy (Phleum pratense L.), the main forage grass species used in eastern Canada. We compared, during two growing seasons (2014-2015), polymer-coated controlled release urea (PCU), blend of 50% PCU:50% urea, and urea treated with an inhibitor of urease (Urea + NBPT) broadcast at early spring to calcium ammonium nitrate (CAN) broadcast at early spring (60%) and after the first cut (40%). Each N fertilizer was added at rates of 50, 100, 150 and 200 kg N ha-1. A control with no applied N was included. The three enhanced-efficiency N fertilizers produced similar annual forage yields than CAN in both years. Yield distribution by cut, however, was significantly affected by the fertilizers. The highest yield was achieved with the blend PCU:Urea and Urea + NBPT at the first cut, and with PCU at the second cut. The soil nitrate content after the first cut was highest with PCU:Urea and Urea + NBPT, but in the fall it was low and not affected by fertilizers. Forage total N and nitrate concentrations were also highest in the first cut with the application of Urea + NBPT whereas PCU mostly increased forage N in the second cut. Urea management options are recommended as alternative to CAN under the climatic conditions of eastern Canada.

Optimising nitrogen application in a cotton farming system

Jonathan Baird1,

1 NSW Department of Primary Industries, Narrabri, NSW, 2390, www.dpi.nsw.gov.au, jon.baird@dpi.nsw.gov.au


The Australian Cotton industry in the last decade has enjoyed extraordinary growth in cotton lint yields, increasing from 2038 kg lint/ha in 2005 to 2610 kg lint/ha in 2015. Higher yields have been driven by both improved varieties and crop management strategies. One issue rising from the increase in yields is the recent industry trend of applying high rates of nitrogen (N) fertiliser to cotton crops. Industry audits are reporting many growers are applying in excess of 300 kg N/ha, in order to achieve yields greater than 2724 kg/ha, in spite of research suggesting these yields are achieve able with applied N rates of 220-250 kg N/ha.

To address the issue, two field experiments were conducted over two years on a commercial cotton farm in the Liverpool Plains of Northern NSW. Experiment treatments included varied N rates, with the aim to quantify research outcomes conducted within a research institute experiment. The investigation found N rate significantly impacted on cotton yield, NUE and the economic optimum N rate. On average there was a 7% increase in yield at every additional 50 kg N/ha increment from 150 to 300 kg N/ha (2552 to 3040 kg/ha of cotton lint).The economic optimum N rate was determined to be 237 kg N/ha over the two seasons. This trial was conducted within the Upper Namoi region of Northern NSW and thus optimum management systems should be developed for other regions that are specific to their growing environments.

Developing a decision support tool for optimising organo-mineral fertilisation strategies and improving nitrogen use efficiency

Johannes Biala1, Daniele De Rosa1, David Rowlings1, Peter Grace1

1Institute for Future Environments, Queensland University of Technology, Brisbane, QLD 4000, Australia, https://www.qut.edu.au/research/research-projects/greenhouse-gas-research, j.biala@qut.edu.au


Farmers are under pressure to operate more efficiently and reduce negative environmental impacts while maintaining or increasing production. Accurate accounting for nutrients supplied with organic soil amendments and appropriate reduction of mineral fertiliser inputs provides an easy way of achieving these goals. This paper outlines what is necessary to develop a decision support tool for optimising fertilisation strategies that utilise both organic and synthetic nutrient sources and improve nitrogen use efficiency. Novel aspects of the proposed calculator are that (i) it integrates organic and synthetic N sources, (ii) it caters for repeat applications and accounts for long-term nutrient release, (iii) it incorporates a paddock-scale nutrient budget, and (iv) it has scope for future expansion to include changes in soil properties brought about by the use of organic soil amendments.

Nitrogen supply and greenhouse gas emissions from a Black Vertosol amended with urea and ENTEC® urea

Constance M.Coverdale1, Alice R. Melland2, Diogenes L.Antille2

1 University of Southern Queensland, Toowoomba, QLD, 4350, Australia, c.coverdale12@gmail.com

2 University of Southern Queensland, National Centre for Engineering in Agriculture, Toowoomba, QLD, 4350, Australia


The Australian cotton industry currently has an average nitrogen (N) use efficiency of 25% and is aiming to improve this to 40%. Improving the timing and rate of soil and fertiliser N supply can help meet this target. This research compared the soil and fertiliser mineral N supply after application of urea and ENTEC® urea (which contains a nitrification inhibitor). Greenhouse gas emissions of nitrous oxide, methane and carbon dioxide were also compared. Data were collected by conducting a 60 day aerobic incubation of pots of a Black Vertosol soil under a constant air temperature (25oC) and soil moisture range (>75% field capacity). The two N fertilisers were applied at 600 kg/ha N and were compared with an unfertilised control. Soil nitrate and ammonium concentrations and greenhouse gas fluxes were measured on up to nine occasions throughout the incubation. Mineral N supply from ENTEC® urea continuously increased over 60 days whereas the mineral N supply from urea peaked by day 14. The ENTEC® urea treatment also yielded 73% lower nitrous oxide emissions than the urea treatment. In the field, if N fertiliser was applied at cotton planting, the N supply from ENTEC® urea may better coincide with peak plant demands than urea.

DMPSA application reduces N2O emissions from exogenous NH4+ and NO3- sources in irrigated maize

Sonia García-Marco1, Guillermo Guardia1, Alberto Sanz-Cobena1, Laura M Cardenas2, Elizabeth R Dixon2, Miguel Ángel Repullo2 and Antonio Vallejo1

1Chemistry and Food Technology Department, E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain sonia.garcia@upm.es; guillermo.guardia@upm.es; a.sanz@upm.es; antonio.vallejo@upm.es

2Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB, UK laura.cardenas@rothamsted.ac.ukliz.dixon@rothamsted.ac.uk


Agriculture is a major anthropogenic source of nitrous oxide (N2O). Application of nitrogenous (N) fertilizers enhances the emission of this greenhouse gas (GHG), mainly due to the biogenic processes of nitrification and denitrification. The use of nitrification inhibitors (NIs), that delay the microbial oxidation of NH4+ to NO3, has been reported as a successful tool for mitigating N2O losses. In this context, a field experiment using 15N labeled fertilizers was carried out in an irrigated Mediterranean maize field aiming to evaluate the effectiveness of the NI 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA) on mitigating N2O emissions, and assess the processes involved in its production. The experiment, performed in 1 m2 microplots, involved the application of 15NH4NO3 or NH415NO3 (with and without DMPSA) to quantify the amount of N2O coming from exogenous NH4+, exogenous NO3 and endogenous soil N. The resulting N2O fluxes confirmed that the addition of DMPSA led to a significant (54%) abatement of this GHG. In this experiment, both nitrification and denitrification were partially inhibited by DMPSA. When NI was not applied, the largest N2O emissions were expected from NH4+ than from NO3-based fertilizers due to nitrification.