Nitrogen use efficiency (NUE) and tools for farmer engagement: a good reason for being imprecise

Ashley Evans1, Donna Lucas2, Dr Doris Blaesing2

1 RM Consulting Group, PO Box 396, Penguin, Tasmania, 7310,,

2 RM Consulting Group, PO Box 396, Penguin, Tasmania, 7310


A nitrogen use efficiency (NUE%) calculator was developed to engage with cropping farmers and advisors on reducing nitrogen (N) losses from crop production.

The calculator utilises the ‘partial nitrogen balance’ (or ‘output-input ratio’) method to calculate NUE% for an individual crop, a rotation or a whole farm. It also enables estimating the monetary value of potentially unused mineral and organic nitrogen fertiliser.

Experience has demonstrated that both, farmers and advisors, are keen to engage with the tool due to its ease of use and the value of the results in supporting decisions on farm and monitoring NUE% over time. Farmers and advisors have used the calculator for a variety of reasons, including for verification of current best management practices, a means to assess whether or not fertiliser application is efficient and as a way to benchmark groups of producers in a region or groups growing a specific crop.

Calculating NUE% is a successful way to engage with cropping farmers and advisors. The review of nitrogen inputs, removal and costs, based on easily available data, proved an effective starting point for moving to more in-depth discussions about overall nitrogen, soil and crop management. This supported good planning and decision-making for farmers. In our experience, attempting a review of management practices with complex information and using assumptions where actual farm data is not available can disengage people.

Towards an integrated tool to calculate institution carbon and nitrogen footprints

Allison M. Leach1, James N. Galloway2, Elizabeth Castner2, Jennifer Andrews1

1University of New Hampshire, 131 Main Street, 107 Nesmith Hall, Durham, NH, 03824 USA,
2University of Virginia, PO Box 400123, Charlottesville, VA, 22904 USA


Hundreds of institutions have calculated, tracked, and managed their carbon footprint to help improve their sustainability. Although important, greenhouse gas emissions address just one aspect of sustainability. We propose an integrated carbon and nitrogen footprint tool to allow institutions to track and manage a broader picture of their environmental impacts. This integrated tool will bring together the Campus Carbon Calculator (a tool developed in 2001 at the University of New Hampshire that is used by colleges and universities across the United States) and the Nitrogen Footprint Tool (a new tool developed in 2009 at the University of Virginia that is completing a beta testing phase with 18 institutions). We will present the methodology for this integrated tool, case study results for five universities, and management scenario analyses for a variety of reduction strategies. Preliminary analyses have found strong comparisons between the carbon and nitrogen footprint in both the food and energy sectors. In addition, we found reductions to both footprints for a variety of management strategies. This analysis holds significance for all institutions, regardless of whether they have calculated their own footprint, because it will identify the most effective footprint management strategies across institutions that could then be used in sustainability planning.

<For the full paper, please contact Allison Leach at>

Institutional barriers and opportunities for improving policy approaches to reducing excess reactive nitrogen from U.S. agriculture

Otto C. Doering III

Agricultural Economics Dept., Purdue University, 403 West State Street, West Lafayette, IN, USA,


Agriculture in the U.S. is the major source of anthropogenic reactive nitrogen. The control and management of this nitrogen is a major challenge. The challenge is magnified by the nature of the nitrogen cascade; the ability of nitrogen to change form and move between land, air and water. This is only one of the factors making excess reactive nitrogen a wicked problem. The U.S. Environmental protection Agency and the U.S. Department of Agriculture are major players in dealing with reactive nitrogen and have different institutional histories, responsibilities, and structures. Yet, in order to effectively manage and control reactive nitrogen these institutions and their activities are going to have to encompass and mirror the nitrogen cascade. Institutions that internally have barriers between segments of the cascade will have to overcome them. Parts of the cascade that involve other institutions will have to be coordinated with those institutions. To accomplish this there has to be the coordination of functions carried out by the two primary agencies. This is made all the more difficult by the fact that EPA plays a regulatory role in contrast to the Department of Agriculture’s supportive sectoral role.

Nitrogen Use Efficiency, Nitrogen balance, and Nitrogen productivity – a combined indicator system to evaluate Nitrogen use in crop production systems

Frank Brentrup1, Joachim Lammel1

1 Yara International, Research Centre Hanninghof, Hanninghof 35, 48249 Duelmen, Germany,,


Several indicators are discussed to evaluate nitrogen use in agricultural production. Nitrogen use efficiency (NUE) can be defined as the ratio between N applied and N removed by the crop. NUE is, however, only one aspect of sustainability of N use. To account for environmental risks due to excess N, N balance (N input – N output) is seen as an appropriate indicator for N losses to the environment. While NUE and N balance focus on resource use efficiency and environmental pollution, the main purpose of agricultural production is providing food. It is therefore important to include the productivity dimension into the considerations, which can be crop N yield (crop yield * N content of the harvested product). The indicator system presented here considers these three important aspects of N use at the same time, i.e. resource use efficiency (NUE), environmental risk (N balance), and productivity (N output). All parameter can be derived from the same base data, N input and N output. Even more important as the way of calculation is the interpretation of the results. Examples from field trials show that very high as well as low NUE values may represent unsustainable systems and that the interpretation of NUE values requires a sound qualification scheme including acceptable boundaries for N balance and N output. This study explains (1) how the multi-dimensional indicator scheme works and how target values can be determined and (2) examines how agricultural practices such as precision farming tools support farmers achieving the defined targets.

The effect of inhibitor use and urea fertiliser application on pasture production and nitrous oxide emissions

Kevin Kelly1, Graeme Ward2

1 Agriculture Victoria, Department of Economic Development, Jobs, Transport and Resources, Tatura, Vic. 3616, Australia.,

2 Agriculture Victoria, Department of Economic Development, Jobs, Transport and Resources, Warrnambool, Vic. 3280, Australia.


The application of nitrogen (N) fertilisers to pasture is known to increase nitrous oxide (N2O) emissions. There is currently little information available on emissions from N fertilised dairy pastures in Australia. The objective of this work was to quantify the effect of inhibitor coatings on urea fertiliser on pasture DM production and N2O emissions.

Field experiments (five treatments by five replicates) were conducted at two sites in south-west Victoria with contrasting drainage characteristics. Treatments were nil, urea, urea coated with dicyandiamide (DCD), urea coated with 3,4-dimethyl pyrazole phosphate (DMPP) and urea coated with N-(n-butyl) thiophosphoric triamide (nBPT). The urea+DCD treatment was replaced with urea ammonium nitrate (UAN) in Years 2 and 3. The N treatments were applied at the start of the growing season and again after every second harvest. Pasture production was measured for three years and N2O emissions were measured for two years.

Pasture responded to the application of N fertiliser at both sites every year. There were no differences in pasture production between the urea, urea plus inhibitor coatings or the UAN treatments. Cumulative N2O emissions where no N was applied varied with year and site, ranging from 0.23 to 0.53 kg N2O-N/ha/year, while emission factors for urea use ranged from 0.09 to 0.31%. The use of a nitrification inhibitor reduced emissions by 30 to 75%, with the magnitude of the reduction influenced by soil water content around the time of N application. The urease inhibitor had no effect on N2O emissions.

Estimating nitrogen excretion and deposition in Australian grazing dairy systems for improved nutrient management

Sharon R Aarons1, Cameron JP Gourley1, Mark Powell2, Murray C Hannah1

1 Agriculture Research and Development, Department of Economic Development, Jobs, Transport and Resources, Ellinbank Dairy Centre, 1301 Hazeldean Road, Ellinbank, Victoria 3821, Australia website,

2 US Dairy Forage Research Center, USDA Agricultural Research Service, 1925 Linden Drive West, University of Wisconsin, Madison, WI 53706, USA


Current nutrient management approaches in Australian dairy systems largely target the application of fertiliser nutrients. However, increasing animal densities and greater reliance on purchased feeds means that nutrient inputs in feeds have increased.  Consequently, the role of grazing animals in nutrient flows and deposition needs to be accounted for in dairy industry nutrient management plans.  However, quantifying nutrient intakes and therefore nutrient excretion is difficult, due to challenges in estimating pasture dry matter intake by grazing cattle.  To quantify N fluxes through grazing dairy cows we modified an animal performance method for estimating annual dry matter intake to calculate daily N intake and excretion.  Using the excretion data, we estimated N loading rates to specific locations visited by the lactating herds within the dairy farms.  The results indicated that these herds received a mean of 52% of their energy requirements from supplementary feeds despite the grazing base of the dairy systems.  Calculated annual N flows through the lactating herds were 60% of total N inputs onto these farms. Mean N intakes (545 g/cow/day) were well in excess of recommended levels resulting in excretion on average of 433 g N /cow/day in these systems.  The resulting deposition of excreted N to pasture paddocks was not uniform, with 30% more N returned to paddocks that were generally closer to the dairyshed.  The smallest mean annual load of excreted N was deposited in the dairyshed and yards.  However, this N load is typically applied as effluent to paddocks closest to the dairyshed which further exacerbates N accumulation and potential losses in these parts of dairy farms.  These results demonstrate that quantifying excreta N loads and spatial nutrient distribution by grazing dairy cows is required for improved N management in grazing system dairy farms.

Dairy cow urine sodium content and soil aggregate size influence the amount of nitrogen lost from soil

Toru HAMAMOTO1, Yoshitaka UCHIDA2

1 Graduate School of Agriculture, Hokkaido University, Environmental Biogeochemistry Lab, Kita9 Nishi9 Kitaku Sapporo, Hokkaido, Japan, 0608589,,

2 Research Faculty of Agriculture, Hokkaido University, Environmental Biogeochemistry Lab, Kita9 Nishi9 Kitaku Sapporo, Hokkaido, Japan, 0608589


Cow urine deposition on pasture soils is a major source of N-related environmental impacts in the dairy farming systems. The urine-N can potentially be lost in reactive forms to the groundwater as nitrate (NO3) and to the atmosphere as nitrous oxide (N2O) and ammonia (NH4+). These N-related environmental impacts are possibly related to the sodium (Na+) concentrations in urine. We sampled a pasture soil and separated it into three aggregate size groups (0–3, 3–5, 5–7 mm). Then, cow urine with variable Na+ concentrations (4.3–6.1 g Na+ /l) was added to the soil cores. We treated the cores with simulated heavy rains and measured the amounts of inorganic-N leached from the soils. Increasing Na+ concentration in urine decreased the loss of NO3 (−20%), after repeatedly applied simulated rain treatments (30 mm × 3) but increased the loss of ammonium (31%). Field level studies and studies focusing on the mechanisms behind the changes in nutrient losses are needed.

Novel methods for estimating urinary N production from two contrasting dairy systems

Mark Shepherd1, Diana Selbie1, Gina Lucci1, Paul Shorten1, Maryann Pirie1, Brendon Welten1, Kevin Macdonald2, Chris Roach2 & Chris Glassey2

1 AgResearch Ltd., Ruakura Research Centre, Private Bag 3123, Hamilton 3240, New Zealand,

2 DairyNZ Ltd., Private Bag 3221, Hamilton 3240, New Zealand


Two demonstration farmlets representing the grazed pasture component of contrasting dairy systems were established in 2011 in the Waikato region of New Zealand to compare production, profitability and mineral nitrogen (N) leaching risk.  The farmlets ran for four seasons and differed in: annual N fertiliser input (c. 150 vs. c. 50 kg N/ha), with stocking rate adjusted to available feed (3.2 vs. 2.6 cow/ha); and also in hours grazed during autumn and winter.    We report on three methods for estimating urinary N production from the systems, which is the primary source of N leaching from grazed paddocks.  We compared a herd N balance calculation and two novel methods: direct measurement of the urine patch N immediately after voiding onto the soil and urine sensors which, when attached to the cow, provide real-time measurements of urine production over a 24 hour period.  The three methods differed in temporal and spatial scale of measurement but produced consistent conclusions.  The low N system generated 19% less urine per ha as a mean of the three measurement methods but the same amount of urine N per cow. When cows in the low N system were removed onto a ‘stand-off’ pad for 6 hours per day, the urine sensors estimated a further 23% decrease in daily urine deposition directly on paddock.  Using a combination of methods provides insight into N flows through complex farm systems.

Mitigation of nitrogen losses with Australian zeolites during the anaerobic digestion of swine manure

Thushari N. Wijesinghe1, Kithsiri B. Dassanayake2, Peter J. Scales2, Deli Chen1

1 Faculty of veterinary and Agriculture Sciences, The University of Melbourne, Parkville, Victoria, 3110

2 School of Engineering, The University of Melbourne, Parkville, Victoria, 3010


Anaerobic digestion (AD) is one of the most effective and sustainable methods of handling swine manure that convert organic wastes into a greener energy, effectively reducing methane (CH4) and ammonia (NH3) emissions. Production of higher levels of total ammonia-nitrogen (TAN) during the acidogenesis due to the high nitrogen (N) contents in swine manures significantly reduce the CH4 yield. Australian zeolites have a high adsorption capacity of ammonium (NH4+).Therefore; reduction of N during the AD through zeolite not only improves the CH4 production but also reduces potential environmental risks associated with NH3 emissions from swine manure. This study is aimed at determining the optimum Australian zeolite dose that produces maximum TAN recovery at optimum CH4 production. Swine manure was treated with natural and sodium zeolites at 0, 10, 40, 70, 100mg/L and digested anaerobically for 60 days.  Natural zeolites at a dose of 40g/L resulted in the highest increase (29%) in total CH4 yield from swine manure compared to the untreated manures, while natural and sodium zeolites at a dose of 100g/L reduced 50% and 52% of NH4+ in the medium respectively, compared to the control. However, the increases in CH4 yield under those two treatments were only 10% and 12%.


Integrated assessment of manure transport induced by European environmental regulations: a life cycle approach for liquid pig manure in Germany

Kuhn, T. 1, Kokemohr, L. 1

1 Institute of Food and Resource Economics, Bonn University, Nußallee 21, 53115 Bonn, Germany,,


Concentration of livestock production at the farm and regional level decouples nutrient cycles between animal and plant production. Export of excess manure from livestock to crop farming systems closes cycles without structural change of the production system. In the EU, manure transport is triggered by command and control regulations under EU environmental law. We apply a life cycle approach to assess the environmental impact of raw liquid pig manure transport in northwest Germany. Transport is caused by the proposed revision of the German National Action program implementing the EU Nitrates directive. Results indicate that manure transport decreased NH3, N2O, NOx, NO3 emissions and P surplus compared to a baseline without transport. Reduction of GHG emissions from replaced mineral fertilizer outweighed transport emissions. When exporting farms do not need to replace exported organic nutrients with mineral fertilizer, there is even a reduction in GHG emissions. Despite emission reductions in total, manure importing farms increased NH3 and NO3 losses, caused by higher emissions from manure application and lower efficiency of organic N compared to mineral fertilizers. Results illustrate the potential of manure transport as a short-term solution to reduce environmental burdens caused by livestock concentration. However, additional regulations are needed to prevent negative impacts of regional pollution swapping.