Comparing nitrogen budgets in shrimp and rice-shrimp ponds in Vietnam

Duc Dien Luu1,2, Huu Hiep Le2, Michele A. Burford1, Jesmond Sammut3

1 Australian Rivers Institute, Griffith University, 170 Kessels Road, Nathan, Queensland 4111, Australia,, Email:
2 Research Institute for Aquaculture No.2, 116 Nguyen Dinh Chieu Street, District 1, Ho Chi Minh City, Vietnam
3 School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington 2052, Australia


Saline water intrusion has become a severe issue facing the Mekong region of Vietnam, especially in coastal areas. This issue has resulted in farmers diversifying from growing exclusively rice to adopting integrated rice-shrimp culture systems. However, the nitrogen (N) cycling and N use efficiency of these systems remains poorly understood. To address this knowledge gap, we examined nutrient budgets across 12 farms adopting integrated rice-shrimp ponds or intensive grow-out ponds over a one year period. The main N input (95%) in the rice-shrimp ponds came from inlet water, while only 2% of N in outlet water was due to shrimp farming. Shrimp survival rates in mixed rice-shrimp systems were low over the year (4.3 – 5.6%). In contrast, intensive grow-out ponds growing only shrimp on the same farms had significantly higher survival rates (66.4 – 82.3%) when the crop survived through to harvest. In these ponds, formulated feed was the highest input (65% N) with 44% N being in shrimp harvest. These results show that N in the rice-shrimp ponds was used less efficiently than in grow-out ponds and that mechanisms to improve survival rates and production are urgently needed.

Surface atmosphere exchange of NO and CO2 in a grazed semi-arid ecosystem: comparison of measurements and model predictions

Claire Delon1*, Corinne Galy-Lacaux1, Dominique Serça1, Ndiobo Camara2, Eric Gardrat1, Idrissa Saneh3, Rasmus Fensholt4, Torbern Tagesson4, Valérie Le Dantec5, Bienvenu Sambou2, Cheikh Diop2, Manuela Grippa6, Eric Mougin6.

1 Laboratoire d’Aerologie, Université de Toulouse, CNRS, UPS, France, *

2 Institut des Sciences de l’Environnement, Université Cheick Anta Diop, Dakar, Sénégal

3 Centre de Recherche Zootechnique, Dahra, Sénégal

4 Institute of Geography, University of Copenhagen, Copenhagen, Danemark

5 Centre d’Etudes Spatiales de le BIOsphère, Université de Toulouse, CNES, CNRS, IRD, UPS, France

6 Geosciences Environnement Toulouse, Université de Toulouse, CNES, CNRS, IRD, UPS, France


This paper presents a comparison between measurements and model predictions of biogenic nitric oxide emissions and respiration (CO2 emissions) from soils in a Sahelian grazed ecosystem in Senegal (Dahra site, 15.2°N, 15.2°W). Nitric oxide (NO) and CO2 emissions are large at the beginning of the wet season when the first rains fall on dry soils (pulse emissions), due to microbial and biological processes reactivated in the soil when moisture conditions are favourable. The model shows a correct representation of pulses of NO and CO2, but underestimates fluxes in the drier periods between rain events and after the wet season. We hypothesize that in the drier periods the model over-predicts the death rate of microbes, involving a lag between mineral N content availability and N emissions. Spatial heterogeneity of soil and vegetation characteristics and presence of livestock also involve differences between modelled and measured fluxes.

Quantifying the supply of plant-available nitrogen from dairy effluents to grow crops

Johnstone P1, Norris M1, Houlbrooke D2, Dexter M2, Sharp J3, Selbie D2, Hedderley D4

1The New Zealand Institute for Plant & Food Research Limited, Havelock North, 4130

2AgResearch Limited, Hamilton, 3214

3The New Zealand Institute for Plant & Food Research Limited, Lincoln, 7608

4The New Zealand Institute for Plant & Food Research Limited, Palmerston North, 4442



The use of dairy effluent to grow forage and arable crops represents an opportunity to more sustainably reuse shed, feed pad and barn nutrients that are generated from intensive dairy systems. To do so in a profitable and low risk manner requires an understanding of the effect of effluent characteristics on nutrient supply patterns, including both the quantum of release and rate of release. Between 2014 and 2016 we have conducted several assays to investigate the nitrogen (N) supplying power of dairy effluents and link this to effluent characteristics measured at the time of application. This paper reports on Assay 1 where we quantified release patterns for five slurry and six solid dairy effluents collected from commercial farms in the Waikato region of New Zealand. These effluents were applied to a single, low N (0.36 % total N) soil at a target application rate of 100 kg N/ha and subsequently incubated in 500 ml units at 20°C and 90% of field capacity for 182 days. Units were leached a total of 15 times during the assay and the drainage water characterised for inorganic N levels. Estimates of N supply were calculated, corrected for background N supply from a non- effluent control, and relationships with a wide range of effluent characteristics assessed. The assay showed that the pattern and magnitude of N supply across slurry and solid effluent treatments varied considerably, consistent with the large variation in effluent characteristics. Strong positive correlations were found between the water-soluble N and carbon (C) effluent characteristics and the rate of N supply in the first month after effluent addition. There were few clear correlations between effluent characteristics and the rate of N supply during the later stages of the assay (112-182 days). At the end of the assay (182 days), final N supply for respective slurry and solid effluents ranged from 3.7 to 74.2 % and 1.5 to 34.3 % of total effluent N applied. Net N supply values which adjusted for inorganic N in the effluents at application (expressed as either a percentage of total N or organic N) were positive for seven of the eleven treatments (three slurries and four solids) indicating a net N mineralisation effect and negative for the remaining four (two slurries and two solids), indicating a net N immobilisation effect. Work is ongoing to identify the causes of the large variation in N supply.

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.