Archive for the category: Feature Presentation

Laura Cattell Noll¹, Allison M. Leach², Verena Seufert³, James N. Galloway¹, Brooke Atwell¹, Jan Willem Erisman⁴, Jessica Shade⁵

¹ University of Virginia, 291 McCormick Rd, Charlottesville, VA, 22903, http://www.virginia.edu/, 22903 USA, lcc5sd@virginia.edu

² University of New Hampshire, 131 Main Street, 107 Nesmith Hall, Durham, NH, 03824 USA

³ University of British Columbia, 6476 NW Marine Drive, Vancouver, BC, V6T 1Z2, Canada

⁴ Louis Bolk Institute, Hoofdstraat 24, 3972 LA, The Netherlands; VU Amsterdam, The Netherlands

⁵ The Organic Center, 444 N. Capitol St. NW, Suite 445, Washington D.C. 20001 USA

Abstract

Using a nitrogen (N) footprint model, we estimated the Nr lost per unit Nr consumed for organic food production in the United States and compared it to conventional production. Additionally, we quantified the types of Nr inputs (new versus recycled) that are used in both production systems.

Nr losses from organic crop and animal production are estimated to be of comparable magnitude to conventional production losses. While Nr losses from organic grains and vegetables are slightly higher (+13%, +43%, respectively), and from organic starchy roots and legumes slightly lower (-1%, -17% respectively), losses from organic poultry, pigmeat, beef and dairy production are generally higher than from conventional production (+40%, -7%, +58%, +81%, respectively). Due to high variability and high uncertainty in both systems, we cannot make conclusions yet on the significance of these differences. Conventional production relies heavily on the creation of new Nr (70-90% of inputs) whereas organic production primarily utilizes already existing Nr (0-50% of inputs from new Nr).

Consuming organically produced foods has little impact on an individual’s food N footprint, but it changes the percentage of new Nr in the footprint. Per unit N in product, Nr losses from organic production are comparable to conventional production, but organic production introduces less new Nr to the global pool.

For the full paper, please contact Laura Cattell Noll at lcc5sd@virginia.edu.

Osvaldo Salazar¹, Ricardo Cabeza¹, Yasna Tapia¹, Claudia Rojas¹, Carla Soto¹, Miguel Quemada², Manuel Casanova¹

¹ Departamento de Ingeniería y Suelos, Facultad de Ciencias Agronómicas, Universidad de Chile, Santa Rosa 11315, Santiago, postcode 1004, Email: osalazar@uchile.cl

² Technical University of Madrid (UPM), Ciudad Universitaria, Madrid, 28040. Email: miguel.quemada@upm.es

Abstract

The main purpose of this study was to evaluate the Nitrogen Use Efficiency (NUE) as an indicator for monitoring the environmental sustainability of maize production in the O’Higgins Region in central Chile. Additionally the NUE indicator was used for evaluating the extension services offered for a Clean Agreement Program (CAP) developed for the Chilean Government for the maize-farmers in this Region. A crop management survey was carried out in 80 maize fields during the season 2014-2015, where most of the NUE values were less than 50% using traditional farmer N fertilisation rates, being related to N over-fertilisation. For the 2016-2017 season, 85% of the NUE values would be between the two NUE references values of 50% and 90% if a N recommendation scenario based on a mass N balance by the CAP is applied by the maize-farmers. Thus NUE showed that it is necessary to reduce the N input for improving the environmental sustainability of maize production in this Region.

Robert Norton¹, Elaina vanderMark²

¹ International Plant Nutrition Institute, 54 Florence St, Horsham, Victoria, 3400, Australia, anz.ipni.net, rnorton@ipni.net

² Southern Farming Systems, 23 High St, Inverleigh, Victoria 3321, Australia.

Abstract

A survey was undertaken of 118 growers covering 474 fields over five years across south-eastern Australia. Crop type, grain and hay yield, residue management and fertilizer use were recorded and used to derive N partial nutrient balance (PNB) and N partial factor productivity (PFP). Estimates of the amount of N derived from biological fixation were made for pulse crops. Fertilizer N rates were higher for the higher rainfall regions, averaging 39 kg N/ha for cereals and 56 kg N/ha for oilseeds. Biological nitrogen fixation (BNF) was estimated for the fields based on legume seed or estimated pasture yields and BNF accounted for 16%, 29%, 14% and 50% of the N input for the High Rainfall Zone, Mallee, Southern New South Wales and Wimmera respectively.  The regional median values for both PNB and PFP were higher than the mean values, indicating that there were relatively more high values in all regional data sets. Median PNB was less than 1 of all regions, but there were over 10% of fields in the High Rainfall Zone and the Mallee where PNB was more than 2, and the mean N deficit was highest in those regions at 13 kg N/ha/y and 10 kg N/ha/y respectively. PFP values were highest in Mallee, possibly a consequence of the inherently lower soil N status there. These data demonstrate that understanding the inherent variability in nutrient performance indictors, and also linking soil fertility assessments, is important in developing strategies to improve nutrient management.

S F Ledgard¹, J Rendel², S Falconer¹, T White¹, S Barton³ and M Barton³

¹ AgResearch Ruakura Research Centre, Hamilton 3240, New Zealand, stewart.ledgard@agresearch.co.nz

² AgResearch Invermay Research Centre, Mosgiel 9053, New Zealand

³ Farmer, Hingarae Road, R.D. 1 Turangi 3381, New Zealand

Abstract

Farms in the Lake Taupo catchment of New Zealand have a farm-specific nitrogen (N) leaching limit per hectare. A beef cattle finishing farm in the catchment was used as a case study to compare optimised scenarios with and without N constraints and with flexible supply to meat processing companies or a requirement for regular supply to restaurants based on a premium price for beef with a low N footprint. Scenario analyses included evaluation of sourcing surplus young beef cattle from breeding farms or from dairy farms. A life cycle assessment method was used to estimate all reactive N emissions through the life cycle of beef. Leaching of N from the finishing farm was <20 kg N/ha/year from N-constrained scenarios and 43 kg N/ha/year with no N constraint. Profitability decreased with N constraints and with regular beef supply requirements, which could be countered by a price premium. The N footprint from beef production ranged from 95 to 156 g N/kg meat, being least from the N-constrained scenarios. It was lower from dairy-derived beef and higher with regular beef supply requirements. The farm stage dominated the life-cycle N footprint (78% of total emissions) with the only other significant contributor being the final waste (sewage) stage at 21% of the total, based on a traditional urban waste water treatment system. Preliminary analysis indicated that the Taupo town sewage system of land application to pasture for silage production and feeding back to cattle can further decrease the N footprint over the life cycle of beef.

David Wheeler¹, Caroline Read ²

¹ AgResearch, Ruakura Research Centre, Hamilton, New Zealand, 3124, david.wheeler@agresearch.co.nz

² Overseer Management Ltd, PO Box 11785, Wellington, New Zealand, 6142

Abstract

OVERSEER^® Nutrient Budgets (OVERSEER) is a whole-farm nutrient budgeting tool using a yearly time scale. It calculates a nutrient budget for the farm, taking into account inputs, outputs, and some of the internal recycling of nutrients around the farm. The model integrates multiple animal enterprises (dairy, sheep, beef, deer, dairy goats) and different land uses, including pastoral, cropping (arable, vegetable, fruit), and cut and carry areas. Nutrient budgets are calculated for the nutrients nitrogen (N), phosphorus (P), potassium (K), sulphur, calcium, magnesium, and sodium. With an increased emphasis on water quality, the model is being used to assess N leaching from pastoral farms. This paper discusses some perspectives and emerging practices that are occurring as a result of using an integrated farm systems model like OVERSEER, with a focus on urine patch, irrigation, effluent management and fodder crops.

Cameron J P Gourley¹, Kerry J Stott² , Sharon R Aarons¹, Innocent Rugoho¹

¹ Agriculture Research, Ellinbank Centre, Department of Economic Development, Jobs, Transport and Resources, Ellinbank, Victoria 3821, AUSTRALIA

² Agriculture Research, Parkville Centre, Department of Economic Development, Jobs, Transport and Resources, 32 Lincoln Square North, Carlton, Victoria 3053 AUSTRALIA

Abstract

Nitrogen (N) inputs are critical for productive and profitable grazing-based dairy systems, but inefficient use can contribute to excess N in the broader environment. Whole-farm N balance (WFNB) provides the commonly used recovery metrics: N use efficiency (NUE), milk production N surplus and N surplus/ha; all recognised as environmental performance indicators. We determined annual WFNB for the Australian dairy industry over a 22 year period, and for a diverse range of 16 commercial dairy farms for the 2013/2014 production year. The industry as a whole demonstrated a long-term declining trend in all N recovery metrics, associated with ongoing intensification. Individual farms in a single production year had a wide variation in NUE, productivity N surplus and N surplus/ha, and a poorly defined relationship between NUE and N surplus/ha. At an industry level, the determination of average farm NUE, milk production N surplus and N surplus/ha provides a useful environmental performance indicator but total industry N surplus needs to be adjusted for changes in contributing land area. For individual farms in any production year, we suggest that in addition to quantifying annual N surplus, employing standardised indices that specifically target key N fluxes and utilisation efficiencies at the component level. These will establish more appropriate industry benchmarks for improving N recovery and inform and improve on-farm N management decisions.