Nitrogen use efficiency and nitrogen balance in Australian farmlands

J.F. Angus1 and P. R. Grace2

1CSIRO Agriculture and Food, GPO Box 1600, Canberra 2601, ACT, Australia and EH Graham Centre, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia

2Queensland University of Technology, 2 George St, Brisbane, Queensland 4000, Australia

Abstract

Farms producing crops and animal products occupy 14% of the Australian land mass. Within this agricultural land, 7% consists of intensive industries (dairy, horticulture and viticulture, sugar cane, cotton, irrigated cereals and feedlots) for which the input of fertiliser nitrogen (N) is typical of such industries worldwide. The sugar and dairy industries are adjacent to populated and environmentally fragile water bodies where nitrate (and phosphate) runoff and leaching contributes to water pollution. The nitrogen use efficiency (NUE) of these industries is low but NUE for the inland irrigated rice and cotton industries are relatively high. The remaining 93% of agricultural land grows dryland crops and animal products (wheat, coarse grains, canola, grain legumes, cattle meat, sheep meat, and wool) partly from continuous crops, partly permanent pasture and partly from phased crop-pasture systems. Until the mid-1990s the source of most of the N in dryland crops was from mining the soil organic matter and increasingly, since the 1950s, from N built up from biological N-fixation by pastures grown in phased rotation. Export of N in products from dryland farms exceeded the input from N fertiliser. Since the mid 1990s N fertiliser input increased to an average of about 45 kg N ha-1, only about half of which is taken up by crops. Of the rest, most is retained in the soil after harvest and about one quarter is lost from denitrification, ammonia volatilisation and leaching. Overuse of N fertiliser in dryland farming is rare because neither products nor fertiliser are subsidised. Arid and semi-arid land occupies 86% of the continent, half of which is not used for production and the other half produces cattle meat, sheep meat and wool with no fertiliser input. The source of N is rain, biological N fixation and redistribution from dust, the amounts of which are greater than the controlled N inputs in the agricultural regions. The feature of N cycling in Australia that distinguishes it from other developed countries is the importance of natural N sources, reflecting the extensive and relatively young agricultural system.

Economic perspectives on nitrogen in farming systems: managing trade-offs between production, risk and the environment

David J Pannell

University of Western Australia, [email protected], www.davidpannell.net

Abstract

The economics of nitrogen in farming systems are complex, multifaceted, fascinating and sometimes surprising. Economic insights are crucial for making sound decisions about farm-level management of nitrogen, and also about regional or national policy, such as for water pollution. In this paper I present key insights from a large and diverse literature that is often neglected by technical scientists. Issues covered include: the economics of nitrogen as an input to production; nitrogen and economic risk at the farm level; the economics of nitrogen fixation by legumes; the existence of flat payoff functions, which often allow wide flexibility in decisions about nitrogen fertilizer rates; explanations for over application of nitrogen fertilizers by some farmers; and the economics of nitrogen pollution, at both the farm-level and the policy level. Economics helps to explain farmer behaviour, and to design strategies and policies that are more beneficial and more likely to be adopted and successfully implemented.

Animal production and Nitrogen: Global trends in growth and efficiency

Qian Liu1, Jingmeng Wang1, Zhaohai Bai2, Lin Ma2, Oene Oenema1,#

1 Wageningen University, Environmental Sciences, PO Box 47, NL-6700 Wageningen, Netherlands

2 Center for Agricultural Resources Research, Chinese Academy of Sciences, 286 Huaizhong Road, Shijiazhuang 050021, China

# Email: [email protected]

Abstract

This paper briefly reviews the changes in global animal production during the last 50 years, when total production has roughly tripled. Cattle dominate the world in terms of animal biomass but pigs and poultry increase faster in number and production. Animal production systems are highly diverse across the world, and have a relatively large impact on the environment through emissions of greenhouse gases and ammonia to the atmosphere and nutrients (mainly nitrogen and phosphorus) to water bodies. Losses greatly depend on system, management and regulations. The total amounts of nitrogen and phosphorus in manure produced annually are larger than the global use of synthetic fertilizer annually, but manure nutrients are often not used efficiently. Nitrogen use efficiency (NUE) at animal level ranges from 5 to 45%, depending on animal category, feeding and management. NUE at crop-animal system level may range from 5 to 65% depending on NUE at animal level and the utilization of manure nitrogen and new nitrogen inputs. It is a huge challenge to increase NUE at animal and system levels globally and to diminish the environmental impacts.

Fates of 15N-urea in black soil – maize system and their response to straw incorporation in northeast China: a case study

Zhi Quan1, Shanlong Li1, Feifei Zhu1, Yunting Fang1, *, Peipei Li2, Limei Zhang2, Rong Sheng3, Wenxue Wei3, Jizheng He2

1Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China

2State Key Laboratory of Urban and Regional Ecology, Research Centre for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China

3Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China

*Correspondence: [email protected],

http://research.iae.ac.cn/web/ShowArticle.asp?ArticleID=2442

http://www.researcherid.com/rid/G-4456-2012

Abstract

A better understanding of the fates of fertilizer N is critical to design appropriate N management strategies in intensively cultivated croplands. In this study, we evaluated the fates of 15N-urea in a field experiment on a black soil-maize system and their responses to straw incorporation in Gongzhuling, Northeast China. In order to get realistic results, we adopted the field management used by local farmers. Results showed that the crop N uptake was the main sink, recovering 52-53 % of the fertilizer N. Total 15N recoveries in plant organs followed the order: grain (27-29%) > leaf (11-12%) > stem (6%) > tassel, silks, leaf sheath, husks, etc. (5%) > root (2%) > cob (1%). Tracer N remaining in soil was the second largest sink (25-33%), and most (18-29%) was located in the ridge 0-20 cm layer (fertilized area). The total loss of fertilizer N was 13-23%. Straw incorporation increased the retention of applied fertilizer N and decreased its losses, although there was no significant difference in  plant N uptake. The contribution of fertilizer N to total  N uptake was 36-37% at the physiological maturity stage of maize. Fertilizer N was an important N source for maize growth but soil N was still the main N source. Our results indicate that Nitrogen Use Efficiency (NUE) in maize cultivation system in northeast China is not as low as that reported by many previous studies using difference or balance method. Considering the low NUE in China, our next aim is to find out which region, and which kinds of crops lowered the overall NUE in Northeast China.

Global nitrogen fertiliser demand and supply: trend, current level and outlook

Patrick Heffer1 and Michel Prud’homme1

1 International Fertilizer Association (IFA), Paris 75116, France, www.fertilizer.org, [email protected]

Abstract

In the perspective of a world reaching more than 9 billion people by 2050, and the need to alleviate persistent hunger, which still affects more than 800 million people, nutrient management shall ensure continuous increase of agricultural production. The latest projections by the Food and Agriculture Organization of the United Nations (FAO) show that feeding that many people would require raising overall food production by some 60% between 2005/07 and 2050 (FAO, 2012) in the absence of changes to current biofuel mandates. This shall be done while mitigating environmental impacts of farming in general, and improving plant nutrient management in particular. Agricultural intensification using fertilizer best management practices is a desirable and necessary goal. The alternative –agricultural extensification– means increased conversion of natural habitats to farmland, biodiversity loss, and a significant increase in global greenhouse gas emissions.

The need to improve food security strongly influenced world fertilizer demand over the past decades. Future demand is likely to be driven by a broader set of considerations, including the need to reduce environmental impacts from nutrient losses. The paper analyzes global nitrogen (N) fertilizer demand and supply trends and outlook under this changing operating environment.

Sustainability, a change of thinking

Bruce Smith

Technical Director, Eko360 Limited, PO Box 87039, Auckland 1742, New Zealand

Email: [email protected]    website: www.eko360.com

Abstract

In New Zealand the use of nitrogen fertiliser has in past 25 years increased 600% while dairy production, where much of the nitrogen fertiliser is used, has increased by 270%. The unintended consequences of the excessive use of nitrogen have been a cost to the overall environment.

A paradigm shift is needed to achieve sustainable farming systems. Much of the science to support this shift has been published and it is time to dust off these research papers   re-educate and share the established knowledge with industry leaders taking responsibility.

Sustainability is a journey. It is about the People, the Planet and Profit. Practices must change to ensure they meet today’s needs while ensuring future generations have the ability to meet their needs.

Enhancing nitrogen use efficiency for Victoria and the world: a combined knowledge and innovation systems perspective

Priit Kaal1, Richard Vines2

1 DEDJTR, 1 Spring Street, Melbourne, Vic, 3000, [email protected]

2 DEDJTR, 1 Spring Street, Melbourne, Vic, 3000, [email protected]

Abstract

Since September 2012, knowledge management specialist staff within Agriculture Victoria, (Department of Economic Development, Jobs Transport and Resources and its predecessor institutions) have been developing a number of different digital applications to foster more effective online collaborations across the public, research, private service provider, community and education sectors. Adoption of these work practices and systems, including governance systems has the potential to improve the means by which those involved in the design, deployment and monitoring of research, development and extension programs and projects can reach and engage audiences, facilitate co-design of solutions with target audiences and improve access to information and expertise.

In this paper, we explore these possibilities and articulate the benefits for adopting these innovations in line with the overarching theme of this conference: that is through the aspiration of developing solutions to enhance nitrogen use efficiency for the world. The context will be the Victorian dairy sector and in particular a project called: Manure Technologies To Drive Resource Efficiencies.  This project is situated within a policy context that intensification of all agricultural industries including the Victorian dairy industry is desirable and inevitable. This global trend towards agricultural intensification is increasing place-based conflicts involved with securing a social license to underpin a ‘right to farm’. The Victorian Government State Government in Australia is grappling with the complexity of the trade-offs between these two policy objectives.

The central claim of the paper is this. Embedding principles of good practice knowledge management into the way programs and projects are designed and managed will do much to ameliorate the tensions inherent between the policy objectives of enabling agricultural intensification and securing a social license underpinning any ‘right to farm’. The complexity associated with the trade-offs between these dual objectives involve many technical challenges. To enhance nitrogen use efficiency in the dairy sector, solutions are required across many domains –for example in facilitating the re-use of nutrients, addressing soil nutrient accumulation, reducing gaseous emissions and odour and eliminating nutrient contamination of water and air, particularly those where there are larger herds and intensive operations involved.

It will be concluded that effective knowledge management needs to address two overarching challenges (Snowden 2003). The first is to create the conditions within which innovation can emerge via effective sense-making, collaboration and innovation systems thinking that apply in both face to face and online environments. Practical examples from other sectors will be discussed to highlight how technology can be harnessed to create the conditions within which representatives of “communities of practice” (CoPs) can co-learn and co-evolve with representatives of “communities of interest” (CoIs)  in order that solutions to problems involve principles of co-design. It will be emphasised that such approaches have significant potential in the realm of manure technologies and enhancing nitrogen use efficiency. The second is to enhance the quality of decision support systems. In the case of agriculture such support systems need to be flexible and extensible enough to apply at different levels in integrated ways (i.e. across farms, catchments, industry development, community based and public policy levels). The problem at the moment is that current decision support systems do not take into account the need to integrate and value the many different types of evidence to support decision making across these different levels.

Wheat straw biochar reduces N2O emission by increasing denitrification in alkaline and acidic submerged paddy soils

Jun Shan1, Xu Zhao1, Shutan Ma1, Xiaoyuan Yan1

1 State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China, Email: [email protected] or [email protected]

Abstract

Paddy fields are one of the most important N sinks in terrestrial ecosystems, and considerable N loss is caused by denitrification. Biochar has been recognized as useful soil amendment to paddy field in mitigating nitrous oxide (N2O) emission. However, the key mechanisms responsible for the reduced N2O emissions by biochar in paddy soils are still obscure. Here, using two paddy soils with contrasting pH, the denitrification and N2O emission were investigated in soil amened with different amounts of biochar (0%, 0.5% and 5%) via soil slurry incubation combined with N2/Ar technique. The results showed that biochar amendment significantly increased the pH values both in the alkaline and acidic soils. Biochar at 5% amendment rate significantly increased denitrification and significantly decreased N2O emission in soils. In the alkaline soil, biochar at 0.5% amendment rate significantly increased denitrification, but had no effect on N2O emission. Conversely, in the acidic soil, biochar at 0.5% amendment rate did not affect denitrification, but significantly reduced N2O emission. The N2O/(N2+N2O) ratio was significantly reduced by biochar amendment irrespective amendment rate both in alkaline and acidic soils. In the alkaline soil, biochar at 5% amendment rate significantly increased the abundance of nosZ genes, whereas biochar had no effect on the abundance of nosZ genes in the acidic soil irrespective of amendment rate. Our results suggested biochar effects in the alkaline soil were attributed to increase of denitrifying community, whereas biochar effects in the acidic soil was attributed to increase of pH.

Influence of nitrogen fertilizer and compost mix application on greenhouse gas emissions from humid subtropical soils

Anuga Liyanage12, Peter R Grace1, David W Rowlings1   Clemens Scheer1

1 Institute for Future Environments, Queensland University of Technology, 2 George Street, Brisbane, QLD 4000, Australia.     [email protected] [email protected] [email protected]

2 Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya, 81100, Sri Lanka.

Abstract 

The application of organic amendments (OA) is a strategy to improve soil fertility and offset the high cost of mineral fertilizers used in agricultural systems. However, information on the interaction of OAs with synthetic fertilizers and the resulting greenhouse gas emissions from these combinations are not well understood for different soil types. A 36 day laboratory incubation experiment (3 compost x 3 N rates) was conducted to quantify soil N2O emissions along with CO2 and mineral N from subtropical soils in Gatton, Australia. Nitrous oxide emissions  decreased by 68% and 57% in  60N and 120N treatments respectively with the increase in compost applications  rates up to 30 t/ha and 60 t/ha. Adding 60 t/ha compost and 120 kg N/ha is considered  as the optimum fertilizer rate to minimize N2O and CO2 emissions from  a sub-tropical Vertosol and potentially conserving soil physical, chemical and biological properties for a sustainable crop growth.

Modeling ammonia volatilization over Chinese croplands

Ziyin Shang1, Feng Zhou1, Shuoshuo Gao 1, Yan Bo1, Philippe Ciais 2, Kentaro Hayashi 3, James Galloway 4, Dong-Gill Kim 5, Changliang Yang 6, Shiyu Li 6, Bin Liu 6

1 Sino-France Institute of Earth Systems Science, Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing, 100871, P.R. China, Email: [email protected]

2Laboratoire des Sciences du Climat et de l’Environnement, CEA CNRS UVSQ, 91191 Gif-sur-Yvette, France

3Carbon and Nutrient Cycles Division, National Institute for Agro-Environmental Sciences, 3-1-3, Kannondai, Tsukuba, Ibaraki 305-8604, Japan

4Environmental Sciences Department, University of Virginia, Charlottesville, Virginia 22904, USA

5Wondo Genet College of Forestry and Natural Resources, Hawassa University, PO. Box 128, Shashemene, Ethiopia

6Research Institute of Engineering Technology, Yunnan University, Kunming, 650091, P.R. China

Abstract

Ammonia (NH3) released to the atmosphere leads to a cascade of impacts on the environment, yet estimation of NH3 volatilization from cropland soils (VNH3) in a broad spatial scale is still quite uncertain in China. This mainly stems from non-linear relationships between VNH3 and relevant factors. Based on 495 site-years of measurements at 78 sites across Chinese croplands, we developed a nonlinear Bayesian Tree Regression model to determine how environmental factors modulate the local derivative of VNH3 to nitrogen application rates (Nrate) (VR, %). VNH3-Nrate relationship was non-linear. VR of upland soils and paddy soils depended primarily on local water input and Nrate, respectively. Our model demonstrated good reproductions of VNH3 compared to previous models, i.e., more than 91% of the observed VR variance at sites in China and 79% of those at validation sites outside China. The observed spatial pattern of VNH3 in China agreed well with satellite-based estimates of NH3 column concentrations. The average VRs in China derived from our model were 14.8 ± 2.9% and 11.8 ± 2.0% for upland soils and paddy soils, respectively. The estimated annual NH3 emission in China (3.96 ±0.76 TgNH3·yr-1) was 40% greater than that based on the IPCC Tier 1 guideline.

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