Archive for the category: Nitrogen budgets and calculators to aid decision making

Cong Shi¹, Fankang Meng^1,2, Toshihiro Watanabe¹, Fuyuki Satoh³, Takayoshi Koike¹*

Graduate School of Agriculture, Hokkaido University, Sapporo 060-8689, Japan

1. College of Life Science, Nankai University, Tianjin 300071, China
2. Hokkaido University Forests, Sapporo 060-0809, Japan

*Corresponding author: Takayoshi Koike: tkoike@for.agr.hokudai.ac.jp

Abstract

To clarify effects of ozone (O₃) on foliar nitrogen (N) contents dynamics in three representative woody plant seedlings: birch (Betula platyphylla var. japonica), oak (Quercus mongolica var. crispula), and beech (Fagus crenata) grown in elevated O₃ (eO₃), we investigated N contents in live and senescing leaves, the relation of N content differences and leaf mass per area (LMA) of each species. The 3 species seedlings were planted in a free-air O₃ enrichment system for one growing season with 3 replicated plots exposed to the air or O₃ at about 2.5 times the ambient. In our study, about 60 % of foliar N was retranslocated under eO₃ conditions in birch; nearly 70 % of N in live leaves of oak was decreased by O₃; and negative correlations were found between LMA and N at ambient. Based on the results, we discussed plausible understanding physiologically and biochemically to conclude that foliar N contents of birch is more sensitive than beech in response to O_3, especially for the senescing leaves; on the other hand, LMA may be considered as an index parameter in speculation of the changes in foliar N contents at ambient O₃ concentrations.

Elizabeth S. Milo¹, Elizabeth A. Castner¹, Lia R.Cattaneo¹, James N. Galloway¹, Allison M. Leach²

¹University of Virginia, 291 McCormick Rd, Charlottesville, VA, 22904 USA, esm9gq@virginia.edu

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

Abstract

Reactive nitrogen is both essential and detrimental to life on Earth. While nitrogen is a key component of protein, it is also a pollutant that can cause climate change, eutrophication, and more. The University of Virginia (UVA) is the only university that has approved a nitrogen footprint reduction goal. This goal was approved by UVA’s governing board in 2013 and aims to reduce the University’s nitrogen footprint by 25% below 2010 levels by 2025. Note that for this study, the boundaries of the N footprint calculation at UVA include on-campus university operations but excludes the food component of the universities’ health system.  UVA has calculated its footprint for 2010 and 2014 and will continue to complete a benchmark calculation every four years. The UVA N footprint group and the Office for Sustainability have determined a number of scenarios to reduce the University’s N footprint. Examples of these include implementing a Meatless Mondays program, composting all food waste at the University and switching from coal to natural gas at the heating plant. Since the 2010 baseline year, UVA’s N footprint has changed from a total of 403 to 393 MT N; the total reduction needs to be to 303 MT N. The decrease in the universities N footprint can be partially attributed to the decrease in coal use in the universities’ heating plant.   UVA hopes to serve as a model for other universities and institutions that want to reduce their environmental impact by setting and achieving N reduction goals.

Yuhei Hirono¹, Shigekazu Nakamura², Tomohito Sano³, Kunihiko Nonaka³

¹ National Agriculture and Food Research Organization, 2769, Kanaya-Shishidoi, Shimada, Shizuoka, 428-8501, Japan, E-mail: hirono@affrc.go.jp

² Shizuoka Prefectural Research Institute of Agriculture and Forestry, Mobata, Shimizu, Shizuoka, 424-0101, Japan

³ National Agriculture and Food Research Organization, 2769, Kanaya-Shishidoi, Shimada, Shizuoka, 428-8501, Japan

Abstract

Large amounts of nitrogen fertilizer are required in the cultivation of tea (Camellia sinensis (L.)), relative to other crops, resulting in nitrate contamination of surrounding water systems and high rates of nitrous oxide emissions. In response to these problems, the amount of nitrogen fertilizer applied to tea fields in Japan has been decreased by the improvement of fertilizer application methods in recent years. In this study, we aimed to assess the changes in water quality due to the reduction of nitrogen input and determine the environmental response to improved fertilizer application methods in tea fields. First, we analyzed 21-year water quality monitoring data in an intensive tea-growing area in Japan. We found nitrate concentrations significantly decreased at most studied sites in water systems in the tea-growing area, indicating that water quality was improved by reducing nitrogen fertilizer application in tea fields. Second, we modeled nitrogen leaching from tea field soil based on the data obtained by lysimeter experiments. This showed that the calculated amounts of water and nitrogen leachate agreed well with the observed results.

Kirsten Barlow¹, Thabo Thayalakumaran², Philip Moody³

¹ Agriculture Victoria, DEDJTR,124 Chiltern Valley Road, Rutherglen, Victoria, 3685, Kirsten.Barlow@ecodev.vic.gov.au

² Agriculture Victoria, DEDJTR, 32 Lincoln Square North, Carlton, Victoria, 3053

³ Department of Science, Information Technology and Innovation, Brisbane, Queensland, 4000

Abstract

As agricultural systems continue to intensify there is a need for farmers and farm advisors to understand how soil, climate and management interact to affect nitrogen (N) losses at the paddock scale. Computer-based decision support tools have been widely used to build farm advisors’ capacity to understand the risks of N losses to the environment. However, existing tools often only provide an average annual risk of nitrogen loss from a paddock, even though nitrogen export is dependent on daily interactions between soil water content, water movement through deep drainage and runoff pathways and N availability. In this paper we present the design of a decision support tool for high rainfall cropping systems building on SafeGauge for Nutrients (developed for the sugarcane industry in Queensland, Australia). This tool (SG_Grains), allows users to define the system including location, cropping season, soil type and management decisions (e.g. fertiliser rate and timing, cultivation, stubble management). Information on management practices is combined with relevant modelled daily crop growth, soil water, drainage and runoff sourced from a library of simulation runs for various soil types and climates. Taking account of  N uptake and cycling, the daily nitrogen balance and risks of nitrogen losses via the various pathways are calculated. The risks are then modified to account for differences in slope and paddock position in the landscape. The results are presented as a risk gauge for all three loss pathways (runoff, leaching and denitrification), as well as a summary report on nitrogen input/output balance for the selected paddock. SG_Grains will be used as part of the training for advisors within the Fertcare Program, allowing the investigation of how management affects the risk of N export through various pathways.

Xinsheng NIU^a  Baojing GU^b  Xiaotang JU^c[1]

^a Qu Zhou Experimental Station, China Agricultural University, Quzhou 057250, PR China.

^b Department of Land Management, Zhejiang University, Hangzhou 310058, PR China.

^c College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, PR China.

Abstract

To find out the critical problems of reactive nitrogen (Nr) on township scale and ascertain Nr flows in basic agricultural farming unit, we carried out a research of Nr budget at the township scale in North China Plain (NCP). Results showed that chemical N fertilizer dominants the Nr imported into a town, which was concerning with complex economic, social and conventional issues. Low Nr using efficiency in cropland subsystem was found in ecotone of agriculture-animal husbandry due to natural condition dependent and meteorological changes adaptive crop. Environmental Nr loads mainly derived from cropland subsystem due to excessive N fertilizer application and irrational applying universally used in NCP. Thus, application rates of N fertilizer synchronized to demand of crop and alternatives of scientific and advanced application measurements were necessary. Huge losses of Nr during storage of human feaces and manure due to inaccessible to treatment facilities and ignoring the rational management on wastes should be given a priority consideration. The extension of new extensive technologies of livestock husbandry for achieving higher converting ratio of feed and provided with facilities of treating manure with great efforts seem necessity especially in ecotone of agriculture-animal husbandry.

Elizabeth A. Castner¹, Allison Leach², Beth McGee³, James N. Galloway⁴

¹ University of Virginia, Charlottesville, VA, 22903, www.N-print.org, eac6e@virginia.edu

² University of New Hampshire, Durham, NH

³Chesapeake Bay Foundation, Annapolis, MD

⁴ University of Virginia, Charlottesville, VA

Abstract

Nitrogen footprints provide an important link between the body of work concerning human alteration of the global nitrogen cycle and the actions that can be taken by individuals, institutions, and policy-makers. The nitrogen footprints calculated for institutions of higher education serve as a link between research, education, and management. The research component demonstrates which activities of the institution contribute most heavily to nitrogen pollution in the form of a data-intensive sustainability metric, which in turn is used to educate the community and promote management strategies that reduce the institution’s impact. Nitrogen footprints for individuals also serve as education and management tools, and can be applied in regions where nitrogen pollution has the most effect. A nitrogen footprint calculation tool for residents of the Chesapeake Bay watershed (USA) aims to teach users how their actions impact water quality in the bay and suggests actions that individuals can employ to reduce their impact. In both institutional and individual N footprints, the most important sector is food production. Broad changes in consumption patterns have the most potential for reduction. The Nitrogen Footprint Network addresses the needs of multiple communities at different scales, and data collected from novel footprint calculations for institutions and individuals informs how best to reduce their N pollution.

David Herridge¹

¹ School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, www.une.edu.au, david.herridge@une.edu.au

Abstract

Effective management of plant-available nitrogen (N) by farmers will generally have beneficial productivity, economic and environmental consequences. The reality is that farmers may be unsure of plant-avalable N levels in cropping soils at sowing and by necessity make decisions about how much fertiliser N to apply with limited information about soil N supply. NBudget is an excel-based decision-support (DS) tool developed to assist farmers/advisors in Australia’s northern grains region estimate (i) plant-available soil N and water levels pre-sowing, (ii) target yields, (iii) fertiliser N requirements for cereals and oilseed crops and (iv) N₂ fixation by legumes. NBudget does not rely on soil testing either for nitrate-N, organic carbon or water. Rather, the tool relies on rainfall data plus basic descriptions of soil texture and fertility, tillage practice, information about the previous two years paddock use plus rules-of-thumb values and stand-alone or linked algorithms. Winter and summer versions of NBudget cover the major crops of the region. Groundtruthing of NBudget against three independent data sets (n=55) indicated generally close agreement between measured and predicted values for sowing soil nitrate (r²=0.76). A limitation of the tool is that it does not account for denitrification losses of soil N. The usefulness of NBudget would be enhanced by transforming the current Excel-based tool to a stand-alone app or web-based tool.