Sensing Technology for Measuring Crop Nitrogen

Glenn J Fitzgerald1, Eileen M Perry2

1 Agriculture Victoria, 110 Natimuk Rd., Horsham, VIC, 3400,

2 Agriculture Victoria, Cnr. Midland Hwy and Taylor Street, Epsom VIC 3551


Quantitative remote sensing has advanced in its ability to measure plant and canopy parameters, with nitrogen being one of the principal components of interest for crop N management. A plethora of sensors and imagers including multispectral, hyperspectral and fluorescence with different characteristics (e.g., passive vs active) have provided researchers and the agricultural industry with choices for measurement. Platforms for mounting sensors range from handheld and tractor mounted to satellites and unmanned aerial vehicles (UAVs). How to quantify canopy N using these hardware tools with spectral indices has been the focus of research for some time. Examples of recent work integrating sensors, platforms and spectral indices will be presented for ground-based proximal fluorescence sensing and passive sensing using ground and aerial platforms.

Nitrogen inputs by rainfall, throughfall and stemflow in Brazilian semiarid

R. L. Deusdará1 2, M. C. Forti1, L. S. Borma1, R. S. C. Menezes3, J. R. S. Lima4, and J. P. H. B. Ometto1, E. R. Sousa-Neto1, K. Ribeiro1

1 Centro de Ciência do Sistema Terrestre – CCST, sala 5, 3º andar,  Instituto Nacional de Pesquisas Espaciais – INPE, Avenida dos Astronautas, 1758, 12227-010, São José dos Campos, SP, Brasil,


3 Departamento de Energia Nuclear – DEN, Universidade Federal de Pernambuco – UFPE, Av. Prof. Luiz Freire, 1000, 50740-540, Recife-PE, Brasil

4 Universidade Federal Rural de Pernambuco – UFRPE, Avenida Bom Pastor, s/n, Garanhuns – PE, 55292-270, Brasil


The aim of this study was to quantify nitrogen inputs by the rainfall, throughfall and stemflow, assessing the canopy role in the nitrogen transfers between atmosphere and soil in a rural tropical semiarid region in the Brazilian Caatinga. Samples were collected during two wet seasons, one during an extremely dry year (2012) and one during a year with normal rainfall (2013). The ionic concentrations of N-NH4+, N-NO3, dissolved organic nitrogen (DON) and dissolved total nitrogen (DTN) was 0.04 and 0.15, 0.07 and 0.10, 0.49 and 0.48, 0.61 and 0.73 mg l-1 in the rainfall for 2012 and 2013, respectively. The canopy enrichment for DON were 3 times for both wet seasons and for DTN were 3 and 2 times in relation to rainfall values for 2012 and 2013, respectively. There were no differences in N-NO3 between rainfall and throughfall. The enrichment for stemflow were 31, 8, 15 and 17 times for N-NH4+, N-NO3, DON and DTN for the wet season for 2013, respectively. We report a low bulk nitrogen deposition during both wet seasons and an estimative of about 2.05 kg N ha-1 ano-1. We estimated slightly lower annual inputs than previous global estimates, likely due to the low rainfall depths that occurred during the studied years and the lack of measured data for South America. Our findings contribute to the knowledge of nitrogen deposition in the northeastern Brazil by providing information for this poorly studied tropical and semiarid ecosystem.

The effect of defoliation severity during late autumn on herbage production, regrowth and nitrogen uptake of diverse pastures in Canterbury, New Zealand

Grace S. Cun*, Grant R. Edwards, Racheal H. Bryant

Faculty of Agriculture and Life Sciences, Lincoln University, Lincoln 7647, Christchurch

*Corresponding author email:


Pasture management strategies are sought to reduce nitrate leaching by enhancing nitrogen (N) uptake over the winter period. The objective of this study was to determine the effect of five post grazing heights on herbage production, and N uptake of a diverse pasture mixture containing perennial ryegrass, white clover, chicory, plantain, and lucerne during the late autumn/winter season. In late autumn, pastures were defoliated to five residual heights (20, 30, 40, 50, 60 mm), and herbage dry matter (DM) and N accumulated over a 112 d regrowth period was measured. Swards defoliated to 20, 30 and 40 mm accumulated more herbage above ground level (1884, 1508, 1322 kg DM/ha, respectively) than those defoliated to 60 mm (1289 kg DM/ha) over 112 days. Repeated measures analysis on herbage N concentration showed a significant interaction (P=0.012) of defoliation treatment with time. For the 20 mm defoliation, N concentration increased over time from 18.8 to 29.7 g N/kg while for the 60 mm defoliation, decreased from 26.1 to 24.9 g N/kg during the regrowth period. During this 112 d regrowth period, pastures defoliated to 20 mm accumulated more DM and more N than plots defoliated to 60 mm (56 vs. 32 kg N/ha, respectively). The results indicate grazing severely to post grazing heights <40 mm may improve growth and N uptake in the late autumn/winter.

Improving nitrogen use efficiency in subtropical dairy systems – A modelling approach using POAMA and DayCent

Martin Labadz1, Clemens Scheer1, David W. Rowlings1, Beverly Henry1, William Parton2, Peter Hayman3, Oscar Alves4, Griffith Young4 and Peter Grace1

1 Institute for Future Environments, Queensland University of Technology, 2 George Street, Brisbane QLD 4000, Australia

2 Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523, United States

3 Government of South Australia, SARDI, 2b Hartley Grove, Urrbrae SA 5064, Australia

4 Centre for Australian Weather and Climate Research, Melbourne, Victoria, Australia


The DayCent biogeochemical model was used to assess the applicability of POAMA-2 weather forecasts to assist dairy farmers in future nitrogen fertiliser decisions. Simulated soil mineral nitrogen, water-filled pore space, and biomass was calibrated and validated against field measurements from a dairy farm in subtropical Queensland, Australia, for the season 2012/2013 with a ryegrass/kikuyu rotation. DayCent was able to predict water movement in the soil profile, soil nitrogen dynamics and biomass production; however, there were some discrepancies between simulated and measured mineral nitrogen content in the soil and biomass production. This study showed that combining weather forecasts with biogeochemical models as a decision support tool for farmers to estimate mineralisation and assess N fertiliser demand is a promising approach to avoid excessive nitrogen application for dairy cropping systems. However, there are still shortcomings in an accurate simulation of soil nitrogen turnover and plant nitrogen uptake, in particular in highly fertilised systems such as the one presented here. More confidence in the accurate representation of the complex nitrogen transformation processes on dairy farms in biogeochemical models is necessary to use weather forecasts as fertiliser nitrogen decision support tool.

Substitutions of corn silage, alfalfa silage and corn grain in cow rations impact N use and N loss from dairy farms

Mark Powell1, C. Alan Rotz2, Peter A. Vadas1 and Kristan F. Reed1

1 USDA, Agricultural Research Service, US Dairy Forage Research Center, 1925 Linden Drive, Madison, Wisconsin 53711 USA,

2 USDA-Agricultural Research Service, Pasture Systems and Watershed Management Research Unit, University Park, Pennsylvania 16802 USA


Many dairy farms in the USA are growing and feeding more corn silage (CS) and less alfalfa silage (AS) to reduce feed costs. More corn grain (CG)-based concentrates are also being promoted to reduce enteric methane, a potent greenhouse gas. Whole farm simulations illustrate that growing more CS and less AS reduces the land requirement for feed production by approximately 27%, maintains milk production, increases animal N use efficiency (from 20 to 25%), and decreases manure N excretion (from 26.5 to 20.8 g N/kg milk). Growing more CS however, requires more fertilizer N (80 kg N/ha) and increases N losses (by 35 kg N/ha). Feeding more CG does not greatly impact milk production or animal N use efficiency, but requires about 40% more CG land area, more fertilizer N (23 kg N/ha), and increases nitrate leaching (by 10 kg N/ha). CS, AS and CG were labeled with stable isotope 15N and fed to mid-lactation dairy cows. Consumed 15N from AS and CS were distributed similarly into milk N and faecal N. Relatively more of the 15N contained in CG was transformed into milk N compared to 15N contained in AS and CS. After land application, more of the manure 15N from AS and CG was taken up by corn silage than manure 15N from CS. Trade-offs in N use and N loss need to be more fully considered when recommending more CS and CG in dairy cow rations.

Nitrogen budgets for lowland temperate beef and sheep grazing systems: The North Wyke Farm Platform

Tom Misselbrook1, Alison Carswell1, Graham McAuliffe1, Taro Takahashi1,2, Laura Cardenas1, Michael Lee1,2

1 Rothamsted Resesarch, North Wyke, Okehampton, Devon EX20 2SB, UK,;

2 University of Bristol, School of Veterinary Sciences, Langford, Somerset BS40 5DU, UK


The North Wyke Farm Platform comprises three 22 ha beef and sheep grazing ‘farmlets’ which are highly instrumented to monitor hydrology, weather, nutrient flows and productivity. Typical management for lowland UK grazing systems, based on permanent pasture, was applied to all three systems for an initial two-year baseline period. Following that, the platform has been progressively modified with the underlying principle being to improve the sustainability (economic, social and environmental) of two of the three farmlets, by reseeding of one with a grass-clover sward to drive production through nitrogen (N) fixation and one with a grass monoculture utilising the latest grass breeding advancements and higher yield potential. The third farmlet continued under permanent grassland. This paper presents the framework to be used in assessing the impacts of the reseeding period and to estimate system scale N budgets for the three systems. Data are being compiled with no results yet available, but will consist of a combination of measurements and modelled N pools and flows based on detailed management and production data. N use efficiency will be evaluated at the partial (forage production) and full (livestock product output) system level. A range of metrics expressing N flows on a product and land area basis will be derived. For a more complete understanding of the impacts of the system interventions and potential for future interventions to further improve NUE, further measurement data are required including N losses though denitrification, ammonia volatilisation and total N losses to water and N inputs through fixation.

Assessing three nitrogen use performance indicators for pig supply chains in East and Southeast Asia

Aimable Uwizeye1,2,3*, Pierre J. Gerber1,2, Rogier P.O. Schulte3, Imke J.M. de Boer1

1 Animal Production Systems group, Wageningen University, PO Box 338, 6700 AH, Wageningen, the Netherlands

2 Food and Agriculture Organization of the United Nations, Animal Production and Health Division, Viale delle Terme di Caracalla, 00153 Rome, Italy

3 Teagasc – Crops, Environment and Land Use Programme, Johnstown Castle, Wexford, Ireland


Pig supply chains are developing rapidly in East and Southeast Asia (ESEA), fuelled by population growth, growing incomes and urbanization that lead to increased demand for animal produce. Pig supply chains, however, are associated with losses of reactive nitrogen (Nr) to the environment at various stages of the chain. To benchmark livestock supply chains and identify improvement options, we previously developed a framework to assess Nr use efficiency at chain level. This framework compromises three indicators: life-cycle nitrogen use efficiency (life-cycle-NUEN), life-cycle net nitrogen balance (life-cycle-NNBN), and nitrogen hotspot index (NHIN). The aim of this study is to apply these three indicators to pig supply chains in ESEA. Preliminary results showed that the computed Life-cycle Nr use efficiency indicators vary greatly between backyard, intermediate and industrial supply chains. Industrial supply chains had relatively higher estimates of life-cycle-NUEN than intermediate and backyard supply chains. Our data showed a negative relationship between life-cycle-NNBN and NHIN demonstrating the presence of hotspots of Nr losses in backyard and intermediate supply chains, as compared to industrial supply chains. These differences between supply chains result from differences in the origin of feed material, feed conversion, manure management system and animal health status. This study demonstrates that there is a scope to improve the Nr use efficiency in pig supply chains in ESEA, especially by focusing on the optimization of fertilization of local feed crops and manure management systems. Further research is required to assess the potential effectiveness of each of these interventions.

Modelling nitrogen use efficiency by world pig production systems in 2050 under contrasting production and dietary scenarios

Luis Lassaletta1, Lex Bouwman1,2, Fernando Estellés3, Henk Westhoek1, Arthur Beusen1,2, Jonathan Doelman1, Salva Calvet2, Elke Stehfest1, Hans van Grinsven1.

1 PBL Netherlands Environmental Assessment Agency, 3720 A H Bilthoven, The Netherlands.

2 Department of Earth Sciences – Faculty of Geosciences, Utrecht University, PO Box 80021, 3508 TA Utrecht, The Netherlands

3 ICTA, Universitat Politécnica de Valencia, Camino de Vera s/n 46022, Valencia, Spain


In this study we model the global feed and land demand, nitrogen excretion and nitrogen use efficiency (NUE) for pig production systems in 2050 under different scenarios for pork demand, production performance and dietary composition. We developed a new pig module for the IMAGE integrated assessment model and we constructed a set of scenarios following the storylines of the Shared Socio-economic Pathways. Our model outcomes suggest that pig production systems will play a significant role in the global agro-food system in 2050 including protein supply, land demand and N fertilization. The sustainability of future pig production systems will strongly depend on the livestock production performances, feed rations and manure recycling efficiency. Scenario analysis suggest that the replacement of part of the soybeans by swill and industrial by-products in the feed ration of pigs is a promising solution to increase NUE as well as to reduce the land demand associated with pork production.

Strip planting decreases nitrogen fertilizer requirements while retention of more residue increases them in a rice-wheat-mungbean sequence on a subtropical floodplain soil

Md. Abdul Kader*1,2, Md.Jahiruddin1, Md.Rafiqul Islam1, Md.Enamul Haque1, Md. Sahed Hasan1,SutupaKarmaker1, Md. Mortuba Ali1, Richard Bell2

1Department of Soil Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh

2School of Veterinary and Life Sciences, Murdoch University, Murdoch, 6150 Australia


Conservation agriculture (CA) has not been well developed for intensively cultivated (2-3 crops yr-1) rice-based cropping systems which produce large amounts of crop residues annually. Thus, we examined the effects of two crop establishment systems (minimum soil disturbance by strip planting (SP) or conventional tillage (CT)), two residue retention levels (low and high) and five N rates (60, 80, 100, 120 & 140% of the recommended N fertilizer doses (RFD) on nine consecutive crops on an Aeric Haplaquept under rice-wheat-mungbean sequence. Rice yields were comparable between the crop establishment types but system yields were significantly higher with SP in two out of three years compare to CT. Increased residue retention did not significantly influence rice yield but positively influenced system yields. No substantial differences in optimum N rate was estimated between CT and SP for 90% of maximum yield goal (MYG) for all the three years but substantially decreased in SP compared to CT in two out of three years for 95 and 99% of MYG. The N fertilizer requirement was 6-22% higher with high residue retention compared to low residue retention plots for all the three yield goal levels. High residue retention also increased soil organic carbon (SOC) at 0-6 cm depth in both tillage treatments. In conclusion, introducing CA did not alter the N fertilizer requirements of rice for 90% of MYG but reduced the requirement for 95 and 99% of MYG compared to CT. However, there was evidence that the retained crop residue immobilized N and increased the fertilizer N requirement.

Contribution of nitrous oxide in life cycle greenhouse fas emissions of novel and conventional rice production technologies

Md. Khairul Alam1, Richard W. Bell1, Wahidul K. Biswas2

1 Land Management Group, School of Veterinary and Life Sciences, Murdoch University, Western Australia 6150, Australia

2 Sustainable Engineering Group, School of Civil and Mechanical Engineering, Curtin University, Bentley, Western Australia 6845, Australia


Nitrous oxide (N2O) production and emission under wetland rice (Oryza sativa L.) is difficult to predict due to the trade-off between methane (CH4) and N2O emissions for different establishment and management practices.  Any novel technology with the potential to reduce the emissions of both CH4 and N2O under wetland rice could make a significant contribution to total agricultural global warming mitigation. A streamlined life cycle assessment (LCA) approach to quantify the C footprint of rice production process in the Eastern Gangetic Plains (EGP) was adopted. The GHG emissions from one tonne of rice production were studied for the following cropping practices: a) conventional puddled transplanting with low residue retention (CTLR); b) conventional puddled transplanting with high residue retention (CTHR); c) unpuddled transplanting following strip tillage with low residue retention (UTLR) and; d) unpuddled transplanting with high residue retention (UTHR). Total pre–farm and on–farm emissions for 1 tonne of rice production amounted to 1.11, 1.19, 1.33 and 1.57 tonne CO2–eq for UTLR, UTHR, CTLR and CTHR, respectively, in the 100-year time horizon. For all four treatments, the predominant GHG emission was soil CH4 (comprising 60-67% of the total) followed by emission from on-farm machinery use. The UTLR was the most effective GHG mitigation option (it saved 29% of the total GHG emissions in comparison with CTHR) in wetland rice production. N2O emission contributed 2–3.5% to the total on–farm GHG emitted for rice production of which the lowest portion was shared by UTLR and UTHR. The UTLR reduced both CH4 and N2O emissions simultaneously. The novel minimum tillage establishment approach for rice followed by UT has potential to increase global warming mitigation of wetland rice in the EGP, but further research is needed to assess the contributions of N2O in the LCA of rice production in other similar rice growing areas.