Adaptive digital tools for nitrogen management: utilising remote sensing data, modelling and sparse ground truthing

Christine Lion1, Ben Jones1, Anastasiia Volkova1

1FluroSat Pty Ltd, 2-4 Cornwallis Street, Eveleigh, NSW, 2015, https://flurosat.com, hello@flurosat.com

Abstract

Remote sensing data can be used in conjunction with crop modelling and data analysis tools to estimate the crop canopy nitrogen status and provide up-to-date information to underpin in-season management decisions. In this study cereal tissue samples were calibrated against indices calculated from satellite imagery and used to generate nitrogen mapping models for wheat and barley at tillering (whole plant) and heading (youngest emerged blade) in South Australia. Crop type was not significant for whole plant samples at tillering (p>0.99) but was for youngest emerged blade at heading (p<0.001). Biomass dilution (related to NDVI/NDRE) was the main component of variation in tissue N% (91% of variance), and (apart from crop type, 75% of variance) the CCCI was the main remote sensing component related to youngest emerged blade N% at heading (17% of variance). The nitrogen maps allowed agronomists to test in some fields rather than all and to use a nitrogen map generated using the remote sensing data as a substitute. In conjunction with tools for management zone creation and nutrient prescription, the nitrogen maps were used to target nutrient application in-season with minimal effort on the agronomist’s behalf.

Biological amelioration of subsoil acidity via excess anion uptake by wheat

 Zhe (Han) Weng1, Peter Sale1, Guangdi Li2, Caixian Tang1

1Department of Animal, Plant & Soil Sciences, Centre for AgriBioscience, La Trobe University, Melbourne, Vic 3086, Australia, 2NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, PMB, Pine Gully Road, Wagga Wagga, NSW 2650, Australia, Corresponding authors: h.weng@latrobe.edu.au; c.tang@latrobe.edu.au

Abstract:

Excess anion uptake in the form of nitrate has been shown to reduce soil acidification at depth. This root-induced alkalization of rhizosphere soil can be extended to bulk soil. This study investigated ways to maximize the alkalinizing effect of calcium nitrate in reducing subsoil acidity in wheat (ET8) and canola (44Y90). A controlled environment experiment was carried out over 35 days. A Chromosol with topsoil (0-8 cm, pHCaCl2 5.4 and 1.5 mg Al kg-1) and subsurface soil (8-15 cm, pHCaCl2 4.8 and 2.9 mg Al kg-1) layers was used. The soil was reconstructed as 0-10 cm topsoil and 10-50 cm subsurface soil in columns (15 cm in diameter, 60 cm in height). Air-dried soils (<2 mm) were treated with three N fertilizers: 1) control, 2) urea and 3) Ca(NO3)2 with and without phosphorus fertilizer at three depths: 1) 0-10 cm, 2) 10-20 cm and 3) 20-30 cm. All N and P fertilizers were applied at 134 kg N ha-1 and 56 kg P ha-1 at sowing. Uptake of Ca(NO3)2 increased pH up to 0.2 units of bulk soil in the 0-10 cm layer compared with the urea application regardless of the placement of the treatments. Rhizosphere alkalization was greater at the depth where nitrate and P were combined compared with those with the urea treatment. We highlighted the importance of balancing nutrient supply at depth in encouraging anion uptake by plants, which enhances rhizosphere alkalization in acid subsoil.

 

Nitrogen fluxes in dairy farm soils in response to fertilizer or “urine”

Michael W. Heaven1, Craig Beverly2, Cameron Gourley1, Jenny Collins1, Sharon Aarons1, Michael Adelana3, Thabo Thayalakumaran3, Evan Dresel4

1 Agriculture Victoria, Department of Jobs, Precincts and Regions (DJPR), 1301 Hazeldean Road, Ellinbank, Victoria, 3821, https://intranet.djpr.vic.gov.au/, Michael.heaven@ecodev.vic.gov.au, 
2 Agriculture Victoria, DJPR, 124 Chiltern Valley Rd, Rutherglen, Victoria, 3685,
3 Agriculture Victoria, DJPR, 5 Ring Rd, Bundoora, Victoria, 3086,
4 Agriculture Victoria, DJPR, Midland Hwy, Epsom Victoria 3551 Epsom, 3685

Abstract:

Eutrophication in the Victorian Gippsland Lakes has been linked to agricultural nitrogen (N) inputs and their potential contribution to leaching losses. Quantifying N fluxes through dairy soils will indicate the importance of leaching to N losses in these systems. Movement of N through the soil profile of a dairy farm in the Gippsland, Victoria, was investigated over a 24-month period. Urine treatments resulted in sizeable yield responses with ~100% increase in pasture dry matter yields above control treatments at first harvest after urine application. Pasture response continued up to four more harvests with N uptake from 19-47%. Fertiliser resulted in almost negligible N leached. The implication of this research is that cow urine is a larger determinant than fertiliser use of N lost from farms.

 

A guidance document for agronomic best practice soil sampling in Australia

Cameron Gourley1,2, David Weaver 3 and Jeff Kraak4

1 Agriculture Research Victoria, Department of Economic Development, Jobs, Transport and Resources, Ellinbank, VIC 3821;
2 School of Chemistry, Monash University, Clayton, VIC 3800;
3 Department of Primary Industries and Regional Development, 444 Albany Hwy, Albany WA 6330;
4 Fertilizer Australia, 40 Macquarie Street, Barton ACT, 2600.

Abstract

Fertiliser recommendations for agriculture should be supported by soil analysis and interpretation, the basis of which is underpinned by collected field samples which accurately represent the plant root environment, and calibration experiments. Field variability of soil characteristics can exist horizontally and vertically, with induced soil nutrient variations caused by animal management, tillage, drainage, crop removal and fertiliser and ameliorant inputs. Vertical variation can be associated with natural or induced soil horizon differences, nutrient mobility, waterlogging, mechanical disruption and nutrient placement. A third dimension of variation is that of temporal change; between years, between seasons or even more rapidly from applied fertiliser or animal manure. Agricultural practices such as minimal tillage, deep soil amendment, row cropping, raised beds, precision fertiliser and ameliorant placement, and variable rate applications, can all impact on soil conditions and nutrient availability within the root zone. Nutrient additions may involve organic, liquid and granular forms. Technological advances now allow for immediate and easy access to site-specific aerial and satellite imagery, capture of geo-coordinates, real-time access and upload of field and meta-data. Sampling equipment continues to advance with the availability of power-driven sampling tools, reducing labour requirements so more samples can be taken and enabling deeper soil profile sampling. The purpose of this paper is to introduce the new Fertcare® soil sampling guidance document which describes ‘fit for purpose’ soil sampling approaches with the aim of improving consistency and accuracy of on-farm in soil sampling.

Effect of co-application of phosphorus and potassium fertilisers on phosphorus uptake by Mungbeans

Kyin Kyin Htwe1, Chris Guppy1, Richard Flavel1, Graeme Blair1

1 Agronomy and Soil Science, University of New England, Armidale NSW, Australia, gblair@une.edu.au

Abstract:

Deep placement of phosphorus (P) has been shown to increase the effectiveness of fertiliser application in soils with a long cropping history. This cropping history has also often depleted potassium (K) reserves. Research on co-application of phosphorus and potassium has produces variable results. Factors contributing to these variable results such as placement, pH, and K source have been investigated in a glasshouse trial. 32P labelled P fertiliser was applied alone or mixed with four K sources (nitrate, chloride, sulfate, potassium phosphate) to test if the anion associated with K affected P and K uptake by mungbeans [Vigna radiata (L.) Wilczek]. There was no significant difference between treatments in fertiliser P recovery with either surface or deep placement. The only significant effect was higher shoot and root yield and higher fertiliser P and K recovery in most treatments compared with the zero K treatment with the highest values in the P+K2SO4 surface treatment. This increased uptake was not attributable to increased root growth in the fertiliser band or to a difference in band or rhizosphere pH as these were not significantly different in this treatment from the other K source treatments.

 

The effectiveness of alternative sources of fertiliser sulfur for plants

Nguyen Tien Hai1, Graeme Blair2, Chris Guppy2 and Michael Faint2

 1 Institute of Agricultural Sciences for Southern Vietnam, Ho Chi Minh City, Vietnam,
2 Agronomy and Soil Science, University of New England, Armidale NSW, Australia. gblair@une.edu.au

Abstract

Sulfur (S) can be added to fertiliser either during, or post manufacture of the primary fertiliser. The easiest way to add S is as prills of elemental S/bentonite. Several processes are available to prepare these and the question arises as to their effectiveness in supplying S to plants.

This was evaluated using a range of commercially available products and comparing the S release rate from them with that from mono-ammonium phosphate (MAP) coated with both elemental and sulfate S, and from sulfate S from double superphosphate either alone or supplemented with S/bentonite prills. The results show that no form of uncrushed S/bentonite tested could supply S to plants in the short term. Crushing the prill resulted in a 10-fold increase in apparent fertiliser S recovery by the plant. Adding S/bentonite to double superphosphate resulted in an approximate 5% recovery of the added S.Coating or a mixture of elemental and sulfate S on the surface of the MAP granule was agronomically acceptable.

More Profit from Nitrogen Program: delivering cross-sector collaboration in NUE research

M.White1, A.Williams2, C.Phelps3, F.Driver4, B.de Kock5

1 ICD Project Services, 13 Flannel Flower Fairway, Shoal Bay, NSW, 2315, www.crdc.com.au/more-profit-nitrogen, mwhite@icdprojectservices.com.au 2 Cotton Research and Development Corporation, 2 Lloyd St, Narrabri NSW 2390, www.crdc.com.au , allan.williams@crdc.com.au3 Dairy Australia Ltd, 40 City Rd, Southbank, VIC 3006, www.dairyasutralia.com.au, CPhelps@dairyaustralia.com.au, 4 Sugar Research Australia, 50 Meiers Rd, Indooroopilly QLD 4068, www.sugarresearch.com.au, fDriver@sugarresearch.com.au, 5Hort Innovation Australia Ltd, 606 St Kilda Rd, Melbourne VIC 3004, www.horticulture.com.au, Byron.deKock@horticulture.com.au 

Abstract

The More Profit from Nitrogen Program (MPfN) is a four year partnership between Australia’s four most intensive users of nitrogenous fertilisers:  cotton, dairy, sugar and horticulture. The Program is conducting research and development to the increase nitrogen use efficiency (NUE) across the four sectors whilst improving profitable and sustainable use. By better understanding the influence of contributing factors on NUE in farming systems, the Program is:

  • Generating greater knowledge and understanding of the interplay of factors to optimise N formulation, rate and timing across industries, farming regions and irrigated/ non-irrigated situations;
  • Generating greater knowledge and understanding of the contribution (quantifying rate and timing) of mineralisation to crop or pasture N budgets; and
  • Generating greater knowledge and understanding of how enhanced efficiency fertiliser (EEF) formulations can better match a crop or pasture specific N requirements.

The Program is supported by $5.889 million funding from the Australian Government’s Rural Research and Development (R&D) for Profit program in addition to cash and in-kind contributions from each of the industry sectors, research organisations and collaborating partners equating to $9.757 million.

The MPfN Program is at the mid-way point of research activities but is already resulting in a more collaborative research effort to accelerate aligned research methodology, standardising terminology to reduce confusion for industry end users and communicating NUE outcomes using common indicators across the four industry sectors. MPfN is a proactive collaboration formed to expedite NUE across Australia’s intensive cropping and grazing industries to reduce environmental impact and increase the long-term sustainability of Australian farming businesses by increasing yield, product quality and overall profitability.

Understanding the amelioration processes of the subsoil application of amendments

Iman Tahmasbian1 2, Zhe H. Weng1, Yunying Fang3, Graeme Poile1, Albert Oates1, Shihab Uddin1, Binbin Xu1, Graeme Sandral1, Roger Armstrong4, Ehsan Tavakkoli1 2*

1New South Wales Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, NSW, 2650,
2Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW,  2650,
3NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle NSW, 2568, Australia,
4Agriculture Victoria Research, Department of Jobs, Precincts and Regions, Horsham, VIC, 3400

* Corresponding author: ehsan.tavakkoli@dpi.nsw.gov.au

Abstract:

A series of field and incubation experiments were conducted to address the amelioration process of physicochemical constraints of alkaline sodic dispersive subsoils. A range of organic and inorganic amendments were applied in the top and subsoils with the plots sown to barley and wheat in 2017 and 2018, respectively. The initial results indicated that deep application of combined organic and inorganic amendments resulted in significantly improved soil physicochemical properties and increased yield in the two consecutive years. The deep application of gypsum and organic amendments reduced the soil pH and exchangeable sodium percentage (ESP) and improved soil aggregate stability, addressing both chemical and physical constraints. The results indicated that amendments and strategies with different mode of actions are required for improving soils with multiple physicochemical constraints.

Host

The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

Photo Credits

David Marland Photography david_marland@hotmail.com Graham Centre for Agricultural Innovation, Charles Sturt University

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