10 Sep 2018

DPIRD soil nutrition project underway

The Department of Primary Industries and Regional Development (DPIRD) is leading the ‘Nutrient re-distribution and availability in ameliorated and cultivated soils in the Western Region’ project, announced earlier this year by the Grains Research and Development Corporation, which was also discussed in last quarters SoilsWest newsletter. The Department is also working with the University of Western Australia (UWA), Curtin University, Murdoch University, CSIRO and MapIQ to deliver the project. The field trials for this project are now underway at various sites across the state. The feature image shows DPIRD research officer Dr Craig Scanlan and a delegation of Australia’s leading soil scientists discussing the trial at Meckering.

Department plant nutritionist Dr. Craig Scanlan said “that the field trials established this year would help researchers gain a better understanding of the long-term effect of rotary spading and deep ripping on soil nutrient availability and the impact on yield responses to fertiliser. Specifically, the trial at Meckering will provide us with a better understanding of how deep ripping changes the yield response to nitrogen (N) applied this year and if it has any impact on the residual benefit of this N in 2019”.

Dr. Scanlan also advised “that another trial established at the department’s Badgingarra Research Facility has been designed to measure the effect of the type of crop residue buried by inversion tillage in 2019 on the grain yield response to nitrogen fertiliser. Further paddock scale wheat trials have also been set up this season to gain an insight into how the yield response to potassium (K) fertiliser varies spatially on ameliorated soils”.

The trials at Mingenew, Meckering and Esperance are being undertaken on paddocks where Controlled Traffic Farming (CTF) is being used. These paddocks are like massive field trials, where CTF is being used to accurately place the fertiliser treatments and measure the corresponding yield data.

Stephen Davies?

Image: Crop sown using precision guidance into previous stubble (Stephen Davies, DPIRD)

The variation in the yield response to the potassium treatments across the paddocks will be used to target areas for soil sampling, to investigate which soil factors are influencing the yield response to K fertiliser on ameliorated soils. As a result of this work, the department will be able to provide some guidance on how growers should be doing their soil testing on ameliorated soils.

The department’s research complements two other projects, one led by UWA on increasing profits from fertiliser inputs in a range of emerging crop sequences and the other by the CSIRO to improve soil sampling methods to better predict soil nutrient availability and supply. Together, the research projects will quantify how yield response to fertilisers in ameliorated soils compared to current no-till practice. The outcomes of this work will be used to update existing decision support systems for fertiliser use. For more information on the research work contact Dr Craig Scanlan.

25 May 2018

Increasing water use efficiency, grain yield and profit in a no-till system (Western Australia)

Conservation agriculture (no-till) cropping systems is considered by many to have improved soil health, timeliness of sowing, moisture conservation and resulted in higher grain yields. The key components of this system are full crop residue (stubble) retention, diverse rotations and minimal soil disturbance. However the recommendation for full residue retention is sometimes seen as a major constraint to the adoption of no-till, and increasingly the use of tillage to combat herbicide resistant weeds or non-wetting is employed by growers.

Dr Ken Flower (The University of Western Australia), in partnership with the Western Australian No-Tillage Farmers Association (WANTFA) and CSIRO, leads a long term research site established in 2006 at Cunderdin on an alkaline red sandy clay loam. The experiment which has co-investment from the Grains Research and Development Corporation (GRDC) aimed to determine the long term benefits of the key components of conservation agriculture and has shown that significant amounts of residue can build up through the removal of livestock from the system and no removal or burning of stubble. Using four different cropping philosophies i) cereal rotation, ii) diverse rotation, iii) control (monoculture wheat) and iv) ‘farmer’ rotation (cereal, cereal, break crop or fallow), a total of 11 crop sequences were established; and from 2010 a subset of plots had residue retained and spread behind harvester or were wind-rowed behind the harvester and burned, to consider the impact of stubble load on production.

Wind-rowing and burning were effective at decreasing residue levels by 40 to 60 per cent, with a variable influence on grain yield observed depending on crop residue type and amount. When there was relatively little cereal residue present after harvest (less than about 3 t/ha), retaining all the residue resulted in yield gains compared to where residues were reduced by wind-row burning; whereas, the opposite was true under greater stubble loads with higher yields from windrow burning.  By contrast, the effect of windrow burning of canola residue on the following wheat yield was small regardless of high residue levels.

Continuous wheat and the cereal rotation had the highest cumulative nine year average gross margins, despite higher grain protein and improving yields under a more diverse rotation. Lower gross margins in the diverse rotation were associated with poor legume performance in many years and low canola yields in dry seasons. Improving the reliability of these break crops in this growing environment is the key to increasing their uptake by farmers. Cover crops in the rotation generally negatively impacted gross margins.

At this relatively low rainfall site, with Mediterranean-type conditions, in south-western Western Australia, highest profitability came from having moderate residue amounts, in a rotation dominated by cereals and not including cover crops. The experiment will continue to inform longer term outcomes for production, weeds diseases and soil health. A recent publication can be found here. For further information please contact Dr Ken Flower ([email protected]).

Image: Burnt windrow after Canola. Image attribution: Ken Flower, University of Western Australia

25 May 2018

Accessing Online Farm Trials Information

The Online Farm Trials (OFT) portal was initiated in 2013 as a co-investment between Federation University Australia (FedUni) and the Grains Research and Development Corporation (GRDC). The purpose of OFT is make the results of grains industry research trials and demonstration trials much more discoverable and publically assessable. The OFT team is led by FedUni Senior Research Fellow Dr Nathan Robinson and includes both social scientists and a great team of web developers at the Centre for Research and Digital Innovation (CERDI) at FedUni in Ballarat, Victoria. Main Image-The OFT team: Paul Freely, Julie Parker, Dr Ben Wills, Andrew Macleod, Dr Nathan Robinson

The primary function of the OFT tool is to maximise enduring profitability of the Australian grains industry by providing easy and ongoing access to grains related field trials research from across Australia. This is achieved via a publicly accessible, searchable and simple to use online database, supported by contributions from a wide range of collaborators and partnerships. Trials information contained in OFT includes both new and legacy trials, a significant portion of which have been funded by GRDC.

While to date key users of OFT have tended to be researchers and providers of agronomic advice, OFT now also provides collections of seasonally relevant trials aimed directly at growers.

The website features a self-service module which allows research organisations or individuals to upload and manage their data. An important aspect of this tool, is that the data ownership and accessibility is maintained by the contributor. Dr Robinson said that “one of the important features of the project is that control of the data stays with the data contributor, they can edit and remove data if they wish, they even have the ability to embargo the publication of data”.

Currently the portal hosts information on over 6600 trials, 85 per cent of which are publicly accessible. Data contributors to date include individuals, grower groups, farming systems groups, state government and private research providers, and universities.

Data can be extracted from the system in two primary forms. Either as a downloadable PDF copy of the research report, or additionally in some instances, numerical research data which allows for a graphical comparison between multiple trials. A key consideration going forward is data quality and comparability, and ensuring users of the system continue to access the maximum number of trials, while also being able to make informed decisions about the statistical robustness of any given trial and its suitability for their needs.

Image: Professor David Lamb from the Precision Agriculture Research Group at the University of New England using Online Farm Trials

 

 

 

 

 

 

To aid this continued development an expert advisory group has been convened, and includes representatives from a range of stakeholder groups, including; farmers, agronomists, university and public sector researchers, research managers and the GRDC. The panel is focusing on how to add value, including via the development of tools and functionality for currently active trials which will reduce the double handling of data. Additional planned developments include easy to understand data quality indicators to ensure that users of the portal are able to make informed decisions based on in-depth knowledge of the data quality characteristics of the research.

Organisations also have the opportunity to download an OFT ‘widget’, which is essentially a mini version of the OFT search engine, that can be embedded in other websites. The full OFT website can be accessed at www.farmtrials.com.au; and an example of the OFT widget can be viewed on the Soilswest website.

For more information about this project contact Dr Ben Wills ([email protected])

Image Attribution: Ms Julie Parker (CeRDi)

25 May 2018

Potassium nutrition on frost resistance in cereal crops

The role of potassium (K) in protecting crops from damage due to frosts has been alluded to for many years and has been mentioned in plant nutrition textbooks. In studies on other plant types (e.g. potatoes, carnations) potassium has been shown to mitigate potential plant damage from frost events. However little is known about the effect that various concentrations of potassium have in mitigating deleterious effects on plant sterility and yield for cereal crops in Western Australia, apart from some anecdotal reports that frost damage is greater for wheat grown in low potassium soils.

Potassium is critical for optimal plant growth from early establishment through to grain development. Regulating the opening and closing of leaf stomata during photosynthesis, potassium supply influences plant responses to both light and the uptake of carbon dioxide. The regulation of both water loss via the stomata and water uptake by the roots, means potassium also has a role in water management in the plant. Potassium also contributes to the synthesis of both protein and starch in the grain, which influence grain filling and quality.

Research by Murdoch University’s Dr Richard Bell and Dr Qifu Ma has recently been published identifying how potassium application could potentially alleviate floret sterility and loss of yield in wheat in Western Australia (Ma et al. 2018). The study was conducted to determine the impact of frost events on a cereal crop using the wheat cultivar Mace, with various applied potassium levels, on floret sterility and yield over two different growing seasons (2015 and 2016) at two different locations (Aldersyde and Beverley). The potassium treatments in 2015 were nil and 80 kg K/ha, in 2016 they were nil, 20, 40 and 80 kg K/ha. Frost events were determined to have occurred if air temperatures below 0°C were measured in the plant canopy or below 2°C measured by the onsite weather station. Frost events between July and October occurred on 24 days during 2015 and on 54 days during 2016.

Changes in frost susceptibility by potassium supply were measured and evaluated in terms of floret sterility, percentage reduction in grain numbers, anti-oxidative activity, net photosynthesis, leaf potassium concentrations, plant growth and grain yield. Yield results suggest that while improved plant potassium status can increase grain yield by between 10-20 per cent in wheat exposed to minor or moderate frost events (canopy temperature at 0 to -3 °C), there was no observed yield response under severe frost events (-4 to -6 °C). For more information or a copy of the paper “Potassium application alleviates grain sterility and increases yield of wheat (Triticum aestivum) in frost-prone Mediterranean-type climate” please contact Dr Richard Bell ([email protected]).

Image: Wheat heads with symptomatic signs of frost. Provided by Richard Bell, Murdoch University.

25 May 2018

Nitrogen

The University of Western Australia (UWA) and Department of Primary Industries and Regional Development (DPIRD) have recently partnered in a Grains Research and Development Corporation (GRDC) co-investment with organisations from both the public and private sectors, to provide updated information on soil nutrient supply to Western Australian growers’ to improve profitability through more efficient nutrient use.

One node of the nutrient investment program led by Professor Daniel Murphy (UWA) has nitrogen (N) as its focal point. It will focus on understanding soil processes and how the timing and supply of soil N can be matched to various fertiliser strategies to provide the potential for the best return on investment from nitrogen fertiliser.

Professor Murphy said that “Water and N interactions are major drivers for plant growth and grain yield. Nitrogen is also a primary constituent of wheat protein, so sufficient soil N is an essential ingredient in meeting quality aspects of specific wheat grades” The uptake of N, is a factor influencing both early plant growth and yield potential, and later on in the growing cycling a remobilisation of N into the grain of the wheat affects final protein content.

Plants require more N than any other nutrient. The majority of N in soil originates from commercial fertilisers, soil organic matter, crop residues and animal manures. The release of mineral N from decomposition of organic matter is a significant source of N for grain crops in Australia. Although N can be added to soil in either inorganic or organic forms, plants take up only inorganic N and the other forms must be transformed prior to use. Nitrogen can be lost from the soil due to a number of processes and these include denitrification, volatilisation, leaching, crop removal and soil erosion/runoff.

With increasing climate variability and changes to growers’ cropping programs, the decision to determine when and where to apply N and at what rate has become more complex.  Growers’ N requirements are dependent on a number of major factors and include rainfall patterns as they unfold through the year, soil N supply, residual fertiliser N, logistics, and if economics are included, the price of N and the price of grain.

New research will focus on the residual benefit of organic and inorganic N on the following crop, with a focus on decision points for N management. It will investigate which components of the N cycle require a better understanding to improve the prediction of fertiliser N requirements. A component of the work will include using a stable isotope (15N; Nitrogen-15) technique to quantify specific N pathways in the soil.

Insights will be obtained via a series of laboratory, glasshouse and field experiments that investigate the N cycle, the impact of specific processes on plant available N supply, grain yield and profit response to fertiliser N. For example, there is considerable uncertainty about the rate of N required because yield potential is unknown at the time of planting and varies significantly within and across seasons due to soil and organic supply versus consumption. Soil mineral N can make up a large component of N supply to the crop; however, to our knowledge, there is no information on how wheat, barley and canola respond to different levels of soil mineral N at the same site.

Field experiments will determine whether wheat, barley and canola crops can effectively utilise soil derived N and examine crop specific responses to soil mineral N concentrations. Additional field experiments will also be undertaken to quantify the residual effects of crop sequence on the yield response to fertiliser N application. Identifying rotational sequences and management strategies that result in a run-down, steady-state or build-up of soil N will help in determining appropriate strategies to sustain productivity without running down the ‘bank’.

Data will be used to determine if refinements to the “Select Your Nitrogen” (SYN) model are required and the parameters for SYN optimised for data from current cropping systems, to provide a basis for economic analysis.

For more information contact Daniel Murphy (UWA, [email protected]) or Craig Scanlan (DPIRD, [email protected])

Photo:Daniel Murphy et al.; Image Attribution: UWA

Resources: 

http://soilquality.org.au/factsheets/soil-nitrogen-supply

http://soilquality.org.au/factsheets/mineral-nitrogen

         

04 Apr 2018

Phosphorus

The University of Western Australia’s Professor Zed Rengel leads new research in soil phosphorus (P) supply as part of the new co-investment targeting better nutrient use efficiency. As fertiliser costs are one of the highest variable costs for grain producers in WA, and with changes in climate and farming systems in recent years, the scientific knowledge that underpins these P fertiliser management decisions needs to be updated.

Phosphorus is an essential element in several key plant structural compounds and is part of numerous enzymes. In grain crops, good P acquisition results in improved growth and development, increased resistance to plant diseases, stem strength, earlier crop maturity, enhanced flowering and seed production, and is also linked to increases in grain quality.

As with the other nutrients of interest, factors which influence the availability of P in soil includefertiliser application and crop removal, climate conditions and soil type. The amount of available P is determined by many specific factors including soil pH, iron and aluminium content, availability of other nutrients, clay content and type of clay, organic matter, soil temperature, soil aeration, soil moisture, soil compaction and also timing and placement of fertiliser application.

Soil P has accumulated across much of WA agricultural region, with a recent survey showing a large percentage of soils with soil P levels above the critical concentration that allows for 90% of maximum production to be achieved. With current fertiliser decisions being based on the premise of P deficiency, it is clear that P fertiliser management in local soils must change, but the current body of knowledge needed to implement this change is inadequate. In soils with sufficient P for example, Prof Rengel asks “How long can people farm with current drawdown rates of P and how does the rate of drawdown vary across soil types and under different cropping systems? These are some of the key questions that require answers”.

Together with industry partners CSBP and Summit who each contribute experimental sites to this project, the Department of Primary Industries and Regional Development and the University of Adelaide, future experiments will focus on identified research gaps as outlined.

  • Primer P – The seed has its own store of P but may benefit from an additional small priming application of P to increase root and shoot establishment and plant vigour. How much extra P (the primer amount) is required to assist the plant to achieve this optimally will be determined for wheat, canola and narrow-leaf lupins on soils that would historically have been considered P sufficient. Prof Mike McLaughlin (University of Adelaide) will co-supervise a PhD student that will undertake some of this work using P isotopes.
  • Drawdown – A certain amount of P, the drawdown quantity, is removed from the soil following harvest. The aim of this work will be to determine the amount of drawdown that occurs across a number of field sites over four seasons, allowing for different soil types, application rates of P and varying climate patterns. Determination of P drawdown rates can then inform the industry about the amount of P required annually to keep soil above the critical P threshold for that soil.
  • Subsoil P deficiency – Data suggest a large difference between the P content in the upper soil zone (0 to 10 cm) than deeper (below 10 cm) in the profile. In a large number of cases there is sufficient P in surface soil but a deficit in deeper layers. This is of particular interest because of changes to management practices where farmers are now mechanically mixing the soil via deep ripping, inclusion plates and spading for example. Quantifying the location and amount of P re-distributed down the profile will be one of many aspects considered in this project.

Knowledge gained from these programs will be used to communicate to the grains industry changes in nutrient management strategies and modelling of the economic responses to any new P management strategies undertaken to update nutrient decision guidelines. For more information contact Zed Rengel ([email protected]).

Photo:Zed Rengel (Image supplied by Zed Rengel)

resources :http://www.cropnutrition.com

04 Apr 2018

Economics

Providing updated information to improve WA grower profitability through more efficient nutrient use for nitrogen (N), phosphorous (P) and potassium (K) is a primary outcome for a recent co-investment between the Grains Research and Development Corporation (GRDC) and partnering organisations the Department of Primary Industries and Regional Development, University of Western Australia, Murdoch University and private sector partners.

Dr Craig Scanlan of the Department of Primary Industries and Regional Development leads the nutrient project, with Dr Elizabeth Petersen (UWA adjunct) and Dr Fiona Evans (Murdoch) undertaking the economic and sensitivity analyses for the project and working with research partners to update model parameters. At the outset of this comprehensive investigation, stage one of the economic analyses and reporting will be completed by the end of this year and will focus on N.

To determine the most economically viable N application rates for a specific farm or paddock (depending on the scale of interest), an economic model is usually used that includes information on how responsive a site may be to fertiliser application. Suggested fertiliser application rates are determined based on a number of parameters and inputs, and can be dependent on which model is being used. A component of this project is to review and benchmark the performance of “Select Your Nitrogen” (SYN) by comparing predicted versus actual yield as well as grain quality (e.g. protein, oil) response where appropriate for a variety of crop types including barley, canola, lupins and wheat in recent, current or proposed field experiments.

Under investigation will be the sensitivity of model inputs and parameters on the numerical output of the model (the economically optimal rate of N), as well as the uncertainty (error) of the model inputs and how this also affects the output of the model.

Dr Petersen explains that “With increasing climate variability and changing sowing patterns, a grower’s decision regarding when to apply N and at what rate is becoming more complex. Nitrogen requirements depend on rainfall patterns as they unfold through the year, soil N supply, residue N, the price of N and the price of grain. Our research will be considering what factors most effect the economically optimal rate of nitrogen to help prioritise future research work into components of the N cycle.”

Ultimately the goal is to quantify the overall precision of the model, so that the model output is accurate to achieve profit targets for growers. For example, 90% probability of exceeding a return on investment of greater than 2:1.

Photo: Liz Petersen; Image attribution: Bruce Petersen

      

04 Apr 2018

GRDC Perspective-Nutrition Investment Program

 

With $8.3 million invested from the Grains Research and Development Corporation (GRDC) and partnering co-investments equivalent to $6.2 million from the Department of Primary Industries and Regional Development (DPIRD), The University of Western Australia (UWA), CSIRO, Murdoch University, CSBP, Summit Fertilizers, The University of Adelaide (UA) and grower groups; a program of work in soil and crop nutrition that is largely unprecedented in Western Australia (WA) in terms of scale and the level of collaboration between government, grains industry stakeholders and a number of Universities is now underway.

This new investment into WA soils and crop nutrition research had gained momentum in response to grower and advisor feedback that had been gathered through extensive GRDC consultation which included the Western Regional Panel and Regional Cropping Solutions Network (RCSN) groups. The goal of the largest of the three soils and nutrition projects, worth a total of $9.7 million over five years and led by UWA (UWA adjunct Dr Craig Scanlan, DPIRD) through the SoilsWest Alliance (Assoc. Prof Fran Hoyle, Director), is to provide updated information to improve WA grower profitability through more efficient nutrient use.

A highly experienced cross-section of industry partners including scientists, agribusiness, farmers, sampling and analytical specialists will allow the project to draw on the wide range of skills and scientific knowledge available within this group, with a focus on providing knowledge that underpins more profitable nutrient management. The research aims to improve knowledge about nitrogen cycling and availability (Prof Daniel Murphy, UWA), soil phosphorus (Prof Zed Rengel, UWA) and potassium (Prof Richard Bell, Murdoch). Experimental work will consider nutrient storage, sources of nutrient supply, responsiveness of crops and the economics of application, with an overall emphasis on providing better understanding of soil supply and fertiliser requirements to meet plant demand. Quantifying soil nitrogen supply for example is crucial for grain growers, given it affects the rate of nitrogen fertiliser required and is one of the few in-season management strategies available to improve returns. Industry partners are contributing an extensive geographical spread of field experiments that will help build a knowledge base of the response of crops to phosphorus fertilser application in current farming systems.

Worth a total of $3.5 million over four years, a second project focuses on soil amelioration and is led by DPIRD (Dr Craig Scanlan) under the SoilsWest alliance in cooperation with The University of Western Australia, Curtin and Murdoch Universities, CSIRO and industry. This investment will improve understanding about how ameliorating soil constraints with strategic tillage changes the availability of nutrients in the soil, the duration of the effects and the implications for fertiliser requirements. Increasingly, grain producers in WA are ameliorating constrained soils with mouldboard ploughing, deep ripping, rotary spading and delving, while to date the effects of ameliorating soil constraints on soil nutrient availability (and thus implications for optimised fertiliser strategies) has seldom been measured.

The third investment ($1.4 million over three years) led by Dr Phil Ward (CSIRO) working in collaboration with the other project teams, is focussed on reviewing existing soil sampling methods to find the best options for accurately estimating crop available soil nutrients as well as soil acidity. A review of the variability of nutrients at different spatial scales such as within different zones, on and off-row, or at different depths is needed to better design nutrient management strategies to optimise profitability and decrease inefficiencies.

Dr Rowan Maddern, Manager for the GRDC’s Agronomy, Soils and Farming Systems West says that “knowledge stemming from these GRDC co-investments will help in the development of updated soil testing methods, refined crop response information, improved fertiliser predictions and sustainable grower profits”.

 

 

Photo (from back left) Daniel Murphy1, Qifu Ma2, Richard bell2, Zed Rengel1, Mark Gherardi3, Raj Malik, Eddy Pol3, Rowan Maddern4, Andreas Neuhaus5, James Easton5, Craig Scanlan6, Fiona Evans7, Frances Hoyle1, Yoshi Sawada1, Phil Ward8

1UWA, 2Murdoch, 3Summit Fertilizers, 4GRDC, 5CSBP, 6DPIRD, 7Curtin, 8CSIRO

resources: https://grdc.com.au/news-and-media/news-and-media-releases/west/2018/02/collaboration-to-drive-new-crop-nutrition-research

04 Apr 2018

Potassium

Fertilisers are one of the highest variable costs for grain producers in Western Australia (WA). Due to changes in climate and farming systems in recent years, the current scientific knowledge that drives potassium (K) fertiliser management decisions needs to be updated. Upon completion of this research, the updated knowledge will allow for more cost effective decisions going forward.

Murdoch University is a partner in a Grains Research and Development Corporation (GRDC) co-investment with other organisations from both the public and private sectors, researching soil K supply to improve profitability for Western Australian grain growers’ through more efficient nutrient use. Led by Professor Richard Bell, with Senior Research Fellow Dr Qifu Ma and two full-time PhD students at Murdoch University, this project aligns with other investment nodes in soil nitrogen (N) and phosphorus (P) supply.

Potassium supply is critical for optimal plant growth and development, from early growth through to grain development. Regulating the opening and closing of leaf stomata during photosynthesis, K influences the plant response to light and uptake of carbon dioxide. It also plays a role in water management in the plant, both through water loss via the stomata and water uptake by roots. Thus adequate K allows the plant to use water more efficiently, increasing the vigour of the plant. Importantly K also contributes to the synthesis of both protein and starch in grain, influencing grain filling and quality.

Factors influencing the amount of K in soil include weathering and erosion, crop fertilisation and removal, climate and mineralogy of soil. The amount of plant-available K can also be determined by many other specific factors including soil pH, soil temperature and aeration, soil moisture, soil compaction (or other subsoil constraints that impede root growth), low organic matter content, clay content, as well as soil availability of sodium (Na), calcium (Ca) and magnesium (Mg).

The overreaching goal of this project will be to provide advice on K management for growers. A large study undertaken in 2011 using CSBP results from over 100,000 soil samples (0-10 cm depth)  collected across the south-west of WA showed that 8% of wheat crops and 49% of pasture would be K deficient (the critical  K limit is higher for the shallow-rooted pasture species). Dr Richard Bell said that “the aim is to provide better guidelines for farmers to use K more strategically and profitably using work packages as outlined below”.

  • Quantify K leaching (soluble K) to depths below the root system of the crops. The movement of K in the soil profile depends mainly on cation exchange capacity of the soil, soil texture, irrigation or rainfall, and the rate and solubility of any added fertiliser. Glasshouse trials using different soil types will be undertaken to quantify if leaching is a significant component of K loss. During these trials, tests of new fertiliser formulations will be assessed to determine if leaching can be minimised. The team will also look at existing models and use the results to calibrate for different soil types or to improve the model.
  • K cycling under different rotational sequences in 3 field experiments with different soil types (Mingenew, Katanning and Esperance). Experiments will run for four years and consider various crop rotations, for example canola and lupin, which will quantify which crops help to recycle K back into the topsoil.
  • Subsoil K levels sampled after several years of farming have shown that subsoil K becomes lower over time. It is believed that crops can become at risk of K deficiency if the soil dries out and there is not enough reserve in the subsoil. If this occurs at a critical stage of crop development then plant growth could be compromised. To determine if there are benefits in correcting subsoil K deficiency, a one year, controlled environment pot experiment will be conducted and dependent on results, field experiments where required.
  • Uncertainty about the soil test methods currently utilised for K (e.g. Colwell K on finer textured soils), and whether or not the inclusion of a K buffering measurement may be required exists. A review of soil test methods available from around the world will be completed to determine if another test that may be more suitable for WA soils. Glasshouse protocols will be used to test the accuracy of the existing K soil test (Colwell k) method at predicting fertiliser requirements and pot tests will be used to evaluate other K tests to provide data to determine which test give the most accurate results for each soil type.
  • Glasshouse experiments will be conducted to determine how Na, Ca and Mg interfere with or assist with K uptake in plants. In some species, particularly canola and barley it has been shown that if K is deficient then moderate levels of Na will allow these crops to grow adequately despite the apparent lack of K. There are currently no existing field data that indicate how Ca and Mg in soil effect the K response.
  • Using knowledge from these research programs, the team, including an economist, tasked to complete this work will model economic responses to the various K management strategies that will come out of the research.
  • Industry partners CSBP and Summit Fertilisers are contributing field experiments on K  (one each per year).

This work together with other nodes of investment in nitrogen and phosphorus are led by UWA adjunct Dr Craig Scanlan (DPIRD) within the SoilsWest alliance. For more information contact Richard Bell ([email protected]).

Photo: Richard Bell, Murdoch University

 

Resource: http://www.publish.csiro.au/cp/cp13006

04 Apr 2018

Soil Sampling

The goal of the Grains Research and Development Corporation’s (GRDC) co-investment of $1.4 million across three years in soil sampling strategies with CSIRO and led by Dr Phil Ward, is to review and provide updated information on soil sampling and analytical methods for measuring nutrients including phosphorus (P), potassium (K) and nitrogen (N) and soil acidity in a range of farming systems, with a focus on engineered soils.

There are five key features to this program and they are briefly discussed below:

  • Re-analyse existing nutrient and pH data, including where available collation of data from other sources such as the fertiliser decisions database, other researchers’ data and fertiliser companies.
  • Spatial soil sampling with input from DPIRD, UWA and industry partners, information on optimal depths, timing and number of samples collected, as well as whether samples should be collected on row or between rows will be gathered to identify soil sampling strategies thatgive the best information on nutrient availability. This sampling will be undertaken on existing field trial sites.
  • Crop modelling with existing model APSIM to determine the potential impacts of crop nutrients at depth and what overall effect will that have on crop yield.
  • Communication with fertiliser companies, soil sampling providers and other end users to ensure that any new guidelines and or methodologies are both reasonable and practicable.
  • Economics – taking the key features from the various GRDC programs to determine how any new information will affect growers’ profitability.

Image (Gaus Azam, DPIRD): Sampling strategies to spatially represent changes in soil under new management practices need to be assessed. 

The review and possible modifications to existing soil sampling methodologies are needed because current soil sample collection protocols were developed in an earlier era when both farming and fertiliser practices differed significantly from those in current use. Sampling strategies more in line with modern farming systems should allow growers to boost the accuracy of fertiliser decisions to better match major crop inputs to plant demand and minimise losses and tie-up in the soil, with a focus on greater efficiency, decreased risk and enhanced profitability.

Dr Ward said “The goal is to develop a new robust sampling standard that is applicable to different farming operations and different soil types. I think it is likely we will need different protocols depending on farming operations (mouldboard vs no till for example) and different soil types”

The last 20-30 years of farming have introduced a lot of spatial variation in nutrient distribution. Farming systems have undergone major changes from zero till, to extreme disturbance and the use of mouldboard ploughing or deep ripping. Minimum disturbance systems are often characterised by organic matter and nutrients concentrated in the top 10 cm of the soil. With increasing tillage, soils are generally more evenly mixed and often were considered more homogeneous. However with the advent of ‘re-engineering’ of soils and the adoption of strategies such as mouldboard ploughing and spading, mechanical disturbance of the soil can result in seams of nutrient rich organic matter and residual fertilisers, making it difficult to assess nutrient requirements.

Changes in tillage systems and crop sequences used by WA growers has led to a review of how well current soil sampling methods, developed in previous systems, can assess the store of plant-available nutrients.  The review, and additional research work will help guide the design of new soil sampling guidelines for WA growers. The time frame for this project is to deliver the new guidelines by 2020. For more information on this project, please contact Dr Phil Ward at CSIRO ([email protected]).

Photo top right: Phil Ward, CSIRO