ORCID Profile
0000-0002-0332-2203
Current Organisation
NSW Department of Primary Industries
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Wiley
Date: 09-08-2021
DOI: 10.1111/SUM.12748
Abstract: The application of biosolids to cropping soils may improve soil health, supply nitrogen and other nutrients for crops. There are specific guidelines on the quantity of biosolids that can be applied to a soil to grow selected crops. However, some recommendations overlook environmental factors such as soil organic N and N supplied by irrigation water. We conducted a three‐year field monitoring programme to study the effect of biosolid application on sodicity, soil nitrogen and organic carbon status to a depth of 1.8 m in a vertisol with a history of sewage effluent water irrigation. Biosolid application had no effect on soil sodicity. Improvements in soil organic carbon (SOC) were short‐lived and occurred only during the first year. N accumulation and leaching below the root zone (1.2 m) occurred after two years and suggest a possible off‐farm environmental risk. The higher residual mineral N in biosolid treatment 2 years after application implies an opportunity to reduce N inputs in vertisols treated with biosolids and effluent water. The biosolid application rate of 35 Mg ha −1 was well below the nitrogen‐limited biosolid application rate (NLBAR) (100 Mg ha −1 ) under the current guidelines. This warrants further refinement of NLBAR to suit specific circumstances such as effluent‐enriched water irrigation and additional in‐crop fertilizer application.
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/CP08103
Abstract: Low soil phosphorus (P) availability commonly limits yield in Australian broadacre organic production systems where superphosphate fertiliser is not permitted, and alternative P nutrition strategies are sought. Glasshouse experiments were conducted to investigate the potential of faba beans (Vicia faba L.) (FB), or field peas (Pisum sativum L.) (FP), grown in acidic sandy loam or alkaline clay, to accumulate P, which could then be supplied to a subsequent crop as part of a green manure rotation or after harvest. Another experiment investigated differences in growth and P acquisition between corn (Zea mays L.) cultivars: Hycorn 424 (a modern hybrid), and four traditional cultivars used in organic production. The experiments were carried out under conditions of P stress and had rock phosphate (RP), poultry manure (PM), or single superphosphate (SP) applied at 50 kg P/ha. For FP, maximum P input to the soil from incorporation would occur at or after pod initiation. However, P uptake by both legumes in both soils from sparingly soluble RP was low, with fertiliser P-use efficiencies of 0–1.3% compared with 1.8–12.7% for PM and 6.1–9.9% for SP. In the corn experiment, P fertiliser source had much larger effects than cultivar on plant biomass and P uptake, with responses generally ranked SP PM RP Control. Hycorn 424 generally produced higher dry matter and P uptake than the traditional cultivars under all P treatments. The implications of these preliminary investigations for Australian broadacre organic agriculture are discussed.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 09-2022
Publisher: Elsevier BV
Date: 07-2016
DOI: 10.1016/J.SCITOTENV.2016.03.105
Abstract: Herbicide runoff from cropping fields has been identified as a threat to the Great Barrier Reef ecosystem. A field investigation was carried out to monitor the changes in runoff water quality resulting from four different sugarcane cropping systems that included different herbicides and contrasting tillage and trash management practices. These include (i) Conventional - Tillage (beds and inter-rows) with residual herbicides used (ii) Improved - only the beds were tilled (zonal) with reduced residual herbicides used (iii) Aspirational - minimum tillage (one pass of a single tine ripper before planting) with trash mulch, no residual herbicides and a legume intercrop after cane establishment and (iv) New Farming System (NFS) - minimum tillage as in Aspirational practice with a grain legume rotation and a combination of residual and knockdown herbicides. Results suggest soil and trash management had a larger effect on the herbicide losses in runoff than the physico-chemical properties of herbicides. Improved practices with 30% lower atrazine application rates than used in conventional systems produced reduced runoff volumes by 40% and atrazine loss by 62%. There were a 2-fold variation in atrazine and >10-fold variation in metribuzin loads in runoff water between reduced tillage systems differing in soil disturbance and surface residue cover from the previous rotation crops, despite the same herbicide application rates. The elevated risk of offsite losses from herbicides was illustrated by the high concentrations of diuron (14μgL(-1)) recorded in runoff that occurred >2.5months after herbicide application in a 1(st) ratoon crop. A cropping system employing less persistent non-selective herbicides and an inter-row soybean mulch resulted in no residual herbicide contamination in runoff water, but recorded 12.3% lower yield compared to Conventional practice. These findings reveal a trade-off between achieving good water quality with minimal herbicide contamination and maintaining farm profitability with good weed control.
Publisher: Elsevier BV
Date: 10-2019
DOI: 10.1016/J.MIMET.2019.105695
Abstract: It is essential that s ling procedures for biological measurements are done in a way that reflects the soil processes, whilst limiting s ling artefacts. In heavy clay Vertisol soils, coring lubricants are often considered necessary in order to extract and recover soil for quality and health assessments. Previous reports into the use of coring lubricants have found soil carbon measurements to be inflated but to date, a study to evaluate the effects of these lubricants on soil microbial activity, has not been forthcoming. We measured soil carbon dioxide (CO
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/SR16047
Abstract: Leaching of nitrogen (N) in intensive irrigated agriculture can be a significant loss pathway. Though many studies have focussed on losses of mineral N, and in particular nitrate, dissolved organic N (DON) has received less coverage. In the present study, over a 5-year period (2008–2013), 740kgNha–1 fertiliser was applied to an irrigated cotton–wheat–maize rotation on a cracking clay (grey Vertosol). Deep drainage from the undisturbed soil profile at the site was measured at 2.1m below the soil surface using a variable tension lysimeter. In total, 108mm of drainage occurred during the 5 years and the majority of the drainage and the irrigations occurred during the cotton seasons. The majority of the N loss occurred during the first 3–4 irrigations and neither the N loss nor its composition were affected by the product or timing of the fertiliser application. The N in the drainage was composed of 12.8kgNOx-Nha–1, 8.7 DON-N and 0.1 NH4+-Nkgha–1, which shows that DON is an important component (40%) of the deep drainage N from irrigated Vertosol cotton production systems. Overall the total N flux lost via deep drainage represents 3% of the applied N fertiliser.
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 03-2019
Publisher: Elsevier BV
Date: 2020
Publisher: Soil and Water Conservation Society
Date: 2017
Publisher: Elsevier BV
Date: 09-2021
Publisher: Wiley
Date: 22-04-2021
DOI: 10.1002/SAJ2.20192
Abstract: The Vertosols of the lower Namoi valley in New South Wales, Australia, have been extensively developed for irrigated cotton ( Gossypium hirsutum L.) production. However, there are competing demands for water from mining, environmental needs, and agriculture, with climate change forecasts suggesting reduced rainfall and hotter climates. This means irrigators need to improve water efficiency, which requires methods to monitor the soil volumetric water content (θ, m 3 m –3 ). The aim of this study is to assess if a multicoil electromagnetic instrument (DUALEM‐421), which measures soil apparent electrical conductivity (EC a , mS m –1 ), can be used to value add to limited measurements of θ and allow extrapolation along a uniformly heavy clay irrigation furrow. Specifically, we seek to invert EC a using EM4Soil software to generate electromagnetic conductivity images, whereby the estimates of soil true electrical conductivity (σ, mS m –1 ) in the topsoil, subsurface, and subsoil are correlated with θ measured by Decagon GS3 sensors installed at the same depths. We also compared the usefulness of inversion of different combinations of DUALEM EC a : DUALEM‐1, DUALEM‐2, and DUALEM‐21. We found estimated σ from inversion of DUALEM‐421 EC a had good agreement (i.e., Lin's concordance = .84) with measured soil bulk electrical conductivity (σ b , mS m –1 ). We explored the relationship between DUALEM‐421 estimated σ and θ using an artificial neural network. The predictions showed the model had good coefficient of determination ( R 2 = .74) with good accuracy (RMSE = 0.04 m 3 m –3 ) and demonstrated good agreement between measured and predicted θ (Lin's = .84).
Publisher: Elsevier BV
Date: 10-2012
Publisher: Springer Science and Business Media LLC
Date: 12-09-2017
DOI: 10.1038/S41598-017-11681-4
Abstract: The traditional soil potassium (K) testing methods fail to accurately predict K requirement by plants. The Diffusive Gradients in Thin-films (DGT) method is promising, but the relationship between the DGT-measured K pool and plant available K is not clear. Wheat ( Triticum aestivum L ., cv. Frame) was grown in 9 Australian broad acre agricultural soils in a glasshouse trial until the end of tillering growth stage (GS30) with different plant K demands generated by varying plant numbers and pot sizes. Different K concentrations in soils were varied by 4 rates of K fertilizer application. The relative dry matter and K uptake were plotted against the soil K test value (CaCl 2 , Colwell and NH 4 OAc and DGT K measurements). To obtain 90% of maximum relative dry matter at low root density (closest to field conditions), the critical value of the NH 4 OAc K method was 91 (R 2 = 0.56) mg kg −1 . The DGT K method was not able to accurately predict relative dry matter or K uptake due to a weak extraction force for K from soils with high CEC values. Further endeavor on increasing K extraction force of the DGT method is warranted to obtain accurate plant available K results.
Publisher: Springer Science and Business Media LLC
Date: 06-08-2009
Publisher: Wiley
Date: 04-06-2019
DOI: 10.1111/SUM.12510
Publisher: Elsevier BV
Date: 09-2020
Publisher: Science Alert
Date: 15-03-2007
Publisher: Springer Science and Business Media LLC
Date: 21-02-2022
DOI: 10.1186/S42397-022-00114-X
Abstract: Australian cotton production predominantly occurs on Vertisols. The average lint yield of cotton grown in Australia is 2 260–2 700 kg·hm −2 , which is 2.5 to 3 times the world average. This high productivity per unit of land area requires efficient use of resources such as water and nutrients. However, high yields accelerate the export of nutrients such as phosphorus (P) in seed, depleting the soil reserves of P more than in other countries with lower cotton yields. Recent surveys of cotton industry indicate that P application rates should match seed P export (30~ 40 kg·hm −2 ), but historical depletion within subsoil is still evident and is continuing. Depletion of soil P is typically more pronounced in the subsoil than in the topsoil (0~ 20 cm) where P fertiliser is applied, as cotton roots rely on these layers as important sources of plant available water and available P. This mismatch between zones of P uptake and resupply may increase stratification of available P in the soil profile. Recent studies showed that cotton responded poorly to banded applications of fertiliser P, while dispersal of fertiliser throughout the plant beds was more successful. Researchers have also observed sporadic cotton responses to applied P fertiliser in soils where available P concentrations were well above the previously determined critical concentrations indicative of fertiliser P responses in Australia. To sustain high-yielding cotton production in Australia, a greater understanding of cotton root acquisition of applied P, as well as a re-examination of critical soil P concentrations for each production region are required.
Publisher: CSIRO Publishing
Date: 04-11-2021
DOI: 10.1071/SR20223
Abstract: Context Predicting the nitrogen (N) mineralisation from soil organic matter is a key aid to fertiliser decision-making and improving the N fertiliser use efficiency of a crop. Aims and methods Field experiments were conducted to assess the amount of inorganic N derived from soil organic matter mineralisation over two seasons (2017–2018 and 2018–2019) across treatments differing in irrigation frequency and amount. During both seasons, the plant line soil in each treatment was sequentially s led at each irrigation event. Key results There was an effect of the soil water deficit on the measured accumulated soil inorganic N derived from mineralisation in both measurement years. It was observed that soil inorganic N accumulated in the plant line rather than in other hillside and furrow positions for all soil moisture deficit treatments in both years. In 2017–2018, N accumulated in the plant was significantly greater than the measured accumulated inorganic N (0–300 mm). Conclusions and implications The sequential soil s ling approach was challenging in irrigated systems and we propose a hybrid measurement of pre-season available soil N and/or plant N uptake in nil N fertiliser plots as a means of estimating N derived from soil organic matter mineralisation.
Publisher: Wiley
Date: 2020
DOI: 10.1002/JEQ2.20006
Publisher: Soil and Water Conservation Society
Date: 05-2016
Publisher: Elsevier BV
Date: 12-2016
Publisher: Elsevier BV
Date: 05-2007
DOI: 10.1016/J.MIMET.2007.02.002
Abstract: In order to develop a method of measuring the level of microbial activity in soil that is suitable for use by farmers, land managers, and other non-scientists, a simple method for determining soil microbial activity was evaluated and compared with two standard techniques. Soils s led from vegetable farms in south east Queensland were incubated in the laboratory under controlled moisture and temperature conditions. Three methods were used to measure soil microbial activity, a respirometry method and two methods using the cotton strip assay (CSA) technique (image analysis and tensometer). The standard CSA method measured loss of tensile strength over a 35 day incubation period of buried cotton strips using a tensometer. The new CSA technique measured the intensity of staining by microbes using a flatbed scanner to create an image of the cotton strip whose staining percentage was determined using Photoshop software. The respirometry method used the substrate induced respiration rate (SIR) to determine microbial biomass in the soil at day 12 of incubation. The strong correlation between the image analysis method and the tensometer method (r(2)=0.81), a technique used by scientific researchers, suggests that the image analysis method could be used to monitor aspects of soil biological health by general community land-care groups and farmers. The image analysis method uses equipment which is readily available and, while not strongly correlated with more precise measurements of soil biological activity such as microbial biomass (r(2)=0.26), it can detect gross trends in biological health in a soil monitoring program. The CSA method using image analysis was the cheapest technique to measure soil microbial activity. CSA using image analysis can be a valuable tool in conjunction with other simple indicators of soil physical and chemical health such as slaking and pH to monitor soil amelioration or rehabilitation programs.
Publisher: Soil and Water Conservation Society
Date: 09-2016
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/SR19242
Abstract: Although sowing winter cereal crops in rotation with irrigated cotton (Gossypium hirsutum L.) is practised by many Australian cotton growers, summer cereals such as maize (Zea mays L.) are sown more frequently than previously. Our objective was to quantify the impact of sowing maize rotation crops on soil properties, greenhouse gas emissions, incidence of black root rot (BRR) disease and crop yields in an ongoing long-term experiment located in a Vertosol in north-western New South Wales. The historical treatments were cotton monoculture (sown after either conventional or minimum tillage) and a minimum-tilled cotton–wheat (Triticum aestivum L.) rotation. The experiment was redesigned in 2011 by splitting all plots and sowing either maize during summer following the previous year’s cotton or retaining the historical cropping system as a control. pH and exchangeable cation concentrations were highest, and electrical conductivity (EC1:5) lowest during 2012, the season following a flood event, but were unaffected by sowing maize. In subsequent seasons, with the onset of dry conditions, pH and cation concentrations decreased, and EC1:5 increased. The upper horizons (0–0.3 m) of plots where maize was sown had higher concentrations of exchangeable Ca and Mg during 2012, and 0.45–1.20 m had higher concentrations of exchangeable Na and exchangeable sodium percentage, but these differences disappeared in subsequent years. Soil organic carbon (SOC) in the surface 0.15 m was higher with maize, with differences becoming evident three years after maize was first sown but without any increases in SOC storage. Soil under maize was less resilient to structural degradation. BRR incidence was lower in maize-sown plots only during 2012. Stepwise linear regression suggested that high concentrations of exchangeable Ca and Mg in the surface 0.15 m played a role in reducing BRR incidence during 2012. Maize rotation introduced into cotton monocultures improved lint yields and reduced greenhouse gas emissions but had little impact in a minimum-tilled cotton–wheat rotation. Maize is a suitable rotation crop for irrigated cotton in a two-crop sequence but is of little advantage in a cotton–wheat–maize sequence.
Publisher: Science Alert
Date: 15-08-2007
Publisher: Elsevier BV
Date: 11-2018
Publisher: MDPI AG
Date: 21-07-2017
Publisher: Springer Science and Business Media LLC
Date: 09-03-2017
Publisher: Wiley
Date: 03-2019
DOI: 10.1111/SUM.12476
Abstract: The role of microbiology in soil carbon and nutrient cycling under cotton systems has been the focus of our recent work however, reporting is no longer just an exercise in journal publication and reporting to funders. Extension now has to incorporate funders, farmers, students, teachers and the general public. This results in one message being told many times in different ways, but raises questions regarding the best means of delivery, the preferred method of reception and the gathering and interpretation of audience feedback. This paper reviews our efforts to date across three main extension formats: printed material, digital material (including social media) and direct connections. Analyses indicate that no single method satisfies every potential audience and that some audiences want variety in their extension material formats. To meet this requirement, teams need to be familiar with several extension platforms, identify the key people that audiences look to for information so that the message is heard and assistance asked for from extension professionals when needed.
Publisher: Springer India
Date: 2017
Publisher: Science Alert
Date: 15-03-2007
No related grants have been discovered for Gunasekhar Nachimuthu.