Plant based monitoring for irrigation scheduling in vegetable horticulture: A case study in South Australian onions

Direct measurement of plant water status for irrigation scheduling may be more sensitive, and promote better horticultural crop quality, than indirect methods such as soil moisture monitoring. In our research project, we sought to identify instances where direct methods of plant-water status previously used in horticultural crops in Australia. We present the outcomes, suitability or obstacles for adoption by horticultural producers.

Increased profitability through product diversification and improved sugar quality.

The proposed simplified Integrated Sugar Production Process (ISPP) using membrane technology would allow the sugar industry to produce new product streams and higher quality mill sugar with increased sugar extraction efficiency. Membrane filtration technology has proven to be a technically sound process to increase sugar quality. However commercial viability has been uncertain partly because the benefits to crystallisation and sugar quality have not outweighed the increased processing cost. This simplified ISPP produces additional value-added liquid streams to make the membrane fractionation process more financially viable and improve the profitability of sugar manufacture. An experimental study used pilot scale membrane fractionation of clarified mill juice confirmed the technical feasibility of separating inorganic salt and antioxidant rich fractions from cane juice. The paper presents details on the compositions of the liquid streams along with their potential uses, values and challenges in getting these products out to market. This paper was presented at the 2010 Australian Society of Sugar Cane Technologists annual conference.

Using Trichogramma Westwood (Hymenoptera: Trichogrammatidae) for insect pest biological control in cotton crops: an Australian perspective.

Trichogramma Westwood egg parasitoids alone generally fail to suppress heliothine pests when released in established cotton-growing regions. Factors hindering their success include indiscriminate use of detrimental insecticides, compensation for minimal pest larval hatch due to their activity via reduced larval cannibalism or mortality in general, singly laid heliothine eggs avoiding detection and asynchronous development benefiting host over parasitoid. Yet, despite these limitations, relatively large Trichogramma pretiosum Riley populations pervade and effectively suppress Helicoverpa (Hardwick) pests in Australian Bt (Bacillus thuringiensis Berliner)-transgenic cotton, Gossypium hirsutum L., crops, especially in the Ord River Irrigation Area (ORIA) of tropical northern Australia, where their impact on the potentially resistant pest species, Helicoverpa armigera (Hubner), is considered integral to the local insecticide resistance management (IRM) strategy for continued, sustainable Bt-transgenic cotton production. When devoid of conventional insecticides, relatively warm and stable conditions of the early dry season in winter grown ORIA Bt-transgenic cotton crops are conducive to Trichogramma proliferation and biological control appears effective. Further, there is considerable scope to improve Trichogramma's biological control potential, in both the ORIA and established cotton-growing regions, via habitat manipulation. It is proposed that Trichogramma may prove equally effective in developing agricultural regions of monsoonal northern Australia, and that environmental constraints on Trichogramma survival, and those of other natural enemies, require due consideration prior to their successful application in biological control programs.

Economic Analysis of Sugarcane Farming Systems for Water Quality Improvement in the Great Barrier Reef Catchments.

In this report we analyse the private financial-economic impacts of transitioning to improved sugarcane management in the National Resource Management regions of the Wet Tropics, Burdekin Dry Tropics and Mackay Whitsundays. In order to do so, we: 1) compare farm GMs; 2) present information on capital investment associated with the transition; 3) perform a net present value analysis of the investments and; 4) undertake a risk analysis for cane and legume yields and prices. It must be noted that transaction costs are not captured within this project.

The Application of Near Infrared Spectroscopy for the Assessment of Avocado Quality Attributes, Infrared Spectroscopy. Chapter 14

Quality and safety evaluation of agricultural products has become an increasingly important consideration in market/commercial viability and systems for such evaluations are now demanded by customers, including distributors and retailers. Unfortunately, most horticultural products struggle with delivering adequate and consistent quality to the consumer. Removing inconsistencies and providing what the consumer expects is a key factor for retaining and expanding both domestic and international markets. Most commercial quality classification systems for fruit and vegetables are based on external features of the product, for example: shape, colour, size, weight and blemishes. However, the external appearance of most fruit is generally not an accurate guide to the internal or eating quality of the fruit. Internal quality of fruit is currently subjectively judged on attributes such as volatiles, firmness, and appearance. Destructive subjective measures such as internal flesh colour, or objective measures such as extraction of juice to measure sweetness (oBrix) or assessment of dry matter (DM) content are also used, although obviously not for every fruit – just a sample to represent the whole consignment. For avocado fruit, external colour is not a maturity characteristic, and its smell is too weak and appears later in its maturity stage (Gaete-Garreton et al., 2005). Since maturity is a major component of avocado quality and palatability, it is important to harvest mature fruit, so as to ensure that fruit will ripen properly and have acceptable eating quality. Currently, commercial avocado maturity estimation is based on destructive assessment of the %DM, and sometimes percent oil, both of which are highly correlated with maturity (Clark et al., 2003; Mizrach & Flitsanov, 1999). Avocados Australia Limited (AAL (2008)) recommend a minimum maturity standard for its growers of 23 %DM (greater than 10% oil content) for the ‘Hass’ cultivar, although consumer studies indicate a preference for at least 25 %DM (Harker et al., 2007).

AQUAMAN: a web-based decision support system for irrigation scheduling in peanuts

Peanut (Arachis hypogaea L.) is an economically important legume crop in irrigated production areas of northern Australia. Although the potential pod yield of the crop in these areas is about 8 t ha(-1), most growers generally obtain around 5 t ha(-1), partly due to poor irrigation management. Better information and tools that are easy to use, accurate, and cost-effective are therefore needed to help local peanut growers improve irrigation management. This paper introduces a new web-based decision support system called AQUAMAN that was developed to assist Australian peanut growers schedule irrigations. It simulates the timing and depth of future irrigations by combining procedures from the food and agriculture organization (FAO) guidelines for irrigation scheduling (FAO-56) with those of the agricultural production systems simulator (APSIM) modeling framework. Here, we present a description of AQUAMAN and results of a series of activities (i.e., extension activities, case studies, and a survey) that were conducted to assess its level of acceptance among Australian peanut growers, obtain feedback for future improvements, and evaluate its performance. Application of the tool for scheduling irrigations of commercial peanut farms since its release in 2004-2005 has shown good acceptance by local peanuts growers and potential for significantly improving yield. Limited comparison with the farmer practice of matching the pan evaporation demand during rain-free periods in 2006-2007 and 2008-2009 suggested that AQUAMAN enabled irrigation water savings of up to 50% and the realization of enhanced water and irrigation use efficiencies.

Nitrogen leaching from the root zone of sugarcane and bananas in the humid tropics of Australia

Loss of nitrogen in deep drainage from agriculture is an important issue for environmental and economic reasons, but limited field data is available for tropical crops. In this study, nitrogen (N) loads leaving the root zone of two major humid tropical crops in Australia, sugarcane and bananas, were measured. The two field sites, 57 km apart, had a similar soil type (a well drained Dermosol) and rainfall (∼2700 mm year -1) but contrasting crops and management. A sugarcane crop in a commercial field received 136-148 kg N ha -1 year -1 applied in one application each year and was monitored for 3 years (first to third ratoon crops). N treatments of 0-600 kg ha -1 year -1 were applied to a plant and following ratoon crop of bananas. N was applied as urea throughout the growing season in irrigation water through mini-sprinklers. Low-suction lysimeters were installed at a depth of 1 m under both crops to monitor loads of N in deep drainage. Drainage at 1 m depth in the sugarcane crops was 22-37% of rainfall. Under bananas, drainage in the row was 65% of rainfall plus irrigation for the plant crop, and 37% for the ratoon. Nitrogen leaching loads were low under sugarcane (<1-9 kg ha -1 year -1) possibly reflecting the N fertiliser applications being reasonably matched to crop requirements and at least 26 days between fertiliser application and deep drainage. Under bananas, there were large loads of N in deep drainage when N application rates were in excess of plant demand, even when applied fortnightly. The deep drainage loss of N attributable to N fertiliser, calculated by subtracting the loss from unfertilised plots, was 246 and 641 kg ha -1 over 2 crop cycles, which was equivalent to 37 and 63% of the fertiliser application for treatments receiving 710 and 1065 kg ha -1, respectively. Those rates of fertiliser application resulted in soil acidification to a depth of 0.6 m by as much as 0.6 of a unit at 0.1-0.2 m depth. The higher leaching losses from bananas indicated that they should be a priority for improved N management. Crown Copyright © 2012.

Benefits of oxygation of subsurface drip-irrigation water for cotton in a Vertosol

Australian cotton (Gossypium hirsutum L.) is predominantly grown on heavy clay soils (Vertosols). Cotton grown on Vertosols often experiences episodes of low oxygen concentration in the root-zone, particularly after irrigation events. In subsurface drip-irrigation (SDI), cotton receives frequent irrigation and sustained wetting fronts are developed in the rhizosphere. This can lead to poor soil diffusion of oxygen, causing temporal and spatial hypoxia. As cotton is sensitive to waterlogging, exposure to this condition can result in a significant yield penalty. Use of aerated water for drip irrigation (‘oxygation’) can ameliorate hypoxia in the wetting front and, therefore, overcome the negative effects of poor soil aeration. The efficacy of oxygation, delivered via SDI to broadacre cotton, was evaluated over seven seasons (2005–06 to 2012–13). Oxygation of irrigation water by Mazzei air-injector produced significantly (P < 0.001) higher yields (200.3 v. 182.7 g m–2) and water-use efficiencies. Averaged over seven years, the yield and gross production water-use index of oxygated cotton exceeded that of the control by 10% and 7%, respectively. The improvements in yields and water-use efficiency in response to oxygation could be ascribed to greater root development and increased light interception by the crop canopies, contributing to enhanced crop physiological performance by ameliorating exposure to hypoxia. Oxygation of SDI contributed to improvements in both yields and water-use efficiency, which may contribute to greater economic feasibility of SDI for broadacre cotton production in Vertosols.

Water-use efficiency and productivity trends in Australian irrigated cotton: a review

The aim of this review is to report changes in irrigated cotton water use from research projects and on-farm practice-change programs in Australia, in relation to both plant-based and irrigation engineering disciplines. At least 80% of the Australian cotton-growing area is irrigated using gravity surface-irrigation systems. This review found that, over 23 years, cotton crops utilise 6-7ML/ha of irrigation water, depending on the amount of seasonal rain received. The seasonal evapotranspiration of surface-irrigated crops averaged 729mm over this period. Over the past decade, water-use productivity by Australian cotton growers has improved by 40%. This has been achieved by both yield increases and more efficient water-management systems. The whole-farm irrigation efficiency index improved from 57% to 70%, and the crop water use index is >3kg/mm.ha, high by international standards. Yield increases over the last decade can be attributed to plant-breeding advances, the adoption of genetically modified varieties, and improved crop management. Also, there has been increased use of irrigation scheduling tools and furrow-irrigation system optimisation evaluations. This has reduced in-field deep-drainage losses. The largest loss component of the farm water balance on cotton farms is evaporation from on-farm water storages. Some farmers are changing to alternative systems such as centre pivots and lateral-move machines, and increasing numbers of these alternatives are expected. These systems can achieve considerable labour and water savings, but have significantly higher energy costs associated with water pumping and machine operation. The optimisation of interactions between water, soils, labour, carbon emissions and energy efficiency requires more research and on-farm evaluations. Standardisation of water-use efficiency measures and improved water measurement techniques for surface irrigation are important research outcomes to enable valid irrigation benchmarks to be established and compared. Water-use performance is highly variable between cotton farmers and farming fields and across regions. Therefore, site-specific measurement is important. The range in the presented datasets indicates potential for further improvement in water-use efficiency and productivity on Australian cotton farms.

Targeting resource investments to achieve sediment reduction and improved Great Barrier Reef health

Concerns about excessive sediment loads entering the Great Barrier Reef (GBR) lagoon in Australia have led to a focus on improving ground cover in grazing lands. Ground cover has been identified as an important factor in reducing sediment loads, but improving ground cover has been difficult for reef stakeholders in major catchments of the GBR. To provide better information an optimising linear programming model based on paddock scale information in conjunction with land type mapping was developed for the Fitzroy, the largest of the GBR catchments. This identifies at a catchment scale which land types allow the most sediment reduction to be achieved at least cost. The results suggest that from the five land types modelled, the lower productivity land types present the cheapest option for sediment reductions. The study allows more informed decision making for natural resource management organisations to target investments. The analysis highlights the importance of efficient allocation of natural resource management funds in achieving sediment reductions through targeted land type investments. © 2012.

Identifying risk-efficient strategies using stochastic frontier analysis and simulation: An application to irrigated cropping in Australia

In irrigated cropping, as with any other industry, profit and risk are inter-dependent. An increase in profit would normally coincide with an increase in risk, and this means that risk can be traded for profit. It is desirable to manage a farm so that it achieves the maximum possible profit for the desired level of risk. This paper identifies risk-efficient cropping strategies that allocate land and water between crop enterprises for a case study of an irrigated farm in Southern Queensland, Australia. This is achieved by applying stochastic frontier analysis to the output of a simulation experiment. The simulation experiment involved changes to the levels of business risk by systematically varying the crop sowing rules in a bioeconomic model of the case study farm. This model utilises the multi-field capability of the process based Agricultural Production System Simulator (APSIM) and is parameterised using data collected from interviews with a collaborating farmer. We found sowing rules that increased the farm area sown to cotton caused the greatest increase in risk-efficiency. Increasing maize area also improved risk-efficiency but to a lesser extent than cotton. Sowing rules that increased the areas sown to wheat reduced the risk-efficiency of the farm business. Sowing rules were identified that had the potential to improve the expected farm profit by ca. $50,000 Annually, without significantly increasing risk. The concept of the shadow price of risk is discussed and an expression is derived from the estimated frontier equation that quantifies the trade-off between profit and risk.

Quantifying the response of cotton production in eastern Australia to climate change

Abstract The paper evaluates the effect of future climate change (as per the CSIRO Mk3.5 A1FI future climate projection) on cotton yield in Southern Queensland and Northern NSW, eastern Australia by using of the biophysical simulation model APSIM (Agricultural Production Systems sIMulator). The simulations of cotton production show that changes in the influential meteorological parameters caused by climate change would lead to decreased future cotton yields without the effect of CO2 fertilisation. By 2050 the yields would decrease by 17 %. Including the effects of CO2 fertilisation ameliorates the effect of decreased water availability and yields increase by 5.9 % by 2030, but then decrease by 3.6 % in 2050. Importantly, it was necessary to increase irrigation amounts by almost 50 % to maintain adequate soil moisture levels. The effect of CO2 was found to have an important positive impact of the yield in spite of deleterious climate change. This implies that the physiological response of plants to climate change needs to be thoroughly understood to avoid making erroneous projections of yield and potentially stifling investment or increasing risk.

Changes in quality and bioactivity of native food during storage

Australian native foods have long been consumed by the Indigenous people of Australia. There is growing interest in the application of these foods in the functional food and complementary health care industries. Recent studies have provided information on the health properties of native foods but systematic study of changes in flavour and health components during processing and storage has not been done. It is well known that processing technologies such as packaging, drying and freezing can significantly alter the levels of health and flavour compounds. However, losses in compounds responsible for quality and bioactivity can be minimised by improving production practices. This report outlines research developed to provide the native food industry with reliable information on the retention of bioactive compounds during processing and storage to enable the development of product standards which in turn will provide the industry with scientific evidence to expand and explore new market opportunities globally.

Understanding the barriers to the implementation of precision agriculture in the central region

There is an increasing requirement for more astute land resource management through efficiencies in agricultural inputs in a sugar cane production system. A precision agriculture (PA) approach can provide a pathway for a sustainable sugarcane production system. One of the impediments to the adoption of PA practices is access to paddock-scale mapping layers displaying variability in soil properties, crop growth and surface drainage. Variable rate application (VRA) of nutrients is an important component of PA. However, agronomic expertise within PA systems has fallen well behind significant advances in PA technologies. Generally, advisers in the sugar industry have a poor comprehension of the complex interaction of variables that contribute to within-paddock variations in crop growth. This is regarded as a significant impediment to the progression of PA in sugarcane and is one of the reasons for the poor adoption of VRA of nutrients in a PA approach to improved sugar cane production. This project therefore has established a number of key objectives which will contribute to the adoption of PA and the staged progression of VRA supported by relevant and practical agronomic expertise. These objectives include provision of base soils attribute mapping that can be determined using Veris 3100 Electrical Conductivity (EC) and digital elevation datasets using GPS mapping technology for a large sector of the central cane growing region using analysis of archived satellite imagery to determine the location and stability of yield patterns over time and in varying seasonal conditions on selected project study sites. They also include the stablishment of experiments to determine appropriate VRA nitrogen rates on various soil types subjected to extended anaerobic conditions, and the establishment of trials to determine nitrogen rates applicable to a declining yield potential associated with the aging of ratoons in the crop cycle. Preliminary analysis of archived yield estimation data indicates that yield patterns remain relatively stable overtime. Results also indicate the where there is considerable variability in EC values there is also significant variation in yield.