Graeme Wright

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.

Validation of analytical parameters of a competitive direct ELISA for aflatoxin B1 in peanuts

Abstract Analytical validation of a competitive direct SUNQuik ELISA with a reference High Performance Liquid Chromatography (HPLC) method and other methods including a minicolumn method and the VICAM Aflatest® system for aflatoxin in peanuts was conducted. Both the ELISA and the VICAM Aflatest® system, using the same peanut extracts were analytically comparable with the HPLC method (R=0.998, p<0.000). The minicolumn method was also found to be acceptable as a low cost rapid semi-quantitative test. Despite the large variation in sampling, the correlation between the SUNQuik ELISA and HPLC using the different peanut sub-samples was considered acceptable over the range of 0–1200 µg kg−1 (R=0.938). No false negatives were found using the SUNQuik ELISA and false positives were either nil or negligible in all the studies conducted. The repeatability of the SUNQuik ELISA run on the same day was good with only±10% deviation. The reproducibility of the SUNQuik ELISA between days was also acceptable, but with a higher deviation. Applying the SUNQuik ELISA for aflatoxin surveys of peanuts in Indonesia proved that the method can deliver high quality, cost- and time-effective analysis with very little establishment capital and maintenance.

Agronomic benefits and risks associated with the irrigated peanut–maize production system under a changing climate in northern Australia

Abstract. With the aim of increasing peanut production in Australia, the Australian peanut industry has recently considered growing peanuts in rotation with maize at Katherine in the Northern Territory—a location with a semi-arid tropical climate and surplus irrigation capacity. We used the well-validated APSIM model to examine potential agronomic benefits and long-term risks of this strategy under the current and warmer climates of the new region. Yield of the two crops, irrigation requirement, total soil organic carbon (SOC), nitrogen (N) losses and greenhouse gas (GHG) emissions were simulated. Sixteen climate stressors were used; these were generated by using global climate models ECHAM5, GFDL2.1, GFDL2.0 and MRIGCM232 with a median sensitivity under two Special Report of Emissions Scenarios over the 2030 and 2050 timeframes plus current climate (baseline) for Katherine. Effects were compared at three levels of irrigation and three levels of N fertiliser applied to maize grown in rotations of wet-season peanut and dry-season maize (WPDM), and wet-season maize and dry-season peanut (WMDP). The climate stressors projected average temperature increases of 1°C to 2.8°C in the dry (baseline 24.4°C) and wet (baseline 29.5°C) seasons for the 2030 and 2050 timeframes, respectively. Increased temperature caused a reduction in yield of both crops in both rotations. However, the overall yield advantage of WPDM increased from 41% to up to 53% compared with the industry-preferred sequence of WMDP under the worst climate projection. Increased temperature increased the irrigation requirement by up to 11% in WPDM, but caused a smaller reduction in total SOC accumulation and smaller increases in N losses and GHG emission compared with WMDP. We conclude that although increased temperature will reduce productivity and total SOC accumulation, and increase N losses and GHG emissions in Katherine or similar northern Australian environments, the WPDM sequence should be preferable over the industry-preferred sequence because of its overall yield and sustainability advantages in warmer climates. Any limitations of irrigation resulting from climate change could, however, limit these advantages.