Summer crops: relative water use efficiencies and legacy impacts in farming systems

Take home message • While summer crops offer rotational options in the farming system, choose the correct crop to match your available soil water and crop history • Sorghum is a reliable performer often exceeding other options in terms of $returned per mm used • Cotton and maize require higher water availability and produce less reliable WUE ($/mm). However, cotton has legacy impacts on water availability for subsequent crops that should be considered • Mungbean can produce higher $/mm in low water availability situations ( 150 mm of plant available water will maximise crop WUE and profitability. Every extra mm at sowing could be worth as much as$35-70 extra return/ha • Higher density sorghum crops may provide greater crop competition against weeds and potential upside yield benefits in good season. We have seen limited legacy benefits (e.g. improved ground cover) or costs (e.g. greater soil water/nutrient extraction) for soil water or nutrient availability

Nitrogen and water dynamics in farming systems – multi-year impact of crop sequences

Take home messages • Grain legumes have utilised soil mineral nitrogen (N) to the same extent as cereal crops and have higher N export which often offsets N fixation inputs • Additional applied N reduced the depletion of background soil mineral N status at most sites; we are recovering a high percentage (>50%) in soil mineral pool. • Application of ~50 t/ha of compost or manure (10 t/ha OC) coupled with N fertiliser rates for 90th percentile yield potential has dramatically increased the soil mineral N in four years • Decreasing cropping frequency has reduced N export and so stored more N over the longer fallows, which has reduced N fertiliser requirements for following crops • Long fallows are mineralising N and moving N down the soil profile even under some very dry conditions • Most excess N is not lost in the system rather it is moved down the soil profile for future crops • The marginal WUE of crops (i.e. the grain yield increase per extra mm of available water) is lower when crops have less than 100 mm prior to planting. Hence, waiting until soil moisture reaches these levels is critical to maximise conversion of accumulated soil moisture into grain • The previous crop influences the efficiency of fallow water accumulation with winter cereals > sorghum > pulses. Long fallows are also less efficient than shorter fallows (<8 months). This has implications for assuming how much soil moisture may have accumulated during fallows

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Mungbean management guide 2nd edition

The mungbean management guide includes a checklist for growing mungbeans, and information about different varieties and seed quality, nutrition, weeds, disease and insect management, irrigation, harvesting, marketing and budgeting. The guide highlights the importance of: talking to marketers before choosing a variety choosing an approved, high germination and vigour seed planning weed and herbicide strategies monitoring for diseases timely insect control timely dessication

A bioeconomic framework for phosphorus deep-placement decisions

Research indicates potential yield benefits from replenishing phosphorus (P) in sub-surface layers (10-30cm) if soil tests indicate a deficiency; however, it was unknown if amelioration has economic merit. Deep-P placement is a longer-term decision due to initial application and P fertiliser (MAP) costs with potential benefits that can last for many seasons. However there are risks due to unknown future season types. The fundamental question of deep-P placement is “how much P and how often?” We developed a bio-economic framework and used a case study in the Goondiwindi region with a deep-soil Colwell-P of 5 mg/kg to demonstrate the risk and benefit of applying different amounts of MAP at depth for a “short-rotation” (3-years) and “long-rotation” (7-years). The results indicate: (a) the optimal MAP rate was 135 kg/ha and 270 kg/ha for the short- and long-rotations, respectively, resulting in real-annual returns of $43/ha/year and$76/ha/year; (b) the short-rotation risked a loss of -$14/ha/year compared to$6/ha/year for the long-rotation (worst case); and (c) due to the lower investment cost with the short-rotation, the expected return on investment was 142%, compared to 67% p.a. for the long-rotation. The payback period for both decisions was around 2-years. As with all risky decisions, the farmer will have to weigh up the benefits, risks and their financial situation. Economic results will change when biophysical or pricing parameters change. As our knowledge of deep-P responses improve they can be incorporated into this bio-economic framework

Developing and testing an analysis framework for long-term fertiliser decisions: Deep-P Calculator

Grain growers in Queensland and northern New South Wales are facing a new challenge in crop nutrition management: phosphorus (P) depletion of many soils below 10 cm. Research has indicated potential yield benefits from replenishing P in sub-surface layers (referred to as a ‘deep-P’ application). However, it was unknown if amelioration had economic merit. The fundamental question of deep-P placement is ‘how much P (what rate) should be applied and how often (at what frequency)?’ A program of close consultation was implemented, with leading scientists, fertiliser industry researchers, advisors and growers all contributing knowledge. Focus groups, a literature review and case studies were conducted. The iterative process implemented by this project effectively utilised various extension techniques to engage industry and leading researchers. This knowledge was used to develop a framework to produce a web-based tool that answers the fundamental question of deep-P fertiliser placement, ‘how much P and how often?