A Grains Research and Development Corporation update was held at the Gunnedah band hall on the 24th July. This event saw local growers and agronomists from the Narrabri, Mullaley, Gunnedah, Tamworth and Breeza areas gather to be presented with several important topics within the grains industry.
The topics consisted of farming systems in northern and northwest NSW, which highlighted how commodity price, gross margins, water use efficiency and crop sequencing were key factors for an enterprises productivity. Water extraction, water-use and subsequent fallow water accumulation in summer crops was another topic.
A key point from the water use presentation was how soil water extraction under differing row configurations, particularly in sorghum are small. It was also stated that wider row configurations tend to reduce your fallow efficiency due to less groundcover. Chris Guppy touched on the impacts of poor water quality and the impacts these can have on your soil. Chris highlighted how important it was to have a leaching fraction, particularly when irrigating with bore water with an electrical conductivity above or equal to 2 deci semens/m. It was noted that irrigating with bore water without receiving any rain is risky as there is no leaching fraction (fresh water) to move the salts from the bore water down the soil profile away from the rooting zone. The sodium adsorption ratio was also an important irrigation quality consideration. The impact rain-fed cotton had on grain production in northern farming systems was presented by Jon Baird. Sowing sorghum earlier into cold soil temperatures was another interesting topic, with the risk and rewards of this practice highlighted. Further understanding of sowing into cool soil temperatures in August is important before the practice of super early sowing can be commercialised. New forms of weed control was another topic presented to the group. The most intriguing point of this presentation was the use of robotic lasers to differentiate weeds from the crop, particularly grass weeds in wheat, oats and barley crops.
The top three topics I took the most out of where minimising the yield gap, reserve phosphorus and potassium availability and release and also, methods to predict plant available water capacity using programs which encompass soil-landscape associations.
The average yields for the Liverpool Plains between 2000 and 2014 are 2.6 t/ha. This is 2.3 t/ha below the water limited yield potential for dryland wheat, which costs growers $575/ha. The water limited yield is the optimum yield the paddock can achieve with the only limiting factor being water. This yield gap of 2.3 t/ha can be closed by applying considerably more nitrogen fertiliser to wheat crops, grow a greater variety of crops, soil test a larger proportion of fields, adopt new technologies earlier and get on top of resistant weed issues quickly. Zvi Hochman stated the farms that are achieving their water limited yield are more likely to use a fee for service agronomist and are less likely to grow wheat following a cereal or pasture.
From the reserve potassium and phosphorus presentation the key points to take home were that blends of muriate of potash mixed with ammonium phosphates and calcium phosphates can initially decrease soil solution phosphorus when placed in bands. Monitoring of these fertiliser bands tends to suggest that these blends are forming less soluble reactions products, i.e. the potassium and phosphorous are forming rock (struvite). It is hypothesised that these two compounds when banded together cause the phosphorus to precipitate out of solution, therefore, making it unavailable for plant uptake.
Kirsten Verburg discussed how tools such as, SoilMapp and eSPADE can provide the grower with their soils plant available water capacity. This can allow the grower and agronomist to observe where differences in yield may occur which can aid with variety selection based on how much water is available on differing soil types.
I would like to thank the GRDC for organising the update. Thanks must also go to the researchers for continuing to resolve and discover issues within the industry. It is important to address these issues so that growers and agronomists can continue to implement best management practices to ensure the industry can be more profitable and sustainable into the future.