Hay and Silage
TRIALS of a relatively new approach to fertilising dryland cereal crops during the growing season have entered their second year, following promising results in 2016.
Trials showed that mid- row banding of nitrogen (N) in-season increased the uptake of nitrogen fertiliser in wheat by more than 50 per cent – when compared with other methods of in-season N application.
The trials, which were run across Victoria last year, found overall the fertiliser uptake greatly improved.
Agriculture Victoria’s regional research agronomist, Ashley Wallace, who started the work as part of the Grains Research and Development Corporation (GRDC) and Victorian Department of Economic Development, Jobs, Transport and Resources’ (DEDJTR) Bilateral Research Agreement, describes the outcomes as encouraging.
“Trials of mid-row banding of N in-season have produced promising results, including increasing fertiliser uptake by an average of 46 per cent and up to 52 per cent in wheat,” he said.
“The method also boosted grain yield by up to 0.5 tonnes/hectare.”
Results from mid-row banding trials in 2016 are being validated this year, with further trials currently under way.
Mr Wallace said there had been a significant swing towards in-season management of N fertiliser, particularly in southern dryland cropping regions, as growers looked to improve management amid variable seasonal conditions.
“The time when crops are sown is a period when seasonal forecasts and hence yield predictions have limited accuracy,” Mr Wallace said.
“This makes decisions around N application up-front difficult and risky – applying N during the growing season better matches the timing of application to crop demand.
“Unfortunately, surface application of N fertilisers, such as urea, during the growing season increases the risk of N loss through volatilisation.”
Mr Wallace explained that midrow banding of fertiliser, where N is applied below the surface of every second inter-row, has the potential to reduce risk - current research has focused on application during the growing season, rather than up-front during sowing.
Last year’s trials at Longerenong and Quambatook were undertaken in collaboration with Birchip Cropping Group, and aimed to compare mid-row banding with other forms of in-season N application, including top-dressed, liquid foliar and mid-row surface applications of N.
Mid- row banded treatments of liquid N were applied using a purpose- built three- point linkage mounted fertiliser banding gear, which used twin- disc openers to place fertiliser at a depth of 30 millimetres below the soil surface.
Each pair of discs was followed by a press wheel to assist with furrow closure.
Fertiliser treatments were applied at one of two times between the start of stem elongation and second node growth stages.
At each trial site, the first timing of application coincided with forecast rainfall in the days following, while the second timing of appli- cation coincided with dry weather forecast in the days following.
This approach was used to examine the effects of rainfall following application on potential losses of N and fertiliser use efficiency of the crop.
“Results from 2016 indicated that the benefit of mid-row banding to crop uptake of N was greater where rainfall was limited soon after application, and the surface applied urea was not washed into the rooting zone,” Mr Wallace said.
“This indicates that mid-row banding could be a more effective way of applying N under drier seasonal conditions.”
A report of the 2016 trial results, co-authored by Mr Wallace, is available for viewing and downloading via the GRDC website at https://grdc.com.au/mid-row-n-fertiliser.
NITROGEN MID-SEASON: Agriculture Victoria’s regional research agronomist, Ashley Wallace, at a trial site that examines the use of nitrogen application mid-season.