A push by Regional Cropping Solutions Network members to review local nutrient practices after a period of variable seasons in Western Australia resulted in the establishment of demonstration sites in 2018 and 2019.

Known as ‘yardstick’ demonstrations and supported by GRDC, the research followed work by the Merredin and Districts Farm Improvement Group (MADFIG) in the Kwinana East Port Zone from 2015 to 2018. The demonstration sites were designed to gauge whether local nutrition strategies resulted in any difference in cultivar ranking compared to the rankings provided by the National Variety Trials (NVT), where varieties are tested under higher nutrient regimes.

Although the expanded port zone demonstrations in 2018 and 2019 used different varieties and nutrient strategies at each site, meaning comparison across sites was not possible, generally it was found that fertiliser decisions largely do not affect the relative local performance of different wheat, barley and canola varieties.

Each site had a Yield Prophet scenario run, with nitrogen strategies catered to seasonal decile scenarios, with increasing deciles allowing for increased nitrogen application.

Geraldton port zone

Mingenew-Irwin Group research agronomist Madi George, who supervised the yardstick trials for the Geraldton Port Zone, says it was concluded from the results that the season and location of trial affected yield more than variety choice and fertiliser decisions, with the optimum nutrition regime differing between locations and seasons.

“Both seasons were challenging as crops were stressed at all sites due to low finishing rains and high temperatures, and it highlights the need to extend these sorts of trials over a longer time period,” Ms George says.

Varieties with different maturities were selected, with two varieties of wheat, barley and canola tested under four nutrition strategies in 2018 and four varieties of wheat and barley with three nutrition strategies in 2019 at four sites each year – Yuna, Morawa, Mingenew/Irwin and Three Springs.

Target yields were determined by local growers and agronomists, who predicated yield on whether they had a decile one, four or seven rainfall year. The nutrition strategies were then developed for the three rainfall scenarios by considering target yield for a particular site. A ‘play the season’ strategy was included in 2018.

“A good example of the variability in crop performance that we saw occurred at Morawa, where in 2018 the decile seven nutrition treatment for wheat yielded significantly higher than all other decile nutrition treatments. Scepter (PBR) yielded 3.73 tonnes per hectare and Ninja (PBR) 3.48t/ha,” Ms George says.

“However, in 2019, there was no significant difference between nutrition treatments for wheat at Morawa.

“If we then consider the profitability of the treatments at Morawa, no specific fertiliser strategy was consistently the most profitable over the trial period (accumulated two-year return per hectare), which can be attributed to varied seasonal conditions across the two years. For example, the fertiliser strategies attracting the highest returns for wheat were decile seven in 2018 at $1148 and decile one in 2019 at $415.

The trials were a worthwhile exercise in demonstrating the impact of rainfall and nutrition on crop yield and overall profit in two varied seasons.

“They highlighted the importance for growers to consider adjusting their fertiliser strategy throughout the year to increase yield or improve grain quality, and ensure inputs are not wasted by the crop.”

Albany and Esperance port zones

Kalyx western business manager Barrett Sinclair, who oversaw the yardstick trials in the Esperance and Albany port zones, says the 24 trials in 2018 provided very little evidence to support the idea that the two varieties tested differed in their response to increasing nutritional inputs such that it could be exploited by growers. A similar finding was made in 2019, when the number of varieties was increased to four, with no evidence to support the idea that varieties differ in their response to increasing nitrogen nutrition.

In fact, the opposite was true for most parameters measured at most sites, with varieties of each crop responding in similar ways for yield and grain quality.

“The lack of strong evidence of a variety-by-fertiliser interaction in these environments indicates growers and advisers need only consider a crop and not specific varieties in their agronomic management,” Mr Sinclair says.

We also concluded from the two seasons of results that the optimum nutrition package differed between seasons and the overall season and site had a greater effect on yield and grain protein than individual variety or nutrition strategy.

Sites were selected on soil tests and established and maintained by Kalyx as small-plot trials across the Albany and Esperance port zones. Trials were located at Hyden, Kojonup, Jerramungup, South Stirling, Mount Madden, Munglinup, Gibson and Scaddan in 2018. In 2019 the Scaddan site was relocated to Salmon Gums.

In 2018, two varieties of wheat, barley and canola differing in maturity were tested at two times of sowing and under four nitrogen and phosphorus strategies representing nutritional inputs considered suitable for decile one, three and six seasonal rainfall, along with a ‘play the season’ strategy. The parameters were changed in 2019 to four varieties each of wheat and barley tested at one time of sowing under nitrogen inputs representing decile one, four and seven. Crop performance was assessed by measuring early crop growth, yield and grain quality.

The 2018 season had good summer rains at Hyden, Munglinup, Gibson and Scaddan, damaging winds that sand-blasted trials at Jerramungup and South Stirling, severe frosts at Kojonup and low winter rainfall at Mount Madden. In 2019 all sites experienced a decile one season.

Table 1: Return on nutrition investment (Net farm gate margin, Net return $/ha) for wheat, barley and canola for 2018 and 2019. Results are presented as averages for each crop type.

Notes:

Net return is the gross return minus cost of fertiliser. No other input costs were considered.

Returns were calculated for each variety using grain quality and yield for each variety at each sowing time. Each crop type was then averaged.

Source : Kalyx

When the wheat variety performance was averaged for an economic analysis (Table 1), it was shown that increasing nitrogen generally increased yield but it did not necessary result in increased returns.

Kwinana East and West port zones

Richard Devlin, manager of the Kwinana East and West port zones yardstick projects with Living Farm, says the demonstration sites illustrated that the genetics of crop varieties are the main driver of performance.

This was confirmed, for example, at seven of the eight wheat trial site locations in 2019, where variety choice was the main driver of yield rather than the nutrient strategy (see Tables 2 and 3).

Table 2: Significant wheat variety results from 2019 Yardstick trials.

Source: Living Farm

Table 3: Significant wheat nutrient strategy results from 2019 Yardstick trials.

Source: Living Farm

“We concluded from the yardstick trials that appropriately selected varieties, which are adapted to a region, will generally perform the best, fertilisers will boost yield and nitrogen is more important than phosphorus,” Mr Devlin says.

Wheat was generally the most stable yielder across the sites in 2019; however, the difference was not as great in 2018.

In 2018 two varieties of wheat, Scepter and Trojan ; barley, La Trobe and Bass ; and canola, Hyola 559 and Invigor T4510; were tested at Corrigin, Cunderdin, Merredin, Moorine Rock, Mukinbudin, Yealering and York with four nutrient strategies.

In 2019 four wheat varieties, Scepter , Trojan , Devil and Ninja and four barley varieties, Rosalind , Buff , Spartacus CL  and RGT Planet were tested at Corrigin, Cunderdin, Merredin, Moorine Rock, Mukinbudin, Tincurrin, Wyalkatchem and York with three nutrient strategies.

More information: Madi George, 0409 751 586, trials@mig.org.au; Barrett Sinclair, 0427 002 212, bsinclair@kalyx.com.au; Richard Devlin, 0400 123 596, richard@livingfarm.com.au