Wheat and barley varieties' response to nitrogen 2014 trial report

Comments from Wongan Hills

At Wongan Hills, wheat yields (averaged across variety) increased with addition of 40kg/ha of nitrogen on the wheat stubble and only increased with 20kg/ha nitrogen following canola (Figure 1 and 3 Wongan Hills). There was no yield penalty at 80kg/ha of nitrogen (averaged across variety). In contrast, barley yields increased with addition of 20kg/ha of nitrogen on the wheat stubble and up to 40kg/ha following canola but there was a yield penalty at 80kg/ha of nitrogen (Figure 1-4 Wongan Hills). The trials at Wongan Hills were in adjacent paddocks and classified as sandy earth soils. The growing season rainfall was 276mm. Barley biomass (as indicated by NDVI readings) was significantly greater than wheat, six and 10 weeks after seeding. However, by week 14 after seeding, barley biomass was significantly less than wheat (data not provided).

Figure 1 Wongan Hills: Response of wheat varieties to nitrogen on wheat stubble

Figure 2 Wongan Hills: Response of barley varieties to nitrogen on wheat stubble

Figure 3 Wongan Hills: Response of wheat varieties to applied nitrogen on canola stubble at Wongan Hills

Figure 4 Wongan Hills: Response of barley varieties to applied nitrogen on canola stubble at Wongan Hills

Comments from Cunderdin

At Cunderdin on the wheat stubble, barley and wheat yields (averaged across varieties) increased significantly with added nitrogen up to 80kg/ha (Figure 2). On the canola stubble site at Cunderdin wheat responded similarly. In contrast, barley yields increased up to 40kg/ha of added nitrogen but there was no benefit of 80kg/ha of nitrogen (Figure 2). Although both sites were shallow sandy duplex soils the canola wheat site was classified as a better soil. On these duplex soils, the depth to the ‘B’ horizon was 10cm on the wheat stubble and 20cm on the canola stubble. In addition soil pH at 15-20cm depth was 6.1 at the canola stubble site and 4.5 at the wheat stubble site.

Figure 1 Cunderdin: Yield response of wheat varieties to applied nitrogen at Cunderdin on wheat stubble

Figure 2 Cunderdin: Yield response of barley varieties to applied nitrogen at Cunderdin on wheat stubble

Figure 3 Cunderdin: Yield response of wheat varieties to applied nitrogen at Cunderdin on canola stubble

Figure 4 Cunderdin: Yield response of barley varieties to applied nitrogen at Cunderdin on canola stubble

Economics

Barley and wheat each have different grain quality specifications. Although barley is more productive than wheat at a large number of trials sites, the price of each commodity will influence its profitability and hence the choice of crop and agronomy following wheat or canola.

In today’s market (2014), barley commodity prices are high relative to wheat. Feed barley was priced at $300/t on 15 December 2014 compared to $270 for AGP wheat. Price for malting barley and milling wheats are similar. In this series of trials, barley productivity ranged from 123-411kg/ha higher than wheat (except at Binnu where wheat was 200kg/ha better than barley). Given the current prices and yield advantage of barley, it is likely that barley will be more profitable than wheat (assuming milling and malting grades are achieved). The yield potential of the site will influence the wheat grain price needed to offset improved barley yields. For example, where barley yields 1.5t/ha and wheat is likely to yield 1.3t/ha (yield difference of 0.2t/ha), at a current price for barley of $300/t and $150/t, the break even wheat prices are $346/t and $173/t respectively (Table 2). The yield difference between wheat and barley will also influence prices. At a barley yield of 3.5t/ha at $250/t, when the yield differences between barley and wheat is 0.2t/ha and 0.4t/h, the break even wheat price is $265/t and $282/t respectively. So in today’s market, barley may have been more profitable assuming production costs are similar for both crops. However, barley is less tolerant to acid soils and production costs can be higher. Malt grade can be hard to achieve so site selection is important, as is a good understanding of grain quality and the end price.

Conclusions

Which cereal is more productive?

Based on yield alone, barley was more productive than wheat at a larger number of trial sites on both wheat and canola stubble. Yield differences between barley and wheat averaged across all varieties and nitrogen treatments ranged from 123-411kg/ha. The higher barley yields were achieved through greater head number compared to wheat.

Influence of nitrogen on production

Nitrogen is important component of agronomy of wheat and barley in both canola and wheat rotations. Yields did respond to added nitrogen. However, high rates of nitrogen were a greater risk to barley than wheat. One explanation is the increased tillering capacity and biomass of barley relative to wheat may increase water use and reduce its availability for grain fill if spring rains are limited.

Acknowledgements

Financial support for this research is provided by Grains Research and Development Corporation. The research delivers to the outputs of the Department of Agriculture and Food, Western Australia's (DAFWA) projects DAW00218 Wheat agronomy systems profitability and DAW00224 Barley agronomy. Appreciation to James Hagan (DAFWA Economist) who provided economic analysis. Acknowledgement and appreciation to Melaine Kupsch, Anne Smith, Bruce Haig, Sue Cartledge, Rod Bowey for technical support and DAFWA's research support units for management.