Poor seed quality can be a major barrier to high wheat yields, according to a series of farmer trials in the Liverpool Plains of northern NSW
The trials have been part of the Eastern Farming Systems program, supported by NSW Agriculture and growers and the Federal Government through the GRDC. They aimed to identify the major limiting factors on wheat production in northern NSW.
Five growers, known by other growers as good farmers, simply 'did what they always did' when sowing and growing a wheat crop. After measuring a host of factors at sowing, flowering and again at harvest, (see items monitored, right), germination rates were identified as an initial culprit.
"Germination rates ranged from 60 per cent to 90 per cent," says Giles Buder, research agronomist at the Tamworth Crop Improvement Centre. "That's quite a range, and the impact can be seen in effective sowing rates, plant establishment and in the final yield."
The paddocks with only 60 per cent germination rate showed establishment rates of only 35-40 per cent, while those with the higher germination rates had plant establishment rates of 80-90 per cent. Effective sowing rates were more than halved by poor germination (see below for sowing and germination rates).
Crop factors measured in the Liverpool Plains trials
- full soil test including soil nitrate and soil water
- germination rates
- plant establishment (as plants per square metre)
- pest and disease levels (nematodes, crown rot, common root rot)
- dry matter
- leaf area index
- soil nitrate
- soil water
- soil nitrate
- soil water
- wheat grain yield
- grain protein
Plant germination and establishment rates, and soil nitrogen levels, at trial sites on the Liverpool Plains
|Site||Mullaley||Big Jacks Ck||Tambar Springs||Spring Ridge (a)||Spring Ridge (b)||Spring Ridge (c)||Spring Ridge (d)||Breeza|
|Established plants per m²||57||91||74||42||54||45||65||91|
|Effective sowing rate (kg/ha)||27||40||35||20||25||21||30||41|
|Effective N at sowing (kg N/ha)||192||259||186||449||449||417||417||122|
|Soil N applied at sowing (kg N/ha)||15||92||0||0||0||0||0||0|
Quick sprouting test would help
"Simply sprouting some seed on wet cotton wool would have told growers what they needed to adjust their sowing rate by, to still enable them to target high yields," according to Mr Buffer.
Putting aside the disastrous effects of head blight and black tip, it could have been a good year with ideal weather conditions for high wheat yields. For more than one grower, however, low plant populations meant a target yield of only 4 t/ha was possible rather than the 6 t/ha expected from the levels of soil nitrogen and water.
Mr Butler says these trials begin to answer the basic question that growers in the Liverpool Plains have been asking: "Why can't we reliably produce 7 t/ha wheat crops?"
"The rainfall and temperature conditions we have on the Plains, particularly the warm and dry finish to the growing season, mean that 7 t/ha will probably be the exception rather than the rule. However, 5 t/ha should be achievable in most years," says Mr Butler.
"Producing high-yielding crops is more than simply getting decent germination, but the main message for growers out of this year's trials is to check seed germination rates prior to sowing, especially if they are relying on wheat from their silos that has not been quality tested."
Program 3.5.1 Contact: Mr Giles Butler 02 6763 1100