DAW689 - Enhancing the profitability of wheat growing in the Lakes and Great Southern District

Project Start Date 1 July 2000
Project End Date 30 June 2003
Supervisor Name Wal K Anderson (Principal Research Officer)
Organisation Department of Agriculture Western Australia
Contact name Wal K Anderson
Region West
Summary

This project was conducted in 2000, 2001 and 2002. The project was fully supported by a consultative committee selected by GRDC, consisting of an adviser based at Lake Grace, a grower at Badgebup who is chairman of the Southern Grain Growers, a grower at Kulin, and a grower at Holt Rock who is secretary of the Holt Rock Group.

Conclusions

Grain yield responses of up to 1.6t/ha were found with the addition of copper (Cu) on a marginally deficient soil. Yields were severely depressed (0.5t/ha) with the addition of 20kg or 60kg nitrogen (N)/ha without or with the addition of Cu at seeding.

Significant grain yield responses with the addition of phosphorus (P) of up to 40kg P/ha were found, but at no stage were they economical.

At Newdegate in 2001, yield increases of up to 0.6t/ha were found with working the soil 8cm below the seed compared to a no-till system using knife points. Dry conditions and low yields of 0.6t/ha in 2002 found no increases with cultivation.

Leaf diseases (rust and septoria) appear intermittently throughout the region. However, at borderline levels and late stages examined in the project, it was not economical to spray.

Presence of root lesion nematode (RLN) was examined in the project, in conjunction with project DAW623WR. Although there was a large range in nematode numbers between sites and their rotations in 2000, the conditions experienced during the project were not conducive to any useful results.

The low amount and poor distribution of rainfall during 2000 and 2002 led to no grain yield response to the addition of N. In many cases, there was also no increase in grain protein, indicating no additional uptake of Ν when trials were 'top dressed' prior to early tillering.

The potential new soft wheat, HarrismithPlant Breeders Rights (WAWHT2182), and the two standard wheat head types WAWHT2248 and EGA JitarningPlant Breeders Rights (WHT2433) are all superior to DatatinePlant Breeders Rights in yield and grain quality. Although grain screenings were not excessive during the project, the standard head types were found to be relatively stable in the amount of screenings produced. WAWHT2248 is a high protein achiever relative to the clubhead varieties, hence it requires a more defined Ν management to avoid protein penalties.

Datatine's ear number/m2 appear to limit its response of yield to high Ν rates (70kg/ha) on the heavier soil types i.e. clay or loam.

Broad scale trials are a useful extension tool where growers and grower groups are keen to participate. Results from the broad scale trials supported work carried out in small scale plots. Like small scale plots, care must be taken in choosing treatments, design and implementation. Considerable amounts of valuable seeding and harvest time can be taken up by broad scale trials, so the value of small scale plots should not be under-estimated.

Recommendations

The use of soil and tissue testing kits is strongly promoted to understand the basic P, potassium (K), Cu, zinc (Zn), manganese (Mn) and molybdenum (Mo) levels a grower has in his paddocks. If any element is at marginal or borderline levels, potentially high yielding wheat crops may be limited by that element.

In a no-till system, cultivation may provide economic yield increases above those achieved using nutrition or leaf disease ameliorations. Results of project DAW343 should be extended to the Lakes and Great Southern region.

When spraying for leaf diseases, the thresholds and timing of sprays developed through research (Dr Rob Loughman pers. comm.) must be followed to ensure an economical response.

If growing DatatinePlant Breeders Rights on heavier soil following a non-legume rotation, avoid high Ν rates. Up to 30-35kg N/ha appears to be economical on heavier soil types compared to 70kg N/ha on duplex soils

Project Outcomes

Expected Outcome (benefits)

Economic Outcomes

Several areas that could lead to potential cost savings and increased efficiency of fertiliser use were identified in this project. Higher levels of Cu may be required than previously thought in high yielding crops in the better seasons. Responses to Ρ fertilisers may be improved when placed at depth below the seed in no till systems or by periodically cultivating the soil at depth. Improved management of Ν to soft wheat varieties can improve the success rate of obtaining protein levels that qualify for price premiums. These findings will enable growers to fine tune their management of wheat crops in the Great Southern and Lakes areas, a region that grows approx. a million hectares of wheat annually. It is estimated that an increase in net profit of $5/ha could result from cost savings and efficiencies identified in this project.

Environmental Outcomes

More accurate applications of Ρ and Ν fertilisers to wheat crops according to their yield potential should eventually reduce the losses of these nutrients to streams, thus reducing the threat of eutrophication.

Social Outcomes

More profit for growers can mean more local employment and better facilities in rural areas.

Achievement/Benefits

Overview of Project Achievements

Project aims

  1. Determine nature, extent and amelioration of biotic (diseases) and abiotic (nutrition, soil type) limitations to wheat yields and genotype interaction in the Lakes and Great Southern region of Western Australia (WA).
  2. Undertake grower participatory broad scale trials to extend the information generated in previous studies to enhance grower returns in the Lakes and Great Southern region of WA.

Achievements

Nutrition

Average wheat yields have increased to more than 2t/ha in the Great Southern and 1.75t/ha in the Lakes region. Some growers are now achieving more than 3.5t/ha and they are concerned that wheat yields may be limited by marginal nutrient deficiencies. The extent is not known, but the problem is becoming more evident with numerous reports of 'canola syndrome'. Research undertaken in South Australia (SA) has found that there are some wheat lines that differ considerably in the efficiency of Cu, Zn, and Mn uptake (Prof Zed Rengel, pers comm.). The internal differences in efficiencies of WA lines are largely unknown, and may be the reason for yield stability or lack of it.

In 2000 and 2001, seven trials were set up to examine the extent of nutrient deficiencies and genotype interaction (in conjunction with DAW635). In 2000, the average yields of these trials ranged from 0.6t/ha to 2.7t/ha, well below average due to the dry conditions. Under these conditions, there were three sites that had significant grain yield responses to P with varying soil Ρ tests and one to N following two years of a non-legume crop. Grain yields were responding up to 20kg P/ha on a soil test of 20ppm of a very low Ρ sorption category soil. This result, however, was likely to be confounded with the dry conditions and Ρ being less mobile. No significant interactions were found between genotype and treatment to indicate any internal differences in the efficiency of BrooktonPlant Breeders Rights, StilettoPlant Breeders Rights and WestoniaPlant Breeders Rights.

A huge response of 1.6t/ha to Cu was found at Tunney in 2001. Results from whole tops indicated that Cu was marginal to low (2.3ppm) at mid tillering. However, in an attempt to increase grain yields through the addition of N, yields fell (Figure 1, Attachment 5). The results show the classical interaction between Cu and Ν where high biomass due to the Ν severely depresses the Cu concentration in the plant (R. Brennan pers comm.). It is suggested that a Cu level of greater than 2ppm is adequate for healthy plant growth (The Wheat Book: 2nd edn., P. 97). Although only whole tops were measured in the trial, it would appear that for yields of more than 3t/ha, tissue concentrations of greater than 2ppm may still indicate a responsive situation for Cu.

A significant variety by treatment interaction suggested that the grain yields of Brookton may be more sensitive to Cu deficiency than CammPlant Breeders Rights or Westonia. However, at no stage did the tissue or grain analysis indicate that Brookton had a lower Cu concentration than Camm or Westonia or any internal differences in efficiency.

Response to Ρ was investigated again in 2001 and 2002 in respect of application rate, type of cultivation and Ρ placement. Grain yield responses of up to 40kg/ha were significant in both years, but they were uneconomic with the largest increase being only 400kg/ha in 2001 (Figure 2a, Attachment 5) or 150 kg/ha in 2002. Figure 2a clearly indicates that cultivation is the main factor limiting grain yield at this site. Figure 2b shows a similar trial on the same site, where to avoid cultivation confounding the results, cultivation to a depth of 12cm was carried out before all the treatments were applied. Placing Ρ with the seed, but cultivating 8cm below the seed was still the highest yielding treatment. There was no difference between cultivation treatments in the dry year of 2002.

Disease

Apart from nutrition, root and leaf disease limitations to crop productivity were identified as being among the highest priorities. Collaboration was sought between the GRDC project 'Impact and management of Root Lesion Nematode in WA (DAW623WR)' and this project.

In 2000, the presence of RLN was examined under the nutrition trials. Although at no stage did the plants appear to be damaged, there was a large range in nematode numbers between sites. Sites following lupins had extremely low levels of 50 RLN/g to 400 RLN/g root dry weight, pasture had moderate levels of 3,300 to 15,000 in a canola/wheat/wheat rotation or 31,000 RLN/g dry weight following canola. Rotations are important in controlling the initial level of RLN burdens, but the relative reduction in yield is unknown.

The presence of RLN was examined under several trials in 2001 and 2002, but the levels were considered too low to continue any further research.

Each year, the project had a site to investigate the extent and effect of leaf disease (rust or septoria) in the Lakes and the Great Southern region. The year 2002 was the only year where there was an incidence of stripe rust high enough to consider spraying with fungicide. No significant or economic yield responses were found. Not a surprising result given the late spraying time, flowering, and the dry conditions experienced at Newdegate in 2002. Leaf disease was also examined in the broad scale trial, but no responses were found (see section below).

Nitrogen

Nitrogen rate trials were conducted each year to examine the issue of low grain protein levels throughout the region. Only one trial out of six responded to the addition of N. Lack of rainfall severely limited any grain yield response to Ν in the Lakes region. In 2000 and 2001, there was also no grain protein response to the addition of N. These trials had additional rates of Ν topdressed four to six weeks after sowing (WAS). Nitrogen uptake in plant material at flowering indicates that the additional Ν may have been lost through volatilisation or just not taken up with the dry conditions. In 2002, all Ν was applied at seeding but with the dry conditions again, only grain protein responded to the addition of N, starting at a minimum of 12%.

Yield stability

It was anticipated that with the aid of a grower or grower group, a detailed GPS paddock monitoring study of a high yielding variety versus a 'proven variety' would be undertaken to examine the yield stability of varieties over a range of soil types. Variety trials would also be established on two different soil types within the paddock to further examine if variety rankings may change. Unfortunately, due to problems with the GPS technology, seeding problems, late breaks and dry conditions, no useful data were obtained to examine variety stability.

Soft wheat agronomy

Previous research in DAW407WR indicated that downgrading due to excessive screenings (small grains) was influenced more by variety. Varieties with smaller grain size, such as soft wheat (TincurrinPlant Breeders Rights and DatatinePlant Breeders Rights ), are more prone to excessive screenings. Soft wheat production in the Great Southern region has fallen from a peak of 367,000t in 1997/1998 to 320,000t in 1998/1999, with approx. 30% downgraded to feed, primarily due to screenings. It is anticipated that the release and adoption of a number of potential clubheads and standard head types will reduce this fall in soft wheat production (e.g. EGA JitarningPlant Breeders Rights). These varieties yield 10%-12% higher than Datatine and the grain size of the non clubhead varieties is larger than the existing clubheads.

Three potential soft wheat varieties were evaluated over the duration of the project. HarrismithPlant Breeders Rights (WAWHT2182, released 2001) is a clubhead, while WAWHT2248 and WAWHT2433 (EGA Jitarning, released 2003) are standard head varieties. Australian Hard (AH) varieties yielded as well or significantly higher than Datatine, with the only exception being Harrismith when exposed to high levels of stripe rust.

All three varieties are superior in grain size or small grain screenings, particularly the standard head varieties. Although the level of screenings was not excessive during the project, Figure 3 (Attachment 5) does indicate different relationships between grain size and screenings for the two head types. The standard head varieties WAWHT2248 and EGA Jitarning have a larger kernel and a 'flatter' slope compared to Datatine and Harrismith, which has a smaller average kernel weight and a 'steep' slope. Grain weight is not stable for both head types, but the proportion of screenings for the standard head type is. A point of interest for EGA Jitarning is that given its late maturity, it is assumed that EGA Jitarning would not be so stable for screenings. The clubhead types, Datatine and Harrismith, have similar slopes, but Harrismith performs slightly better than Datatine due to its larger average grain size.

WAWHT2248 tends to have higher protein than the clubhead varieties. Table 1 (Attachment 5) shows that although WAWHT2248 was the highest yielding variety, it was more likely to incur a dockage or be downgraded due to high protein. This variety requires a lower rate of N than the clubhead varieties to achieve a required protein content of less than 9.5%, but it will be to the detriment of yield. This trend is not as clear for EGA Jitarning and will be investigated further in project DAW00012.

The efficiency of N use was similar for all soft wheat varieties evaluated in the project. However, in 2001 and 2002, Datatine's yield did not respond to additional N at the higher rates of 70kg/ha on the 'heavier' or clay soil types (Figure 4, Attachment 5), when Harrismith did. Yield component data suggest that Datatine reaches a 'maximum' ear number/m2 at a lower Ν rate than Harrismith on the 'heavier' soil types.

Unfortunately, Harrismith was found to be very susceptible (VS) to the recent stripe rust race and is now not recommended. WAWHT2248 is still being evaluated for a suitable rust management package given it is susceptibility to stripe and leaf rust.

Broad scale trials

A total of 10 broad scale trials were designed between 2000 and 2002. The trials primarily investigated the response of varieties to the addition of N. Other treatments included fungicide, K, P and variety performance.

The seasons provided the greatest challenge to the success of these trials. In 2000, the June start to seeding meant growers had too many commitments in their own seeding program to undertake the broad scale trials. Dry seeding was considered as an option in 2002 when the break was late again. It would have been successful if more rain had been received during the growing season (122mm in total). The site was following lupins and had a very low weed burden.

Only one broad scale trial out of the final three sown showed an economical response to the addition of Ν as urea. This site was sown mid May following canola i.e. a responsive site compared to following pasture or field peas with yields of more than 4.5t or 5.2t/ha, respectively. In the latter case, the two N rates considered, 30kg and 50kg N/ha, may have limited the yield. However, yields of this magnitude are rarely achieved in the Holt Rock area, hence a 'top up' had not been considered. Flexi Ν was used as the Ν source in the Newdegate broad scale trial, applied seven and 11 WAS. The dry conditions during June and July and the late application may have restricted grain yield response to Ν, but there was a significant grain protein increase of 0.5% for every 25kg N/ha, suggesting that the Ν was taken up. A small plot trial in the area had no grain yield or protein response, suggesting very little of the Ν applied as urea at tillering was taken up.

Two broad scale trials looked at the response to the application of fungicides. In 2001, the foliar fungicide treatments were not applied due to the lack of disease (septoria or rust). In 2000, there was leaf rust and some septoria nodorum blotch (below levels currently recommended to spray). There was no significant grain yield response to the application of Tilt®# or Triad®#. This was possibly due to the late timing of the fungicides for the leaf rust on Stiletto (ear emergence was complete).

Other broad scale trials found no grain yield response to the addition of Ρ or K. Even with grain yields of 4.5t and 5.2t/ha, Ρ was not limited with a soil test result of 39ppm of low Ρ fixing. This trial could have been conducted on an 'average' Ρ site (25-30ppm) to ensure more of a response. Alternatively, the K levels were low (43ppm) at the broad scale trial looking at the response to Κ, but the trial design may have emphasised any site effect, but not Κ effect. A small scale trial at Katanning also found no significant Κ response, but the overall yield increase was more than economical. Again, the trial design of 03GS82 should have been different to more accurately detect a Κ response.

Growers were very keen to test a number of varieties on their properties and with their machinery. Rankings of the varieties were very similar to those achieved in small plot trials in the region. Problems only arose when a variety had a low germination percentage, making it difficult to compare with other varieties at higher plant densities.

Extension activities

Field walks were conducted throughout the project at Gnowangerup, Tunney and Newdegate. Field days were held at the Great Southern Agricultural Research Institute (GSARI) and Newdegate Research Station. Crop Update talks were conducted in Perth, Lake Grace and Katanning.

Other Research

Low yield potentials in this project prevented investigation of whether nutrients are becoming limiting at the higher yields and under the no-till system. Extension of the GRDC project DAW716WR 'Improving fertiliser advice for no-till and wide row spacing cropping systems' should provide answers under more average seasonal conditions.

Examine the various methods to ameliorate soil structure decline as a limitation to wheat yields.

Additional Information

Attachments

1. Crop Update paper - Maximising performance of wheat varieties.

2. Crop Update paper - No-till copper, phosphorus and zinc experiments.

3. Manual on grower participatory broad scale trials in the Lakes or Great Southern region (2000-2002).

4. Supplementary data.

5. Figures and Table.

Published Date 13 July 2018
PDF Download PDF Version
Attachments
Disclaimer Disclaimer
Go back to listing page