Farmers' Newsletter No 181, Spring 2009

• The delayed permanent water treatment based on the greatest water stress between irrigations reduced water use by 16% and increased water productivity by 11% compared to the conventional irrigation treatment.
• The delayed permanent water practice produced a lower economic return per hectare than the conventional practice but a higher return per megalitre. The economic benefit is strongly influenced by the weed control costs associated with the delayed permanent water practice.
• Research into refining the irrigation frequencies of the delayed permanent water practice, timing of nitrogen applications and confirmation of the results in a different season is required.

Delayed permanent water tested on three farms (796 k)

• Fallowing the field ahead of the rice crop will improve soil moisture content and water saving, improving the chance of sowing and establishing the crop on rainfall moisture.
• On-farm demonstrations showed that rice is able withstand significant periods of moisture stress from establishment through to late tillering.
• Flushing irrigations were successfully managed in conjunction with rainfall to minimise water use.
• Yield results were variable in the 2008–09 season due to heat stress and subsequent cold at flowering.

• Mixtures of Magister (clomazone) and Stomp (pendimethalin) applied post seeding and pre-crop emergence in drill sown rice have demonstrated equivalent or improved control of barnyard grass.
• This combination of herbicides is likely to increase the reliability of weed control in drill sown crops managed with delayed permanent water.

• Landholders with alligator weed infestations have become pro-active in their approach to inspections, herbicide treatments and removal of the weed on their properties.
• With the best winter rains for five years, subsoil moisture is being replaced and it is expected that the incidence of alligator weed regrowth next season will be much higher than in previous seasons.

• Production of seedless watermelons continues to expand with aggressive marketing, improved varieties and increased consumer demand.
• NSW DPI variety trials have demonstrated that many of the currently available varieties are suitable for production in local Riverina conditions.

• Applying nitrogen at stem elongation appears to be the best general strategy for irrigated wheat in fields with low levels of soil fertility. Applying 120 kg N/ha at stem elongation produced good yields with minimal risk of lodging.
• In fields with higher levels of soil fertility, nitrogen application should be delayed until the awns are visible, as this strategy produced the highest yields with minimal lodging.
• Grain protein levels increased with increased rates of applied nitrogen and the application of nitrogen at the awns visible stage was the most effective application time for increasing grain protein levels.
• The main factor affecting wheat yield and grain protein was the amount of nitrogen in the crop, regardless of whether it came from natural soil sources or topdressed fertiliser.

• A new fungicide as been developed which has the potential to offer both fast acting and long lasting control and protection from foliar diseases in wheat and barley.
• In trials in southern Australia, the new product has shown control of stripe rust, leaf rust, stem rust, yellow leaf spot and septoria nodorum in wheat; and net form net blotch, spot form net blotch, powdery mildew, leaf scald and leaf rust in barley.
• Development trials continue in 2009 and an application for registration has been made.

• Canada has been successful in using the herbicide tolerant genetically modified crop technology, achieving higher profits and cleaner paddocks.
• The USA has also had success but the lack of crop rotation, and the continuous growing of herbicide tolerant genetically modified crops is leading to major issues with glyphosate resistant weeds especially in cotton.
• Australian farmers will benefit from access to herbicide tolerant genetically modified canola varieties, which should provide better weed control and yields than the triazine tolerant varieties – but there needs be a diverse rotation that has a two year gap between herbicide tolerant genetically modified crops.
• In conjunction with the new technology, farmers also need to use integrated weed management techniques like pre-emergent herbicides, diverse rotations, rotation of knockdown herbicides and non herbicide methods.

• Better soil moisture retention and better soil health as a result of stubble retention are worth the effort to overcome barriers to adoption.
• Straw spreading at harvest is crucial for effective management of stubble at the next sowing.
• Microbial stubble digestors and the use of compost may have a place in irrigation cropping systems and need further investigation.