Overdependence On Agrochemicals
The Effects of Windrow Burning
The project is primarily focusing on locally relevant research utilising two harvest weed seed control options, narrow windrow burning and the EMAR chaff deck or a farmer made equivalent. Both of these options provide a low cost method of controlling weed seeds . The yearly activities included
one farmer led windrow burn
one paddock harvested incorporating an EMAR chaff deck, or farmer made equivalent.
Two separate farms were chosen for each method of weed control; two harvest weed management sites and two control sites. An investigation was conducted using the EMAR chaff deck at North Parkes Mine as well as the windrow burning data being collected for the season.
The data from these two sites is currently being analysed and will distributed to our members this year.
The two above images show how beneficial windrow burning can be in retained stubble systems. The image on the left indicates that the weed seeds have been condensed within the windrows whereas they have been distributed by header spinners in the image on the righthand side. By condensing the weed seeds into the windrow we are providing a hostile environment for a weed to germinate under. In this particular case the germination event occurred after summer rains. Even without burning there is a significant reduction in the levels of viable seeds as they are subject to decay and breakdown.
If you would like some additional information regarding the project feel free to email us at cwfs@dpi.nsw.gov.au or contact Diana Fear 02 6895 1016.
Sowing Pastures and Biodiversity – What We Want Versus What We Get
By Caitlin Langley
Farmers and managers understand that one of the keys to the reduction of weed populations and increasing drought tolerance in pasture is getting away from conventional monoculture. Indeed many are progressing to the idea that by having multiple grass varieties in a pasture system by investing in greater pasture biodiversity it will encourage long term persistence. Biodiversity in pasture systems suppresses competition of unfavorable varieties that are either less palatable to livestock, as well as accounting for variation in the landscape.
When considering the investment such as establishing a new pasture, it may be that you are offered a range of options, including complex mixtures that will promise to achieve biodiversity. But how many of these selected varieties of plants ultimately survive to maturity when competing for resources during early growth establishment is often held to question, particularly in the instance of products such as the complex ‘shotgun mixes’.
What stands to question is if in the instance of establishing new paddocks, is using such mixtures for establishing pasture achieving efficient persistence for all species included? For many, the approach to establishing biodiversity is by sowing up to 7 to 8 species and ostensibly leaving the paddock to do the rest. But how effective is this method, and how uniformal is success for all selected varieties?
Diversity of plant species in Australian grasslands has been the subject of extensive ecological studies over the last 25 years its primary focus has been that relating to biodiversity and its consequences. And while most of these studies comprehensively support the fact that in the instance of established pastures increased biodiversity results in greater plant productivity and and increased nitrogen (Hector et al 1999), other similar studies concluded that drought resilience and long term stability were also increased with biodiversity.
In a study conducted in the permanent pasture zone in southern NSW within the Murrumbidgee and Murray catchments in Spring 2005, a survey of 61 paddocks on over 35 farms was conducted to investigate persistence of establishment of new paddocks. In the study it was shown that despite farmers having sown on average 5 species per paddock, in most cases only two species could be found. In addition to these findings is was shown that in all of the paddocks surveyed that there was no appreciable persistence of the 5 species sown.
So aside from potentially ‘throwing away’ money in sowing species that were found in these studies to be unsuccessful at persisting to maturity in new paddock systems, does it then follow that there is a diminished productivity when paddocks sown with these multiple varieties experience the loss of the non-persistent species?
A further study of phalaris – the most persistent perennial species, demonstrated two significant factors relating to this question. The two discoveries were that pastures contained more phalaris if they were sown with fewer or no other perennial grass species, and were well fertilized.
So does it then come down to commercial interests driving the sale of multiple varieties for sowing new pastures? While this might not be the definitive answer, there is little (if any) legitimate studies that are able to provide evidence that it results in successful germination of all of the selected species. It is important to note that this particular study is region specific and may not be able to be readily applied to other regions, but it is worthwhile considering that the evaluation of many species selected by agronomists for these complex pasture mixes are usually evaluated in monoculture plots for their suitability – that is to say, it does not necessarily follow that these varieties are suited to or even complementary to growing with each other when put in an uncontrolled environment when they are potentially competing for resources.
In conclusion, while it is proven and acknowledged that in established pasture systems biodiversity leads to optimal persistence, it is important when considering pasture mixtures for establishing new pastures that the focus should be the persistence of the individual species best suited to your specific farming system, and for some farmers choosing to stick to simpler mixtures could be the key to establishing a robust pasture.
Article source:
Virgona, J., & Hildebrand, S. (2007)
“Biodiversity and sown pastures: What you sow is not what you get”
Proceedings of the Grassland Society of Southern Australia, Echuca VIC
Weed Suppressive Wheat Genotypes
Herbicide resistant weeds and the overdependence on agrochemicals are on the rise within central western NSW. For example, the glyphosate resistant weeds that are now quite common within Australian farming systems include fleabane, annual ryegrass, barnyard grass, liver seed grass, windmill grass and brome grass just to name a few. Within Australian farming systems, weeds are having the largest impact on yield in comparison to pests and diseases. In Australia, alone weeds cost the agricultural industry about $4 billion dollars per annum in lost productivity and decreased grain quality.
This significant cost to the system has resulted in the development of wheat cultivars with an inherent competitiveness against herbicide resistant weeds. Competitive crop genotypes have the enhanced capability to access light, moisture and soil nutrients in a limited space. With genotype competiveness and weed suppression in mind, a trial was conducted in Condobolin NSW.
The core aims of the project were:
To assess the competitive nature of Australian wheat genotypes within the southern grains region of NSW.
To assess the impacts of environmental factors such as moisture and temperature on the weed suppressive nature of wheat.
To assess and measure wheat metabolites involved in weed suppression.
To measure the suppression of weeds by wheat stubble post-harvest.
In the first year of the experiment, it was demonstrated that the genetically diverse wheat cultivars performed differently in the two separate trial locations at Condobolin and Wagga Wagga. The varying rainfall patterns allowed for significant differences in crop biomass, weed counts as well as biomass between cultivars.
The results proved that even though the suppressive nature of wheat is driven by genotype the environment will also have a significant impact on the suppressions success. The cultivars Espada, Condo and to a lesser extent Janz performed well in both regions. At Condobolin, Janz CI produced the highest level of biomass while Wedgetail produced the lowest followed by Condo, Whistler and Gregory. In regards to weed suppression within the Condobolin area, Condo proved to be the most effective genotype for reducing weed biomass
Additional field experiments will be conducted over the next three years to determine the impacts of year and location on wheat cultivar performance and weed suppression.
Mwendwa.J, Weston.L.A., and Brown.W.B Mechanisms of weed suppression in early vigour and weed suppressive wheat genotypes. 1 Graham Centre Of Innovation (NSW Department of Primary Industries and Charles Sturt University), Wagga Wagga, NSW Australia 2015
Understanding the Influence of Row Spacing and Direction in the Mallee
A recent two-year trial has produced encouraging data to help Mallee farmers understand the role that row spacing and orientation play in crop performance and weed control.
With insight from trials undertaken in Western Australia and New South Wales, Birchip Cropping Group has recently completed a project to investigate the influence of row spacing and orientation to manage weeds.
The trial aimed to determine whether sowing direction and row spacing could be used to reduce grass weed pressure and what impact they have upon crop performance, specifically in Mallee growing conditions.
In 2015, a trial plot was established in a farmer’s paddock at Jil Jil, 23kms north of Birchip. Tame oats were broadcast as a weed treatment before seeding and established at 42 plants/m². Mace wheat was sown on the 23rd
May using knifepoints and press wheels at 22.5cm (9 inch), 30.5 (12 inch) and 38cm (15 inch) row spacing, with a target plant density of 150 plants/m². In addition to the different row spacing, the trial plot included rows sown in a northsouth and east-west direction.
Encouraging early season rainfall events resulted in good crop and weed establishment across the trial site. However, the season ended as a decile one, with much of the wheat failing to tiller and low overall yields. Between 30% and 50% of the oats died, with the remaining oats being short with only one or two panicles.
The trial was monitored with incrop assessments including crop and weed counts throughout the growing season, as well as grain yield and quality testing after harvest.
