In 2009, 95 farmers in the mixed cropping zone of NSW were surveyed in relation to their use of pasture species with perennial pastures being a key focus. The survey found that 52% of the land was under crop, 29% contained perennial pasture and 19 % contained annual pastures.
Stemming on from the survey was a series of large scale experiments, three at Ariah Park and one at Brocklesby in southern NSW in 2009. Two further experiments were also conducted in 2010 to compare the effects of cereal crop sowing rates on the establishment of perennial lucerne, phalaris, cocksfoot and chicory. The persistence and productivity of these species was monitored for two years after sowing.
Comparing the dry and wet years
It is a typical rule of thumb that when cover cropping farmers reduce the sowing rates of the cereals, which was the case at Ariah Park. Although this wasnt the case in the higher rainfall area’s at Brocklesby where the barley rates didn’t differ when sowing a cover crop. As expected the drier years resulted in a lower survival rate of the pasture as well as a significantly lower level of dry matter production when compared to the stand-alone pastures. Even during spring for the wetter years there was still a clear difference between the cover crop perennial pasture and the stand-alone perennial pasture.
Perennial pastures
Looking at the survey it was decided that it was important to distinguish between the proportion of farms that have a particular species present. This allows us to determine the popular pasture species in southern NSW.
Lucerne: Lucerne was the most common pasture species grown in the eastern (86%) and western parts (82%) of southern NSW.
Phalaris: After lucerne the next most common pasture species was phalaris, on average 48% of farmers reported growing phalaris.
Native Grasses: The bronze medal goes to native grasses with 35% of the farmers in the eastern zone and 29% in the west growing native grasses. The land that was devoted to growing native pastures is often assumed to be unimproved or naturalised as sowing Australian native pastures may be problematic.
Chicory: Chicory was sown on 36% of the farms in the eastern zone, but only 18% of farms in the west were growing chicory due to its lower levels of persistence in the lower rainfall regions.
Chicory Pasture
Establishing perennial pastures
The majority of farmers reported using cover crops at some point or another to establish pastures. In the Western areas of NSW 69% of farmers mostly or always used cover crops . The main advantages of using cover cropping that the sale of the grain covercrop offset the cost of establishing the pasture. Some farmers also noted that the crop stubble also protected the young pasture seedlings in the year of pasture establishment.
It was noted by NSW farmers that cover cropping in years of low rainfall
often resulted in poor pasture establishment.
Cover cropping in the dry year of 2009: The total annual rainfall for the year of 2009 at Ariah park and Brocklesby was more than 100mm below the long term average.
How did the cereal crop go: The cereal plant populations were heavily influenced by the sowing rate of the cover crop. With the higher pasture sowing rates resulting in less crop plants per square meter. Although there was no difference in crop above ground dry matter or yield between the different sowing rates.
How did the pasture go: All pastures species were successfully established in May to June 2009, with no significant difference in plant populations regardless of whether they were sown with or without a cover crop present. Although for species common to more than one location the populations varied considerably across sites. The impact of the dry spring seemed to be the primary factor that thinned out the pastures grown under a cover crop, in some cases a density of 43 plants per square meter was reduced to a mere 3-4 plants per square metre by the dry spring.
Second year pasture growth: During the second year of pasture growth it was found that the major issue was the weed populations. During the first year choices are quite limited when it comes to chemicals for weed control and there is a much thinner pasture stand that is failing to out-compete the weeds. The density of cocksfoot and phalaris in the second year as also negatively effected by sowing into a dry year.
Cover cropping with annual legumes: Annual legumes were also measured during the experiment although they failed to survive long enough under the dry conditions of 2009 (Ariah Park) for any data to be collected. When data was collected from the other sites it was shown that the cereal crops significantly decreased the level of dry matter production by the annual legumes. In relation to the annual legume seed set there was less than half the seeds produced in order to maintain a robust pasture into the up and coming year.
Sub Clover
Conclusion: Even though there is a financial benefit to being able to strip a cash crop in that year the financial benefit is offset in varying degrees by poor pasture establishment even in areas of higher than average rainfall. Another downfall is the potential for increased weed incursions into the pasture as a result of poor plant densities.
So access to full paper by CSIRO feel free to follow the link Cover crops
