October means a shift in attention to harvest and its potential challenges; planning logistics, servicing machinery, storage options and stubble management.
It is well understood that retained stubble provides valuable ground cover and a carbon source for microbial activity and nutrient availability, but it also provides challenges.
BCG research manager Claire Browne said to avoid issues associated with stubble retention such as seeder blockages, poor crop emergence and reduced herbicide efficacy, stubble left standing in the paddock after harvest should be even and at the appropriate length (according to crop rotation and machinery capability), and chaff and straw should be spread evenly across the paddock.
“Cutting height will vary according to crop type and yield, crop planned for the following season, harvest logistics and the capabilities of seeding equipment.” Ms Browne said.
Cutting the crop shorter increases the time needed for harvest; on average, you reduce header speeds from 9.5ha/hour to 5.6ha/hour when harvest height is reduced from 60cm to 15cm.
Additionally, stubble loads, machinery capability, crop type and rotation, and pest, disease and weed burden, all need to be considered when determining stubble management at harvest.
Stubble provides habitat for many diseases over summer and understanding the disease burden of the paddock can assist in making decisions about rotations and stubble management.
To calculate the amount of stubble in a paddock, multiply the grain yield by 1.5 to give an approximate tonnes per hectare of stubble.
While shorter stubble can be beneficial for sowing management, it also can also hinder emergence of smaller seeded crops like canola, due to more straw and chaff being placed between the rows.
BCG, VNTFA, SFS and ICC are collaborating on guidelines and other resources, which will provide growers with information on negotiating the challenges of retained stubble farming systems. Visit thestubbleproject.wordpress.com for more.