The haze of smoke settling across the Wagga region was eminent last night and that haze may stick around for a while longer yet. This is because stubble burning activities are in full swing in an attempt to manage high stubble loads, improve weed control and ensure effective sowing for the upcoming season. Interestingly, despite being rich in biodiversity, the Australian soils are some of the most depleted in the world. So to ensure a bumper crop, season after season we must take very good care of our soils. Burning, however, is not always the most profitable treatment nor the best option when it comes to caring for your soil health. Don’t get me wrong, I understand that occasional, strategic burning of stubble based upon sound agronomic principles can be a valid choice and farmers should have flexibility to use this option when appropriate but it should also be known that there are proven benefits of retaining stubble rather than burning. These are:
- Increases both the amount and activity of microorganisms in soil, resulting in greater soil nitrogen supply in the long-term. This is important because regular inputs of organic matter are required to maintain soil health and optimise biological functioning of the soil
- decreases erosion by lowering wind speed at the soil surface and decreasing run-off.
- Increases in soil water and plant available water by decreasing run-off and increasing infiltration
- Improved soil air and pore spaces for better plant root exploration
- Decrease in off-site leaking/loss of nutrients and pesticides
- Potential increase in the amount of available energy for grazing animals
WHAT CAN YOU DO?
Ground cover should be maintained at a level where at least 50% of the soil surface is protected (this will mean different stubble loads for different crops)
Retain as much stubble as possible to maintain soil structure, provide a store and source of plant available nutrients and promote a wide diversity of soil biota
If controlling weeds is the aim, burning windrows is more effective than burning standing stubble and also decreases erosion risk.
Stubble-borne diseases can be managed without burning by use of resistant cultivars and crop rotation.
Use of zero-tillage when sowing.
NOTE: When moving from burning to cereal stubble retention, there can be an initial tie-up of soil nitrogen as the stubble decomposes, and starter nitrogen may need to be increased at sowing. Over two to three seasons the soil usually adjusts to the new conditions, and in the long-term is able to supply a greater amount of nitrogen for crop growth and yield