Residue management and the techniques that improve soil health and water retention
Residue management is the process used to manage crop residue in between harvesting one crop and sowing the next. In dryland farming this is especially important due to the lack of natural rainwater and the risk of declining soil health. Having optimum soil health provides the best opportunity to produce high yielding and quality crops. Maintaining soil organic matter, the soil that arises from the decomposition of the crop residue, provides the nutrients for the next crop’s growth including the all-important nitrogen.
Over the last decade, tillage practices have been evolving in response to environmental and sustainability factors. The importance of maintaining and increasing soil health, reducing the risk of erosion from wind and water, and boosting water efficiency, are all at the forefront of farmers minds.
What is residue management?
Residue management is the practices that a farmer undertakes between seasonal crops to improve soil health and maximise water retention. Given that the vast majority of broadacre cropping in Australia is classified as dryland farming, water retention is an important aspect of farm management. Conserving moisture is crucial for crop growth, so where there are significant periods of low rainfall, residue management techniques play an integral part to preserving any moisture you can.
Maintaining and improving soil health is just as important for yielding quality crops. Soil organic matter which produces the carbon and nitrogen that a crop feeds off, can be protected from water and wind erosion by implementing residue management techniques. It is important to achieve optimal pH levels in the soil and there are several techniques that can be used to help achieve this. What is optimal can depend on the growing environment and farm conditions. For example, some areas in Australia are more prone to acidification, meaning maintaining nitrogen becomes more challenging. The CSIRO reports that other areas are prone to water repellant soil issues because of the sandy surface texture within the soil. The breakdown of organic matter causes waxy compounds to dry out the surface soil.
Residue management techniques
There are several techniques that farmers can adopt to manage crop residue on dryland farms. Techniques that assist in improving soil health, retaining moisture and reducing soil erosion, will all help to increase crop yields from season to season. The amount and condition of crop residue, crop rotation systems, the available machinery and equipment, and the individual farmer approach, can determine which techniques are more desirable than others.
Retaining crop residue
Leaving crop residue on the soil surface helps protect against erosion, reduced soil quality and water evaporation. The remaining residue breaks down over time and provides nutrients and soil organic matter to promote a healthy base for the next crop’s germination. As the residue decomposes, the nitrogen is immobilised by soil microbes and then subsequently mineralised to provide an inorganic form of nitrogen that is essential for plant growth.
The Department of Agriculture, Forestry and Fisheries reported in their 2022 Agriculture Snapshot, that many broadacre cropping farms are now retaining stubble and minimising tillage.
Incorporating crop residue
Incorporating the crop residue back into the soil after harvest is one technique that helps maintain and increase soil structure, organic matter and soil fertility. By decomposing the crop residue quickly, there is less time for nitrogen to be dispersed into the atmosphere and more time for organic nitrogen to be turned into mineral nitrogen.
Utilising the rich soil organic matter that is left behind after stripping, fosters a healthy germination of the next crop. Traditional tillage such as ploughing and harrowing can be used to break up the soil and incorporate it back into the ground. Or no-till practices can be used whereby seeds are planted directly into the undisturbed soil using a specialised seeder that cuts through the residue.
Livestock grazing
Grazing livestock on the crop stubble helps remove the residue whilst providing nutrients to the soil through animal waste. The management of grazing needs to be closely monitored to avoid over grazing and the compacting of the soil from constant livestock movement, especially in the thoroughfares to dams and gateways. Grazing with low stock numbers and close monitoring doesn’t appear to have a detrimental impact on the future crop yield.
Composting crop residue
Breaking down and recycling the nutrients and soil organic matter by composting the crop residue, is an effective way of maintaining healthy soils whilst reducing waste. Windrowing can be used to create piles of the residue to allow moisture and oxygen to breakdown the organic matter. Greenhouse gases are reduced as the carbon and nitrogen is put back into the soil rather than being released into the atmosphere.
Burning crop residue
Burning crop stubble is a quick and effective way to remove crop residue. However it does negatively impact on air quality and can reduce soil fertility. The soil can dry out and lose its carbon matter that is needed for water retention. On the upside, it does help control pests and weeds. Burning off stubble is reliant on appropriate weather conditions. Cool and still evenings are the ideal time to burn.
Cover cropping
Planting cover crops like cereal rye after harvest helps reduce wind and water erosion, suppresses weeds and adds additional organic matter to the soil including nitrogen. Cover crops can be planted using conventional tilling such as ploughing and harrowing or no-till techniques by planting the cover crop seeds directly in over the harvested crop residue. When the next cash cropping season comes around, this cover crop is then stripped by mowing or slashing.
What are the benefits of residue management?
There are several benefits of using residue management techniques in dryland farming. These include improved soil health, reduced soil erosion, improved water retention and increased crop quality and yields.
By implementing effective residue management practices, you will improve the soil structure and prevent the soil from being eroded. The nutrients that remain in the healthy soil, will help produce a sustainable, healthy and fertile base for growing a quality, higher yielding crop.
AusCut services the cropping industry by manufacturing innovative and high-quality mowers and slashers that can be used for crop residue management and maintaining sustainable farming practices. Contact one of our friendly team members on 1800 517 417 to discuss the most effective way to manage your crop residue.