13 December 2017
Cereal crop stubble at Briandra near Mingay Vic requires careful management with stubble loads from 6-8 t/ha of barley and wheat. Owner’s Brian and Sandra Wilson aim to manage crop residue to minimise machinery issues at seeding, return nutrient value to the soil, reduce allelopathy and where possible maximise the feed value of the stubble during the Feb-May feed gap in their grazing enterprise.
Over 20 years Brian has implemented on-farm trials on crop stubble to assess the benefits of varying management practices, including cutting heights, incorporation, burning, mulching and biological residue management*; the application of specific biology (digest fungi) to stubble post-harvest to promote breakdown of cellulose and nutrient return to the soil.
Initial trials in 2004 of the digest fungi stubble treatment demonstrated significant yield improvements to the following canola crop; a minimum 39% yield increase over all other stubble treatments. The trial was undertaken in-conjunction with Southern Farming Systems at Briandra.
Brian comments “The trial showed the benefit to the next crop when breaking down stubble with the digest fungi treatment. In comparison to incorporation and incorporation with urea, it increased the following crop yield outcome significantly.”
“Previously in years with wet and warm autumns, allelopathy caused by acetic acid exudates, severely affected the next crop. Since using the digest fungi on cereal stubble we haven’t had allelopathy, even in wet and warm autumns.”
Other benefits include increased feed value cereal stubble for stock. The fungi in the treatment are designed to break down the cellulose component of stubble, which is often hard to digest, which improves the palatability of the residue to stock and increases the nutrient value of the stubble as a feed source.
“We get a lot of feed value from our barley stubble with the digest fungi treatment. As an example, in 2015 we ran mature age ewes at 18 DSE on barley stubble we had treated post-harvest. The ewe’s maintained condition and required no supplementary feed from December 2015 through to June 2016 when the paddock was prepared for the next crop. Over the years we normally average 14 DSE during these months on treated stubbles. The nutrient value and palatability of treated stubble is ideal for keeping stock maintained during the seasonal feed gap.”
Brian has also observed results of a part paddock trial, where sheep preferentially graze the areas of stubble which have been treated with the digest fungi, while untreated areas are still standing.
The picture above highlights the improved palatability to stock where the digest fungi has been sprayed; a two metre strip the length of the paddock was overlapped and received a double dose. The picture demonstrated the sheep’s strong preference for grazing this area.
Brian comments “There are multiple benefits including handling of stubble at seeding, because the stubble becomes brittle and breaks up easily. Feed value, especially from barley stubble, which helps address feed gap and minimises supplementary feed requirements. Improved soil quality by returning more nutrient and carbon from stubble back into the soil.”
“Together with stubble treatment and using humates and biologic blend, our soils have changed markedly in physical and chemical properties, we have seen significant soil structure improvement.”
The fungi in the treatment are designed to breakdown the cellulose component of stubble and through this process will normally return three times more nutrient from stubble than with incorporation of stubble only. Increasing the nutrient return from stubble to the soil builds the base for the next crop yield to benefit.
Biological residue management involves the application of specific biologicals (fungi) and their food sources to stubble post-harvest.
Utilising specific fungi species speeds up the breakdown process, it acts by breaking down the cellulose component, stubble becomes brittle enabling easy handing with seeding machinery.
Biological residue management is applied as a liquid spray to stubble with a boom spray. It can be applied immediately following harvest, a light rain or heavy dew event. For optimal results apply to rolled or incorporated stubble to maximise contact between soil and stubble.
The liquid combines a number of fungal species selected from Australian soils for their cellulose digesting functions and to be hardy and drought resistant. Combined with the biological component are stimulants and nutrients the fungal species require.