January 14, 2013
The problem of waterlogging is ever-present in Victoria’s Western District, but one producer is trialling a combination of potential solutions. Wickliffe farmers George and Barbara Burdett operate in an area with 550mm of annual rainfall and 410mm of growing season rainfall. Their problem is the exact opposite of many of Australia’s croppers – too much of a good thing. “With our heavy soils with shallow topsoil, it doesn’t take too much rain to cause waterlogging,” Mr Burdett said. To combat this, the Burdetts have conducted subsoil manuring trials for the past three years, testing the impact of deep ripping and banding chicken manure in terms of improving soil structure and by extension yields. And so far Mr Burdett is optimistic the ripping and manure applications, along with the use of faba beans as a legume phase, is improving his soil. The Burdetts are using faba beans as the pulse phase of the rotation in an area traditionally bereft of legume options, due to pulses being more susceptible to waterlogging than other crops. However beans are the most waterlogging-tolerant of the pulses, and are widely grown in relatively similar climatic zones such as the southern Wimmera, and the initial findings are positive in the Western District. The Burdetts are conducting their research in conjunction with the GRDC and research group Southern Farming Systems (SFS), comparing various manure application methods against synthetic fertiliser applications in high rainfall zone areas of over 500mm. The manuring involves applications of up to 20t/ha of chicken manure in a range of treatments. Using chicken litter is having some impressive results. Previously, phosphorus was applied in the form of MAP at 80-100kg/ha at sowing, but for the past two seasons Mr Burdett has cut this back to just 50kg/ha with the only obvious difference in early crop vigour and no discernible difference in yields – a move that has added up to considerable cost savings. This cut is due to the use of the chicken manure, but it is not solely due to the pure nutrient value of the manure, with Mr Burdett saying the improved soil structure means plants have better access to nutrients at times when they really need it, such as grain fill. “We don’t actually see a huge difference in the trial area in terms of vegetative growth during the year or in the appearance of the crop at harvest – it’s the access to water and nutrients in spring that is increasing the size of the grain and helping the head to fill to its capacity, leading to better yields,” Mr Burdett said. “By applying the chook manure, we’re obviously getting more nutrients, but I think the change in the soil structure and using the plants that we grow on it to maintain the soil structure is going to be the biggest benefit.” Mr Burdett said he was looking to improve soils that have just 10cm of topsoil before becoming heavy clays. “It’s very dense and the moisture just seems to get into it and then can’t move through it, which causes the surface waterlogging,” Mr Burdett said. And there can also be a problem should the season turn dry. “It’s hard for the crops to extract water from the soils because it is so tightly held by the clay.” Previous management options have included early planting to ensure plants are robust enough to deal with heavy winter rain, but this is not an option in years where there is no early break to bring the crop up. Raised beds are also an option but, with 550mm annual rainfall, would not be necessary if the soil was better structured. The crop rotation is heavily skewed to the popular Western District trinity of wheat, canola and barley, but Mr Burdett also sows at least 10 per cent of his land to either faba beans or hay oats in order to rotate herbicides for rye grass control, and in the case of the faba beans, provide a nitrogen boost to the soils. Significant yield improvements were recorded in the first year of the trial, with the deep-ripped plots of Revenue feed wheat that were fertilised with 20t/ha of chicken manure yielding 11.9t/ha compared to untreated plots which yielded 7.5t/ha. Yield improvements were again recorded in the second year, however the benefits were impacted by growing back to back cereal crops, with the latter crop hit by yellow spot and septoria, as well as increased competition from annual ryegrass. Even so, it yielded 5t/ha against a control plot which yielded 4t/ha.