Friday, August 29, 2008

Improve Soil Carbon for Higher Yields

Benefits of building soil organic matter go beyond sequestering carbon.

Increasing plant-available water capacity, maintaining better soil structure and improving yields were important benefits from building soil organic matter according to a key speaker at the Grains Research and Development Corporation (GRDC) Update at Manangatang on August 19.

Dr Peter Fisher of the Victorian Department of Primary Industries told more than 100 growers attending that while soil organic carbon levels could be boosted by increasing soil organic matter, the benefits went beyond measures to reduce climate impacts. Dr Fisher said trials at irrigated sites in northern Victoria and southern New South Wales found that increasing soil organic matter throughput – the rate at which it is added to the soil to be broken down and recycled – over several years would boost soil carbon levels. “At the paired sites studied, every tonne per hectare per year of extra above- and below-ground organic matter – maintained for 10 years – resulted in approximately 0.2 per cent higher soil carbon,” he said. “This increase is greater than most carbon modelling suggests.” Dr Fisher said the experiment had demonstrated a clear relationship between higher levels of organic soil matter and higher yields.

“Yield benefits from higher soil carbon values are very hard to measure and there is little reported data,” he said. “This is because soil carbon changes occur slowly, and thus the impacts are difficult to separate from other factors. “These trials compared long-term yields from paired paddocks with low and high soil organic matter levels.

At sites where wheat and canola have been grown for the past 10 years, the average yields for each paddock with high organic matter levels were equal to or higher than yields from paddocks with low organic matter. “The results are quite startling, and although it’s not scientific proof, the data does constitute convincing evidence for growers.”

While this data covers only the typical temperate grain farming areas, it is indicative of the facts.......improving the soil carbon can lead to higher yields. Other work also investigated issues surrounding fertiliser usage, availability and soil retention of nutrients. More benefits.

Can you afford NOT to consider using management practices that build soil carbon?

[partially sourced from GRDC media reports]

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