Waterlogging, can you speed up recovery?

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Waterlogged soil

As many farmers across eastern Australia continue to battle well above average rainfall, many are faced with waterlogged and flooded properties, impacting soil, plant and stock health.

Depending on your farming system you will either want to recover pastures for hay, silage or grazing, or you will want to repair soil health for a future crop.

Although research is limited, we have two sources which say soils can manage up to 14 days inundated without serious damage to soil health, but after this time there is a disruption to the soil microbiota.

During flooding, soils become saturated with water, changing soil conditions from aerobic to anaerobic thus altering the soil microbiota. This combination results in oxygen-depleted soils, microbes decreasing in numbers and less nutrient solubilisation.
Reduced oxygen levels create soils with unavailable essential nutrients such as nitrogen, manganese and sulphur, which are highly leachable. There is also a general reduction of all nutrient availability due to the shift in the types of active microbes in the soil which normally solubilise nutrients. Basically, your non-leachable nutrients are there, but your soil life comes to a standstill and they are unavailable to the plant.

The disturbance to oxygen levels, microbiota and nutrient cycling can all lead to further soil health issues such as compaction, structural damage and poor plant health.

Over time nature will sort itself out and the native soil biota will return to balance. While prior preparation (ie building soil carbon to increase water infiltration and buffer soils against adverse conditions) provides the best results, there are steps you can take to speed up the process of soil recovery.

If you are looking to help pastures on their way to recovery, applying a plant biostimulant once the water resides (like NutriSoil) as a foliar will help in a number of ways –

• NutriSoil increases plant photosynthesis, so plant roots will be pumping out more exudates (sugars) feeding the soil biota and helping return balance to the soil ecology
• NutriSoil contains billions of microbes in the right balance, these will be taken up by the plant leaves and delivered to the soil via the plant roots
• NutriSoil contains plant available nutrients and other secondary metabolites essential to healthy plant function, assisting the plant to grow bigger root systems and biomass

The second crucial step in helping soils recover from waterlogging is growing a diversity of plants. The relationship between plants and soil microbiota is symbiotic. Healthy growing plants, and diversity of plants, is necessary to create diversity in soil biology, and beneficial insects. Both below and above ground biology and insects are essential to healthy plants which are more resilient to environmental pressures such as disease, pests and climate.

If you have the opportunity to sow a multispecies crop, it’s a great tool to break up soils compacted from floods and they feed lots of different microbes in the soil. The multispecies crop could be brown or green manured prior to a cereal crop in Autumn, or once fully established (ie allowed to develop a big root system) it could be grazed. Using NutriSoil as a seed inoculant will provide a diversity of microbes and secondary metabolites around the seed, protecting it from pathogens and solubilising nutrients for the seed to have in the right ratios, as it needs it.

Root biomass will be key in your recovery from the high rainfall and flooding events many are experiencing. The bigger the plant roots the better, as they hold the soil structure together by increasing aggregation, stimulating microbial activity and increasing organic matter in the soil, which can turn into carbon.

The NutriSoil team is always available to talk through your situation, and if we can’t answer your question, we know someone who can.

Call us today on 02) 6020 9676 or send an email to marketing@nutrisoil.com.au

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