Here we are using a mini disk permeameter to get some idea of how fast the water moves into the soil, and how wide the wetting patterns become. This all helps us to manage salt and nutrients.
We pumped water from the aquifer at an electrical conductivity of 0.8 dS/m. This equates roughly to 0.5 g of salt for every litre of water applied. So when we apply 159 mm of irrigation water we also add 865 kg of salt per ha. We did not measure which salts were in the water, but most of it is likely to sodium chloride. Plants don’t like sodium chloride. We can let it build up a bit in the soil, but eventually we have to apply extra water – more than the plants requirements, to leach the salt out.
The groundwater also contained 30 mg/L of nitrate. So when we are irrigating we are also applying some fertiliser.
On the 'wet side' we applied 159 mm of water, which has 865 kg of salt dissolved in it and this included 11 kg of nitrogen (in the nitrate form).
On the 'dry side' we applied 134 mm of water, which has 686 kg of salt dissolved in it and this included 9 kg of nitrogen (in the nitrate form).
That takes care of the input side of the equation. By collecting water from the wheelie bins - the water that the couve did not use - we can complete the output side of the picture (on a per hectare basis).
On the wet side we collected the equivalent of 18.6 mm of drainage water which had 241 kg of salt dissolved in it which included 11 kg of nitrogen (in the nitrate form).
On the dry side we collected the equivalent of 2.7 mm of drainage water which had 26 kg of salt dissolved in it which included 0.1 kg of nitrogen (in the nitrate form).
We pumped water from the aquifer at an electrical conductivity of 0.8 dS/m. This equates roughly to 0.5 g of salt for every litre of water applied. So when we apply 159 mm of irrigation water we also add 865 kg of salt per ha. We did not measure which salts were in the water, but most of it is likely to sodium chloride. Plants don’t like sodium chloride. We can let it build up a bit in the soil, but eventually we have to apply extra water – more than the plants requirements, to leach the salt out.
The groundwater also contained 30 mg/L of nitrate. So when we are irrigating we are also applying some fertiliser.
On the 'wet side' we applied 159 mm of water, which has 865 kg of salt dissolved in it and this included 11 kg of nitrogen (in the nitrate form).
On the 'dry side' we applied 134 mm of water, which has 686 kg of salt dissolved in it and this included 9 kg of nitrogen (in the nitrate form).
That takes care of the input side of the equation. By collecting water from the wheelie bins - the water that the couve did not use - we can complete the output side of the picture (on a per hectare basis).
On the wet side we collected the equivalent of 18.6 mm of drainage water which had 241 kg of salt dissolved in it which included 11 kg of nitrogen (in the nitrate form).
On the dry side we collected the equivalent of 2.7 mm of drainage water which had 26 kg of salt dissolved in it which included 0.1 kg of nitrogen (in the nitrate form).
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