Up to 98mm of rain needed to bring soil moisture deficits back to zero

Up to 98mm of rain is needed in some areas of the country to bring soil moisture levels back to field capacity, according to figures for July 17 from Met Éireann.

The extreme deficit will continue to hamper crop growth and development, although cooler conditions this week and small amounts of rain at the weekend were welcomed.

Soil moisture deficits (SMDs) are recorded on well-drained soil, moderately-drained soil and poorly-drained soil by Met Éireann.

The SMD is the amount of rain needed to bring the soil back to field capacity.

To put SMDs into perspective, a field is at capacity at a SMD of zero; a field is at saturation when the SMD is -10.

SMD readings can be seen in the images below. There is variation across the country, but a clear difference can be seen between readings in the north-west of the country and the south-east of the country.

The majority of SMD readings from Co. Dublin to Co. Waterford are at 90mm or more on all three soil drainage types, highlighting that 90mm of rain is needed to bring the soil to field capacity.

Image source: Met Éireann

SMD figures in the midlands are in the high seventies and eighties, while figures are significantly less in the west and north-west of the country.

The SMD at Malin Head, Co. Donegal is 45 for well-drained and moderately-drained soil, while 50mm of rain is needed to bring soils back to field capacity on poorly-drained soil.