When was the last irrigation reading taken on your orchard and what was the soil moisture level? How long has the soil been saturated? Is your sub-surface drainage still flowing?
Understanding the moisture levels in your soil profile will be highly valuable in determining your blocks exposure to stress, and assist in understanding the condition of your blocks prior to chemical thinning.
AgFirst’s soil moisture monitoring service has a considerable database on the soil moisture trends in Hawke’s Bay. Our soil moisture data shows a full point through the profile down to one metre depth (field capacity), and a trigger point to show when further irrigation may be necessary.
These three three soil moisture profile readings below show a comparison between the same profile in 2021, 2022 and 2023. It is important to note that this irrigation tube is on a non-cyclone effected block.
In 2023, the soil moisture content is roughly 10 VSM% above full point from 200mm profile depth right down to a metre.
This particular irrigation tube has been regularly monitored, with all readings since the 1st April showing the soil moisture levels above full point even though the property has subsurface drainage. As expected, September 2021 and 2022 both show the profile to be much drier.
Keeping in mind that Impeded drainage or perched water tables will exacerbate any soil moisture issues. Root systems sitting in waterlogged soils will be suffering from lack of oxygen, and as a result the fine root hairs are likely to be shallow and inactive. When the soil profile does finally start to dry out, managing block irrigation is going to be important to ensure moisture levels are correct within the active rootzone.
Meg Becker
Agfirst Horticultural Consultant
