Soil type and nutrient availability

Many soils in the northern part of the Waikato region are ideal for growing vegetable crops. Bryan Hart, Senior Crop Manager for AS Wilcox & Sons, explains why Patumahoe clay loam is good for cropping and why growers need to know about soil chemistry.

Question for discussion:

• What does Bryan mean when he says that fertiliser can be locked up by the soil?

Transcript

BRYAN HART

It’s really critical to understand the dynamic of your soil and how it will grow a crop and affect the nutrient availability within that crop life cycle. The soil type here is a Patumahoe clay loam. It’s a red soil of basalt origin and similar to Rangitoto Island, which is derived from a scoria base. So it gives you an idea of how robust that soil is. It’s a soil that has a lot of iron and aluminium in it – silicate bound so very, very rigid chemical crystalline type structure. And what that tells you is it’s very good for cultivation in most conditions throughout the year.

One of the downsides of it is it really binds phosphate very tightly. It’s got a high content of what we call allophane, and so that does mean that, when you’re using certain phosphate-type fertilisers, is that you need to target them very precisely to where your crop’s growing, otherwise you will be wasting that product and locking it up. So we use placement technology to ensure we get efficient use of that fertiliser.

Acknowledgements

Bryan Hart
AS Wilcox & Sons Limited
Interactive soil map viewer, Manaaki Whenua – Landcare Research, licensed under CC BY-NC-ND 3.0 NZ
Still of Rangitoto Island, Matthew Jones, licensed through 123RF Ltd
Still of scoria on Rangitoto Island, Rafael Ben-Ari, licensed through 123RF Ltd