From the Ground Up – Understanding Soils

Led by Jo Powells, Senior Agronomist with South East Local Land Services, the focus of the field days was land capability, soil chemistry and interpreting soil test results.

Key points were:

  1. ‘Land capability’ is the inherent ability of the land to sustain agricultural production. It takes into account the characteristics of the site including slope, vegetation and the physical characteristics of the soil. There is a range of classification from 1 (highly arable) to 8 (only suited to light grazing or conservation). The Rural Living Guide has more information about Land Capability Classes.
  2. Regular soil tests can give you the information needed to recognise the physical and chemical limitations of your soil. The tests can help you to identify key properties of the soil and how it will react to inputs. For example, fertilising without regular soil testing may lead to nutrient imbalances or the over application of a particular nutrient. If you decide to soil test, use a NATA Accredited Lab for the analysis so you know that the result are based on accepted standards and can be compared with other soil tests.
  3. Pasture legumes are sensitive to soil pH and low soil Sulphur which can lead to poor nodulation and reduced nitrogen fixation by the plant. The relationship between soil pH, Aluminium, Phosphorus and Sulphur is currently being researched by South East Local Land Services.
  4. Phosphorus is usually the key nutrient limiting pasture production in Australia. By understanding and using soil test results, you can choose to use different fertiliser treatments to increase pasture production.
  5. Some soils in the Capital region are classed as sodic soils. These soils have an exchangeable sodium percentage (ESP) > 6% and are prone to dispersion and structural collapse when wet. This can lead to erosion problems or a very compacted layer in the soil. Cultivation of sodic soils can increase water infiltration and exacerbate the problems. Sodic soils can be improved by applying gypsum, or a combination of gypsum and lime in acidic soils. Soil testing can guide you in deciding on the best way to manage these soils.

Resources:

Alternative Fertilisers and Pasture Productivity – a South East Local Land Services research project in collaboration with Bookham Landcare to trial a range of alternative fertiliser treatments – the videos reporting on the research findings are excellent and may well challenge your ideas about soil biology and fertilisers.

The Trouble with Sub Project – a South East Local Lands Services research project with Harden Murrumbarah Landcare investigating problems with performance of sub-clover in pastures and relationship to soil chemistry.

Australian Soil Fertility Manual – CSIRO Publishing (edited Graham Price), available from various sources including digital version.

Agskills Manual – Managing for Healthy Soils – a starting point for learning about soils.

Rural Living Guide – useful primer developed by South East Local Land Services for small farms, provides overview of wide range of topics related to managing and farming rural lands with links to many resources.

Introduction to Soil Sodicity – technical note by Co-operative Research Centre for Soil and Land Management.

Best practice guidelines to using poultry manure on pastures – guide to using chicken manure by┬áNeil Griffiths, District Agronomist, Extensive Industries Development, published by NSW Department of Primary Industries.

Soils for Life – website with information about soils regenerative practices

Northern Rivers Soil Health Card – tool developed for farmers by farmers to use to monitor the health of their soils.

These field days were made possible with funding from the Australian Government, in-kind support from South East Local Land Services. Lunch for the field days was provided by the ACT Regional Landcare Facilitator. Thank you to our sponsors of the network, the Palerang Local Action Network for Sustainability, and our host farms for the field days.