Feature | Exploring the depths of sandy soils at the Franklin Harbour Soil Pit Day
Ah sandy soils. One season they are sending your yield monitor through the roof, and the next season they are blowing the stripes off a zebra.
Discussing sandy soils reminds me of a scene from the movie, Forrest Gump (yeah, yeah, showing my age). While cleaning floors with a toothbrush, Forrest Gump’s friend Bubba word vomits the various ways to cook shrimp.
“Shrimp Salad, Shrimp Cocktail, Broiled Shrimp, Fried Shrimp” …… etc, etc, on and on he goes.
A recent conversation about what to do with a problematic sandy paddock this season sounded somewhat similar.
“Well what sort is it?”, I’m asked.
Is it “sandy loam, loamy sand, acidic sand, white sand, non-wetting sand, pain-in-the-a** sand……etc, etc, on and on they go.
Um, next?!
Not all sands are created equal and how to manage them is crucial if you want to optimise your production. These are two of many key messages delivered during the recent Franklin Harbour Soil Pit Day, held at Mitchellville near Cowell.
Local soil encyclopedia, Brett Masters of EPAG Research teamed up with independent agronomist, James Cant of AGRA Agronomy and Sustainable Agriculture Facilitator, Amy Wright of AIREP, to delve deep into managing sandy soil types, amelioration methods and soil profiles at depth.
Three soil pits were dug in a single paddock with different constraints, being:
- Ameliorated with a ripper
- Deep sand
- Control
Getting his hands dirty at the bottom of the first pit, Brett commenced the morning session by conducting pH and carbonate tests to demonstrate what was sitting at various layers throughout the soil profile. Brett explained how the different pH, carbonate and soil strength layers in the soil profile can directly impact crop production, as the plant roots move through the different zones and layers.
Soil nutrition and the importance of organic matter in sandy soil types was discussed, with Brett and James keen to understand the current strategies for farmers in the area. When asked what nutrition testing is commonly undertaken in the area, the majority farmers referred to their agronomists, who generally complete 1-10cm testing and 10-60cm deep N testing.
As recently highlighted during the AIR EP Member Days and Saline Soil & VRT Workshops, the prolonged dry conditions has many farmers and advisors asking about phosphorous rates, placement, residual P and strategies for the coming season. In gauging what the general P management strategies are for the area, some have previously applied liquid P, however cost has been prohibitive in the past.
When referring to P availability in high PBI soil types, farmers were advised to “think of it (P) like your Mother-in-Law’s money. You know it’s there, you could see some of it one day, but bloody hard to get your hands on it”.
As soil amelioration methods continue to advance across the Eyre Peninsula, both farmers and agronomists were keen to understand the best methods to achieve positive results following amelioration, and how to make the benefits/effects last longer.
As explained by Brett and James, the key to successful amelioration is identifying the particulars you need to consider prior to getting started. Items such as:
- What soil constraint are you trying to overcome? Identify your low hanging fruit first.
- Water repellence – do you need to mix soil first?
- At what depths are the high soil strength layers in the profile? Understand your soil profile beyond 1-10cm.
- Identify the appropriate amelioration tool / method to use for the constraint you are addressing. Spend the money doing it right the first time.
- Focus on where you can make your money, get that working first
“To address soil constraints for the long term you need to be mixing soil, preferably at depth to reduce compaction layers,” said Brett.
Farmers with recently ripped sections of their paddocks, were interested to know how much of the fertile soil is being incorporated using inclusion plates. Brett confirmed this is an area currently being researched by Dr Jack Desboilles of Uni of SA, refining a multitude of options to maximise the effects of ripping.
The morning session ended with James Cant facilitating a robust discussion on nutrition, herbicide residues and risks that could be associated with a potentially dry sowing season ahead. As mentioned during his AIR EP Member Day presentations, James encouraged farmers and advisors to undertake bioassays if they have any herbicide concerns, to provide a snapshot of any nasties potentially lurking in the soil profile.
Topics covered throughout the day included:
- Understanding the key constraints in sandy soils
- Stored soil moisture
- Management issues and opportunities
- Amelioration strategies and nutrition
- Post amelioration paddock management
- Phosphorous management and strategies in sandy soils
- Benefits of applying gypsum to increase sulphur (where deficiencies are present)
- Herbicide residues and risk
Additional sandy soils information is available via the GRDC document titled “Sandy Soils of the Southern Region”
The Franklin Harbour Ag Bureau Soils Day was funded by the SA Drought Hub and supported by the Eyre Peninsula Landscape Board through its Soil Extension Officer project, funded by the South Australian Government’s Landscape Priorities Fund (LPF) and its Sustainable Agriculture Facilitator, supported by the Australian Government through funding from the Natural Heritage Trust under the Climate Smart Agriculture Program.
Projects included:
061_AIR Franklin Harbor Ag Bureau Soils Day
051_AIR EPLB Sustainable Agriculture Facilitator airep.com.au/saf
EPLB Soils Extension project landscape.sa.gov.au/ep/soil-management
To view the comprehensive list of AIR EP Projects, simply visit airep.com.au/projects