Variable soil demands a flexible fertiliser program

photo of farmer who manages variable soil types

The Hansen’s crop up to ninety percent of their mixed farm at Coomandook, SA. They grow canola, wheat, barley, lupin, oaten hay and lucerne. There are variable soil types across the 8,500 hectare property. It ranges from red sandy loam over clay and limestone, to deep, infertile, non-wetting sands. Variable soil and seasons challenge annual fertiliser programs.

Yield potential

Andrew Hansen strongly believes crop nutrition drives profits. In 2015 he attended a More Profit from Crop Nutrition II (MPCN II) workshop. Andrew wanted to learn how to improve their return on investment from fertiliser.

Presenters explained why growers should calculate yield potential before applying fertiliser. Yield potential calculations are based on three factors:

  1. rainfall since sowing
  2. an estimate of pre-sowing soil water
  3. the potential outcomes of a dry, wet or in-between finish.

Andrew calculated that in 2015, there was enough N in his cropping paddocks. The 2015 season had a low yield potential and poor seasonal outlook. In 2016, there was above average growing season rainfall. Andrew  put out a higher rate of liquid UAN, with good results.

Managing variable soil nutrients

The sandy soils on Hansen Farms lack boron (Bo) and zinc (Zn). The stony grounds are copper (Cu) and manganese (Mg) deficient. Phosphorus is generally lacking throughout the farm. Nutrient removal from hay can also cause potassium (K) deficiencies. Andrew considers long-term yield average, soil test results, moisture levels and rainfall history to manage nutrients.

At the MPCN workshop, Sean Mason presented results from two GRDC projects:

  1. Assessing wheat responses to targeted trace element applications  
  2. Monitoring of soil phosphorus potassium and sulphur in the southern region how to get the most out of your fertiliser dollar.

He said measuring N, S and K at depth is crucial to calculate nutrient needs. He also said soil types differ in their P responsiveness. Andrew looks at PBI (phosphorus buffering index), DGT (diffuse gradients in thin film) readings, and Cowell P to work out P rates.

Andrew applies trace elements either post-emergence or down the tube at seeding. He uses a seeding system consisting of a double shoot, three bins and a liquid tank. This allows him to apply multiple granular and liquid fertilisers.

More

More detail on Andrew Hansen’s approach to nutrients: MPCN HANSEN FARMS Case Study

Use paddock test strips to get the most out of your fertiliser budget

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