Tuesday 9 February 2021

In The Field, number 04: Strategic tillage

‘In The Field’ began as a post about the use of herbicides for weed control. That was back in November 2018. Today I’m introducing a different farmer – her name is Emma Ayliffe – and she has a slightly different approach to the puzzle of productivity. This farmer will be featured in two posts, and you’re reading the first.

With partner Craig and his family, Emma operates a 1700-acre (688-hectare) farm at Burgooney, Lake Cargelligo (roughly northwest of Wagga Wagga, in the central west of New South Wales, about 550km from Sydney). The land is rolling hills with red loam which gets a relatively modest 360mm of rain per year. 

Primary outputs are wool, first cross lambs, and grains (mainly wheat but also some oats, barley and canola). Here’s a moment during the 2020 harvest.

Secondary outputs: If above average rainfall, may plant canola, chickpeas, mungbeans. Opportunity cropping depends on amount of moisture in the field, the market (some crops might have a higher price at any given time) as well as the time of year.

The challenge

Three challenges are addressed in this report. One is ground cover, which must be maintained in order to prevent erosion and evaporation of water. In Emma’s environment ground cover is critical as she and Craig can never be sure if and when the next rain event is going to occur.

It is a low rainfall production area with a tendency to have a “sharp” (ie hot and dry) finish to the year. Growing season rainfall is only around 180mm, and to put that in perspective the average annual rainfall for NSW is 555mm/year and the high production areas of new like the eastern area like Temora sit closer to 600mm/year.

Another challenge is maintaining soil health. As a seed, a plant requires water, air, nutrients and heat for germination. Then to be able to maximise growth the plant needs a biologically active soil biota. This includes soil fungi and bacteria, which enables good soil structure and nutrient cycling, leading to optimum plant health. It is the interaction between all of these factors that determines how well plants and crops grow.

The third challenge is compaction, which happens when livestock are let into fields after harvest to eat the lost grain and the stubble that remain after a combine harvester has gone through the paddock. Compaction also happens due to farming equipment. And the soils are naturally hard setting.

The solution

Emma’s vision involves capitalising on the resources she and partner Craig have in a marginal environment and finding the systems that best suit their landscape to ensure the farm is able to be productive and profitable well into the future. 

They are moving to a minimum till/strategic tillage system that means using knife-point press wheels. Minimum tillage means avoiding anything that causes major soil disturbance, hence the knife-point press wheel system. Strategic tillage is similar but allows for one significant soil disturbance pass no more than one year in eight. This strategy reduces erosion, conserves moisture, and maintains soil structure.

A knife-point (see photo below) is narrower than a coulter but does the same job, only without disturbing the soil as much. The press wheel comes in behind the knife point and closes the furrow. 

Research tells that working the soil one year in eight is fine. It ensures that Emma and Craig are managing issues like compaction while maximising productivity and soil health. 

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