Science yields results

Science yields results


On Farm
Zero till canola with stubble retention, part of a sustainable well managed farming system.

Zero till canola with stubble retention, part of a sustainable well managed farming system.

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The definition of “sustainability” must be science based writes Bob Freebairn

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One could easily believe “sustainable” farmers are only those who follow particular grazing, cropping, soil management and “lots of trees” philosophies.

Often conventional fertilisers, herbicides like glyphosate and insecticides are no go areas. Nothing could be further from the truth. Most research aims to marry high agricultural productivity with best land management.

Many farmers have adopted this research with verifiable combinations of higher yields and better environmental aspects, like increased organic matter and healthier soils via scientific, not just “feel good” definitions. The definition of “sustainability” must be science based.

A warning of how non-science-based information can be popularised is illustrated in the book Firepower: The Most Spectacular Fraud in Australian History, written by Gerard Ryle.

It describes how prominent politicians, sportsman, governments and other influential people were conned into believing a non-science proven pill could cut fuel consumption and reduce emissions. It ended ingloriously when science proved it didn’t work and shareholders lost millions.

Most farmers aim to run a profitable but also better than sustainable business. There is good science to support what we do can improve natural resource management aspects such as soil quality, good biodiversity, clean water runoff and prevent soil erosion.

Australia feeds around 100 million people (home and export) compared to pre-European days of perhaps one million. Much of our production is from land low in natural soil fertility.

Examples of how farmers are making great progress in improving land and production, is zero till farming with stubble retention. 

Zero till with occasional cultivation has largely arrested declining soil structure, with some research indicating gradual improving soil OM. Erosion is largely eliminated when zero till combines with stubble retention. Soil deficiency correction, like nitrogen in cropping, contributes to greater OM (and yield).  

Research supports that good pastures build and improve soil OM and biological activity. Soil fertility is related to soil health, OM levels and soil carbon. Part of sound grazing includes retention of adequate ground cover, which is a key factor and commonly more critical than any particular grazing management system.

Research indicates that best fertilisers for pasture production and soil health are those that supply missing soil deficiencies, in available forms and in sufficient quantities. Products can include animal manure, provided applied at sufficient rates, as well as products like super.

Fertilised native pastures combine higher productivity, good biodiversity and improved soil quality, including increased carbon and water infiltration rate.

Fertilised native pastures combine higher productivity, good biodiversity and improved soil quality, including increased carbon and water infiltration rate.

An example is a 30-year-old DPI trial I have been involved with at Ulamambri. Sulphur fortified superphosphate led to a doubling of OM, higher biological activity, water infiltration rate seven times better, improved ground cover and soil friability. Correcting soil deficiencies more than trebled pasture productivity.

Superphosphate does not acidify soil if used in combination with perennial pastures, native or introduced species. Acidification is caused by leeching of nitrogen in an annual cropping and pasture system, product removal and to a degree soil organic matter build up. In some soils, “sustainability” includes periodic lime use.

An aspect of sound land care is biodiversity. Some years ago, Inverell NSW DPI district agronomist Bob McGufficke published a paper in a science journal describing a study where well managed fertilised pastures contained more native plant species than unimproved pastures. Well managed perennial pastures also better compete with troublesome weeds.

We, like most farmers, value trees and have planted many shade areas. Historic records for our area, suggest much of it was open country with occasional clumps. Tree planting, often via public money that totally exaggerates pre-European vegetation, can render properties economically disadvantageous with few environmental pluses.

Government funded land care and associated categories, I believe should always be assessed on science and benefit. It is mandatory in some organisations that projects be science based, but I see a lot of allocations that don’t make that criteria.

Next week: Control of Silverleaf nightshade, one of our worst weeds.

  • Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact (0428) 752 149.

Research indicates that best fertilisers for pasture production and soil health are those that supply missing soil deficiencies, in available forms and in sufficient quantities.

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