THE practice of crop rotation has roots that reach back to the ancient cultures of China, Greece and Rome.
In that time, farmers understood growing the same crop year after year on the same piece of land did not achieve the best results.
Through trial and error they learnt to dramatically increase productivity by cultivating a sequence of crops over several seasons.
Fast forward to the year 2013, and today's sustainable farmer is the beneficiary of this ancient knowledge, now well advanced, thanks to modern science and technology.
The benefits of rotation have been widely proven and come down to a few key things, including management of pests and disease, increased productivity and improved soil health.
Typically, crops are alternated in two- or three-year rotations, although it really depends on the individual situation - for example, whether it is a dryland or an irrigated system.
The selection and sequence of crops will naturally depend on their seasonality and requirements for climate, nutrients, soil type and moisture.
Rotations are often more effective when combined with other sustainable farming practices, such as the use of manure, compost and cover crops like legumes.
Together these practices improve soil quality and add valuable nutrients and biomass to the soil. The healthier the soil, the better its capacity to hold water and supply plant roots with sufficient nutrition for vigorous growth.
Once healthy plant growth is under way, the next challenge is to protect it from damaging pests and diseases.
American rotation specialist Kevin Baldwin says farmers who implement a good crop sequence are likely to enjoy fewer insects, weeds and plant diseases.
Soilborne pathogens tend to accumulate when a soil is sown with the same crop or family of crops every year, he says. At a minimum, crops from a particular family should be separated by at least two years of crops from other families.
A two-year rotation has also been found to reduce leaf diseases and disrupt the normal needs of a pest during its life cycle.
The principles of rotation can also be used in mixed-farm enterprises that include livestock production. While it may increase the complexity of the system, the two can work harmoniously to produce reliable feed and productive crops. All things considered, crop rotation is a sensible form of risk management. The crop can be changed to suit prevailing weather conditions or take advantage of market demands. For more ways to improve and protect your land, visit condaminealliance.com.au/10ways.
Andrew McCartney is manager of the Condamine Alliance Sustainable Agriculture program.
Farmer: Glen and Judy Ogden
Location: Cecil Plains
Farm type: Cropping
Size: 2025 hectares
Years on farm: 13
THE most important factor in the Ogdens' crop rotation system is water.
When and what crop Glen plants is determined by the soil moisture level and how much harvested water is available for irrigation.
As a rule, Glen grows only two types of crop at a time.
Because rainfall is unreliable, he doesn't have a fixed rotation but usually follows his main crop, which is cotton, with sorghum or corn.
The stubble from the grain crops is left in the soil to reduce erosion, increase soil health and retain moisture.
The latter is essential to having sufficient soil moisture to plant the next cotton crop.
Glen said it gave the cotton a good start and reduced the amount of extra water supplied through irrigation.
He said soil was the biggest reservoir of water.
It needed to be healthy to deliver maximum water efficiencies and nutrients.
At the Ogden farm, every drop counts.
"It's all about achieving the best return from each precious megalitre of water," Glen said.
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