Ag crop rotation
is easy and
brings big benefits
Weeds, diseases and pests can be beaten with an ag crop rotation that also boosts soil nitrogen, profit and improves produce quality.
Rotation means a planned and flexible alternation of different crops in a piece of land. The aim is to get benefits: the rotation may boost yield; reduce weeds; improve quality (such as grain protein); reduce disease; improve soil fertility or soil structure or provide many other benefits.
An ag crop rotation can be as simple as Crop A followed by Crop B then back to Crop A followed by Crop B.
Or a rotation can run for many years and have many different crops, some of which may be in the ground for several years at a time, particularly if the crop is a perennial pasture.
One of my favorite rotations is 5-8 years of pasture followed by one year of potatoes. This rotation has been particularly successful for some organic farmers I know because it takes little effort and gives a good return.
A pasture-wheat rotation may have a pasture growing for 3-5 years to
- provide grazing
- improve soil structure
- reduce or eliminate diseases
- build up nutrients (particularly nitrogen, carbon, hydrogen and oxygen) and
- rest the soil.
This can allow a better wheat yield (more tonnes) and better quality (particularly protein) and thus lead to better prices and bigger profits.
Ag crop rotations are common in some forms of farming and in some districts and less so in others.
In a vegetable farming enterprise, rotations are often the backbone of the farm design. A good rotation will make a significant difference to yield, diseases, problems and the general ease of farming.
Most ag crop rotations are designed to improve soils and cut weeds and other pests. They do this by mixing
- crops that make money with
- crops that improve the soil and
- crops that provide other benefits such as a reduction in pests, weeds or diseases.
This often leads to a mix of species with
- fibrous roots
- shallow roots
- deep roots or
- a tap root
because this will provide benefits to the soil from
- root decay providing food for soil organisms
- root exudates improving soil structure and providing food for soil organisms
- root activity, particularly in terms of breaking up hard pans
- legumes for nitrogen fixing and
- an accumulation of organic matter
Some basic principles are:
- separate similar plants by as many years as possible to
- reduce the buildup of pests and diseases
- prevent nutrient exhaustion
- reduce the development of hard pans
- reduce the buildup of weeds of one particular type
- rotate crops that are prone to high levels of weeds with ones crops that aren't
- keep the ground covered with undersown crops or green manures for as much of the year as possible
- keep nitrogen levels appropriate to boost yields without swinging the balance towards the nitrogen-loving weeds.
A suitable rotation of pasture and crop can be more profitable and generally sustainable than a rotation of just crops because
- each phase of the rotation makes an income
- costs are generally lower and
- the buildup of problems is slowed or eliminated. For example, a well-managed pasture phase leads to a big drop in weed species growing in the field as well as a drop in the weed seed bank in the soil.
Choosing an ag crop rotation requires:
- understanding the characteristics of each crop
- understanding the needs of each crop
- getting a suitable sequence which meets most of the needs
- finding suitable crops or green manures to fill any gaps
- testing it in the field
- fine tuning it
More on designing your rotation later. In the meantime, the take out to the field message is: ag crop rotation can bring great benefits with minimal or no costs, fiddle or complication.