CARRINGTON, N.D. – The growing of two companion cash crops in the same field might be a way to increase total productivity for that unit of ground, according to Mike Ostlie, North Dakota State University research agronomist at the Carrington Research Extension Center (REC). This involves not only planting two different crops together, but also harvesting them together at the end of their growing season. That usually means some type of post-harvesting operation that will separate the two cash crops.
That separation process demands that the companion crops must have enough differences that they can easily be separated from one another, such as a small seeded crop paired with a large seeded crop.
In the past few years, intercropping has increased in popularity, Ostlie noted.
“Every year it is blown up quite a bit more and it really comes down to removing the limitations,” he said. “Our equipment is so good right now that we can plant and harvest multi-cropping, but also the bin sites on the farm permit handling multi-cropping situations.”
The recent soil health movement has also been a driver in doing more intercropping since it allows for more diversity in the soil, and in some cases helping to reduce the loss of soil. Also, intercropping can also give a grower another tool in helping to mitigate weed and insect problems due to pesticide resistance.
Work at the Carrington REC has focused on planting two crops in the same furrow, according to Ostlie, and this is due mainly to the seeding equipment they have at their disposal. However, some operators are able to do alternating crop rows using dual seed tanks on the planter that sends the seed to alternating furrow planters. The advantage of this is being able to adjust the seeding depth for each of the crops being planted, which is very beneficial when seeding a combination of a small and larger seeded crop.
Others are able to do intercropping using strip cropping as another method, where one crop is planted with one planter pass and the other crop on the next pass.
But the main reason for intercropping is over-yielding. In a single-stand field of a crop, such as wheat or corn, you will have so many plants per acre to maximize your yield. However, when you are working with intercropping, you are putting more plants in a given area than you normally would with a single crop, Ostlie explained. Thus you are trying to use some of those additional resources.
“The concept is you are putting two crops in there and having them compete with each other, but it is not 100 percent competition. They are all not going after the exact same resources, as each plant has slightly different needs, and this gives you some added efficiencies,” he said.
He then gave some actual trial intercropping results at Carrington using canola and field peas, a common intercropping mixture. That trial also looked at nitrogen rates, since you would have a legume and non-legume companion crops, which might reduce the total nitrogen fertilizer needs.
In the various combinations, it was shown that the great increase in percent productivity came from seeding at a rate of 66 percent of the standard field pea seeding rate combined with a 33 percent rate for the canola. This resulted in a 36 percent increase in productivity per acre, when compared to a monocrop rate with no intercropping.
Growers must also pencil in the selling costs of the companion crops to make an accurate determination of the financial advantage of intercropping.
There are some costs associated as well that must be considered:
- Can the additional income from over-yielding cover the cost of separating the grain and the additional seed cost?
- Intercropping increases the need for desiccating or swathing if maturities aren’t closely matched.
- Herbicide options are limited-labeled herbicides are cheaper, but less effective and biological weed suppression is more than you might expect, especially in late-season.
- It takes time to perfect a new system such as intercropping.
Ostlie noted the intercropping combination of chickpeas and flax is another popular system in the region and even more benefits can be found in intercropping roughage crops for hay or silage production.
This information was presented at the Central Dakota Ag Day, which was held at Carrington on Dec. 5.