April Web Exclusive

Intercropping
4/19/2013

 
 
        by Tamara Scully

        Small farmers with market gardens have long benefitted from companion planting. Planting different crops close together can provide pest and disease protection, optimal growing conditions, increased yield, improved soil health and water conservation. Mixing things up can have multiple benefits.

        On a small scale, when grown in garden beds, intercropping is commonly thought of as simple companion planting, which can be implemented by commingling compatible species. However, when you attempt to move those growing partners out into the field, where at least some of the work of preparing, planting, weeding and harvesting will be done with machines, suddenly intercropping vegetables is much more complicated.

        Rob Faux and his wife, Tammy, run Genuine Faux Farm (www.genuinefauxfarm.com) near Tripoli, Iowa, and the couple decided to do just that. In 2010, they applied for and received a Sustainable Agriculture Research & Education (SARE) grant to assist them in finding the most productive ways to scale up their successful companion planting techniques.

        "One of the biggest changes as one scales up from gardening to a larger growing operation is the amount of attention one can give to each crop, much less each plant," Faux said. "As a result, most growers isolate different crops from one another to increase efficiency of work."

        Intercropping is "the growing of two or more crops in proximity to promote interaction between them," according to the publication "Intercropping Principles and Production Practices" (www.clemson.edu/sustainableag/IP135_intercropping.pdf) from the National Sustainable Agriculture Information Service, aka ATTRA. The publication explains how intercropping increases diversity, produces higher yields and enhances pest control. It also discusses principles and strategies associated with successful intercropping systems.

        Vegetable row intercropping
        There are several methods of intercropping, including planting within the same row at the same time, planting in the same row at different times, planting in alternating strips, or planting two or more crops in the field without rows. These techniques can be used in grain operations, orchards, and vegetable and small fruit production.
When Genuine Faux Farm attempted to mechanize its biodiverse, certified organic operation, however, they found that changing the intercropping methods to adapt to larger-scale production was complex.

        "The Genuine Faux Farm is dedicated to maintaining companion planting practices, but is finding it difficult to continue with companion plants due to production challenges brought about by the scale of the operation," Faux wrote in his SARE grant proposal. "Rearranging already complex planting plans for new tools will be difficult. New plans must consider companion planting benefits, rotation issues and production requirements. It is possible that any such plans will either negate benefits of companions, or fail to result in any labor reduction or weed control benefits.

        "The further one moves toward monocropping, the more likely it is that you are creating the perfect environment for the insects, fungi and diseases that will attack your crop," Faux continued. "So the question we ask is this: How can we maintain a diverse and healthy environment for our crops and keep our operation efficient enough to be as large as it is?"

        Some of their research involved intercropping potatoes and beans in a system where a tractor could be used, as well as the control spacing used prior to mechanization. They then examined any difficulties in the tractor system, compared yields, compared pest control results, labor costs and weed pressure. In the bean and potato study, a row of potatoes and a row of beans were planted 12 inches apart in one 40-inch-wide, tractor-accessible bed. The control beds were planted with 6 feet between potato rows, and two rows of beans sandwiched in the middle of each potato row. The objective was to maintain the advantages of companion planting--in this case the control of potato beetles--while adjusting bed/plant spacing to accommodate increased mechanization.

        Their study results did not find any difference in pest pressure in either plot, with the potato beetle damaging only the outer rows or the ends of middle rows in each system, indicating that the companion effect was retained. Labor costs were reduced with the tractor beds. However, weed control was an issue in the tractor bed system, while the canopy in the control beds reduced weeds, and hilling potatoes with the beans so close was difficult.

        "We now grow 2,400 row feet of potatoes. We also grow 2,600 row feet of bush beans with these potatoes in the same field," Faux said. "We now have to consider how we can efficiently pick the beans without harming either crop. And we also must consider different planting dates and cultivation with equipment."

        When they intercropped broccoli and onions in the same tractor-spaced beds, they found that the onions failed, while the broccoli did equally well in both the control and the test system. In the test system, the onions were planted in double rows, with a single row of broccoli in between the double onion rows. Wind roll of the broccoli onto the allium, as well as weed issues, contributed to the problem. Planting the onions much earlier or planting with a smaller brassica are possible alternatives to provide better results in the tractor-bed field, Faux explained. Another option would be to intercrop the broccoli with sage or thyme, providing companion plant benefits.

        "It would be a simple approach to grow a sage or summer thyme plant every 10 cells in starter trays. Then, as people plant, they will place this companion approximately every 20 plants in the row," Faux said. "The additional work for these plants stops at this point. They will be cultivated or mulched in the same way as the rest of the crop. You break up the monoculture that is so attractive to cabbage loopers and cabbage worms."

        Intercropping in agroforestry
        Alley cropping is a type of strip intercropping, where rows of trees are separated by rows of an alternate crop. This agroforestry practice is a way of diversifying the farm by having both an annual crop as well as a long-term tree crop, whether it's for nut, fruit or wood production.

        Trees can be alley cropped with forage crops or field crops, biomass crops or hedgerows. Blueberries, hazelnuts or other perennial shrubs that produce a cash crop can be used in alleys between strips of taller nut or fruit trees. Alternatively, hay crops, grains or vegetables can be alternated in open areas between wide orchard rows. A variety of crops can also be planted between the trees in a row.

        Shade tolerance, competition from roots, adequate soil nutrients for all plants and access to the plants for harvesting, pruning and other needs must be considered. Row orientation of the tree crop can provide maximum sunlight, erosion control or a windbreak for the alternate crop.

        Row spacing will determine how long crops planted between tree rows will be able to produce, with 60-foot rows providing about 10 years of production, according to the Center for Agroforestry (www.centerforagroforestry.org). Wider row spacing provides extra years of utilization between rows.

        Other alley cropping benefits include enhanced wildlife habitat; decreased pest issues due to several factors, including an interruption in the pattern of pest movement and reduced crop visibility to pests; and the benefits of increased diversity, which encourages beneficial insect presence. In an orchard, alley cropping allows for immediate cash income while the trees mature. Or, if row crops are the main income, trees can provide an income off the farm for future generations when trees are harvested for wood.

        "In the end, we are convinced we can maintain profitability while doing something that we believe is better for the long-term environmental health of our farm," Faux said. "Our goal has been to begin building research that established benefits of intercropping and best practices for the same. At present, the literature is scarce, and acceptance of the practice is low."

        While some intercropping systems utilize cover crops as living mulch for the primary crop, Faux believes that intercropping can result in multiple cash crops while providing natural benefits to each crop, as well as to the whole farm.
      
        "If you are not willing to combine companions in the same bed, you can at least grow cash crops that have beneficial interactions in beds that are adjacent and plant them using timelines that insure maximum interaction," Faux said. "What would be wrong with planting a bed of cabbage next to a bed of onions?"

      

       
        The author is a freelance contributor based in New Jersey. Comment or question? Visit         www.farmingforumsite.com and join in the discussions.


        Photos courtesy of Rob Faux, Genuine Faux Farm.