Relay intercropping describes a cropping pattern in which the lifecycle of one crop overlaps that of another crop.

What are the purposes of relay intercropping?

Fig. 9.6 In relay intercropping, the second crop is planted into the first crop before the first is harvested.

The date and method of planting the second crop depends on the crop species involved, their row spacing, and available labor and equipment. The crops involved must complement each other in terms of their growth requirements and maturation times within the context of environmental conditions.

Fig. 9.7 Soybeans may be relay planted into oat when the oat reaches boot stage, as shown here. (Photo courtesy of K. Whigham.)

Fig. 9.8 Planting oats in a skip-row pattern facilitates planting and establishment of the soybean crop. (Photo courtesy of K. Whigham.)

Fig. 9.9 Careful planting is required to minimize damage to oat plants. (Photo courtesy of K. Whigham.)

Fig. 9.10 Harvesting of the first crop is timed so that the second crop can recover from any damage caused by the harvest operation. (Photo courtesy of K. Whigham.)

Fig. 9.11 Although soybean plants were damaged during the oat harvest, these plants are sufficiently established to branch and recover. (Photo courtesy of K. Whigham.)

Relay interplanting is generally more difficult in rigid, closely-spaced crops such as maize, sorghum, and millet because of the risk of stalk breakage. Before plants are too tall, however, interplanting of the second crop can be done simultaneously with the last cultivation of the first crop. Combinations with small grains or rice as the first crop have somewhat greater flexibility in planting time and method.

Table 9.3 Common crop combinations in relay intercropping systems in the U.S.
First Crop Second Crop Planting Comments
Small Grain Soybean or other legume
  • The legume may be overseeded into the small grain.
  • In seeding the first crop, skipping every third or fourth row facilitates planting of the second crop. Weeds, however, may be a problem in the skipped row.
Rice Soybean
  • Seeding may be done by aerial broadcast.
Maize, Sorghum or Millet Soybean or other legume
  • The second crop may be banded between rows if seeded at the last cultivation of the first crop.

As in other multiple cropping systems, cultivar selection, seeding and fertilizer rates, and pest management may need to be adjusted relative to sole cropping practices to optimize the polyculture system. Read this website article for recommended production practices for relay intercropping of wheat and soybean.

Study Question 9.3
Complete each of the following statements for an Ohio relay intercropping system relative to a sole cropping system. The relay intercrop involves planting soybean into wheat.
a) Adapted soybean cultivars yield best.
b) The soybean seeding rate should .

What is the physiological reason for the recommendation that a full-season cultivar be planted at a greater seeding rate than in a sole cropping situation?

Study Question 9.4

Shading of the second crop in relay interplanting systems can hinder its growth and development. Suggest a modification in planting pattern that would reduce the shading of the seedlings.

Fig. 9.12 Oats shade soybean seedlings. (Photo courtesy of K. Whigham)