University of Nebraska-Lincoln Extension, Institute of Agriculture and Natural Resources

March 31, 2006
Figure 1. Drought sensitivity coefficient for corn. (From Meyer et al. 1993)
Figure 2. Effect of corn row position (for a six-row strip) on corn yield, expressed as a percent of yields typically observed with monocrop corn management. The number on top of each column indicates the range of yields (compared with monocropped yields) observed at each position.

Seeding rates for skip-row rainfed corn

The idea behind skip-row planting is to keep developing corn plants from using all of the available water too early in the growing season. Because water in the soil between widely spaced rows cannot be reached by the plants until later in the season, water is available to the plants in July and August. Corn is very sensitive to drought in the silking to blister stage of development (Figure 1).

In an Iowa study where six rows of corn were planted next to six rows of soybeans the outside rows of corn yielded 20% more on the average. See Figure 2. If we use 0.5 lb ears as the standard, we would expect the rows in a skip row to be at least 0.6 lb ears and maybe 0.62 lb ears since there is no row next to them.

Table 1 lists the potential yields for plant-two, skip-one and Table 2 plant-two, skip-two or plant-one skip-one with ear sizes of 0.5 lb, 0.6 lb, and 0.7 lb ears. Use this information along with NebGuide G1528, Recommended Seeding Rates and Hybrid Selection for Rainfed (Dryland) Corn in Nebraska to determine the seeding rates.

With lower seeding rates and non-seeded rows, weed/crop competition is reduced. Herbicide resistant corn has worked well with these lower plant populations and skipped rows. Remember some markets do not accept some herbicide resistant crops. Several weed management strategies can be used for weed control in skip-row corn.

Most producers like the lower risks of the PRE and POST programs, these have worked well with the herbicide resistant crops. They also work well in controlling problem weeds such as sandbur. Recommendations for PRE and POST herbicides may be found in the UNL 2006 Guide for Weed Management in Nebraska, EC130. For example, one possibility would be with Roundup Ready corn a preplant or preemergence treatment of Atrazine plus Balance followed by post applications(s) of Roundup. The Balance would provide control of triazine and ALS resistant weeds. Check labels for rates, soil types, pH, organic matter, and rotation restrictions and replant options.

Also check with your crop insurance representative and Farm Service Agency about skip-row corn.

Bob Klein
Extension Cropping Systems Specialist
West Central REC

Table 1. Yield possibilities for skip-row corn in plant-two, skip-one.
Planted pop. in 2 rows/ac rows/ac Stand pop. in 2 rows planted/ac Stand pop. in 3 rows (only 2 planted)/ac Ear wt/lb = yield/bu Ear wt/lb = yield/bu Ear wt/lb = yield/bu Ear wt/lb = yield/bu
20,000 18,000 12,000 0.5 = 86 0.6 = 103 0.62 = 106 0.7 = 120
24,450 22,000 14,667 0.5 = 105 0.6 = 126 0.62 = 130 0.7 = 147
28,900 26,000 17,334 0.5 = 124 0.6 = 149 0.62 = 154 0.7 = 173
33,333 30,000 20,000 0.5 = 143 0.6 = 171 0.62 = 177 0.7 = 200

Table 2. Yield possibilities for skip row in plant-two, skip-two or plant-one, skip-one.

Planted rows/ac

Stand pop. in 2 rows planted/ac Stand pop. in 4 rows (only 2 planted)/ac Ear wt/lb = yield/bu Ear wt/lb = yield/bu Ear wt/lb = yield/bu Ear wt/lb = yield/bu
20,000 18,000 9,000 0.5 = 64 0.6 = 77 0.62 = 80 0.7 = 90
24,450 22,000 11,000 0.5 = 79 0.6 = 94 0.62 = 100 0.7 = 110
28,900 26,000 13,000 0.5 = 93 0.6 = 111 0.62 = 120 0.7 = 130
33,333 30,000 15,000 0.5 = 107 0.6 = 129 0.62 = 140 0.7 = 150

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Copyright 2006 by the University of Nebraska Board of Regents. All rights reserved.
Published by University of Nebraska-Lincoln Extension in the Institute of Agriculture and Natural Resources Cooperating with the counties and the U.S. Department of Agriculture.
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