Skip-row is a practice that can increase the success on rainfed corn if one has at least 4,000 pounds of wheat residue (the residue from a 40-bushel wheat crop — spread evenly). A stripper header improves the value of this residue because it lasts longer.
This residue reduces soil water losses from evaporation, and the residue also suppresses weeds, which can be a major problem with skip-row systems. You do not benefit from crop competition in helping control weeds in the skipped rows because the canopy never closes, but in the planted rows you do get help controlling weeds because of the higher plant population, which provides more crop competition.
The idea behind skip-row planting is to keep developing corn plants from using all of the available soil 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, soil water is available to plants in July and August when corn enters the reproductive stages of growth. Corn is more sensitive to drought in the silking to blister stage of development.
The first research with skip-row corn in Nebraska was started in 2003. In this trial, all rows of corn were planted and then plants were removed to reduce population, or one or two rows were removed on July 2. By this time, the corn had used 6 inches of soil water. A breakdown of yields from this trial follows:
- Control (19,500 population): 41 bu/ac
- Removing approximately every third plant (14,700 population): 41 bu/ac
- Removing every other plant (11,200 population): 45 bu/ac
- Series of two rows of corn followed by one row removed (equivalent to 13,800 population): 48 bu/ac (17% above the control)
- A series of two rows of corn with the next two rows removed (equivalent to 9,500 population): 54 bu/ac (32% above the control)
Figure 1 shows the results of research with skip-row rainfed corn at Trenton. The plant-2-skip-2 averaged 74 bushels versus 53 bushels for the solid (every 30-inch row) planting. The largest yield advantage was at the high population of 20,000 (40,000 in the planted rows in the plant-2-skip-2) which yield 84 bu/ac versus the solid planting which averaged 44 bu/ac. Check with your Farm Service Agency and crop insurance personnel before adopting skip-row.
Twenty-three field trials were conducted across the central Great Plains from 2004 through 2006 to quantify the effect of various skip-row planting patterns and plant populations on grain yield in rainfed production. A significant pattern by plant population interaction was observed at only one of 23 trials, suggesting that plant pattern recommendations can be made largely irrespective of plant population. In trials where skip-row planting patterns increased grain yields compared to the standard planting pattern treatment (every row planted using a 30-inch row spacing), the mean grain yield for the standard treatment was 44 bu/ac. In those trials in which skip-row planting resulted in decreased grain yield compared to the standard planting pattern, the mean yield was 135 bu/ac.
Skip-Row Planting Recommendations
Based on these trials, the plant-2-rows, skip-2-rows planting pattern is recommended for risk-averse growers in the central Great Plains where field history or predictions suggest likely grain yields of 75 bu/ac or less. Planting one row and skipping one row is recommended for growers with moderate risk-aversion and likely yield of 100 bu/ac or less. Some of these sites did not have at least 4,000 pounds of crop residue, which limited the use of skip-row because of the increased soil water loss from evaporation. The success of skip-row increases with increasing crop residue levels.