Growing Ontario's Corn

Corn Planting Following Early Hay Harvest
By Greg Stewart, OMAFRA Corn Specialist

No-till is attractive

Corn producers looking for an opportunity to replace a declining hay field may consider the option of planting corn following a first harvest of hay.

Figure 1 Late-planted corn for silage after an early hay harvest can boost feed supplies.

This late-planted corn crop is traditionally aimed at silage production, and may in fact allow for earlier planted corn that had been intended for silage to be shifted to grain corn production. In some areas of the province, with proper hybrid selection, the late-planted crop may be targeted for grain corn production. With time and heat unit accumulation being the limiting factors, this corn crop needs to be planted as quickly as possible following hay harvest. For this reason the option of no-tilling the corn crop into the hay stubble is very attractive. In addition, many of the soil structural and erosion control benefits fostered by the previous forage crop will be enhanced and/or prolonged by using a no-till system.

Research Results

Research in Ontario, conducted by the University of Guelph on a site near Woodstock in 1988 and 1989, examined corn silage yields from several different cropping systems. In this work, a five-year-old sod (75% alfalfa) was converted to corn production using both conventional tillage and no-till systems following the removal of a hay crop (as haylage) in early June. Yields obtained from these two tillage systems are outlined in Table 1. Silage yields were equivalent between conventional and no-till in 1989, but no-till yielded dramatically less than conventional tillage in 1988. Rainfall was 7% of normal during June of 1988, which resulted in no-till planting conditions that caused low plant stands and poor early growth. Success of the no-till corn planting following hay harvest in 1989 was attributed to adequate soil moisture during, and subsequent to, the planting operation.

Figure 2 Late-planted corn may be subject to high corn borer pressure - using a Bt hybrid is advisable if you hope to harvest the crop as grain corn.

Similar studies to those in Ontario were conducted by the University of Wisconsin (M. Smith, P. Carter and A. Imholte) during 1985 to 1987 and had somewhat similar results. In their study, no-till corn grain yields following an early season hay harvest were comparable with yields obtained by plowing in only one out of the three years. The successful no-tilling occurred in the year that had above-average June rainfall. In the other two years of the experiment, no-till corn yields averaged 46 bu/acre less than those obtained with conventional tillage.

Factors You Can Control

If you are determined to plant corn following a hay harvest in early June and rain has been limited, the lower risk alternative is certainly one which includes some tillage prior to planting. This tillage does nothing to conserve moisture or soil structure, but it may be essential for good seed-to-soil contact and early corn root exploration in these relatively hard, dry soils. This is a common phenomenon in Ontario. We can measure higher soil moisture in no-till soils, compared to plowed ground, but if dry weather comes early the corn plants cannot establish a root system which allows for exploration of the soil profile. In these cases, no-till performs more poorly than plowed ground. Even though your no-till ground has conserved more moisture, the roots cannot get at it.

However, in years where soil moisture is adequate, it appears that no-till corn can do well in these sod fields providing we can get it established and off to a good start. Here are some suggestions:

This operation will require above average planter unit down pressure and overall planter mass. No lightweights recommended.
Some tight sods, especially those with a lot of grass in them, cannot be suitably worked with a three-coulter system common to many no-till planters. The resulting strip is clumpy, air-filled and not conducive to germination or early plant growth. You may want to try a single coulter along with trash-removing wheels for a firmer, cleaner seedbed.
Cold soils are no longer an issue - be sure to plant into moisture even if that means going to planting depths of 2.5 to 3.0 inches.
Chemical control of the sod and other weeds is critical. Apply a recommended pre-harvest treatment to the hay crop and/or herbicides during pre-emerge or post-emerge windows of the corn crop.
Tough planting conditions may warrant increasing the seeding rate over your normal practices by 10%.
Select a hybrid with a heat unit rating suitable for the delayed planting date and intended use (silage or grain). Late-planted corn may be at greater risk to corn borer damage, so a Bt hybrid is recommended.
Wireworms may be a problem when planting into sod - use an insecticide seed treatment (i.e., D-L Plus).

Table 1 The effect of corn planting systems following early June hay harvest on corn silage yields. Woodstock, Ontario.
Corn planting system	1988	1989
	Corn silage yields @ 65% moisture (tonnes/acre)
Conventional tillage (following hay harvest)	17.0	16.6
No-till (following hay harvest)	8.9	16.8
Planting date	June 2	June 8
G. Aflakpui, T. Vyn, G. Anderson, D. Clements, M. Hall and C. Swanton. University of Guelph.