Northern Illinois Agronomy Research Center

Department of Crop Sciences---University of Illinois

COLLEGE of AGRICULTURAL, CONSUMER AND ENVIRONMENTAL SCIENCES

FEBRUARY 2003Newsletter Issue 20:1 Lyle Paul - Agronomist David Lindgren - Farm Foreman 14509 University Rd. Shabbona, Il 60550 Phone/Fax 815/824-2029 e-mail lylepaul@illinois.edu

/research/rdc/dekalb

2002 Weather Data:

2002 Precipitation (Inches)

2002 Growing Degree Days (Base 50)

2003 Weather Data:

2003 Precipitation (Inches)

Soil Moisture & Grain Yields
Eric Adee, NWIARDC Monmouth, pointed out that soil moisture has been a highly discussed topic this winter. Tiles haven't been running since last fall, river levels are lower than normal and there are reports of barges running aground. The chart of 2002 rainfall shows that 10 of the 12 months were below normal for rainfall. From July 1,2002 to March 1,2003, rainfall was over 10 inches short of normal. Are dry soil conditions and short rainfall something to be concerned about? In areas of the country that depend heavily on winter moisture to replenish soil moisture reserves, such as the high plains, this dry fall and winter would be a major concern. Does this also apply to northern Illinois?

Illinois State Water Survey collects soil moisture data and other weather statistics at NIARC. Using their data and yield reports for DeKalb County from the Illinois Agricultural Statistics (website- http://www.agstats.state.il.us/index.html.) the following charts were made. Chart ! & 2 show January 1 soil moisture levels to 2 meters (under sod) and the crop yields for that year. The stars are at the level which is field capacity (30.96 inches) which is the maximum amount of water that can be held by the soil. Basically, soil moisture levels on January 1 for the past 12 years were about average for all years from 91 to 95 and below average every year since then. Overall, yields have trended upward and soil moisture on January 1 has trended downward.

Charts 1 and 2 also show that the yields for the year in DeKalb County are not closely related to soil moisture on January 1. Some of the best yields have been in the years with the lowest soil moisture level on January 1. Five of the 6 years with corn yields above average occurred in years with below average soil moisture levels and 3 of the 4 years with soybean yields above average were also in years with below average soil moisture levels on January 1

Historic levels of rainfall during March (2.45 inches), April (3.23) and May (3.91) would indicate that there is a good opportunity to replenish soil moisture before the heavy demands of the growing season.

That said, the soil moisture level on January 1, 2003 was the lowest it has been in the past 12 years. Plant available moisture on February 27 was 5.3 inches, which is about 42% of what the soil could hold to the 2 meter depth (12.8 inches). Even with low rainfall amounts since January 1, the plant available water levels has improved about 0.7 inches during that time from January 1 to March 1.

Chart 2: Comparison of January Soil Moisture and Soybean Yield in DeKalb County

Intellicoat^® Seed Coating on Corn
Emerson Nafziger conducted a research trial with polymer seed coating on corn at DeKalb and Urbana. Following is the writeup that Emerson supplied to the seed company on that study.

Intellicoat^® Seed Coating on Corn
Report of 2002 Research

Polymer seed coating that allows water into seeds only when soil temperatures reach a threshold may hold promise as a means to safen corn plantings that are done very early. To test this concept, we established experiments at two Illinois locations - Shabbona (DeKalb County) and Urbana (Champaign County) in 2002.

Seed of coated and uncoated corn was obtained from Landec Ag., and planted as subplots on three planting dates, ranging from early April to mid-May. At DeKalb, about 36,000 seeds were dropped using an IH planter, and about 31,000 seeds were dropped using a Deere vacuum planter at Urbana. Planting dates are given in the tables below. Standard fertilizer and weed control practices were used. Subplots were four (30-inch) rows wide and 73 and 110 ft. long at DeKalb and Urbana, respectively. Daily emergence and final stand counts were taken for all dates at DeKalb, while at Urbana daily emergence counts were made for the first planting only; for the second and third planting dates at Urbana, emergence timing was estimated for coated and uncoated seed.

Table 1. Plant population and grain yields from DeKalb, 2002.

Table 2. Grain yields at Urbana, 2002.

The very large effect of planting date on plant stand and yield at DeKalb was due to the fact that frost occurred on May 21, causing severe loss of stand and yield (Table 1). The two later planting dates produced very good yields, due mostly to better stands but also to the fact that rain occurred in time to help later plantings much more than the earlier one. This also occurred at Urbana, though stress there was considerably greater and yields were lower. Seed coating had no effect on plant stands at DeKalb, and no effect on yield at either location. At DeKalb, the interaction between planting date and seed coating reflected somewhat higher stands and yields from coated seed at the first planting date, but not on the later ones. It is possible that the slight delay in emergence noted for coated seed might have led to fewer frost-susceptible plants when frost occurred, but stands and yields were both lowered greatly (whether from coated or uncoated seed, this corn would have been replanted under normal circumstances), and so little protection was provided by the seed coating, at least in an absolute sense.

To our surprise, seed coating provided only slight delay in emergence, regardless of planting date. At DeKalb, the first planting took the longest to emerge, but the emergence patterns of coated and uncoated seed were virtually identical (Figure 1). Similar trends were seen in the second and third plantings, both of which reached 90 percent emergence in less than 20 days. At Urbana, where the first planting emerged rather quickly due to warm temperatures, we again saw almost no delay in emergence of coated seed (Figure 2). While we did not count emergence of later plantings as closely at Urbana, observations indicated that coated seeds delayed emergence by less than one day. There was no visible effect of seed coating on the time from first to last emergence.

Figure 1. Emergence of seedlings from coated and uncoated seed following the April 6, 2002 planting at DeKalb.

Figure 2. Emergence of the seedlings from coated and uncoated seeds following the April 5, 2002 planting at Urbana.

Although soils warmed faster than usual for early-April planting, at least at Urbana, the lack of much effect of seed coating on days to emergence is surprising. While see coating did not spread emergence over a longer period of time and so did not cause plant size non-uniformity, neither did it provide any clear benefit at these two Illinois locations in 2002. We hope to repeat this study to see how the coating affects emergence when soils stay colder after planting.

Soybean Inoculation 2002
Soybean inoculation work continued in 2002. This year the products used were supplied by Urbana Laboratories. The products were Nod+ & Nod+ and Azosprillium. Azosprillium is reported to increase root growth. The results of the inoculation continued to vary with variety, but with little overall effect on yield in the corn and soybean rotation.
The study was planted on May 29 in 4-30 inch row plots by 100 feet in length with six replications of each variety and treatment. In 2002, six varieties of soybean, Asgrow variety AG 2703, Dwight, Pioneer variety 92B38, Pioneer variety 92B84, Pioneer variety 93B09, and Savoy were used.
In 2002, the yield differences due to inoculation treatments averaged over all varieties was about 0.5 bushels per acre. The Nod+ & Azospirillium treatment yielded about 0.10 bushels per acre more than the untreated check, but was not statistically significant at the 0.1 level. The Nod+ treatment yielded about 0.4 bushels per acre less than the untreated check, but that difference was also not statistically significant at the 0.1 level from either other treatment. The Nod+ inoculation treatment and untreated check with 2 varieties over 2001 & 2002 averaged within 0.04 bushels per acre, not statistically significant different at 0.1 level. In 2002, there were statistically significant differences at the 0.1 level among varieties. There were no statistically significant differences at the 0.1 level among the inoculation treatments and the untreated checks. The difference in yield due to an inoculation treatment varied with variety, but differences within an individual variety due to inoculation treatment were less than 4 percent.

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