Illinois
Fertilizer Conference Proceedings
January 29-31, 1996
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K.B. Ritchie, R.G. Hoeft, E.D. Nafziger, L.C. Gonzini, J.J. Warren, and W.L. Banwart1
No-till corn growth is often slowed early in the growing season by cool, wet soils. Many have questioned whether fertility management could overcome a part of that problem. As a result, two separate but related experiments were conducted from 1993-95 at four locations to evaluate the response of no-till corn to: 1) primary N applications of anhydrous ammonia preplant, UAN broadcast preplant, and ammonia sidedressed at V6; 2) factorial combinations of N, P, and K banded 2 inches beside and 2 inches below the seed (2X2); 3) seed-placed fertilizers with various N, P, and K rates and sources; and 4) dribbling fertilizer on the soil surface near the seed furrow.
Grain yields were highest when ammonia preplant was used as the primary nitrogen source, and sidedressed ammonia performed nearly as well as preplant ammonia. Broadcast UAN did poorly when post-application weather was dry and warm, and yielded 10-25 bu/A less than the ammonia treatments all three years at Oblong. Starter fertilizers banded 2X2 increased yields at 8 of 9 site-years, regardless of previous crop. Average yield increases were 8 bu/A for N alone (25-0-0), 13 bu/A for N and P (25-30-0), and 14 bu/A for N, P, and K (25-30-20).
Plant growth and yield increases were more consistent when starter fertilizer was 2X2 banded instead of seed-placed. The liquid products 10-34-0 and 9-18-9 applied at rates of 10-34-0 and 10-20-10 lbs/A, repectively, did not significantly slow emergence. These seedplaced liquids yielded the same as the 2X2-banded 25-30-20 in 1993 and 1994, but yielded 12 bu/A less at two of three locations in 1995.
Dribbling or broadcasting N (25-0-0) or N+P (25-64-0) yielded 8 bu/A less than seedplaced liquids at 2 of the 6 site-years. The 2X2-banded 25-30-20 yielded 11 bu/A more than the surface-applied "starter" treatments in 4 of 6 site-years. The yield ranking of the starter treatments tested, averaged across all locations, was:
2X2 banded > seed-placed liquid > surface dribble > no starter
Illinois no-till corn producers have three options for applying the majority of their N. These are preplant injection, surface applications of urea-based compounds, or sidedressed injected N. Each method has advantages and potential disadvantages. Injecting N reduces volatilization and immobilization. Surface applications can be rapidly applied, and can preserve surface residue in erodible areas. However, injecting UAN may increase yields by up to 20% more than surface-applied UAN. Sidedressing improves N availability and fertilizer use efficiency while reducing early-season N losses from denitrification and leaching in some situations, but farmers face the risk of not getting N applied in a wet spring, increased chances of crop injury, and conflicts with other spring work.
Nitrogen volatilization losses increase when urea-containing materials are applied to a warm, moist soil with large amounts of surface residue. Rainfall must occur shortly after urea application to avoid N volatilization in no-till. The number of days until 2 inches of rain fell determined potential for ammonia volatilization in Pennslvania (Fox et al., 1986).
Starter fertilizers offer the potential to increase nutrient availability on cool, wet, no-till soils. Several studies have demonstrated that 2X2 banding is a safe, effective way to supply starter fertilizer. In Indiana, Mengel (1990) reported an average yield increase of 10 bu/A at 10 of 11 sites. All sites in this study were high in fertility, where starter would not have been recommended for conventional tillage. In Wisconsin, Shulte and Bundy (1994) observed responses to starter fertilizer in high-testing soils that were cold at planting. In warmer soils, however, responses to starter fertilizer may not occur as consistently as in cool soils. In southern Illinois, Kapusta and Varsa (1990) did not find yield benefits from starter fertilizer.
Applying fertilizers in a 2X2 band requires a significant additional cost to equip planters, and may slow planting speeds. These drawbacks, plus the availability of "low-salt" fertilizers, have resurfaced an interest in seed-placed (pop-up) fertilizers for no-till. It is recommended that no more than 10-15 lbs/A of N+K2O be applied with the seed because of the risk of salt injury. Urea and DAP are not recommended for seed-placed use because they release ammonia, which can be toxic to seedlings. Fluid ammonium polyphosphates (such as 10-34-0) should supply N without the hazard of NH3 toxicity (Mordtvedt, 1976).
After seeing yield increases from banded and seed-placed fertilizers, corn growers often wonder if dribbling fertilizer on the soil surface in a band near the seed furrow might provide a yield boost similar to banded and seed-placed fertilizers, but without the danger of placing fertilizer in contact with the seed or the hassle of running an extra coulter through the soil.
Recent Kansas research by Gordon et al. (1995) suggests that yield responses to starter fertilizers may be dependent upon the hybrid used. In their study, some hybrids did not respond to starter, while starter increased yields of other hybrids by 15 bu/A.
The objectives of these experiments were to determine the response of no-till
corn to: 1) primary N applications of anhydrous ammonia preplant, UAN broadcast
preplant, and ammonia sidedressed at V6; 2) starter fertilizers with factorial
combinations of N, P, and K banded 2 inches beside and 2 inches below the seed
(2X2); 3) seed-placed fertilizers with various N, P, and K rates and sources;
and 4) dribbling fertilizer on the soil surface near the seed furrow. Experimental
locations and soil conditions were varied to gain a better understanding of
how environment might influence these treatments.
Experiments were conducted from 1993 to 1995 at four locations varying in climate, soil type, crop rotation, and soil test values (Table 1). While cooperating farmers were the same, the field or area within the field was different each year. Corn was planted with a 2row planter at rates near 35,000 seeds/A (planting dates are listed in Table 2), and stands were thinned to 29,000 plants/A at the V6 growth stage.
In Experiment 1, three main plot treatments consisted of 160 lb N per acre supplied as ammonia preplant, UAN broadcast preplant, or ammonia sidedressed at V6. Within each main plot, 8 starter treatments (2X2 banded) were applied as factorial combinations of N, P, and K.
Seed-placed, surface-dribbled starter, and 2X2 banded fertilizer treatments were studied in Experiment 2. Twelve treatments compared factorial combinations of N, P, and K. Thirteen seed-placed treatments were included to compare the effect of N source (urea vs. ammonium nitrate), P source (DAP vs. MAP), K source (KC1 vs. K2SO4), and liquid source (10-34-0 vs. 9-18-9). In 1994, three additional treatments of surface-applied UAN and DAP were added. All plots received 160 lb N/acre as preplant NH3. Stand counts were taken for Experiment 2 during the period from emergence to V3.
In 1993 and 1995, all plots at Oblong received a broadcast application of 1201b/A of K20. The Gridley plots were injured by a herbicide application at the V7 stage in 1993; therefore, grain yields are not reported for Gridley in 1993. The Pana location has swales and received excessive rainfall in 1994 and 1995, thus causing stunted plants and highly variable results. These 3 site-years where extenuating circumstances affected yields are not considered in summarizing yields from these experiments. The late-planted 1995 corn sustained heavy stalk borer damage at Ashton and Pana, moderate damage at Gridley, and minor damage at Oblong.
Pioneer 3394, a hybrid that responded well to starter fertilizer in Kansas
(Gordon et al., 1995), was planted all three years at Oblong and Pana, and in
1994 at Gridley. Pioneer 3563, which had very little response to starter in
Kansas, was used at Gridley in 1995 and Ashton in 1993. In 1994, the Ashton
plots were planted with Pioneer 3525, while Pioneer 3769 was grown in 1995.
There was no significant interaction between primary N source and starter fertilizers. Therefore, the results from the primary N source, 2X2-banded, and seed-placed starter fertilizers will each be discussed separately.
Nitrogen Management
Injecting ammonia increased yields every year at Oblong, but plants receiving surfaceapplied UAN had yields similar to the ammonia treatments at the other locations (Tables 3, 4, and 5). It seems likely that N1-13 volatilization after UAN application resulted in significant N losses at Oblong because this location had warm temperatures and less than 1 inch of rainfall within the first week after UAN was applied each year. Ashton and Gridley sometimes went several days after UAN application before accumulating 1 inch of rainfall, but temperatures were colder in these locations.
2X2 Starter
Starter fertilizers consistently increased early season plant growth and often increased grain yields, regardless of the preceding crop. When early season soil test levels of P and K were near the recommended minimums, or broadcast K was added to bring the soil test to recommended levels, adding starter N (25-0-0) increased yields by 8 bu/A. Nitrogen plus phosphorus (25-30-0) improved production by 13 bu/A, and N+P+K (25-30-20) gave a 14 bu/A increase. These results are averaged across all locations. Refer to Tables 6, 7, and 8 for yearly yields at each location.
Because starter fertilizer leads to more vigorous early growth and faster maturity, yield benefits from starter were more evident in the late-planted 1995 crop (Table 8). The average yield increase from starter containing N+P was similar to previous years, but since yields were lower, the proportional yield increase due to starter was greater. Poor root growth in the top soil, plus lower K levels deeper in the soil, probably caused plants to respond more to starter K at Ashton and Gridley in 1995. These locations did not receive any broadcast K.
Contrary to Kansas results finding that the yield of Pioneer 3563 was not significantly increased by starter fertilizer (Gordon et al., 1995), we observed a yield increase due to starter greater than 10 bu/A both times we planted this hybrid. Yield responses to starter by Pioneer 3394 in our studies were similar to those observed in Kansas. Yields of all of the Pioneer hybrids used in our studies were increased by starter fertilizer.
Seed-placed Fertilizers
Plant growth and grain yield were more consistently increased when starter fertilizer was 2X2-banded instead of seed-placed. There was no difference in yield response between dry and liquid fertilizer materials when they were applied at equivalent nutrient rates. Nitrogen fertilizer with a high salt content (ammonium nitrate) or ammonia-releasing compounds (urea, DAP) slowed emergence. Potassium chloride and potassium sulfate gave similar results. When dry fertilizers increased yield, the fertilizer usually contained at least 10 lbs/A of N and P2O5. However, these rates slowed emergence at some locations in 1994 and 1995. The liquid products 10-34-0 and 9-18-9 applied at rates of 10-34-0 and 10-20-10 lbs/A, repectively, did not significantly slow emergence. These seed-placed liquids yielded the same as the 2X2-banded 25-30-20 in 1993 and 1994, but yielded 12 bu/A less at two of three locations in 1995. Yield results from selected seed-placed treatments are shown in Tables 9, 10, and 11.
Seed-placed fertilizers should be used with caution. Injury from seed-placed fertilizers was most pronounced in 1995, when the weather was warm and dry after planting. Urea severely injured plants at Gridley and Oblong. Even though the liquid products 10-34-0 and 9-18-9 did not slow emergence in the field, plants receiving 9-18-9 at Gridley were stunted at the V l growth stage. We have seen leaf tip burning and twisting in our greenhouse experiments with both 10-34-0 and 9-18-9 at rates of 10-34-0 and 5-10-5, respectively.
One disadvantage of seed-placed fertilizer is that only low rates of fertilizer (less than 10-15 lbs/A N + K2O) can safely be used. These lower fertilizer rates are not always enough to provide maximum yield increases, as evidenced by the 10-10-10 2X2 treatment yielding less than the 25-30-20 at two of three sites in 1995 (Table 11).
Surface-applied "Starters"
Dribbling or broadcasting N (25-0-0) or N+P (25-64-0) improved yields by the
same amount as liquid seed-placed fertilizers at 4 of 6 site-years. However,
these liquid seedplaced treatments outyielded the surface applications by more
than 8 bu/A at 2 of the 6 siteyears, and the 2X2 banded 25-30-20 yielded 11
bu/A more than the surface-applied starter treatments in 4 of 6 site-years.
Table 1: Description of experimental locations
Table 2: Planting dates for all locations, 1993-1995
Table 3: Effect of primary N source on grain yield. Experiment 1. 1993
Table 4: Effect of primary N source on grain yield. Experiment 1. 1994
Table 5: Effect of primary N source on grain yield. Experiment 1. 1995
Table 6: Effect of 2X2 banded starter fertilizer on grain yield. Experiment 1. 1993
Table 7: Effect of 2X2 banded starter fertilizer on grain yield. Experiment 1. 1994
Table 8: Effect of 2X2 banded starter fertilizer on grain yield. Experiment 1. 1995
Table 9: Effect seed-placed and banded starter fertilizer on corn grain yield. Experiment 2. 1993
1K.B. Ritchie is a Jonathan Baldwin Turner Fellow, R.G. Hoeft and E.D. Nafziger are Professors, and L.C. Gonzini and J.J. Warren are Senior Research Specialists, Dept. of Crop Sciences; W.L. Banwart is a Professor, Dept. of Natural Resources and Environmental Sciences, University of Illinois.
Fox, R.H., J.M. Kern, and W.P. Piekielek. 1986. Nitrogen fertilizer source, and method and time of application effects on no-till corn yields and nitrogen uptakes. Agronomy. Journal 78:741-746.
Gordon, W.B., D.L. Fjell, and D.A. Whitney. 1995. Starter fertilizer interactions with corn hybrids. p. 102-108. In Proceedings of the Twenty-Fifth North Central Extension-Industry Soil Fertility Conference. Published by the Potash and Phosphate Institute, Manhattan, KS.
Kapusta, G. and E.C. Varsa. 1990. Long term tillage and fertility effects in corn. p. 70-81. In Proceedings of the Twentieth North Central Extension-Industry Soil Fertility Conference. Published by Potash and Phosphate Institute, Manhattan, KS.
Schulte, E.E. and L.G. Bundy. 1994. Another look at the reasons for starter fertilizer. In Proceedings of the 1994 Fertilizer, Aglime and Pest Management Conference 33:17-32. Madison, WI.
