Illinois Fertilizer
Conference Proceedings
January 24-26, 2000
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R.G. Hoeft, E.D. Nafziger, L.C. Gonzini, J.J. Warren, E.A.
Adee, L.E. Paul, and R.E. Dunker1
Strip tillage, a system in which residue is removed and small ridges are formed in the fall in the position of next year's rows, has been developed in an attempt to overcome the adverse effects of cool, wet soils often observed in 0-till corn production. Ammonia is usually injected into the small ridges at the time of their formation. Several farmers have successfully used this system. This project was designed to determine whether the benefit from the system was due to warmer, drier soils, to the presence of nitrogen near the seed bed, or to a combination of the two. The impact of starter fertilizer in combination with strip tillage was also evaluated. To accomplish the objectives, experiments were conducted at DeKalb, Monmouth, and Urbana, Illinois. At each location, a factorial experiment was conducted to evaluate the effect of tillage (conventional, strip till, and 0-till), time (fall versus spring) and placement (under versus between rows) of N, and starter fertilizer on corn yield. Additional treatments were included to determine if surface applied P and K was equivalent to P and K injected into the strip till band.
When averaged across all locations, the data showed no difference due to tillage
system, placement or time of N application, or starter fertilizer. However,
one should not construe the results of this one year of experiments as an implication
that strip tillage may not be advantageous. The 1999 growing season was characterized
by very early warm temperatures and wet soils throughout much of April. Those
conditions resulted in nearly identical temperatures in the seeding zone irrespective
of tillage system by the time corn could be planted in early May. In most years,
soil temperatures would be expected to be warmer in conventional tillage and
in the strip till zones than in 0-till seeding zones. Under those conditions,
emergence and early season plant growth would be expected to be lessened under
0-till conditions.
Slower germination and early season plant growth of 0-till corn have prompted farmers and researchers to look for innovative, low-cost techniques that would allow them to retain the advantage of 0-till while overcoming these disadvantages. Earlier work funded by FREC has clearly shown that the addition of an N- and P-containing starter fertilizer will increase 0-till corn yield on most fields (Ritchie et al., 1996). However, even with use of this yield-enhancing treatment, early season growth on 0-till fields is still slower than on conventionally tilled fields.
Cooler soil temperatures and wetter soils associated with 0-till fields are the primary factors responsible for the slower early season growth. In an attempt to overcome these adverse factors, farmers have developed a system called "strip tillage" that allows them to apply their N in the fall, while at the same time creating an improved environment for spring planting. Special application equipment moves the residue from the row area, applies ammonia, and covers that application band with a small ridge in which next year's crop will be planted. Creation of the ridge allows the seed row area to dry sooner in the spring, and since the residue has been removed, soil temperatures should approximate those in conventional tillage.
While strip tillage has been successfully used by several farmers, there are still questions that can only be answered through a scientifically designed study. These questions include:
Is the benefit from strip tillage associated with the improved seedbed (warmer and drier seed bed), the presence of N in a band near the seed, or both?
Will starter fertilizer in combination with strip tillage result in yield equivalent to that under conventional tillage?
Is placement of ammonia directly under the row a safe and effective method of N application?
While there is considerable data on the impact of ammonia fertilizer placement, only limited data exists on the impact of strip tillage on yield (Pedersen et al., 1997), and this project did not explore the impact of ammonia with the strip tillage. Therefore, this research offers an opportunity to provide new research information for 0-till producers to use in their decisionmaking process. Refinement of strip tillage techniques offers the potential for producers to obtain the benefits of 0-till while overcoming the disadvantage associated with high residue over the row.
The objectives of the project are to:
Evaluate the effect of strip tillage with and without ammonia application in the fall as compared to conventional tillage and 0-till, and
Experiments were established in the fall of 1998 at Urbana, DeKalb, and Monmouth, Illinois. The previous crop at each location was soybean. A split plot experiment with tillage as main plot and a factorial combination of time of ammonia application by ammonia placement as subplot was established. Treatments consisted of conventional till (two-pass tillage in the spring after ammonia application), 0-till, and strip till; two times of ammonia application (fall and spring); and two ammonia placement positions (under row and between rows). Each experimental unit was eight rows by 50 feet. When the corn was planted in the spring, four of the eight rows of each plot received a 2 x 2 placed starter application of 21-19-0, and the other four rows received no starter. Two treatments were added to the study to evaluate the effect of P and K injected into the ridge as compared to broadcast over the surface. At Urbana, two additional treatments were established in the spring to evaluate the effect of ammonia placement under the row versus between the rows on spring strip tillage.
Emergence counts and plant height were taken, and all plots were thinned to a uniform population at approximately the V-4 stage of growth (Table 1). Grain yield was determined at maturity.
There were no significant differences in emergence or plant height at any of the locations due to treatments (Table 2, Table 3, Table 4, Table 5, Table 6, and Table 7). We had postulated that use of strip till may result in somewhat higher soil temperature in the strip as compared to 0-till, and thus it might result in increased early season emergence and plant height. In 1999, there was little if any difference in soil temperature between tillage systems from the date of planting. Since other research has shown substantial soil temperature differences between 0-till and conventional till plots in most years, we need additional years of data to confirm that there is in fact no difference in temperature between strip till and 0-till. While there was no difference in emergence between plots that had received ammonia directly in the band in the spring as compared to the middle of the row, we still do not recommend injection of ammonia in the spring directly in the strip till due to the potential for seedling damage. We have observed, on rare occasions, reduction in emergence associated with fall application of ammonia into the strip till ridge. Conditions under which this may happen appear to be injection of ammonia into a wet soil, followed by rapid soil drying and a very dry seed bed in the spring. Under those conditions, the side-wall compaction of the ammonia knife seals the ammonia into a small zone. Upon drying, the soil tends to crack along the knife track and the ammonia moves up into the seed zone.
Good yields were obtained at DeKalb (Table 8) and excellent yields at Monmouth (Table 9) irrespective of tillage, time and placement of N, or starter fertilizer. Excellent yields were also obtained at Urbana (Table 10), but in contrast to the other two locations, there were significant effects due to treatments. Approximately eight more bushels of corn were obtained from spring versus fall N, placement of N between the rows instead of under the row, and for starter as compared to no starter. When data for all locations was averaged (Table 11), there were no significant differences in yield due to tillage, time or placement of N, or starter fertilizer.
Injection of P and K into the ridge did not have a positive impact on yield at any of the locations (Table 12)
Table 1. Characteristics of the experimental sites
1 R.G. Hoeft and E.D. Nafziger are Professors; L.C. Gonzini, J.J. Warren, and E.A. Adee are Senior Research Specialists; and L.E. Paul and R.E. Dunker are Agronomists, Dept. of Crop Sciences, Univ. of Illinois.
Pedersen, W.L., R.E. Dunker, C.A. Bradley, D.S. Mueller, and J.C. Siemens. 1997. Evaluation of fall and spring strip-till as an alternative to no-till for corn. Agron. Abstr. p. 111. Amen Soc. Agron. Madison, WI.
Ritchie, K.B., R.G. Hoeft, E.D. Nafziger, W.L. Banwart, L.C. Gonzini, and J.J. Warren. 1996. N management and starter fertilizers for no-till corn. In R.G. Hoeft (ed.) Illinois Fertilizer Conference Proceedings. Univ. of D., Urbana, IL. pp 55-65.
