Illinois Fertilizer
Conference Proceedings
January 27-29, 1997
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Kevin L. Barber
Concern over soil and water conservation has resulted in many producers shifting from traditional methods of tillage to the no-tillage system. The common practice of applying phosphorus (P) and potassium (K) fertilizer to the surface of soils under no-till management causes stratification of P and K in the topsoil. Also, adoption of the no-tillage system results in the accumulation of crop residues on the soil surface. A modification of the no-tillage system may involve residue removal from the row area alone or in combination with cultivation of a narrow strip of the row area. The cultivation of the row area is known as strip or zone tillage.
Residue serves as an insulating barrier thereby affecting soil temperature
and water. In South Africa, soil temperature increased and soil water content
decreased as residue-free bands were increased from 0 to 12 inches (Berry and
Mallett, 1989). Fortin (1993) observed that soil temperature in a 12 inch residue-free
band was similar to that in conventionally tilled soil. In the same study, interrow
soil water content was higher with in-row residue removal than with conventional
tillage. Fortin (1993) concluded that in-row residue removal provided a row
environment similar to that provided by conventional tillage and an interrow
environment better suited for conserving soil water than conventional tillage
systems. By preparing strip-tilled rows in the fall, the soil in these rows
may dry and warm in the spring allowing for timely planting and faster corn
development as compared to that under no-tillage management. Because southcentral
Illinois has large areas of soils that are poorly drained, the soils are often
cool and wet during the spring. Hence, strip tillage appears to be well suited
to the area.
Soil fertility researchers have not examined the response of corn grown in strip-tilled
rows to method of fertilizer application. Injecting a band of fertilizer while
performing strip tillage before planting may allow optimal conditions for corn
growth and development. The objective of this study is to assess the effects
of fall versus spring and broadcast versus banded applications of fertilizer
P and K on the growth, P and K uptake, and grain yield of corn grown in strip-tilled
rows.
This experiment was initiated in the fall of 1995 at the Brownstown Agronomy
Research Center on a field previously in corn under no-tillage management. The
soil is a Cisne silt loam (fine, montmorillonitic, mesic Mollic Albaqualfs)
with a nearly level slope. Cisne soil is poorly drained due to its very slowly
permeable subsoil. Chemical characteristics of the surface six inches of soil
were a pH of 6.4, organic matter content of 2.4%, available P content of 70
lb/acre, and exchangeable K content of 232 lb/acre.
A randomized complete block design with four replications was used. Individual
plots were 20 ft wide by 70 ft long. Tillage treatments included no-till and
fall and spring strip tillage. Fertilizer P and K treatments were none, surface
broadcast in the fall, and fall and spring injection. Strip tillage was accomplished
with a gang of three Rawson coulters. The gang of coulters tilled a twelve-inch
wide band of soil to a depth of three to four inches. The granular fertilizer
materials 0-44-0 and 0-0-60 were used to provide 45 lb P205/a and 24 lb K20/a,
respectively. Appropriate amounts of the fertilizer materials were mixed and
either broadcast by hand or injected on 30-inch spacings at a depth of 4 inches
through knives behind ripple coulters. The P and K mixture was delivered to
the knives by a Gandy Orbit-Air pneumatic applicator. For the appropriate treatments,
banded applications of fertilizer P and K were injected at the same time that
strip tillage was performed.
The fall treatments were applied on 21 November 1995, while the spring treatments
were applied on 12 April 1996. All vegetation was killed with a bumdown application
of Roundup and 2,4-D on May 20. Pioneer Brand 3489 was planted in 30-inch row
spacings at 30,800 seeds/acre on May 23. The seed was placed into the previously
prepared strip-tilled rows as well as into the no-till plots using a no-till
planter. All plots received a sidedressed application of anhydrous ammonia at
a rate of 180 lb N/a on June 18.
Soil temperature was measured at a depth of two inches in the seed row from
planting until the V6 (six fully expanded leaves) growth stage. Temperature
was measured twice a week between 3:00 and 5:00 p.m. Emergence of the corn seedlings
was determined every other day from beginning of emergence until no newly emerged
plants were observed. Aboveground tissue of five whole plants was collected
at random from each plot at the V6, VT (tasseling), and R6 (physiological maturity)
growth stages. The tissue was dried, weighed, ground, and analyzed for total
P and K. Grain moisture content and yield were determined by machine harvesting
210 ft (3 rows by 70 ft) of plot on Oct. 31. Grain yields were adjusted to 15.5
% moisture.
Differences in soil temperature among the tillage and fertilizer treatments
were observed 7, 22, and 26 days after planting (Table
1). Soil temperature in strip-tilled rows was generally higher than that
in no-till rows by 1 °F or more on these days. Emergence of the corn seedlings
was similar among the treatments at 5 and 11 but not 7 days after planting (Table
1). On the seventh day, there were more plants per foot of row in the strip-tilled
plots that received fall broadcast or banded P and K than in the no-till/spring
injected P and K treatment. The overall lack of treatment effects on soil temperature
and plant emergence were probably due to high soil temperatures at planting.
About 11 inches of rain were received at the Brownstown Center from April 13
to May 15. Hence, planting was delayed until the third week of May. Soil temperatures
had already reached 75 °F when the corn was planted. At soil temperatures
this high, one would not expect treatment effects on soil temperature and early
plant development to vary widely.
Tillage and fertilizer effects on P and K uptake at three growth stages are
reported in Table 2. No significant differences
in P and K uptake were observed at any growth stage. Aboveground dry matter
accumulation at growth stages V6, VT, and R6 as well as grain yield also did
not vary among the tillage/fertilizer treatments (Table
3). Only 2 inches of rain were received at the Center from July 4 until
September 15. The lack of rainfall during the later half of the growing season
resulted in below normal grain yields.
Results from the second year of this study showed that significant differences
among the treatment variables were limited to soil temperature and plant emergence.
Soil temperatures in rows that were strip-tilled were generally higher than
those in untilled rows at 7, 22, and 26 days after planting. The number of corn
seedlings per foot of row on the seventh day after planting was highest in strip-tilled
plots that received a fall broadcast application of P and K. Planting corn in
strip-tilled rows, regardless of method of fertilizer application, offered no
early growth or grain yield advantages as compared to corn grown under no-tillage
management. This study will be continued in 1997.
Table 1. Tillage and fertilizer treatment effects on soil temperature and plant emergence, 1996
Berry, W.A.J., and J.B. Mallett. 1989. The effect of removing maize surface
residue from the seed-row on seedzone temperature, soil water and maize development.
South Mr. J. Plant Soil 6:108-112.
Fortin, M.-C. 1993. Soil temperature, soil water, and no-till corn development
following in-row residue removal. Agron. J. 85:571-576.
1Senior Research Specialist, University of Illinois, Brownstown Agronomy Research Center, Brownstown, IL.
