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Production Agriculture

Effect of Winter Wheat Crop Residue on No-Till Corn Growth and Development

Dep. of Crop and Soil Sciences, Michigan State Univ., 480 PSSB, East Lansing, MI 48824

^* Corresponding author (thelenk3{at}msu.edu)

Received for publication July 5, 2006.

	ABSTRACT

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Two established methods for increasing the sustainability of production agricultural cropping systems are (i) increasing crop residue levels by reducing tillage and (ii) including a winter annual crop in the rotation. A wide range of crop yield responses have been reported for no-till systems adopted to a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation. However, little research has been done in the Northern Corn Belt on no-till corn following winter wheat (Triticum aestivum L.). The objective of this study was to evaluate the effect of winter wheat crop residue on the growth and development of no-till corn. The experimental design was a randomized complete block. Treatments consisted of no-till systems with three levels of winter wheat residue [no wheat residue (NWR), wheat root residue only (WRR), and wheat root and shoot residue (WRSR)]. Data were collected in 2003, 2004, and 2005. Measurements included plant emergence, plant height, time of tasseling (VT stage), chlorophyll content, presidedress soil nitrate test (PSNT) soil nitrate levels, soil moisture and temperature, corn grain yield, grain moisture, and grain test weight of corn at harvest. In all years, the presence of winter wheat residue above and below ground decreased soil temperature, increased soil moisture, and decreased chlorophyll content in corn leaves and plant height in the early stages of corn development. The VT stage of corn was delayed for about 1 wk in residue systems. Winter wheat residue decreased the amount of plant available N and increased grain moisture and test weight of corn grain at harvest. Emergence and population of corn in 2003 and 2005 were reduced in residue systems. The use of a PSNT-based N application rate was successful in maintaining corn grain yield in wheat residue systems with corn grain yield in NWR systems in 2003 and 2004 despite wheat residue antagonism of corn growth and development. In 2005, corn grain yield in wheat residue treatments was less than in NWR treatments, but was equal to PSNT target yields.

Abbreviations: DAP, days after planting • NWR, no wheat residue • PSNT, presidedress soil nitrate test • WRSR, wheat root and shoot residue • WRR, wheat root residue only

	INTRODUCTION

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HIGH RESIDUE CROPPING SYSTEMS such as no-till and reduced-till systems contribute significantly to the sustainability of production agriculture. No-till adoption in the USA comprises 25.3 million ha of land, about 23% of U.S. cropland (Conservation Technology Information Center, 2004). Recent increases in energy costs are expected to further increase adoption of no-till practices. These systems reduce soil erosion and run-off and increase the percolation of rainfall (Cavigelli et al., 1998). Additionally, soil organic C levels are increased, leading to improved soil nutrient holding capacity and structure (Tisdall and Oades, 1982).

The amount of soil organic matter and the rate of turnover can be altered by different management practices. Cultivation affects soil structure by destroying soil aggregates, exposing physically protected organic material and thus resulting in loss of soil organic matter (Tisdall and Oades, 1982; Elliot, 1986; Angers et al., 1992; Blevins and Frye, 1993; Beare et al., 1994). Tillage enhances decomposition of organic matter by mixing plant residues into the soil, increasing aeration, and enhancing dry–wet and freeze–thaw cycling (Paustian et al., 1997). In contrast, no-till systems reduce soil mixing and soil disturbance, allowing soil organic matter accumulation (Blevins and Frye, 1993). Many studies have shown that no-till farming improves soil aggregation and aggregate stability (Beare et al., 1994; Six et al., 1999). Mycorrhizal fungi, which are promoted by no-till systems, contribute to formation and stabilization of macroaggregates (Tisdall and Oades, 1982; O'Halloran et al., 1986; Beare and Bruce, 1993). Also, compared with conventional tillage, no-till significantly increases soil total C and N levels, number of water-stable aggregates, and labile C and N associated with macroaggregates (Mikha and Rice, 2004).

Winter wheat is commonly grown in rotation with corn and soybean (Michigan Agricultural Statistics Service, 2004). The growth cycle of soybean makes winter wheat a logical sequence crop in the rotation, which in the Northern Corn Belt is usually planted immediately following soybean harvest. There are many advantages of including a winter annual crop such as winter wheat in a cropping system. Sanchez et al. (2001) reported that N mineralization was increased in a diverse cropping system that included wheat in the rotation. In addition, pest cycles can be disrupted with the inclusion of a winter annual crop (Cavigelli et al., 2000) such as the reduced emergence of weeds in wheat residue (Wicks et al., 1995).

Despite many advantages, there are also negative impacts associated with high residue systems. Cox et al. (1990) noted that cool conditions in May in years with less-than-normal growing degree days may result in poorer emergence under reduced tillage because high residue inhibits soil warming and delays corn emergence in northern latitudes. Also, in no-till systems corn emergence rates were slower compared with conventional tillage over 3 yr (Drury et al., 2003). However, despite low emergence rates, final plant stands were not significantly different between treatments in some years. Also, emergence of corn depended on time of planting (early or late) and spring weather conditions (wet or dry, cool or warm).

Winter wheat is an allelopathic plant and soil toxicity depends on both root excretions and residue decomposition (Krupa, 1982; Wu et al., 2000). Active allelopathic compounds inhibit N fixation by free-living and symbiotic microorganisms (Rice, 1984).

Our objective was to verify the reported antagonism of winter wheat residue on no-till corn growth and development and to determine whether the antagonism could be overcome in terms of corn grain yield by using a PSNT based early season N application rate.

	MATERIALS AND METHODS

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Experimental Site and Data Collection
The research was conducted at the Michigan State University Agronomy Farm in East Lansing, MI. The experiment was established on soybean–winter wheat–corn cropping systems from 2001 through 2005 with three cycles located on three adjacent fields. The first cycle included plots planted to soybeans in 2001, winter wheat in fall 2001, and corn in 2003. The second cycle included plots planted to soybeans in 2002, winter wheat in 2002, and corn in 2004. The third cycle was implemented with soybeans and wheat planted in 2003 and with corn planted in 2005.

The first cycle was established on a Capac loam soil (fine loamy, mixed, mesic Typic Hapladulfs). The second and third cycles were established on Colwood (fine loamy, mixed, mesic Typic Haplaquolls)–Brookston (fine loamy, mixed, mesic Typic Argiaquolls) loam soils.

The experiment was a randomized complete block design with treatments consisting of three levels of winter wheat residue: NWR, WRSR, and WRR. Treatments with NWR had a second year of soybean substituted for wheat in the second year of each cycle. In the first cycle, the experiment had four replications. Plots were 14.0 m long and 6.1 m wide. In the second and third cycles the treatments were replicated eight times. Plots were 9.1 m long and 6.1 m wide. Corn row width was 76 cm within each cycle.

In the second year of the experimental cycle, soybean (‘Dekalb 23–51’) was planted on 5 May 2002, 19 April 2003, and 29 May 2004 (rate of planting was 444 600 seeds ha^–1) for NWR treatments. Soybean was harvested on 28 Sept. 2002, 13 Oct. 2003, and 20 Dec. 2004. At planting time, liquid starter fertilizer 6–24–6 (28 kg ha^–1) was added 5 cm below and 5 cm to the side of each seed row, providing 1.7 kg N ha^–1, similar to local common production practices. There were no noticeable differences in soybean yields observed among NWR plots. Soybean yielded 3.59 Mg ha^–1, 2.25 Mg ha^–1, and 3.26 Mg ha^–1 in 2003, 2004, and 2005, respectively.

‘Harus’ winter wheat was planted in fall of 2001, 2002, and 2003. In the following spring, at green up, wheat plots received 246 kg ha^–1 of granular urea (46–0–0). Winter wheat yielded an average of 5.65 Mg ha^–1 in 2002, 7.65 Mg ha^–1 in 2003, and 4.95 Mg ha^–1 in 2004, with no significant yield differences between WRR and WRSR treatments ( = 0.05). After harvest, the remaining wheat straw was about 30 cm tall. The remaining residue was returned to WRSR plots and removed from WRR plots. The highest amount of wheat residue left in the plots was from the first cycle (2001–2003). The average amount of straw left in WRSR treatment was 10.73, 7.39, and 9.63 Mg ha^–1 in 2003, 2004, and 2005, respectively.

An early maturity corn variety (DKC44–46, YieldGard Corn Borer/Roundup Ready, Residue Proven, 94-d relative maturity, Monsanto, St. Louis, MO) was planted into plots using a customized John Deere no-till planter. Corn was planted at a target population of 69000 plants ha^–1 on 30 Apr. 2003, 29 May 2004, and 19 Apr. 2005 and harvested on 16 Oct. 2003, 22 Oct. 2004, and 27 Sept. 2005. In 2003 and 2005, starter fertilizer 6–24–24 was placed 5 cm below and 5 cm to the side of each seed row (269 kg ha^–1), providing 16 kg N ha^–1. In 2004 starter fertilizer (19–19–19) was added 5 cm below and 5 cm to the side of each seed row (140 kg ha^–1), providing 26.6 kg N ha^–1. The weed control program consisted of a burndown application of glyphosate, 840 g a.e. ha^–1 applied 14 d before planting corn in all three study years. In 2003, the preplant burndown herbicide application was followed by a single application of glyphosate, 840 g a.e. ha^–1 applied 78 days after planting (DAP). In 2004, glyphosate, 840 g a.e. ha^–1, and a premix formulation of atrazine 870 g a.i. ha^–1 and S-metolachlor 670 g a.i. ha^–1 was applied preemeregence 4 DAP. In 2005, sequential applications of glyphosate 840 g a.e. ha^–1 were applied 36 and 70 DAP. All applications were made with a 168 L ha^–1 water carrier volume and 0.0025% v/v ammonium sulfate sprayed at 207 kPa.

Additional N was side-dressed based on PSNT results with a yield goal of 8.8 Mg ha^–1 on 25 June 2003, 15 July 2004, and 20 June 2005. Urea ammonium nitrate solution, 28% N, was applied by subsurface injection between corn rows. A PSNT nitrogen management strategy was employed to determine if N management could be used by growers to overcome the observed wheat residue antagonism of corn growth and development. The soil samples for the PSNT test were taken from a depth of 0 to 30 cm on 17 June 2003, 7 July 2004, and 7 June 2005 within each plot and averaged for each treatment. Soil pH and P were measured in 2003 and 2004. The average pH values based on all the plots were equal to 6.1 and 5.6 (1:1 soil–water) in 2003 and 2004, respectively. The average P values were 97.5 and 107 kg ha^–1 (Bray P₁) in 2003 and 2004, respectively. There was no significant difference among the treatments in terms of either pH or P in both 2003 and 2004 ( = 0.05). Potassium content was not measured but assumed sufficient based on soil test data obtained before the experiments.

Soil temperature and moisture were measured weekly every year starting from mid-April until mid-June. In the early spring of 2003, soil temperature was measured at a depth of 20 cm at the early sampling dates and then from a depth 10 cm for the later sampling dates. In 2004 and 2005, soil temperature measurements were taken at the 10-cm depth. Soil moisture was measured using a Trime–FM3 moisture meter with a P3 probe (Mesa Systems Co., Framingham, MA) at a depth of 0 to 15 cm.

Changes in soil temperature ( temperature) of WRR and WRSR treatments as compared with the NWR control treatment were expressed as a ratio between soil temperature values measured in WRR and WRSR plots and the average soil temperature from the NWR plots. Changes in soil moisture ( moisture) were expressed in the same manner as described above for changes in soil temperature.

To monitor corn development, the time of corn emergence, postemergence stand count, time of tasseling (VT stage), and stalk lodging were recorded. Corn height was measured weekly starting from V9 stage until VT stage. Chlorophyll content was measured weekly in 2004 and 2005 from V6 stage until VT stage on the uppermost corn leaf that had formed a collar using a SPAD-502 m (Specialty Products Agricultural Division, Minolta Co. LTD, Japan).

Growing degree days (GDD) were calculated as GDD = [(T_max + T_min)/2] – 10, where T_max and T_min are the daily maximum and minimum temperatures (°C), respectively. If T_max > 30°C, then we set T_max = 30°C. If T_min < 10°C, we set T_max = 10°C.

Two center rows of corn from each plot were machine harvested for grain yield determination. Moisture content, test weight, and field weight of corn were measured by a Grain Gage and HarvestMasterSystem (Juniper Systems, Inc., Logan, UT) mounted on a plot combine. Grain yield was reported at 15.0% moisture content. Grain test weight is reported at harvest moisture.

Percentage of soil surface cover by wheat residue was determined using digital images. In WRSR treatments, winter wheat residue covered 73% of soil surface; in WRR treatments, it covered 58%.

Data Analysis
ANOVA was performed to study treatment effects on the measured plant and soil characteristics. The analyses were performed as RCBD with treatments as a fixed factor and blocks as a random factor in the PROC MIXED procedure of SAS (SAS Institute, 2002). Normality of the residuals and homogeneity of variances were evaluated by examining normal probability plots and box plots. When variances were not homogeneous, the analysis that accounts for unequal variances was performed using REPEATED/GROUP option of PROC MIXED. When the F test showed a significant treatment effect at = 0.05 we conducted mean separations using Fisher protected t tests. For all soil and plant characteristics, only the differences that were significant with P < 0.05 were mentioned in the Results.

The relationships among soil temperature, moisture, plant emergence and height, residue cover, leaf chlorophyll, and PSNT were studied simple linear regression with PROC REG procedure in SAS.

	RESULTS

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Effect of Wheat Residue on Soil Temperature
In all three studied years, WRSR had lower soil temperatures than NWR and WRR in all but one measurement date (Fig. 1a –1c). The exception was 8 May 2003, when soil temperatures were not different among WRSR and NWR treatments. In 2003 soil temperatures in NWR and WRR treatments were not significantly different in all studied dates. In 2004, soil temperatures in NWR and WRR treatments were not different on five of seven studied dates (Fig. 1b). The NWR temperature was higher than that of WRR in 23 and 29 Apr. and 6 June 2004. (The 23 and 29 April dates represent the beginning of the sampling period and 6 June the last sampling date. This suggests that soils were uniformly cool and warm at the beginning and at the end of the sampling period, respectively, and that treatments had more of an effect on soil temperature during the transitional soil warm-up phase.) In 2005, NWR treatment had significantly higher soil temperature than WRR treatment on 5 of 6 studied dates. On 10 May 2005, NWR and WRR temperatures were not significantly different. These results support the findings of Cox et al. (1990), who observed cooler soil temperatures with reduced tillage in the Northern latitudes of New York State.

View larger version (25K): [in this window] [in a new window]   Fig. 1. Average soil temperatures in (a) 2003, (b) 2004, and (c) 2005, and soil moistures in (d) 2003, (e) 2004, and (f) 2005 for NWR (open squares), WRR (black diamonds), and WRSR (black triangles). The measurements were taken at the 20-cm depth in April and May 2003, and at the 10-cm depth on all other dates.

In all 3 yr, soil moisture of NWR and WRR treatments was not significantly different on most of the dates. The exception was 18 May 2005, when WRR had higher moisture than NWR.

Throughout the study, the values of temperature and moisture from WRR and WRSR treatments were significantly negatively correlated (P < 0.05). Lower temperature values corresponded to higher moisture, and higher temperature values were observed in drier soil (Table 1, Eq. [a–c]). Both temperature and moisture were strongly related to percentage residue cover (Table 1, Eq. [d–e]). Higher residue cover corresponded to lower soil temperature and higher soil moisture. The observed cooler temperatures and higher moistures at higher residue cover are consistent with other observations. TeKrony et al. (1989) speculated that corn grain yield antagonism may be attributable to cooler soil temperature in the spring from wheat residue. Lund et al. (1993) associated the reduced yield of no-till, continuous corn with the greater crop residue and cooler soil temperature in the spring (2.7°C lower). Wilhelm and Wortmann (2004) concluded that the advantage of moldboard tillage over no-till for corn yield was greatest in years with low spring temperatures. Tillage may be preferred for soils that are slow to warm or when early planting is preferred.

Effect of Wheat Residue on Stand Population of Corn
In 2003 and 2005, WRSR treatment had lower corn plant stands than NWR and WRR treatments, likely due to delayed corn emergence and cooler soil temperatures (Table 2). The corn population trends resemble those observed in date of emergence results. There was no significant difference in plant stands of NWR and WRR treatments. In both 2003 and 2005, soil temperature was related to corn stand population, with higher values observed in plots with larger temperature values (temperature relative to NWR plots) (Table 1, Eq. [h–i]). This is consistent with findings of Katsvairo and Cox (2000), who recorded that corn densities were less under reduced tillage compared with moldboard plow systems when corn followed corn or wheat–red clover. In 2004, there were no differences in corn plant stands between WRSR, WRR, and NWR treatments. The lack of a treatment effect on 2004 corn plant stands is likely due to the relatively late planting date of corn and higher soil temperatures at and after planting time.

Effect of Wheat Residue on Corn Date of Tasseling
In all years, corn tasseling was delayed in WRSR treatments as compared with NWR and WRR treatments (Table 2), likely due to lower soil temperatures, delayed emergence, and lower amounts of plant available N (Table 3). In 2004, corn tasseling was significantly delayed in WRSR treatments as compared with NWR and WRR treatments despite a lack of differences in corn emergence and relatively high soil temperatures after planting. The delay in corn reaching the VT stage may be attributable to the lower soil nitrate levels measured in WRSR treatments (Table 3). Wheat residue results in microbial immobilization of N because of its very high C to N ratio (80:1) and also possible allelopathy effects (Rice, 1984). In 2003 and 2004, in WRR treatment, VT stage of corn was not delayed and WRR was not different from NWR. However, in 2005, a delay in reaching VT stage was observed for WRR. This delay in reaching VT stage may be related to microbial immobilization of N, because of high C:N ratio of wheat root residue, and/or allelopathy effect (Krupa, 1982; Rice, 1984).

Effect of Wheat Residue on Corn Grain Moisture, Test Weight, and Yield
In all years, WRSR had significantly higher grain moisture at harvest than NWR and WRR treatments (Table 6). This is likely due to delayed emergence observed in 2003 and 2005 and delayed time of tasseling in all 3 yr. Corn grain moisture in NWR and WRR treatments was not different in all years. In 2003 and 2005, WRSR had significantly lower corn grain test weight at harvest than NWR and WRR treatments (Table 6). This is likely due to the higher grain moisture levels, delayed emergence (2003 and 2005), delayed tasseling, and lower amounts of soil plant available N resulting from microbial N immobilization. In 2004, corn grain test weight in all treatments was relatively lower than that of 2003 and 2005, possibly due to the late planting date and higher grain moisture at harvest. There were no differences between the corn grain test weight of the three treatments in 2004.

This research demonstrated that applying N according to PSNT recommendations can overcome reduced corn emergence and early season growth antagonism in no-till corn planted into wheat residue.

	ACKNOWLEDGMENTS

 
We thank the C.S. Mott Chair of Sustainable Agriculture and the Michigan State Agricultural Experiment Station for funding this project. Special thanks to Keith Dysinger and Bill Widdicombe for their indispensable help with the field work.

	REFERENCES

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This Article Abstract Figures Only Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kravchenko, A. G. Articles by Thelen, K. D. Search for Related Content PubMed Articles by Kravchenko, A. G. Articles by Thelen, K. D. Agricola Articles by Kravchenko, A. G. Articles by Thelen, K. D. Related Collections Maize Management