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Impact of Corn Stover Harvest on Soil Properties and Productivity

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Background

  • With the increasing demand for non-petroleum based fuels, corn stover presents a potential raw material for ethanol production.
  • Corn stover provides various benefits to soil including the cycling of nutrients and soil organic matter. Removing this resource for use in ethanol production could affect soil function and crop productivity in the future.
  • Previous studies have shown a negative to neutral impact of removing stover from fields; therefore, understanding the response of specific soil types to stover removal is important in making recommendations to producers. These impacts have not been studied in detail in Wisconsin soils.

Objectives

  • Evaluate the effect of stover harvest on corn productivity and its influence on nitrogen fertilization rates.
  • Determine the impact of corn stover harvest on soil properties.

Study Description

  • Years: 6 (2010-2015)
  • Locations:
    Arlington, WI (Plano silt loam)
    Lancaster, WI (sloped Fayette silt loam)
  • Replications: 4
  • Factors:
    Nitrogen Application Rates -
    0 lbs/acre
    50 lbs/acre
    100 lbs/acre
    150 lbs/acre
    200 lbs/acre
    250 lbs/acre
     

    Stover Removal Rates -

    0%
    50%
    100%
      
  • Plots at both locations were fall chiseled followed with a soil finisher in the spring.
  • Soil samples were collected for bulk density, nutrient, and organic matter analysis.

Results - Impact on Yield

  • Stover removal effects on grain yields during the 6 growing seasons at Arlington were sporadic, often occurring in the nitrogen rates that were lower than the UW-Extension recommended annual application rate of 150 lbs N/acre (Figure 1).
  • Stover removal effects on grain yield at Lancaster were also sporadic and only occurred in plots that were fertilized with rates less than the UW-Extension recommended rate (Figure 2).
Average (2010-2015) corn grain yield in Arlington, Wis., as influenced by nitrogen application rate and stover removal rate.

Figure 1. Average (2010-2015) corn grain yield in Arlington as influenced by nitrogen application rate and stover removal rate.

Average (2010-2015) corn grain yield in Lancaster, Wis., as influenced by nitrogen application rate and stover removal rate.

Figure 2. Average (2010-2015) corn grain yield in Lancaster as influenced by nitrogen application rate and stover removal rate.

Results - Impact on Soil Properties

  • Soil nitrate-nitrogen content from 0 to 2-foot depth at corn emergence from the 150 lb/acre nitrogen fertilization rate were similar between corn stover removal rates within years at the Arlington site (Table 1).
  • At Lancaster soil nitrate-nitrogen contents were similar between stover removal rates during the first 3 growing seasons. During the last 3 growing seasons (2013-2015) at Lancaster nitrate-nitrogen was lower in the 100% removal rate, but overall nitrate contents were generally low (Table 1).

Table 1. Average nitrate-nitrogen content (ppm) in the top 2-foot soil layer for 3 stover removal rates during 6 growing seasons at Arlington and Lancaster.

Average nitrate-nitrogen content (ppm) in the top 2-foot soil layer for 3 stover removal rates during 6 growing seasons at Arlington and Lancaster, Wis.
Soil organic matter content (0-6 inches) for 3 stover removal rates during 6 growing seasons at Arlington, Wis.

Figure 3. Soil organic matter content (0-6 inches) for 3 stover removal rates during 6 growing seasons at Arlington.

Soil organic matter content (0-6 inches) for 3 stover removal rates during 6 growing seasons at Lancaster, Wis.

Figure 4. Soil organic matter content (0-6 inches) for 3 stover removal rates during 6 growing seasons at Lancaster.

  • Soil organic matter content was generally greater at Arlington than Lancaster given the differences in soil origin and slope (Figures 3, 4).
  • A slight decrease in soil organic matter with increasing stover removal rate was observed at Arlington after 4 years, while at Lancaster a similar decrease was observed after 3 years of stover harvest (Figures 3, 4).
Plant available phosphorus concentrations in soil (0-6 inches) for 3 stover removal rates during 6 growing seasons at Arlington, Wis.

Figure 5. Plant available phosphorus concentrations in soil (0-6 inches) for 3 stover removal rates during 6 growing seasons at Arlington.

Plant available phosphorus concentrations in soil (0-6 inches) for 3 stover removal rates during 6 growing seasons at Lancaster, Wis.

Figure 6. Plant available phosphorus concentrations in soil (0-6 inches) for 3 stover removal rates during 6 growing seasons at Lancaster, Wis.

  • Soil test phosphorus concentrations at Arlington varied among years, but no pattern was observed other than a general decrease in soil test phosphorus over 6 growing seasons. In general, soil phosphorus concentrations ranked as excessively high at this site (Figure 5).
  • At Lancaster, soil phosphorus concentrations decreased with increasing stover harvest rate after 3 growing seasons. Soil test phosphorus concentrations were considered optimal during all 6 years (Figure 6).
  • All treatments at both study sites received 13 lb/acre of total phosphorus as starter fertilizer annually.
  • The potassium content in soil at Arlington was reduced with stover harvest after 3 years, but only dropped below optimal levels at the end of the 6 growing seasons (Figure 7).
  • Potassium soil concentrations at Lancaster decreased with increasing stover harvest rate after 3 growing seasons, and overall were below optimal concentrations (Figure 8).
  • All treatments at both study sites received 25 lb/acre of potassium as starter fertilizer annually.
Plant-available potassium concentrations in soil (0-6 inches) for 3 stover removal rates during 6 growing seasons at Arlington, Wis.

Figure 7. Plant-available potassium concentrations in soil (0-6 inches) for 3 stover removal rates during 6 growing seasons at Arlington.

Plant-available potassium concentrations in soil (0-6 inches) for 3 stover removal rates during 6 growing seasons at Lancaster, Wis.

Figure 8. Plant-available potassium concentrations in soil (0-6 inches) for 3 stover removal rates during 6 growing seasons at Lancaster.

Effect of 3 stover harvest rates on soil bulk density at 2 different depths after 6 growing seasons at the Arlington, Wis., study location.

Figure 9. Effect of 3 stover harvest rates on soil bulk density at 2 different depths after 6 growing seasons at the Arlington study location.

Effect of 3 stover harvest rates on soil bulk density at 2 different depths after 6 growing seasons at the Lancaster, Wis., study location.

Figure 10. Effect of 3 stover harvest rates on soil bulk density at 2 different depths after 6 growing seasons at the Lancaster study location.

  • Soil bulk density at the two depths measured at Arlington increased as stover harvest rate increased; however, the observed bulk density is not considered root restrictive (Figure 9).
  • No clear trend in soil bulk density with stover harvest treatments was observed at the Lancaster location (Figure 10). Plots at this site were established on the contour given the sloping field typical of this region, which might have increased traffic across treatment areas and could have contributed to the lack of differences at that field site. Nevertheless, the magnitude of the bulk density values were not indicative of compaction.

Conclusions and Recommendations

  • There were some statistically significant differences in corn grain yield with stover harvest rate, but no clear trend was discernable. In some years, the 100% stover harvest rate had numerically greater yields at both sites.
  • Soil organic matter, phosphorus and potassium were reduced to some degree at both sites after multiple years of stover harvest (3 years or more).
  • Soil bulk density increased after 6 years of stover harvest, possibly due to the additional harvest traffic and reductions in organic matter. However, soil bulk density values at both sites were within an acceptable range for crop growth.
  • Although yields were not clearly reduced with stover harvest in the 6 year study period, given some of the trends in soil properties with stover harvest, it is possible that yield could be suppressed if stover harvest is conducted continuously for longer periods of time.
  • Other soil types or soils with marginal productivity potential would most likely be more negatively affected by continuous 100% stover harvest. However, the 50% stover harvest rate had comparable results to the 0% harvest rate.
  • Given the data presented here, it seems feasible to harvest half of the corn stover biomass after or during grain harvest for biofuel production or other uses. However, it is recommended to restrict the 50% biomass harvest to no more than 3 consecutive years and to incorporate management techniques to mitigate long-term negative impacts to the soil, such as use of cover crops, crop rotations, and reduced tillage.

Research conducted by Francisco J. Arriaga, University of Wisconsin-Madison, as a part of the Pioneer Crop Management Research Awards (CMRA) Program. This program provides funds for agronomic and precision farming studies by university and USDA cooperators throughout North America. The awards extend for up to four years and address crop management information needs of Pioneer agronomists, Pioneer sales professionals and customers.

The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. 2010-2015 data are based on average of all comparisons made in two locations through 2015. Multi-year and multi-location is a better predictor of future performance. Do not use these or any other data from a limited number of trials as a significant factor in product selection. Product responses are variable and subject to a variety of environmental, disease, and pest pressures. Individual results may vary.