CORN RESIDUE MANAGEMENT STRATEGIES FOR IMPROVED SOIL CARBON AND ENVIRONMENTAL IMPACT

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0222176
• Project Start Date: Jun 1, 2010
• Project End Date: May 31, 2012
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIV OF WISCONSIN
21 N PARK ST STE 6401
MADISON,WI 53715-1218

Performing Department
Biological Systems Engineering

Non Technical Summary
Agricultural practices of the twentieth century have decreased soil organic matter (SOM). A study outlining the evolution of cropping practices from 1930 to 1979 in Minnesota cited depletion of organic matter as the second most important factor reducing corn grain yield. Cardwell (1982) estimates that depletion of SOM in corn production systems results in a 9.1 bu/ac yield depression. Soil quality, carbon sequestration and the greenhouse effect are all related. Fuels and fertilizers derived from fossil fuels, burning of plant biomass and SOM decomposition have been agriculture's major contribution to atmospheric carbon levels. However, changes in cropping practices, such as moving from conventional to conservation tillage, have been shown to sequester as much as 0.1 to 0.3 (T/ac)/yr of atmospheric carbon. In reversing loss of soil organic carbon there is an opportunity to increase crop productivity while sequestering CO2, our most abundant greenhouse gas. A residue management strategy is needed to build the SOM pool without destroying soil structure or exposing the soil to erosion. Using current technology, the producer must compromise the productivity benefits of early planting for the retention of residue. If a system was developed that could retain the benefits of residue while ensuring timely spring planting, the environmental impact of production could be reduced while increasing crop yields. The dynamics of this system are admittedly complex. Thus, changes in cropping practices to sequester carbon must be carefully evaluated. This work will uniquely investigate residue management from a machinery perspective. Both existing and novel crop processing technologies will be evaluated for their efficacy to increase soil carbon pools and provide spring planting conditions conducive to a highly productive crop. Each system's energy use will be evaluated to address its impact on the overall energy balance of corn grain and fiber production.

Animal Health Component

100%

Research Effort Categories

Basic

(N/A)

Applied

100%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
402	1510	2020	50%
102	1510	2020	50%

Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 402 - Engineering Systems and Equipment;

Subject Of Investigation
1510 - Corn;

Field Of Science
2020 - Engineering;

Keywords

corn residue

residue

soil organic matter

soil organic carbon

harvesting energy use

corn harvest

combine

stalk chopper

stalk chopping

residue size reduction

Goals / Objectives
The mechanization of agriculture has been credited for increasing the standard of living of people in all parts of the world. However, it has also been implicated in the degradation of both soil and water resources. There is opportunity to reverse this trend as we become more aware of the underlying mechanisms that govern soil productivity. One of the major environmental impacts of mechanized agriculture is destruction of soil organic carbon (SOC) as a result of intensive cultivation. This research aims to reduce and potentially reverse SOC destruction in the production of corn grain and fiber, while maintaining the level of productivity that our society has come to depend on. There is an abundance of corn residue available. When properly managed, the corn residue could be utilized to restore depleted levels of SOM. Corn residue yield follows grain yield via a relationship know as harvest index. Harvest index (HI) is calculated as the grain yield divided by the total grain and non-grain biomass. A conservative HI is 0.50, but ranges from 0.41 to 0.73 depending on climate, soil and corn hybrid. Maintaining this relationship, residue yield has increased with grain yield. Increased levels of residue yields should have a positive impact on production; however, this residue becomes a challenge for both fall tillage and subsequent spring planting. Left-over residue traps soil moisture and insulates soil from the sun's heat. Consequently, soil moisture is kept high and soil temperature low delaying spring planting and subsequent seed germination, both of which have negative consequences on overall crop productivity. As a result, aggressive fall tillage is sometimes utilized to bury part or all of the excess residue in order to provide more favorable spring planting conditions. As an alternative to burying the residue, producers have utilized a minimum tillage strategy after a post-harvest process to both size-reduce and distribute residue. This method is grounded in experience and research as stalk residue decomposition models indicate that residue decay rate is inversely related stem radius. Historically, stalk choppers and rotary mowers have been used for stem size reduction. More recently, the size reduction of the residue has been integrated into the combine's header. Stalk- chopping headers eliminate the need for a second pass but require some of the combine's energy to size-reduce the stalks during harvest, potentially limiting harvest rate and crop value. The impact these systems have on residue decomposition, spring planting and contribution to the energy used during corn grain production has not been investigated.

Project Methods
The relationship between each size reduction technique and subsequent tillage strategy will be of critical importance to understanding the success of each technique. To this end, each of the four replicate samples from each process and site location will be returned to the field site to assess over winter decomposition. To determine extent of residue degradation, samples will be contained in 20 cm by 20 cm nylon mesh bags. These bags will retain the residue so that ash corrected dry matter loss and compositional properties can be determined upon retrieval. Depending on tillage scheme, samples will be either placed on top of the soil or buried 5 cm deep. Soil properties will influence rate of decomposition; thus, three 3.2 cm diameter 25 cm deep soil cores will be collected form each bag location. Samples will be dried at 50C, ground to pass through a 12-mesh screen and sent to the UW-Extension Soil and Plant Analysis Laboratory (SPAL) for analysis of total, organic and inorganic carbon; organic matter; total- and nitrate- N; phosphorus; potassium, pH and conductivity. An effort will be made to relate cumulative temperature, average moisture and C/N ratio to organic matter disappearance, but other compositional properties will be reported as to better understand the soils where the study was conducted. Residue bags will be retrieved before spring tillage or planting. Decomposition will be determined as loss of mass in each nylon bag after correction for both moisture and ash content. Decomposed corn residue is likely to be quite different spectrally than fresh cut material; therefore, neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) as well as carbon and nitrogen will be determined by SPAL using chemical methods. Using SPAL's standard methods, detergent fibers will be determined by the ANKOM filter bag method and carbon and nitrogen will be determined by dry combustion. System-wide energy use and field productivity will be needed to determine the influence each residue management strategy has on corn grain harvest. Productivity of each strategy will be assessed though an on-farm observation. When possible, farm- based equipment will be instrumented to determine energy use. Productivity will be assessed by monitoring harvester's or secondary stalk-chopping process speed, overlap, turning time and down time due to maintenance, plugging and/or failure. A novel monitoring process utilizing a global navigation satellite system (GNSS) receiver and user responder will be implemented in cooperating farmers tractors or combines. This system will request a response each time the harvesting process is interrupted, providing critical data necessary to model field capacity of each farm's harvester.

Progress 06/01/10 to 05/31/12

Outputs
OUTPUTS: Corn grain yields are expected to increase substantially during the next 15 years due to improvements in genetics and management practices. Grain yield increases will result in a similar increase in crop residue, which will have a significant impact on subsequent tillage and planting operations. New strategies and systems to cope with excess residue are needed. Our research helped quantify the cost and benefit of alternative crop residue management systems. This information will help corn producers make informed decisions about the appropriate residue management system for their operation. It will also help direct research and development efforts toward new, alternative and improved residue management strategies. Some corn producers choose to process/size-reduce corn residue to enhance decomposition and improve subsequent field operations like tillage and planting. Processing has traditionally been done soon after grain harvest with a second field operation using a flail shredder. More recently corn headers have been modified to size-reduce residue at grain harvest, eliminating the secondary field operation. Producers have questioned whether the chopping corn headers produce the same level of processing and whether there are any subsequent differences in crop yield. Our research showed that chopping corn headers produced the same level of processing and that the method of residue processing did not significantly affect crop yields. There are positive and negative aspects of both residue processing approaches that resulted in similar net returns no matter if no-till or conventional tillage systems are considered. The data has been presented at professional society meetings where engineers from manufacturers of tillage, planting and harvesting equipment were present. An Extension publication is planned. PARTICIPANTS: Principal Investigator - Kevin J. Shinners; Graduate Student - Craig Slattery; Collaborators - Matt Digman - USDA TARGET AUDIENCES: Target audiences for this work include agricultural machinery manufacturers (e.g. John Deere, CNH Global), commodity groups (e.g. corn growers), and corn producers. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Crop residue processing technologies were evaluated for their efficacy to provide spring planting conditions conducive to a highly productive crop. In our experiment, we investigated three residue management practices (conventional, shredding after corn harvest, and chopping corn head), two tillage practices (no-till and conventional disk chisel). The systems performance was quantified by residue properties like particle-size, decomposition, and composition; plant growth characteristics; silage and grain yield; and machine fuel use. There was no significant difference in residue particle-size that was processed with a flail shredder or chopping corn header and the average particle-size was 64% less than unprocessed residue. Particle-size distribution was similar for both the flail chopper and chopping corn header. Size-reducing residue in the fall increased the dry matter decomposition by 49% compared to not processing. However, residue processing did not have a significant effect on total soil N or immobilized N compared to not processing. When temperatures were typical (2011) processing residue slightly improved the accumulation of soil growing degree days (GDD) during germination and emergence, but in 2012, when temperatures were much greater than normal, residue processing had no impact on soil GDD. The rate of emergence was not significantly affected by residue processing in either year. Residue processing also did not have a significant impact on plant height growth rate. Residue processing had no significant effect on whole-plant silage or grain yield in 2001, when precipitation was typical, or in 2012, when drought conditions reduced average grain yield by 35%. Tillage practice was the only variable that affected silage or grain yield. When precipitation was typical, no-till practices reduced grain yield by about 5% compared to the conservation tillage system but drought conditions reduced no-till yields by 25%. Size-reducing residue increased specific fuel consumption (gal/ac) by 25% to 39% for the chopping corn header and flail shredder, respectively. Flail shredding stalks with a conventional stalk shredder required significantly more fuel per unit area than shredding with a rotary mower or shredding at grain harvest with a stalk shredding corn head. The most intensive corn production system studied involved three field operations: grain harvest, residue processing, and tillage. The least intensive system involved grain harvest with no residue processing or tillage. A partial budget using the average yields across the two years of this study showed that the conservation tillage system produced on average 15% greater net returns than the no-till system. Residue processing produced slightly greater yields using either tillage systems, but the yield increases essentially equaled the added costs of that processing, so there were no significant differences in net return across the residue processing variable considered. Not taken into consideration by this cost analysis are such factors as improved timeliness or field efficiency of other operations, such as planting, that may arise from processing residue.

Publications

• Slattery, C.A., K.J. Shinners and M.F. Digman. 2012. Alternative corn residue management systems. ASABE Technical Paper No. 121337628. ASABE, St. Joseph, MI.

Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: Agricultural practices of the twentieth century have decreased soil organic matter (SOM), which can lead to depletion of soil health and productivity. Maintaining SOM can not only improve soil health, but also sequester atmospheric carbon. Corn residue management practices have a strong influence on SOM. This work has uniquely investigated residue management from a machinery perspective. Both existing and novel crop processing technologies based on chopping corn residue at grain harvest were evaluated for their efficacy to increase SOM and provide spring planting conditions conducive to a highly productive crop. Each system's energy has been evaluated to address its impact on the overall energy balance of corn grain and fiber production. In our experiment, we investigated three residue management practices (conventional, shredding after corn harvest, and chopping corn head), two tillage practices (no-till and conventional disk chisel) across two corn varieties (BT and non-BT). Residue particle-size was quantified, because the relationship between size-reduction and subsequent tillage strategy is important. Over winter, decomposition was quantified by placing mesh bags of residue back in the field and measuring ash corrected dry matter loss and compositional changes after the over wintering period. Fuel use and power requirements for several different residue management strategies were measured. Neither residue management scheme or corn variety had a significant impact on whole-plant (i.e. silage) or grain yield. Tillage practice was the only variable that affected silage or grain yield. Flail shredding stalks with a conventional stalk shredder required significantly more fuel per unit area than shredding with a rotary mower or shredding at grain harvest with a stalk shredding corn head. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Target audiences for this work include agricultural machinery manufacturers (e.g. John Deere, CNH Global), commodity groups (e.g. corn growers), and corn producers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Corn grain yields are expected to increase substantially during the next 15 years due to improvements in genetics and management practices. Grain yield increases will result in a similar increase in crop residue, which will have a significant impact on subsequent tillage and planting operations. New strategies and systems to cope with excess residue are needed. The results of this research will help quantify the cost and benefit of alternative crop residue management systems. This information will help corn producers make informed decisions about the appropriate residue management system for their operation. It will also help direct research and development efforts toward new, alternative and improved residue management strategies.

Publications

• No publications reported this period

Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: Agricultural practices of the twentieth century have decreased soil organic matter (SOM), which can lead to depletion of soil health and productivity. Maintaining SOM can not only improve soil health but also sequester atmospheric carbon. Corn residue management practices have a strong influence on SOM. This work will uniquely investigate residue management from a machinery perspective. Both existing and novel crop processing technologies based on chopping corn residue at the corn head during harvest will be evaluated for their efficacy to increase SOM and provide spring planting conditions conducive to a highly productive crop. Each system's energy use will be evaluated to address its impact on the overall energy balance of corn grain and fiber production. In our experiment, we investigated three residue management practices (conventional, shredding after corn harvest, and chopping corn head), two tillage practices (no-till and conventional disk chisel) across two corn varieties (BT and non-BT). Residue particle-size will be quantified because the relationship between size-reduction and subsequent tillage strategy is important. Over winter decomposition will be quantified by placing mesh bags of residue back in the field and measuring ash corrected dry matter loss and compositional changes after the over wintering period. We will relate soil C/N ratio to organic matter disappearance. System-wide energy use and field productivity will be needed to determine the influence each residue management strategy has on corn grain harvest and economics. Productivity of each strategy will be assessed though on-farm observations. When possible, farm-based equipment will be instrumented to determine energy use. Productivity will be assessed by monitoring harvester's or secondary stalk-chopping process speed, overlap, turning time and downtime due to maintenance, plugging and/or failure. A novel monitoring process utilizing a global navigation satellite system (GNSS) receiver and user responder will be implemented in cooperating farmer's tractors or combines. This system will request a response each time the harvesting process is interrupted, providing critical data necessary to model field capacity of each piece of equipment used to harvest grain and manage crop residue. PARTICIPANTS: Principal Investigator - Kevin J. Shinners; Graduate Student - Craig Slattery; Collaborators - Matt Ruark - Department of Soil Science TARGET AUDIENCES: Target audiences for this work include agricultural machinery manufacturers (e.g. John Deere, CNH Global), commodity groups (e.g. corn growers), and corn producers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Corn grain yields are expected to increase substantially during the next 15 years due to improvements in genetics and management practices. Grain yield increases will result in a similar increase in crop residue, which will have a significant impact on subsequent tillage and planting operations. New strategies and systems to cope with excess residue are needed. Our research will help quantify the cost and benefit of alternative crop residue management systems. This information will help corn producers make informed decisions about the appropriate residue management system for their operation. It will also help direct research and development efforts toward new, alternative and improved residue management strategies.

Publications

• No publications reported this period