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Ontario Grain Farmer Magazine

Impact of tillage, planting systems, fertilizer placement and residue removal on crop establishment

Principal Investigator: Horst Bohner and Greg Stewart  

Research Institution: Ontario Ministry of Agriculture, Food and Rural Affairs

Timeline: April 2011 – March 2015

Objectives:

  • To generate information on different tillage options, planting systems, fertilizer placement and residue removal to determine their impact on crop establishment, development and yield.
  • To maximize crop productivity while maintaining residue levels that have been scientifically shown to significantly reduce soil erosion (i.e., 30% crop residue cover).

Impacts:

  • Field trials that provide an increased understanding of ten different tillage systems, focusing on the economics, soil residue management, and the effectiveness of production systems.
  • Equipment trials that provide a comparative assessment of the economic, yield, and residue management performance of a seed drill to a row unit planter across different tillage treatments.
  • A comprehensive literature review of the relationship between soil erosion and crop residue management.
  • A determination of how each tillage treatment influences soil loss by measuring percent residue cover and relating to the comprehensive literature.

Scientific Summary:

No-till and reduced tillage have economic and environmental benefits compared to conventional tillage. In recent years there has been a trend to revert back to more intensive tillage practices. This is due to perceived production issues associated with no-till systems including lower yields. One of the apparent issues with no-till is the large amount of corn residue left over from the previous crop. This project was designed to study and generate information on different tillage options, planting systems, fertilizer placement and residue removal to determine their impact on crop establishment, development, and yield.  The thrust of this project was to maximize crop productivity while maintaining residue levels that have been scientifically shown to significantly reduce soil erosion (i.e., 30% crop residue cover).

Extensive Ontario field trial data were collected over the three years of this study. Two small plot soybean trials were established each year with 60 different tillage, stalk chopping, seeding equipment, residue removal, and nitrogen fertilizer combinations in soybeans following corn. The residue removal levels were No Removal (NR), Intermediate Removal (IR), and Nearly Complete Removal (NCR). Twelve field scale replicated trials were also established in 2011-13 in soybeans focusing on minimal tillage to verify the results across a number of soil types and growing regions. One small plot corn trial was established in 2011 and four were established in 2012-13 to assess the impact of tillage, residue removal and fertilizer placement in corn following corn production systems. Trial treatments were altered in the final year of the study (2013) for both soybeans and corn based on the findings of the initial two years of data. A comprehensive literature review on the interaction between soil erosion and crop residue cover was completed and submitted as a separate document. This project made possible the completion of a Master of Science Thesis at the University of Guelph.

Results

1) Soybean Production – Possible management strategies that could be employed to minimize potential yield losses were explored in this study. Under the growing conditions experienced at the four small plot sites in 2011 and 2012, it was demonstrated that a traditional no-till (NT) soybean system did not experience a yield deficit relative to the moldboard plow, or any other tillage system. Even as residue was removed, including both the Intermediate Removal (IR) and Nearly Complete Removal (NCR) levels, NT did not yield significantly less than any tillage system. However, there was a large yield decrease to no-till (5 bu/ac) when corn stalks were chopped, and a no-till seed drill was used. This yield reduction could be regained with the use of a row unit no till planter. This finding provides strong evidence that one of the reasons growers may be reporting yield losses in no-till is poor drill performance especially when corn stalks are chopped. Removing the residue improved soybean yield but avoiding stalk chopping operations or seeding with a row planter also regained yield losses. It must be stressed that in the first two years of this study, the primary hypothesis, namely that residue management strategies such as minimal tillage, stalk chopping, residue removal, planter configuration, or nitrogen application can be used to alleviate yield deficits in traditional no-till, was rejected. The reason is that no-till yielded as high as conventional tillage.

A significant yield reduction (4.5 bu/ac) associated with traditional no-till soybean seeding (not disturbing the corn residue) was only observed at one site during the three years of this project. This yield reduction could largely be regained with the use of minimal tillage. These findings provide evidence that when yield reductions are found in traditional no-till a relatively small amount of minimal tillage could be used to regain the loss, without the use of aggressive tillage.

2) Corn Production – Outcomes focused on potential corn cropping system management strategies in the face of balancing alternative corn stalk uses, maximizing corn yields and preventing soil erosion with soil residue cover. Aggressive residue removal resulted in residue surface coverage that was often lower than 30%. However, this was dependent on previous crop yields and tillage systems. Consideration of the feasibility of corn stover removal for use in bio-refineries while still maintaining 30% residue cover should carefully examine previous crop yield, soil type and tillage systems.

Residue removal from a corn-on-corn cropping system generally did not improve corn yields regardless of the tillage system.  This again is an important factor as we consider the advantages of corn stover removal for other uses.  While there may be an economic incentive to use corn stalks, this study does not support the idea that residue removal will improve reduced tillage corn yields.

Chopping of previous corn crop residues had a tendency to improve conservation tillage yields (i.e., vertical tillage via Salford RTS) although the impact was not consistent over years.  In contrast, stalk chopping tended to reduce no-till corn yields. These findings will be used to refine conservation tillage approaches in corn after corn production.

There was no evidence in this study that aggressive tillage (moldboard or disc-ripper) was required to maximize corn yields in a corn after corn scenario. Higher residue tillage options were able to yield as well as these aggressive tillage systems in every situation.

3) Graduate Studies – This project made possible the completion of a Master of Science Thesis by Mike Vanhie at the University of Guelph. It provided valuable information on which soil and plant variables are the most responsible for potential yield differences between no-till and conventional tillage.

4) Literature Review – A comprehensive literature review on the interaction between soil erosion and crop residue cover has been completed. The knowledge gained from the literature aided the implementation of a Knowledge Translation and Transfer strategy regarding tillage, reside cover and soil health.

Recommendations

There is a trend away from no-till soybean production in Ontario. It has largely been suspected that high amounts of corn residue on the soil surface are reducing no-till soybean yields. This perceived yield reduction has caused many growers to revert back to more aggressive tillage, in some cases the mouldboard plow. Some of the issues associated with no-till soybean production include: higher soil moisture, cooler soil temperatures, reduced N availability, delayed plant development, slower nodulation, reduced planter performance and stand establishment. This project has studied soybean performance across a range of management strategies to gain knowledge on improving no-till production. This study has found that in the vast majority of cases there is no yield reduction associated with traditional no-till soybean production in Ontario. However, when corn stalks were chopped, and a no-till drill was used, a yield reduction was found.  This yield reduction could be gained back with the use of a row unit planter. In only one trial in this study was there a significant yield reduction found when using traditional no-till (undisturbed corn residue). In that case minimal tillage (RTS) gained back most of the yield lost. These findings suggest that a strong Knowledge Translation and Transfer initiative should be undertaken to educate growers that traditional no-till soybean production is not disadvantaged compared to aggressive tillage practices in most field situations. On the occasions when yield losses are associated with no-till, a row unit planter or the use of minimal tillage will regain most of the yield losses associated with no-till.

Growing corn after a crop of grain corn has been recently positioned in some areas as a more profitable rotation.  Although corn after corn does not represent significant acreage in Ontario it could be argued from a soil health perspective that getting more corn after corn acres into Ontario crop rotations would be superior to soybean dominated rotations.  In addition, there is interest in using corn stover for a range of other industrial possibilities.  The outcomes and data from this study strengthens the Ontario position to grow corn after corn with cropping systems that maximize stover use efficiency, maintain high yields and provide soil protection with residue cover against soil erosion risks.

External Funding Partners:

Ontario Ministry of Agriculture, Food and Rural Affairs.

The views expressed in this report do not necessarily reflect those of OMAFRA.

Project Related Publications:

None.