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Strip tillage in kura clover living mulch
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jbalexa
Posted 2/16/2021 08:58 (#8836233)
Subject: Strip tillage in kura clover living mulch


Hi AgTalk community,

(This post is paired with another that details grain yield response to fertilizer N rate in kura clover living mulch)

My work focuses on N cycling and agronomic management for intercropping corn with kura clover, a perennial forage legume and today I will be sharing the 2020 results from an experiment conducted at the University of Minnesota’s Rosemount Research and Outreach Center in collaboration with the USDA Agricultural Research Service.

I introduced my work with kura clover living mulch systems in a previous post, but for those who are unfamiliar, I’ll give a brief description.

Kura clover is a cool season legume forage crop that spreads by underground stems to re-establish itself after intensive management. The robust root system anchors the soil and immobilizes nutrients in the early spring when soils under conventional management are fallow or row-crops are not well established. Previous research has found that corn production in kura clover living mulch (KCLM) can reduce soil erosion and nitrate loss by 70%. More recently, my work has focused on fertilizer N management for continuous corn production in KCLM. Results from the 2017 and 2018 growing season suggested that KCLM could reduce fertilizer N requirements while increasing profitability due to increased harvest income from stover removal. While these findings are promising, it can be difficult for a conservation cropping system to compete with conventional production systems. Aside from the risk associated with a drastically different way of farming than most have experience with, we saw a few major drawbacks to managing a KCLM system for corn production.

Some of the major issues that we see as barriers to the adoption of these systems are stand establishment, which I will address in a separate post, and impractical agronomic management practices. The main issue with current agronomic management recommendations is spring tillage. We currently utilize a rotary-tillage tool to mulch ~12” wide rows every 30”. The tool does a great job, however, it requires a lot of horsepower and is very slow.

I decided that we needed an alternative, so I contacted Dawn Manufacturing and Orthman Manufacturing to help us apply alternative tillage treatments for our experiment. Dawn came to Rosemount, MN, with their PluriLite strip tillage tool with an attached ZRX roller crimper and Orthman came to set up our 1tRIPr strip tillage tool. Tillage treatments were applied on May 12 and corn was planted on the next day, and, based on my previous research, fertilizer N was not applied to tillage treatments.

After tillage, I looked closely at the distribution of clover and soil to see what I could learn about how these tools performed in the KCLM. The Orthman tool buried clover with ~1” of soil on either side of the shank. The thick roots were snagged and unevenly distributed along the side of the row, but the soil that was brought up with the shank made a nice wide seedbed. About a week later, I noticed clover begin to grow out from under the layer of soil deposited by strip tillage. I dug into the row a bit and found a rich zone of partially decayed clover residue. I believe that most of this clover later grew its way out and began to compete with the corn, however, if the conditions were different, the clover may not have had enough energy to fight its way out and the corn would receive all of its N.

The coulter-based PluriLite unit surprised me. After tillage, it was apparent the row was not as wide as the Orthman, however, how it accomplished this was much different. It appeared to me that the coulters sliced the root zone and ejected roots and residues about 8” to one side. I found several clumps of dead roots and residues at the center of the interrow space and a cleaner, but narrower row. Because the clover didn’t end up incorporated near the seedling, it might be that you would see less N credits from the KCLM, but I can’t answer that definitively at this point.
After planting, the weather turned cold and wet for the next few weeks, which is ideal for clover growth but slowed the corns emergence/development. The result of this was that the clover was overcompetitive in the early growing season, shading out the corn rows. This bad start to the growing season impacted both stand density and crop development and by June things looked bad in the low N rate treatments.

Because the results were so impacted by N deficiency, I don’t want to make any strong conclusions from these results, but for transparency, I have included grain yield from the tillage management trial. This experiment will be expanded upon for the 2021 growing season. Banded herbicides will be added as another row-establishment treatment, all row establishment/tillage treatments will receive 6 N rates, and the experiment will be conducted at both Rosemount, MN, and Arlington, WI.

Also, if you haven’t looked at my other post, please do. With a proper fertilizer N rate, we were able to grow 235-bushel corn, so, KCLM can work better than this, but I’m happy to make these mistakes so that you don’t have to.


Edited by jbalexa 2/17/2021 09:51




(Rotary zone tillage tool (full).png)



(May 12 - Dawn Pluribus after two passes (full).png)



(May 19 - Dawn Pluribus, residue clump in interrow space (full).png)



(May 12 - Orthman 1tRIPr (full).png)



(May 20 - Orthman 1tRIPr buried residue in row (full).png)



(June 4 (full).png)



(June 11 (full).png)



(July 2 (full).png)



(August 13 (full).png)



Attachments
----------------
Attachments Rotary zone tillage tool (full).png (56KB - 144 downloads)
Attachments May 12 - Dawn Pluribus after two passes (full).png (243KB - 146 downloads)
Attachments May 19 - Dawn Pluribus, residue clump in interrow space (full).png (313KB - 141 downloads)
Attachments May 12 - Orthman 1tRIPr (full).png (224KB - 145 downloads)
Attachments May 20 - Orthman 1tRIPr buried residue in row (full).png (428KB - 144 downloads)
Attachments June 4 (full).png (342KB - 145 downloads)
Attachments June 11 (full).png (272KB - 150 downloads)
Attachments July 2 (full).png (234KB - 142 downloads)
Attachments August 13 (full).png (297KB - 144 downloads)
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