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Cover crop data (WARNING:Long)
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robmgrig
Posted 12/3/2017 22:23 (#6405174)
Subject: Cover crop data (WARNING:Long)


West TN

For the last year, I have seen many posters ask about data from the use of cover crops. Whether it be about yield, costs, management, etc. For the last 2 years, I have extensively tested my use of cover crops to try and find out some answers. I'm sure that even the most die hard conventional farmer will admit that having something growing in the field during the offseason is better for the soil than leaving it bare. And knowing that soil is the backbone of our profession, we must do everything possible to preserve it or make it better. I doubt that anyone will argue with that.

The tricky thing is to still consistently make a profit while preserving our natural resource. After all if a farmer goes out of business, all that soil he maintained and made better isn't going to do him a darn bit of good. This is the road I began going down 7 years ago when I began experimenting with cover crops. Over the last seven years, I have learned a lot (mostly about what NOT to do!).  I have seen many benefits and have spoken to many farmers expounding on these benefits.  I'm not going to go into that here, but if anyone is wanting to know more please feel free to contact me.  But I am going to try and give you some data showing that cover crops CAN lead to higher yields, increased profitability, and reduced risk.

Just to give you a little background about my farm and soils so you can compare to your situation.  I am located in West TN on gently rolling highly erodible soil.  When it rains, our soils seem to dissolve like sugar.  Up until the early 2000's, cotton was the primary crop grown.  The soil was heavily tilled until the mid 90's when no till started becoming popular.  Organic matter when beginning no till was consistently around 1-1.25%.  Topsoil was very thin on the hills.The popular saying around here is that no matter how saturated the soil is, we're always less than a week away from a drought.  The drought of 2007 really showed me that if I wanted to stay in business, I needed to quickly begin repairing my soils.  No till just wasn't going to improve the soil as much as I needed it to.  So in the fall of 2011, I began experimenting with cover crops on very small acreages.  In the fall of 2014, I felt that I was ready to start seeding larger acreages.  Beginning in 2015, every piece of ground had either winter wheat or a cover crop on it.  Also at this time, I quit burning them down early and began planting green.  Needless to say I have experienced major headaches getting a cash crop established.  But I have found solutions that work for me.  To make a long story short, I have found that if you can get a quality stand of a cash crop, your management the rest of the year is so much easier.

OK, enough preaching, I am going to attempt to attach my test plots on Excel spreadsheets to this thread in the order that I describe them.

1.  Test plot 1:  In 2014, I took a square 8 acre field that had been no tilled since 2002.  After the wheat was harvested in June 2015, I put in 3 permanent plots randomly replicated 4 times each.  The 3 plots were: No till, warm season only cover crops, and warm and cool season cover crops.  The thinking was that because double crop soybeans can be risky planted behind wheat, that I might profit more and restore the soil quicker if a warm season cover crop was planted behind wheat instead of soybeans.  So after wheat harvest, I planted soybeans on the no till plots and planted a 7 way mix of summer species on the cover crop plots.  That fall, I planted a 6 way cool season mix on the warm and cool season plots.  The warm season only plots died when frost came.  In 2016, corn was planted on all of the plots.  Normal burndown was applied on the no till and warm season only plots.  Corn was planted green into the warm and cool season plots.  In summary the corn behind the cover crops had a significant yield drag most likely due to the dreaded "carbon penalty."  I believe that there were several factors that contributed to this.  1.  I introduced A LOT of carbon into a no till system quickly and did not have the soil microbes to break down the residue quickly enough, thus releasing nutrients.  2.  I planted a cover crop blend that had too high of a C:N ratio which tied up too much nitrogen during the growing season.  3  I did not adjust nitrogen rates or timing from what I was used to doing in a no till system.

When looking at this plot, the order that the plots are in in the spreadsheet are not the order that they were in the field.  I corrected this on the next plot

2.  Test Plot 2:  This is the same plot as above from this year with cotton planted on it.  After corn harvest last year, I planted a 7 way cool season mix on the cool and warm season plots.  This spring, I did a normal burn down on the bare no till and warm season only plots.  Cotton was planted green on the warm and cool season plots.  In year 2 with cotton planted, yields were better on the cover crop plots vs the no till plots.  However, because I planted green on the warm and cool season plots, I had a skippy stand of cotton which I believe reduced yields some.  The no till plots and warm season only plots had a perfect stand.  The order of the plots in the spreadsheet is the order they are in the field. As an interesting side note, I tissue tested two of the plots weekly, plot #1 and plot #2.  Plot #2 (the first warm and cool season plot) consistently tested higher in most nutrients throughout the season than Plot #1 (the first no till plot).  It also yielded more.

Following cotton harvest, winter wheat was planted and I will see what the yields are on these plots next June.  Following wheat harvest next year, I plan to start over from the beginning with a warm season mix on all  of the cover crop plots and soybeans on the no till plots.  I plan to keep this field in this rotation for as long as I'm able to farm to see what the long term yield effects are of cover crops.

3.  Test Plot 3:  I wanted to test the effects of nitrogen rates in corn vs no till and cover crops.  I wanted to see if cover crops would be able to cover any of my corn's nitrogen needs, thus allowing me to begin reducing nitrogen rates while still maintaining yields.  For this test, I took what I learned in Test Plot 1 and applied it to this test plot. On this piece of land, this is the second year it has had a cover crop grown on it.  The firs year was in 2015 with winter wheat/double crop beans on it in 2016.   I selected a 6 way blend of cool season cover crops with a "neutral" C:N ratio.  I also applied nitrogen earlier in the season.  Normally for no till, I would apply 70 lbs N at around V3 and 130 lbs around V7 for a 200 bu yield.  But for this plot, I applied 85 lbs N at planting and 115 lbs at V4.  So I didn't change the total amount applied, but did adjust the timing and the amounts I put out at those times.  The reason for this was to get the residue breaking down quicker and minimize the amount of nitrogen that was tied up by soil microbes.  Each plot was 30 feet wide and planted in the order listed in the spread sheet.  I harvested 6 rows down the middle of each plot.  I had 2 replications each of 200 lbs N and 85 lbs N comparing them to the control which was 0 lbs N.  The nitrogen source was Urea and Ammonium Sulfate spread dry for the 85 lb application at planting and 32% UAN dribbled down the middles for the sidedress application.  The chicken littler listed under fertilizer at the top was applied in January.  While it likely supplied a tiny amount of nitrogen to the crop, I believe that the majority of the available nitrogen leached out before planting.  As you can see from the results, at regular rates of nitrogen cover crops did not significantly reduce yields.  However, even though the cover crops likely supplied nitrogen, it was just enough to overcome the nitrogen penalty.  As you can see, at reduced rates of nitrogen, yields were negatively impacted by cover crops.  I am DEFINITELY not at the point yet to where I can begin reducing nitrogen rates and expect the same yields.  I plant to repeat this same trial every couple of years to determine how many years it is before I have built up my microbial population and organic matter enough to safely reduce nitrogen rates without enduring the carbon penalty.

4.  Test Plot 4:  Just as an afterthought when I was planting corn, I decided to test a soil health inoculant that I use when planting cover crops.  I frankly expected nothing out of this test but I was pleasantly surprised.  The product I used was Micronoc Dry Seed Innoculant made by SonoAg.  For several years, I had been having major problems getting my clover to nodulate.  Other innoculants I used just didn't get the job done.  Dave Brandt recommended that I try this product.  It did an awesome job getting my clover to nodulate the first year I tried it.  It's supposed to be more than an inoculant, it's a blend of microbes and fungi that are beneficial to plants. 

I have a 12 row planter with individual hoppers on each row so for this plot I mixed in the inoculant on the seed on 6 of the hoppers and planted 2 rounds.  So each plot was replicated 4 times.  The results were obvious.  Each plot with the Micronoc inoculant yielded higher than the next one to it that didn't have the inoculant.  The average yield increase was almost 15 bpa.  Now I don't know if this was a fluke or not but I will definitely test it again next year on corn, cotton, and soybeans.  I have already planted a wheat trial for next year comparing it.  And no, I am not being paid or given product by SonoAg.  This was simply a plot that I decided to do on a whim and it looks like there may be something to it.

I have done some other work exploring if interplanting soybeans in corn will increase yields, but as of right now results are inconclusive the way I am doing it.  I apologize for the length of this post, but if you are someone who is serious about cover crops, hopefully you will find this information beneficial.  I attempted to answer a lot of the questions that I anticipated would be asked, but if there's anything you are curious about that I didn't answer, please feel free to ask.

Thanks





Attachments
----------------
Attachments Adaptive Management 2016 plot.xls (146KB - 279 downloads)
Attachments Adaptive Management 2017 cotton plot.xlsx (13KB - 166 downloads)
Attachments Corn N trials with cover crop 2017.xls (38KB - 273 downloads)
Attachments MicroNoc innoculant seed treatment corn 2017.xls (36KB - 197 downloads)
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