Cornell University

Soybean Nodules

What do you do on a beautiful summer day? Well, spend it in a soybean field of course!  I headed up to Delaware County this morning to complete some more fieldwork on the soybean and lime experiment. Since the soybeans were planted late, they are only just reaching the R1/R2 stage. This is the stage where tissue samples and nodule counts are taken.

The tissue samples were the easiest part of the day. The procedure was to cut off the highest, fully-open trifoliate leaf from 20 plants in each rep. This resulted in 60 individual leaves, once the petioles were removed. The samples will then be dried, ground, and sent off to the lab for analysis.

The harder part of the day was the nodule counts on the roots. Soybeans have the ability to fix their own nitrogen with the help of bacteria.  Prior to planting, soybean seeds are inoculated with a bacterium called Rhizobium japonicum.  This symbiotic relationship between the bacterium and the soybean seed allow atmospheric nitrogen to be converted into a usable form for the plant.  The nitrogen fixation begins with the formation of a nodule on the root of a legume.  For the first few weeks, the nodules are inactive. But 2-3 weeks after planting, the nodules become active.  A healthy nodule will be a pinkish-red inside, caused by leghemoglobin.  These nodules will supply most of the needed soybean plant’s nitrogen for the rest of the growth period.

To count nodules, the soybean plants have to be dug up, being careful not to disturb the root system.  Two plants from five different rows in each plot were sampled for the nodule count.  Once the plants were dug up, the dirt was shaken from the roots, dipped in water and then counted.  The nodule counts ranged from zero all the way up to 30+ nodules.

At harvest time, soil samples will be taken as well as yield monitoring. This is done by counting the number of pods per plant and beans per plot.  The beans will also be weighed to determine the dry matter content.  Until that time, the soybean fieldwork will be quiet.  In the meantime, I have a lot of grinding samples and a few soil tests to run. It should be enough to keep me busy!

Soybean Field in Delaware County

A big part of my internship this summer is to create an agronomy fact sheet that will be posted on the Nutrient Management Spear Program’s website.  The topic is soybeans and lime application.  A field trial was set up on a farm in Delaware County to provide more information for the fact sheet.

The topic of soybeans and lime came up when an extension agent in Delaware County found that fields that were being planted with soybeans had relatively low pHs and the question was asked if the pH of the soil will actually affect yield.  The target pH for soybeans is 7.0, while the fields in Delaware County were testing at mid to upper 5s.  A plot was set up with 8 reps, alternating with four control plots and four plots receiving lime.  The lime was disked into the soil even though this field was normally no till conditions.

Initial soil samples were taken prior to planting and the addition of lime.  I will be running pH tests on these samples as well as ISNT and LOI.  ISNT stands for Illinois Soil Nitrate Test and estimates the readily available nitrates in the soil.  LOI stands for Loss of Ignition, which through a series of drying steps, can estimate soil organic matter.  Soil samples will also be taken at harvest, where the pH will again be measured.

In mid-July, a team of several extension agents from Delaware County and I went to the field to take several different measurements. We took stand counts, plant heights, and plant stages at five different sections of each of the reps with each rep being averaged together.  The next step will be to take nodule counts as the plants reach the R1 stage.  This should be happening within the next week so there will be more to come on this project shortly!

A few weeks ago we tested the subsurfer poultry litter injector on a field at the Musgrave Research Farm in Aurora in hopes that we wouldn’t break the prototype.  Good news is, it didn’t break but the bad news is used it doesn’t work too well.  Instead of using the dry poultry litter, we used separated manure solids from a dairy farm just up the road.  When we first added some solids in at the dairy farm and ran it out on the ground it worked great but that was not the case when we tried it in the field a few weeks later.

The video explains a little more about how exactly the injector works, but in brief, the bed is lined with augers that pull the manure forward and send it through a shoot where two discs separate the soil and put the manure near the roots. The separated solids had a little more moisture than the poultry litter that others used which caused a few problems.  It would build up in the shoots and wouldn’t fall down.  After each plot we would have to clean out each shoot so the manure would fall down.  Another problem is that the augers made tunnels through the manure and wouldn’t pull any more of it forward so nothing would come out.  We emptied out the bed of the injector and are trying to dry out the solids a little more and give it another try in a few weeks. We’ll see what happens.

The second cuttings of all our alfalfa trials are in as of last week.  We collected the forage samples we needed at each of the three locations and I am grinding all the samples.  I look in the store room and see the mountain of brown paper bags and I know I’ve got a lot of work to do!

Whats left after 3 days of grinding...one more field to go!

One of our plots in Valatie had quite a bit of green leafhopper damage.  The green leafhoppers will feed on the stems and underside of leaves on the sap causing those areas to be a lighter color.  There was no sign of leafhopper damage at Coynes field and the alfalfa planted at Aurora was a leafhopper resistant variety and seems to be doing very well.  In no time at all, it will be time for the 3^rd cutting and tip samples.

Alfalfa Field in Valatie

Later this week, I will get to take a first look at the soybean field where my project will be taking place.  I will take the 2 hour trip to Delaware County to take stand counts on the soybeans and meet all the other people involved with the project.  I will also be bringing back some initial soil samples to process.  I am still reading up on soybeans and working through the lime module, but I hope to have more for you on the soybeans soon.  Until then, stay cool and pray for some rain!

Prior to starting my internship over four weeks ago now, I had no idea what to expect to be doing each day and even after four weeks I still don’t know what each day will bring.  I knew I would be working with soil but that was about it.  My first week on the job really gave me a taste of what my summer would include.  The first day I ended up washing and separating root and shoot samples from a cover crop study.  The next day I was in the truck headed to a farm in Western New York to set up plots and spread fertilizer in an alfalfa field.  The next day I was grinding plant samples followed by a day of computer work.  The last day of my first week was spent at the Musgrave Research Farm in Aurora taking soil samples from a multi-year corn/alfalfa rotation study that has been going on for awhile now.  I felt like I was going in a hundred different directions but I loved having a new challenge every day I came into work.

Musgrave Research Farm

I have learned how to do several laboratory tests including ISNT, LOI and Morgan Extractions.  ISNT stands for Illinois Soil Nitrogen Test and it measures the amount of Nitrogen in soil that is available for plant use.  This helps determine if addition of Nitrogen fertilizer will be beneficial to crop yields.  LOI stands for Loss of Ignition and measures the amount of organic matter in a soil.  Morgan Extractions measure the amounts of micro and macro nutrients in a soil sample.  There are still several lab tests that I will be learning in the coming weeks including a Corn Stalk Nitrate Test.

A few weeks ago, I was also given my special project from which I will create an Agronomy Fact sheet which will be published on the NMSP website.  My project is looking at soil pH in soybean fields in Delaware County.  The goal of this experiment is to see whether or not applying lime to fields with low pHs will increase soybean yield.  To prepare for the fact sheet, I am completing a Lime Management learning module located on the NMSP website as well as a lot of reading about soybeans.  There will be a lot more to come in future blogs on this project!

While I am working on a lot of different projects, I have found one that will most likely be my favorite.  At the Musgrave Research Farm, we have a sub-surfer manure injector that we are testing out.  It sounds strange but the main goal of this project is to break the machine which to me is kind of exciting.  This spreader is for no-till surface and sub-surface conditions in pastures and fields that will inject dry poultry litter and cow manure into the soil.  The company we received the prototype from wants to know what is wrong with it so they can make adjustments before releasing it to the general public.  We are just getting started with this and I can’t wait to see how we break this thing!

Subsurfer Prototype