No Till Notes: 'Observations'

We have now planted field peas on all of our dry land fields for a third time in our winter wheat, corn, field pea crop rotation. We have learned quite a bit over this time on growing field peas and what to expect and watch for as this rotation continues over time and I thought I would share some of what we have learned and a few things to watch for in field pea production.

I had several calls earlier this year on how we approach fertilizing our winter wheat following our field pea crop. Field peas are a legume which produces nitrogen during their growth cycle. I have been told field peas will produce a pound to a pound and a half of nitrogen for every bushel of field peas they produce per acre.

A 30-bushel-per-acre field pea crop could be expected to produce from 30-45 pounds of nitrogen per acre. Field peas are one of the best nitrogen producers in the legume family. I have also been told that this nitrogen takes up to 18 months to break down into a plant useable form of nitrogen.

Even though the field peas produce a lot of nitrogen during their growth cycle, I also realize the harvesting of the grain from the field peas is removing a lot of nitrogen from the field. I am hesitant to give the field peas to much nitrogen credit for the winter wheat crop since we are removing a lot of the nitrogen they produced with the grain we remove from the field.

When it comes to fertilizing our winter wheat crop we soil sample each field of winter wheat in the spring to determine the nitrogen requirements for our winter wheat yield goal. We do apply 10 pounds of nitrogen with our starter mix when we plant our winter wheat to get the young winter wheat seedlings off to a good start and carry the wheat through the winter.

Our approach has been to fertilize our winter wheat crop according to the soil samples taken in the early spring. The soil samples allow for 25 pounds less nitrogen due to the fact that we are planting our winter wheat crop following a legume, so there is some reduction in nitrogen requirements following the field pea crop.

We don’t reduce the nitrogen requirement for our winter wheat any more than this reduction from the soil testing lab. Our approach to fertilizing winter wheat following the field peas is to put on the recommended rate from the soil testing lab. We assume any nitrogen produced by the field peas may not be in a plant useable form if the nitrogen requires 18 months to convert to plant available nitrogen.

My observations over this time of producing field peas is that our winter wheat yields have been very good following this method of determining nitrogen requirements for the winter wheat crop. We have had good yields of winter wheat and we have maintained good protein levels in our winter wheat crop. I think the winter wheat crop may benefit from the nitrogen the field peas have left behind as the protein levels in the wheat have remained high with good yields.

My observation for fertilizing winter wheat following field peas would be to follow the recommendations from the soil testing lab and fertilize your winter wheat crop according to these recommendations. I wouldn’t give the field peas any more nitrogen credit than the soil lab recommendation. I do think the protein levels in our winter wheat crop have benefited due to the nitrogen from the field peas.

I do think we may see some reduction in nitrogen requirements from the field peas in the corn crop we grow following the winter wheat crop. My observation over time is that we don’t seem to require excessive nitrogen to produce our dry land corn crop. I wonder if the nitrogen benefits from the field peas may be showing up following the 18 months since the field pea crop.

Next week, I’ll take a look at an old nemesis we have seen come back into winter wheat production following the field peas that has developed over time in our winter wheat, corn, field pea crop rotation.