Which crop should you plant where?
Saturday, January 31, 2015
Having good yield data for your fields is a big help in planning future crops, dealing with the limiting factors and setting yield goals
by PAT LYNCH
Recently I was doing some crop plans with a grower. He has a beans-corn rotation with some edibles. Normally corn is planted after wheat or beans. But this year, since he did not plant all the wheat he planned, he has extra acres for spring planting. On top of that, he wanted to reduce his corn acres slightly. This means we had to readjust the crop rotation for 2015 that we had roughed out in 2013 when we were planning the 2014 crops. We had to go through all his fields and decide which fields would be switched.
In his case, the decision was simplified because he had yield records by field with good notes for the past 15 years. First, we went through all the fields that might be used for corn in 2015. Then we looked at past corn yields in those fields, which made it easy to decide which fields to switch out of corn. Next, we looked at the edible bean yields and soybean yields on various fields to decide where to plant soys and where to plant edibles. In some cases, where it looked like a farm yielded poorly for a certain crop, the grower double-checked his notes to see if there were extenuating circumstances, such as weather, mould or a poor hybrid/variety.
If you have records to enable you to do this, great. A further task that you can do with 15 to 20 years of yield data is to start looking at trends and issues. You can index all yields against your average yield. Then you start looking at these indexes.
If a certain field is constantly lower than average for corn but consistently above average for wheat and soys, you do two things. In the short term, plant more wheat and beans there and less corn. Then take a long look as to why that field cannot grow corn. Do this for every field and every crop. If some fields grow certain crops better than others, then grow those crops more often on that field.
The other thing to do is figure out why a certain crop won't grow on a certain field. Is it drainage, soil type, weed control, fertility? Then you work at the limiting factor. Keep records of what you feel is the problem and how you tried to solve it.
Sometimes a certain field won't grow any crop very well. Often this is because of drainage or the soil is too heavy or too light. If you can't drain it, then get rid of it if it is rented. If that is not an option because you rent other good land from that landlord, find an alternate crop.
I like switchgrass for this. It grows best on good land, but it at least gives a crop on poor land with minimal investment in inputs and time. It will keep soil in place and you can harvest it for bedding. Dairy farmers can use it in a TMR ration. There may in the future also be a place for using switchgrass as a biofuel and it is currently under investigation for other uses.
To take this exercise further, set yield goals for every field. Figure out what a realistic yield is by crop on each field. Then make a list of the three main factors that are holding back yield. Each time you correct a factor such as drainage, low soil test levels or micronutrient deficiencies, establish the next factor that is holding back yield.
This approach is not unique, but neither is it practiced much. Too often attempts are made to increase yield by using an input such as a fungicide, foliar fertilizer or another additive on all fields. More often, it is a combination of factors that must be addressed to increase yields. And these factors are different on different fields. BF
Consulting agronomist Pat Lynch, CCA (ON), formerly worked with the Ontario agriculture ministry and with Cargill.