By Darren Hefty
Getting the balance of available fertility just right for your crop is difficult. Fortunately, there are a couple of cheap and easy tools to help you do just that. The first one is a soil test. How amazing is it that we can analyze the soil and see exactly what’s in it (at least the nutrients that are in it)!? When you think of how much money you spend on fertilizer each year or how much effort it takes to spread manure, etc., for $5/acre or $25-$30 per sample it’s pretty cheap to find out exactly what you need.
As you already know, you can also analyze plant tissue to see if it has the nutrients the plant needs, as well. I look at this as the “report card” for the farmer. You fertilized the field, but did that fertilizer actually get into the plant? Tissue tests only cost around $20. That’s not too bad, but how do you go about doing this and turning the information into actionable items for your farm? I’ll lay out the best plan we’ve found for a plant tissue testing program for your farm. It’s not complicated. It doesn’t take much time either.
- Pick a field.
- Pick a good spot in the field and mark it either with a flag or with GPS.
- Pick a bad spot in that same field and mark that, too.
- Go to those spots once per week on Monday mornings at 8:00 AM and pull a plant tissue sample (could be 20 leaves, could be 10-20 whole plants, depends on the time of year and the crop). Send your samples to the lab in paper bags.
- Do this every week of the growing season if you’d like OR do it for 8 to 12 weeks.
- Track the trends on your farm. Is K high all year long? Is P running out mid-season? Etc.
- Address those issues with your soil fertility program.
Exactly which leaves or plant parts to pull depends on the growth stage of the crop. You can get specific recommendations from your lab as to what they want and how they want it sent in.
Other tips:
- Don’t take only one sample. You really need to look at a trend or you will make mistakes. Nutrient levels change during the year and with weather events.
- Don’t let samples sit around. Send them in shortly after you take them.
- Wash the leaves off with DISTILLED water. If you have soil on the leaves, it will throw the results off.
- Pull samples from the same spot each time. This gives you the most accurate picture of what’s happening over time.
It only takes about 5 minutes to pull a plant tissue test. 5 minutes each times 2 spots in a field times 12 weeks. That’s a $480 investment that took 2 hours total to get. If you’re spending hundreds of thousands of dollars on fertilizer in your farming career, can you think of an easier or better way to see if you’re investing those dollars wisely?