Friday, December 14, 2012
The Art Of Soil Sampling
I offered to stop and pull samples at one of my dear friend readers in Illinois on the way home. I thought why doesn't he already know how to do this? He's a grown man, why doesn't he understand how to pull a good soil sample? Why? Because no one has taught him!
I used to teach how to pull a soil sample to my sophomores or any appropriate class, group or individual. In my travels this week it seems like a lost art.
First you need an appropriate soil probe. I like the one from Gemple's with the foot peg for a starter probe. You walk into the field and decide how am I willing to spread my nutrients and soil amendments compared to the different soils in that field. Most fields have at least 3 different soil types though they may be distinct or different. A garden or small field makes it easy, it is going to be ONE sample.
The VRT guys, that is Variable Rate fellows are going to use electronics help the vary the nutrients and soil amendments. I still pretty much do it by hand by zone or soil type. The 50 acre field behind the house is 3 distinct soil types and I could break it into 5-6 pretty easily. I am willing to do 3 zones, not more.
I try to sample in the fall when it is not too dry and not too wet. If it's too dry the soil may be hard as concrete and if it's too wet the soil sticks to the probe. I pull one sample per acre to get at least 10 or so samples for the school milk carton sized container per sample. If I want to compare two different labs like I am discussing I need more samples yet the two should be as similar as possible.
The probe is my penetrometer and biology and chemistry meter. I can see the biology in the sample and I can feel how the probe goes into the ground. I probe 12 inches or less depending on what I am sampling for. The lab will determine a glimpse of the chemistry in my sample.
That's enough for today. Here I go pulling from my old picture file again. I need to work on that.