Kelly Robertson Farms

I wrote a short statement of philosophy on soil sampling for myself and some other consultants in Illinois a few years ago in hopes of changing the minds of some university and government bureaucrats.  It didn’t work, but I still think this holds true for me and some others who don’t subscribe to the “grid sample the world” mantra of the Land Grant University and the “sell fertilizer at any and all cost” retail industry here in Illinois. 

So here is my “thesis” with a few things thrown in for Ed Winkle’s questions…….

Robertson Philosophy on Soil Sampling

Each soil sample should represent a uniform soil area with similar past management. It is recommended that each sample represent 10 acres or less. Sampling areas should be determined by the soil type, soil color, topography, drainage, past management of the field, manure applications or presence of livestock, and productivity.  Maps of soil electrical conductivity (EC) and GPS yield maps can aid in distinguishing between field areas with contrasting soil properties or crop nutrient removal. 

Consultants should use field observations at the time of sampling to determine which local site factors should guide their sampling pattern within each field.  Soil survey maps, GPS yield maps, bare soil images and input from the farmer as to past land use (fence rows, pastures, building sites and old field divisions) can be used to create geo-referenced zone maps of these factors prior to soil sampling. This will help guide the consultants sample locations in combination with his or her field observations.  

Soil sample zones should be recorded via GPS or geo-referenced maps to insure location and repeatability of sampling.  This also aids in refining the sample zones as more information becomes available about the field or soil, and allows the zone to be used as part of a directed nutrient application (VRT) program. 

Soil sample probes should be taken to the depth of the furrow slice (6-7 inches) or modified based upon tillage practices or the lack of tillage (no till) for the farm.  Each sample should consist of between 10 and 15 cores with cores being collected in a zig zag method thought-out the sample zone.   Each core should be examined prior to placement into the sample bag to insure that it conforms to color, texture and depth for other samples in the management zone.  

Each soil sample should be air dried and all cores in the sample should be ground and thoroughly mixed prior to submission to the laboratory for analysis.  Doing so insures that each sample is truly a representation of the sample area.  

Soil samples should be collected on a regular sampling interval based upon crop rotation, fertilizer or manure applications, or tillage practices.  In many instances under high management it would be appropriate to sample fields every year.  Fields with high test levels or fields receiving manure should be tested every year.  In other cases sampling every two years under a corn-soybean rotation or under a bi-annual fertilizer application would be appropriate.  No more than three years should elapse between sampling intervals. 

Other random notes by GKR: 

1.  If your not going to GPS your sample locations, don’t even pull samples. Your waisting the farmers time. 

2.  If you not using or making GPS/geo-referenced maps, your waisting the farmers time and money.

3.  If you not doing VRT recommendations based on ECONOMICS but on just lbs. applied, then your waisting your farmers time and MONEY.  Whole field recommendations are appropate when there isnt that much varation to justify the extra cost of applicaiton. 

4.  If you can’t collect samples in good soil conditions then your waisting your time and the farmers money.

5.  Find a good lab that can provide you with good quality control, good turn-around time and give you the data set in a format you want, not what they want to do.

6.  Get rid of the paper.  Go electronic.  You can make recommendations, track history and do analysis so much easier in digital than analog.  Paper is still king when delivering your recommendaitons but poor for analysis.  Digital is king.

7.  If you can’t get your head around the ECONOMICS of your recommendations, but only on balancing the soil or applying some magical formula of inputs, your waisting your farmers MONEY.

But as Dennis Miller Says:  Then again, I could be wrong.