Harlan Anderson doubts that grid soil sampling would be profitable for his farm. So, four years ago, he asked his crop consultant to try a different approach.
Instead of dividing fields into three- or four-acre grids and analyzing soil in each grid every several years, the consultant yearly samples one spot in each field.
“You can't run all the tests that we want to run on a grid-soil system and be able to afford it,” explains Anderson, of Cokato, MN. “This is basically a poor-man's grid system — I only have one grid per field.”
The tradeoff between sampling multiple grids in a field vs. focusing on just one grid is validity, says Darrol Ike, Anderson's consultant.
“To extrapolate data off just one data point in an 80-acre field is pretty extreme,” says Ike, of Agro-Info Agronomy Services, Delano, MN. “It has to be a very well-selected data point — one that is most likely to represent the entire field.”
With the right data point, however, the benefits include lower costs, greater speed and more data.
“Under this system, I could monitor all 15 fields in one day,” says Ike. “I could also do it for less than one-fourth the cost compared to grid analyses.”
So far, Anderson has seen three important results from the system. The first is the need to restore micronutrients.
“Where we don't have manure, certain elements are showing up as deficient,” says Anderson, who grows corn and soybeans on half his acreage and alfalfa on the other. “Iron, sulfur and manganese are not being replaced, except where we apply manure.”
Ike agrees that manure provides important micronutrient value.
“The uptake needs of any crop include more than the big three or four nutrients,” says Ike. “There's no doubt that manure is a more constant source of soil fertility and carbon (than commercial fertilizers).”
Anderson has also seen a significant yield increase from applying ammonium sulfate to alfalfa and alfalfa-grass mixtures.
“I've raised hay all my life,” he says, “and never knew that you could get a yield response (from a nitrogen-sulfur fertilizer) until now.”
The last lesson learned is that Anderson's soils benefit more from one large application of manure (as much as 20,000 gallons/acre) every three or four years than from more frequent, smaller applications.
“Results show that the heavier applications didn't raise fertility to levels that would cause concern or environmental harm,” says Anderson. “Manure is a slow-release system, but it really brings fields back to life.”
Ike agrees that Anderson gains valuable information through annual soil testing of multiple nutrients. Yet he would prefer to see Anderson measure yields, too.
“I would like to see more involvement with plots and checks and tissue analysis to quantify results,” he says. “I'd like to see Harlan develop yield maps based on a load sensor similar to what sugarbeet growers are using.”
Even without using load sensor technology, Anderson could benefit by measuring yields with a scale, which he recently installed.
Otherwise, says Ike, “I do like the idea behind this system. It's a revolutionary thought process compared to where the industry is going.”