FROM THE FARM REPORT: THE ICE AGE AND SOILS IN THELAKE CHAMPLAIN BASIN, PART 2

Most farms these days understand the importance of routinely taking soil samples in our fields. While CAFO regulations require most f

armers to sample a minimum of every three years, many sample more frequently to better identify and locate areas of nutrient deficit or excess. Modern tools and technology developed to meet the demands of precision agriculture are extremely useful and allow us to break our fields down into management zones based on soil characteristics or yield data to help achieve our environmental and financial goals. However, even our smaller farms that may not have the desire or ability to invest the capital in these expensive solutions should be conducting their sampling efforts with an eye on the variability within fields and whether there may be value in breaking fields down into smaller management zones.

This point was driven home this summer while installing some drainage research plots funded by the Lake Champlain Basin Program in recently acquired cropland. Lake Champlain is sometimes called the “sixth” Great Lake as it is one of the largest inland freshwater bodies in the U.S., though significantly smaller than the five official Great Lakes of the Midwest. This occasional designation isn’t just an attempt to achieve a higher state of acclaim, though; Lake Champlain shares many characteristics with those lakes, having been created by the same glacial activity that resulted in the formation of the Great Lakes 12,000-14,000 years ago, including that they all drain to the St. Lawrence River and ultimately the Atlantic Ocean via the Gulf of St. Lawrence. One commonality across these watersheds is the complexity and variability of our landscapes and soils because of this geologic past.

As is fairly common in our region, most of a farm’s cropland is comprised of many small fields, rather than large expanses of open fields and similar soils and as such, the geography does some of our zone planning for us. However, even in a small 5-acre field like the one in Pictures A and B, it is apparent that our crops are likely going to be experiencing very different growing conditions. Understanding those differences in the soils can help us more accurately prescribe solutions when things aren’t going as planned.

In the top photos, you can see a stark dividing line where the field abruptly transitions from an extremely heavy clay to a much more sandy, rocky

soil. Compare the closeup photo of the soil profile in the top photo versus the profile and close-up of the heavy clay in the bottom image. While this field is on a mild slope (~1.5-2%) and we were expecting to see some differences in the soil as we moved from upslope to downslope, it was fascinating to see such an abrupt transition between soil types in a field that is only 750 feet from top to bottom.

Consider that a field’s soil sample represents approximately 0.000001% of the total amount of soil in the plow layer and it helps drive home the importance of paying close attention to where and how we sample if we want to receive meaningful data and recommendations. If you see fields routinely differing in their crop production characteristics across different sections of the field, that’s certainly a strong indicator that you should consider breaking the field into multiple management zones. One easy way to check before making that commitment is to sample those sections differently for a year (or two or three) and see what the soil results tell you. Perhaps it’s a consequence of its specific location and little can be changed, but maybe those differences are telling you that something can be alleviated by applying some basic precision management principles without requiring a major capital investment.

— Laura Klaiber

klaiber@whminer.com