Dave Franzen, North Dakota State University Extension soil specialist, thinks about fertilizer 24/7.
"This winter, I was asked to present a talk to the Governor's Historical Society Conference on the history of fertilization in North Dakota," he wrote in a recent NDSU Crop and Pest Report. "At first I thought how boring it would be to show a chart of fertilizer use over the last 50 years and talk about it for an hour; but then I realized that the state had a deeper history of plant nutrients, particularly phosphorus. As the second most applied fertilizer nutrient in the state behind nitrogen, phosphorus is an economic factor in all of our crops both organic and inorganically grown.
"In the 1880's to early 1890's a large business in phosphorus export was active, fueled by settlers gathering buffalo bones from their farms and taking them to rail depots across North Dakota for shipment to bone meal fertilizer factories on the east coast. Although the Northern Pacific railroad records of the exact tonnage of bones hauled from North Dakota were lost in a fire years ago, records from Kansas of bones collected from the remains of the southern buffalo herd suggest that millions of pounds of bones were exported. That would be the equivalent of two years of fertilizer phosphorus application at the present grower rate.
"Our largest export of phosphorus, however, was during the 1930s, when dry weather catalyzed winds carried away the surface 6-12 inches of topsoil from half of the acres in North Dakota. Scientists in the eastern US took samples of the dust that settled on land in New York and analyzed the dust for plant nutrient content, including P. From their analysis and from the tonnage of soil that left North Dakota in the wind, the phosphorus lost during the 1930's was the equivalent of 40 years of phosphorus application at present rate. If one examines wheat yield records in the 1920's during decent growing years compared to decent growing years in the late 1930's, early 1940's, the yields were reduced by one-half after the soil loss. Certainly the loss of organic matter from the topsoil was part of the cause of lower yields, but the loss of plant nutrients, including nitrogen and phosphorus was also catastrophic. Nitrogen and phosphorus and zinc and other nutrients were mobilized and deposited over a period of thousands of years of prairie-grazed soil formation. In under 10 years, about half of it was gone.
"Tree rows sap water from up to 50 feet or their center; however, they also greatly decrease the risk of wind erosion. Growers have told me that with conservation tillage, the need for tree rows was diminished. This is probably true. However, many growers who have never seen significant wind erosion consider the tree rows as a pest and take them out without changing their low-residue tillage habits. Near Borup, Minn., on May 14, I witnessed a line of ex-tree rows stacked waiting to be burned while the ditch was filling up with black silt and sand. I am astonished how many growers think that most of the wind erosion ends up in their ditch, and all they need to do is scrape it out and put it back onto the field. The ditch silt is only a small fraction of the soil lost. Most of the soil lost to wind travels for hundreds and thousands of miles. Ocean researchers track the buildup of sediment on the ocean floor over time. Wonder where the sediment comes from? Your fields.
Source: NDSU Crop and Pest Report