Iowa Public Television


Researchers and farmers tackle soil loss

posted on November 17, 2000

In the past few years, soil and nutrient runoff have grabbed national attention. In Iowa, the E-P-A classified many of the waterways as polluted, mostly by eroded soil. That revelation prompted the state?s government to allocate more funds to conservation reserve programs and other edge-of-field practices.

Many in the research world feel buffer strips are fine as a last line of defense, but they argue the buffer strips only filter a problem that started in the field. For researchers, the real prophylactic for soil and nutrient runoff is to prevent soil and nutrients from moving across a field.

Whether it is soil and phosphorus concerns or a nitrate induced shortage of oxygen in the Gulf of Mexico, known as hypoxia, rural America is a key player in water quality issues. But, some have taken responsibility for their fields AND found success. Tyler Teske reports.

Researchers and farmers tackle soil loss The question of nutrient load recently was taken up by the U-S geological survey. The study monitored nutrient movement in the Mississippi river watershed in an attempt to more accurately pinpoint non-point source pollution. The results show cities introduce a disproportionately large nutrient load to waterways when compared to the amount of land area a city covers. Yet, the fact remains that farm country is responsible for as much as 75 percent of all nutrient pollution in the Mississippi watershed?and the number one pollutant in rivers and waterways is eroded soil.

Dr. John Moncrief, University of Minnesota: ?For instance, in this state, half of the people live in the metropolitan, twin cities area, and the other half live in the rest of the state. Half of what goes in the river comes from the metropolitan sewage and half comes from some diffuse source out in the state, we both have to reduce our inputs into the river because if we don't, there's going to be regulations and there's going to have to be more restrictive handling of manure fertilizers and soil management.?

Like many other researchers across the country, Dr. John Moncrief is monitoring runoff from farm fields. His monitoring sites use side-by-side comparisons of soil tillage techniques on watersheds of similar size and topography. The monitoring stations record nutrient movement, as well as soil runoff. Controlling soil erosion is one key factor in keeping nutrients in the field.

Dr. Moncrief: ?That's probably the place to start but it also has to be integrated into a fertility program and that means managing their manure properly and their fertilizer inputs and making sure that doesn't get delivered to a water body because the concentration of phosphorous in fertilizer and manure is a million times greater in concentration than the critical level in a lake.?

While researchers continue to gather information that helps farmers assess their contribution to waterway pollution, others have been implementing practices to reduce environmental impact for many years.

Tony Thompson is one of a number of farmers in southwest Minnesota using management intensive practices in his fields. Thompson?s farm uses ridge till, a process that builds ridges along planting rows. After harvest, fertilizer is deep banded into the soil underneath the ridges while leaving plant residue in place. In the spring, seed is planted directly into the stubble. Fields usually are cultivated twice a growing season.

When Thompson was younger, a heavy rainfall caused washouts in his fields and washed thousands of dollars of recently applied chemicals into the surrounding waterways. Meanwhile, his ridge tilling neighbors saw no such loss.

Tony Thompson, Willow Lake Farm: ?Our soil just got terribly compacted and the ridge till fields were nice and soft and deep, loamy soil, easy to stick a soil probe into, and I thought that must be reflecting something good. And since then, we?re finding that we?re realizing now, something like a four fold increase in water infiltration rates over chisel plowing.?

Thompson also cites other advantages to ridge till such as lower per acre machinery and fuel costs, mostly related to fewer passes in the field each season.

Ridge till does require more management, such as with weed control, and it does not eliminate problems with cold wet springs that all farmers in the area face. But Thompson believes the long term benefits far outweigh the disadvantages.

Thompson: ?I think there are very few problems with being a maximum tillage yield conscious, yield focus farmer. It's a very good way to farm. In the short term, there are very few problems. I do see though in the long term, there, that sort of farming does erode soil and pollutes rivers and streams and I just don't think that our cousins are who every farmer has cousins that live in the city?our cousins aren't going to stand for it forever because they want to be fishing and swimming and motorboating and canoeing and in the same water that is passing through our farms and they're just not going to stand for it. ?

Nearby, Paul Turner and many other farmers employ a more recently developed technique that combines ridge till and no till into a fall tillage system called strip till.

The equipment rips furrows and applies fertilizer only in the strips of land that will be used during spring corn planting. The result is similar to ridge till, soil is held in place by residue, the ground is ready to plant in the spring, and fuel costs are reduced as a result of less passes in the field.

Paul Turner: ?Initially, it was a labor and time saver and my father is getting up there in years and I didn't like spending all the time on the tractor and doing preparation work for those tillage?.for a seed bed and things like that. That kind of drove me there. Then, now, the economics have kind of come around and there's other benefits with soil erosion and wind erosion and I think it works really well.

Farmers and researchers have found both advantages and disadvantages in management intensive systems, but their complaints are concerned less with tillage techniques, and more with farm policy.

Paul Turner: ?Well, right now, there's no incentive for anybody to do this, sort of conservation practices. People think chisel plowing is a conservation practice, and I don't know about that, but there's no financial reward going to strip tilling other than you will eventually have some cost savings, but, you know, you?ve got tochange equipment and you?ve got to find a bander to do this.?

Dr. Moncrief: ?But when you look at it from a downstream perspective, you know, if you're contributing a lot of contaminants, there's going to start to be more restrictive management scenarios and regulations. So, we have to reduce ?..and we, I'm speaking of a farming community now, has to reduce their contribution the best they can.

Tony Thompson: ?I hope that as that policy is developed that it rewards the good stewards rather than penalizing those who don't show this sort of initiative. It's not an agronomic issue at this point in time anyway. I think it's a social issue.

For Market to Market, I?m Tyler Teske.

Tags: agriculture Energy/Environment erosion news oil pollution research