Mulching Soybeans

Final Report for FNC00-293

Project Type: Farmer/Rancher
Funds awarded in 2000: $678.00
Projected End Date: 12/31/2003
Region: North Central
State: Iowa
Project Coordinator:
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Project Information


Our farm operation is located on 550 acres of bluff land. 350 acres are in woodlands, 150 acres tillable and the rest in pasture and land around buildings. Our tillable acres are organic certified and have been for the last 5 years. Our main cropping program consists of corn, soybeans, and oats with hay ground used mainly for green manure crop. Our pastures are used by managed grazing of a neighbor’s cow/calf herd. The woodlands are professionally managed by a forester. Our farming practices prior to being organic certified were managed as sustainably as was possible, using limited herbicides, non commercial fertilizers and no insecticides. The work currently being done on the farm is done mainly by a hired worker and two sisters of the Abbey.

The project goal was to determine if mulch will control weeds in a row cropped organic soybeans, in order to reduce tillage and sustainably improve soil fertility, after the last cultivation.

We first flail chopped dried prairie grass for mulch. This as initially the first year broadcast by hand. A 6 foot length in 4 rows of soybeans that had been planted in 36 inch rows a ½ inch depth of mulch was put down after the 2nd cultivation. Another 6 foot length of mulch was placed at 1 inch depth and another 6 foot length of mulch was placed at 2 inch depth. The mulch was applied at various depths to see if there would be any difference in weed control. The first year of the project was done on a small scale. The following year it was planned to apply the mulch by mechanical means as placing mulch by hand over a large area would be impossible.

In the initial phase of planning the local university extension personnel and state ISU extension individuals were consulted.

Mulch applied at ½ inch depth provided adequate weed control with a minimum of weeds. The 1 inch and 2 inch depth there were no weeds but grass grew through in places. However this was a very small area and it was planned for the following year to cover large area and reassess and count weed types and to measure yield of beans. The 2nd year however I was involved in an accident and unable to complete my project. we did however the 2nd year broadcast the mulch via manure spreader. This did not work out the best. We discovered on the 1st year test plot that mulch placed at the 1 inch and 2 inch depth interfered with harvesting of the beans. Corn was planted in the field we broadcasted mulch from the manure spreader the following year this year. We found that the corn in the area where the mulch had been the previous year was stunted and upon chisel plowing the area this fall we found it very difficult to plow. Was it the result of the mulch or compaction from extra field passes or other factors?

Initially I was very hopeful that mulching would boost soil organic matter, control weeds, preserve moisture, and limit the number of field cultivations. At some point I would like to try again to further test the results. I would locate a spreader or shredder that could broadcast at a more even depth. However considering the time involved in mowing, shredding, broadcasting which means repeated trips to refill with mulch I would be hesitant to recommend this practice to other to be used an a large scale.

A field day was held the first year with approximately 25 people in attendance. Plans were tentatively made to write an article in one or two organic agricultural newspapers but my accident prevented a proper evaluation and conclusion to the project so nothing was written. The people attending the field day were made up of neighboring farmers and some other organic farmers from this part of the state.


Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.