Source:
Vegetable Farmers and their Sustainable Tillage Practices [DVD]. V. Grubinger. 2007. University of Vermont Extension. Available for purchase at: http://www.uvm.edu/vtvegandberry/Videos/tillagevideo.html (verified 31 Dec 2008).
This is a Vegetable Farmers and their Sustainable Tillage Practices video clip.
Watch this video clip at https://www.youtube.com/watch?v=pCj58isK1xE
Featuring
Harold van Es, Department of Crop and Soil Sciences, Cornell University. Ithaca, NY.
Audio Text
In the last 50 years or so, we’ve focused a lot of our attention on the chemical functions of the soils and we’ve established a good info structure for soil testing and providing advice to farmers about the chemical functions of the soils. But the physical and the biological functions have not been developed very well and as a result we have seen many of our soils have become physically and biologically degraded.
Farmers have a real challenge with managing the physical and the biological health of the soil because traditionally tillage is a very integral part of the cropping system. Yet we now know that tillage also has a strong negative impact on the health of the soil and certainly if tillage is repeated year after year for many decades we see tremendous degradation of the soils. So we need to focus on finding alternatives tillage systems to build up those soils again and make them productive for our crops.
Tillage affects soil health in a complex way; in the short term tillage provides benefits by loosening the soil and allowing for water infiltration and oxygen to enter into it. The long term however, repeated tillage oxidizes organic matter that’s critical for soil aggregation and structure, and so what we see after decades of repeated intensive tillage that the soil degrades and become dense and compacted.
The moldboard plow has been used for centuries to invert the soil. It’s a very effective tillage tool, but it also breaks up soil aggregates, oxidizes the organic matter which is critical to good soil aggregation. It also causes plow pans that reduces root proliferation into the subsoil.
The rotovator is a tool that does an excellent job of creating a seedbed and has been used in vegetable systems for that reason. The concern about the rotovator is that, much like the moldboard plow, is that it’s a very intensive tillage tool and in the long run it causes the destruction of soil aggregates.
The disc harrow in a way performs less intensive tillage which is good, but it has one particular problem, that it causes a lot of pressure at the bottom of the discs especially when it’s offset at a wide angle and this causes some compaction which results in what we call a disc pan.
To build healthy soils we need to use good management practices and I look at it as a balance sheet. Tillage and intensive mono-crop production are practices that reduce the health of the soil - they degrade the soil. Other practices, like cover cropping, good rotation especially those including sods and legumes, and the addition of organic matter like manure and compost help build the soil. In general, what a farmer wants to achieve is a good balance between those practices. One of the interesting things we’ve found is that these soil-building practices can also mutually reinforce each other. For example combining reduced tillage or no tillage with cover cropping, enhances the benefits of both.
This video project was funded in part by the Northeast Sustainable Agriculture Research and Education Program (USDA).
