|Douglas Jr, Clyde|
Submitted to: Direct Seeding Intensive Cropping Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/5/1999
Publication Date: N/A
Interpretive Summary: This paper presents data from our first look at a side-by-side soil comparison of 16 year no-till, first year no-till, and plowed summerfallow. Chemical-fallow after 16 years of NT is a little better than in the first year of no-till, but still not performing nearly as well at providing moisture near the surface as conventional summerfallow. Organic matter has increased about 1200 pounds per acre, not including the undecomposed residue laying on the surface. Earthworms are thriving in no-till in high numbers, which we don¿t see in any of our tilled plots. The 16-year no-till measured much higher infiltration capacity using the double-ring method in the spring. Finally, the soil is a lot softer than it was in the first year we no- tilled, and the plow pan is disappearing.
Technical Abstract: The ARS/OSU station has maintained a no-till (NT) wheat experiment since 1982. Since 1989 the rotation has been winter wheat/fallow. In 1997 the plots were extended to start another NT winter wheat/fallow experiment that matches the original. A set of conventionally-tilled and rod-weeded winter wheat/fallow plots was also added. This allowed comparison of 16-year NT with one year NT conventional tillage. Some preliminary results are presented here. Even after 16 years of NT, the surface soil layer does not function like the blanket of dust mulch created by intensive tillage. To reach 14% moisture seed would have to be placed 1.5 in. deep in the conventional, 3 in. in the 16 yr NT and 3.5 in. in the 1 yr NT. The first year NT plots have the greatest soil strength as measured by cone penetrometer; conventionally-tilled plots, plowed to a depth of eight inches, are weakest. After 16 years of no- till, soil strength more closely matches the tilled than the first year no-till. Soil organic matter averages 2.07% in the top eight in. of the 16-year NT field and 2.02% in the conventionally-tilled plots. The 0.05% difference translates to 1200 pounds per acre of organic matter. Carbon dioxide loss is accelerated by tillage. Plowed plots averaged 60 lb CO2/day, 16 yr NT 20 lb, and 1 yr NT 14 lb. The long-term NT plots had over 8 earthworms/sq. ft, which is about 20 times the other treatments. A double-ring infiltrometer measured 5.1 in./hr infiltration into 16-year NT, 1.1 in/hr in 1-year NT, and 0.04 in/hr in the plowed soil.