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Tillage Study Results - WLEB

 

Western Lake Erie Basin Conservation Tillage Study Results

Five Years of Data Sheds Light on Status of Conservation Tillage

Western Lake Erie Basin Watershed Map

 

The USDA Natural Resources Conservation Service (NRCS) has released the results of a five year program to collect data on the status of conservation tillage in the Western Lake Erie Basin Project Area.

The project was carried out from 2006 through 2010 with cooperation and support from local Soil and Water Conservation Districts (SWCD) and the University of Toledo Remote Sensing Department. Western Lake Erie Basin (WLEB) project funds were provided to the local SWCD’s and the University to assist NRCS in the project.

The data provides a snapshot of conservation tillage adoption rates over the five year period in the Maumee River Watershed, the Portage River Watershed, and several smaller tributaries that discharge directly into Lake Erie. The area covered encompasses 4.9 million acres in Northwest Ohio, Northeast Indiana, and Southeast Michigan. Of the 4.9 million acres, approximately 66% or 3.23 million acres, is cropland.

Each of the five years, local SWCD staff drove predetermined routes of 100 miles or more in each county, collecting crop and tillage data at more than 400 geo referenced sample points in each county annually. Data was collected at the same points each year for consistency. The data was then compiled by the University of Toledo and NRCS, segmented into eight digit hydraulic units, and converted to acres of conservation tillage by conservation tillage type and by crop types.

  Tillage Definitions
No-Tillage = acres in which the soil is not stirred and more than 30% residue is left at planting
Mulch Tillage = acres in which the soil is stirred and which leaves more than 30% residue cover on the surface at planting
Conservation tillage = the sum of acres planted using either Mulch Tillage or No-Tillage
conventional tillage = acres stirred extensively (chiseling and disking, etc) such that there is less than 30% residue  and/or clean till acres that have been moldboard plowed

The data is presented in two ways. Table 1 presents a five year average of the crops grown and the tillage types for each crop. This data was calculated by taking the average percent tillage types for the three major crops in the basin times the average cropland acres. Typically the planted acres will fluctuate slightly from year to year, but there has been no major increase or decrease in the amount of cropland acres in the watershed. Thus the same average figure was used for each year of the analysis and this was multiplied by the percent of transect points counted for each for the crops according to tillage type. The data does not account for special crops such as tomatoes which are a small percent of the watershed and typically not grown under conservation tillage. Table 2 presents the data as the percent of conservation tillage by year for the total of the three crops. Table 2 segments the data into mulch and no-tillage percents for each year and shows the year to year variation in tillage used.

Analysis of the data reveals:

  • Conservation tillage of some form was practiced on an average of 58.6% of the cropland in the project area over the period 2006 thru 2010.
  • Total conservation tillage held very steady over the five year period. The annual fluctuation is between 57% and 61%, of the cropland, with no significant trend of increase or decrease.
  • No-till is the predominant form of conservation tillage practiced. Of the 58.6% of the watershed farmed with conservation tillage, No-till was practiced on 84% of the conservation tillage acres and mulch till on 16% of the conservation tillage acres.
  • In any given year, approximately 40% of the watershed still has no form of conservation tillage or protective residue cover on the soil surface at the time of planting. That equates to 1,263,207 acres of bare cropland soil in the watershed at planting time.
  • Soybeans and wheat are by far the crops most often planted with conservation tillage. For soybeans, 73% of the crop acres were planted with conservation tillage, and for wheat the figure was 76% of the acres. In contrast, only 32% of corn acres were planted using any form of conservation tillage.
  • It is important to look at both the percent of a crop under conservation tillage and the total planted acres. For instance, wheat is a crop that is planted with a high percent of no-tillage but wheat is only grown on an average of 14% of the planted acres.
  • No-till is the system of choice for soybeans. 65% of the soybeans planted are grown using no-till.
  • No-till is seldom practiced on corn, with only 19% of the planted corn acres grown using the no-till system.
  • Nearly 7 of every 10 corn acres are still grown without any form of conservation tillage, using either moldboard plowing or a system which aggressively stirs the soil.
  • One of four acres in the watershed is conventional tillage corn each year on average, and for all the cultivated crops (corn, soybeans and wheat) approximately 4 of 10 acres is in some form conventional till each year.
  • If tillage were distributed uniformly, over a 10 year period a field would be no-tilled every other year, (half the time, 5 years), conventional tilled 4 of remaining 5 years, and mulch tilled one of the remaining 5 years.
  • There is considerable difference in the rates of conservation tillage adoption in some of the individual 8-digit Hydrologic Units.

The DRP or Dissolved Reactive Phosphorus Issue

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Data by region and 8-digit HUC units - (PPTX, 450 Kb)