1996 Annual Report for AS96-025
Controlling Cheat and Annual Ryegrass in Small Grains Using Novel Crop Harvesting Technologies (LS96-081)
Summary
Since McCormick first invented his reaper about 150 years ago, the age old drudgery of grain harvesting has slowly yielded to mechanization. After decades of gradual improvements, the grain binders and stationery threshing machines were finally joined together into machines known as “combined reaper-threshers” and later called combines. Modern grain combines rapidly and efficiently harvest and collect grain and return the straw, chaff, and weed seeds to the field. Over the past 75 years, the primary function of grain combines has remained the same. That is, collect the grain crop and return everything else to the field. An advantage of the old grain binder plus stationery thresher harvesting system was that weed seeds were carried off the field with the bound shocks of grain. Our project is designed to regain this advantage by advancing grain harvesting technology to include separate collection of the seeds of weedy grasses, particularly cheat and Italian ryegrass, that now pass through a combine and return to the field.
Objectives
1. Investigate three distinct modifications to conventional grain harvesting procedures designed to either
remove cheat and annual ryegrass seed from the field during the wheat harvesting process or devitalize
it.
2. Evaluate the new harvesting procedures as a component of an integrated cultural grassy weed control
system.
3. Determine the economic feasibility.
4. Disseminate our findings.
During the three harvests (1996, 1997, and 1998) covered by this project, the following engineering related issues were investigated in depth:
1a. Capturing weed seed and other materials at the combine shoe by removing the material from the combine cleaner air stream.
Chaff and weed seed were collected with the Redekop collector. The system was acceptable for collecting and removing all of the discharged weed seed from the field. The principal weakness of the system was the large amount of weed seed deposited into the clean grain stream.
1b. Capturing weed seed and other materials at the combine shoe by reducing combine cleaner air velocity and removing weed seed with the grain.
Essentially all weed seed was captured, however small plant parts and chaff were collected with the clean grain. This nearly doubled the volume of the material to be recleaned.
2. Recleaning the grain.
Two cleaners, an aspirator cleaner and a screen-auger cleaner, were investigated as recleaners on the combine. When cleaning only wheat with cheat, these cleaners were highly efficient. However, the addition of large amounts of chaff, short straws, and wheat heads, that occurred when the combine was operated to capture all weed seed, greatly reduced efficiency.
3. Capturing weed seed for Animal feed.
Bagging and binning have been evaluated. Both methods worked good. Feed values have been determined.
4. Devitalizing weed seed for deposition in the field.
A major objective of this research was to develop a mechanism to mechanically devitalize weed seed. Farmers have stated that they want the flexibility to kill the weed seed and to return it to the field rather than collecting it for feed. Mechanisms investigated were roller mills and hammer mills. Results of this research have been reported in the journal articles included in this report. A hammer mill was chosen because of its relatively high capacity and flexibility. The one horsepower mill could easily process all material removed by the on-combine 3-stage aspirator recleaner.
This work shows that weed seed can be removed while combining, and devitalized or collected for processing as animal feed. Ongoing experiments to be completed in 1999 are designed to quantify agronomic benefits of using this type of equipment.
December 1998.