120 acre farm, corn-soybean rotation changed over to no till I 1993.
PROJECT DESCRIPTION AND RESULTS
Goals of the project were:
– Continuing on farm research on cover crop effects on soil quality and soil arthropod population densities and biodiversity.
– Develop a simple kit that farmers can use to measure selected soil arthropod population densities in their cropping systems
– Further develop an identification guide of the most common southwest Michigan soil arthropods associated with row crops.
During the project year plots were planted to no till soybeans. Cover crops were seeded into soybeans prior to leaf drop so that the red would have good soil contact. All covers were seeded the same day. Samples were taken during October and November. This sample window is important because covers need to produce biomass prior to sampling, but if sampling is done to late, some groups of arthropods will be missed due to migration to deeper soil levels as the soil cools.
Herbicide-Roundup 20 oz April 30, 1999
Herbicide-Roundup 16 oz July 14, 1999
Planted-May 11, 1999
1-Annual Rye Grass – Seeded September 6, 1999 20lbs/A
2-Hairy Vetch – Seeded September 6, 1999 20 lbs/A
3-Control – Not seeded-bare ground
– Natural Resources Conservation Service – equipment for plot work John Barclay
– MSU Extension Service – consultation – Dale Mutch, Todd Martin, and Larry Dyer
– MASA – partial funding and consultation – John Durling
Results and Discussion:
Data indicates that both the total biomass of the cover and the type of cover used have an influence on arthropod populations in corn and soybean fields. Since ground covers/cover crops do influence arthropod diversity and population density they have the potential for inclusion into pest/crop management programs. Ground cover influences on the micro and macro environments as well as on beneficial arthropod populations in the agricultural community may play a key role by providing the potential mechanism for shifting ecological parameters in favor of increased biotic potential for natural controls and at the same time increase the influence of limiting factors for pest species. Detritus feeing segments of the food chain may need to be considered equal in importance to predators and parasites in helping to reduce the amplitude of fluctuation around the equilibrium population and creating a higher level of stability within the agro-ecosystem.
This report includes summary graphs of data for the past five years. Data for specific groups of arthropods varied from year to year but the trends were consistent.
Results for 1998 and 1999 are consistent with trends noted over the life of the project regarding sustainable agro ecosystem enhancement and stability. One, both diversity and density of arthropods increased with increasing ground cover biomass. Two, the type of cover used can have a negative, positive or neutral influence on the various groups and species of arthropods in the community.
On average annual rye grass/annual rye grass mix plots obtained the largest biomass by November (95 grams/square meter). Hairy vetch obtained 42.2 grams. Percent clover over the ground surface was 100 percent for annual rye grass treatments, 70 percent for hairy vetch and 2 percent in the plots with no covers.
The annual rye grass mix did the best job of weed control. Few weeds were present in the annual rye grass mix plots. Hairy vetch plots reduced both the number and diversity of weed species over the control. However, dandelion and chickweed were common in hairy vetch plots. Control (no cover) plots were mostly clean in the fall but had a variety of weed species growing in them. After five years weed density and species diversity are showing greater differences in each treatment. Treatments are starting to take on their own characteristics in respect to weed diversity.
Arthropod populations in most groups were higher in plots with cover crops than in plots with no cover. For example, Collembola populations were up to three to five times higher in the cover crop plots than in the no cover plots. Oribatid mites populations were also three to five times in plots with cover crops. Carabid beetles were three to six times higher in plots with cover.
Arthropod populations between plots with the annual rye grass mix and hairy vetch were somewhat mixed. Groups such as Carbidae, Geophilidae, Lithobiomorpha were higher in the annual rye grass mix plots. Groups such as Collembola and Oribatei were similar in both types of covers. Staphylinidae and spider populations were higher in hairy vetch plots.
When specific arthropod populations were compared by year from 1995 to 1999 data shows that populations are increasing in both control plots and in plots with cover crops. However, the density is much greater in plots with cover crops.
Average grain yields were highest in those treatments with covers. However, no difference was noted between annual rye grass and hairy vetch plots.
One of the interesting aspects emerging from this project is how various covers influence arthropod diversity at the specific level. We are just starting to develop the information base to evaluate plots by species. Preliminary data shows that the type of cover crop has an influence in determining which particular species inhabit a particular plot. For example within the Carabid family species such as S. conjunctus and E. anceps had similar populations in both types of cover but populations were reduced in plots with no cover. Other species such as P. permundlus and A. cupripennies were collected mostly in hairy vetch plots. Staphylinide also varied with species, Scopaeus sp. was equal in both covers while A. cibratum inhabited vetch plots, T. limbatus was collected only in annual rye grass plots and Apolellus sp. was collected only in plots with no cover. This kind of information will be indispensable as we look at the development of “designer” ecosystem for crop management systems. This species level information will also be required to evaluate indicator species for soil quality.
When we measured the rate of decay during the winter months data showed increased decay of corn stalks, soybean straw and cotton strip in plots with cover crops. Decay rates were similar in both types of cover, but greatly increased over plots with no cover.
– Big Rapids, January 1999, 80
– Frankenmuth, January 14, 1999, 125
– Marshall, January 27, 1999, 175
– Interactive Sites, January 30, 1999, 250
– Agr Action, March 1999, 170
– Michigan Irrigation, December 1999, 75
– Veg Growers, January 19, 2000, 300