Objective 1: Determine how species diversity within crop mixtures can influence arthropod communities, particularly weed seed predators. Research has established that increased plant species diversity maintains a more stable community, is more productive, and provides additional habitats for animals. These additional niches allow greater diversity of arthropod species to inhabit crop mixtures compared to monocultures. I expect arthropod abundance and diversity, specifically weed-seed predators, to increase as crop mixture diversity increases, and increase weed suppression. If weed-seed predators show no preference for broadleaf and grass weeds, I expect weed functional groups to be suppressed equally and increased crop species diversity in mixtures will only increase the rate of consumption, but not alter the composition.
Objective 2: Determine how functional groups within crop mixtures can shift or suppress weed composition. I will test functional groups (grasses, broadleaves) in mixtures of forage crops to determine their influence on the weed community. I will measure both composition, the proportion of grass and broadleaves, and suppression, the total number of weeds. Because of planting density, herbicides and optimal timing and depth for rapid germination, I expect the forage crops to outcompete, and therefore suppress, weed populations of the same functional group. Consistent with my preliminary results, I expect grass forage crops to better suppress grass weeds, shifting the weed community to comprise more broadleaf weeds and the opposite for broadleaf forage crops.
Objective 3: Determine how an increase in weed seed predators and selective suppression of functional groups ultimately influences the number and composition of weeds in forage crop mixtures. I aim to quantify interactions of the first two objectives to determine the ultimate result of weed community suppression and composition. The dominant functional group of the forage mixture, regardless of the number of species, is likely to shift the weed composition. However, increased number of forage species is expected to increase the rate of consumption by weed-seed predators and therefore suppress overall weed abundance. By evaluating these interactions, I will identify which pressure, the functional group or the number of crop species, drives the weed community.
Objective 4: Quantify productivity of forage mixtures and tradeoffs among input costs, yield and quality. I will quantify forage yields to compare biomass, quality and determine gross profit. Input costs, including herbicides, will be used to calculate net return, quantify economic value of weed control and compare input and net return for each forage mixture.
This is important to understand how species diversity in forage systems can help sustain beneficial arthropods in forage systems. This may have great potential in managing weeds, attracting weed seed predators and influencing weed composition. At the end of this research we hope to better understand the ecology of how weeds are suppressed by both species diversity in the cropping system as well as by preference of weed seed predators (arthropods). We also aim to predict potential needs for weed suppression and document economic value in reduced chemical controls of weeds in forage systems.
We have ordered seed, greenhouse supplies and reserved a field for next year. We have yet to begin the research.
Not yet applicable.
Education & Outreach Activities and Participation Summary
Currently, we have not started the field study. We expect to have much more outreach and field days to show the research next summer (2019) when the field study is planted.
Currently, we have not measured impact but expect data from the first field season in 2019.
So far, we have developed the planning for this project – ordered seed, greenhouse supplies and reserved a field for next summer to conduct the research. The research has not been conducted yet, but greenhouse experiments are expected to start early next spring.
One challenge we have identified is plant-plant spacing in greenhouse experiments. We have decided to have representative spacing of field rows (15 inch rows) rather than closer spacing for conserving greenhouse space.