High School Student Discovers the Benefits of Intercropping

Alana Kornelsen, Alison Nelson and Dean Spaner

At the University of Alberta, high school students are being given a chance to experience University level research. Alana Kornelsen, a grade 12 student at Scona High School in Edmonton, worked with Alison Nelson, a graduate student in the Department of Agricultural, Food and Nutritional Science to investigate ways to suppress weeds without chemicals. This project was part of the Women in Scholarship, Engineering, Science and Technology (WISEST) summer research program.

WISEST is an organization that seeks to increase gender diversity by encouraging women to choose careers in science, engineering, scholarship and technology and men to consider areas of science that are less traditionally male. The Summer Research Program partners young women with researchers (preferably female) in science and engineering. Young men are partnered with researchers in nursing, human ecology and nutrition. This program pairs young women and men in high school with researchers for six weeks. It is designed to show young women and men about science and engineering disciplines that are non-traditional for their gender.

As part of a summer 2006 work experience with the wheat breeding and agronomy program at the University of Alberta, Alana worked alongside Alison to compare monocrops and intercrops for yield and weed biomass in both organic and conventional cropping systems.

The main purpose of the study is to compare soil biological communities of annual intercrops in organic and conventional systems in Alberta. We are interested in comparing soil microbiological diversity under cropping regimes of differing diversity levels. We believe that with greater crop diversity there will be greater soil biological diversity. Soil microbes carry out a number of beneficial functions in cropping systems, including nutrient cycling. Ensuring a diversity of soil microorganisms will help maintain the soil's ability to supply nutrients to
crops.

Studying soil microorganisms requires specialized skills and a great investment of time. However, the same intercrops in which we are measuring microbial activity also have weed suppression benefits. Alana’s project measured these benefits during the field season.

Organic farmers differ from conventional farmers in that they do not use herbicides to control weeds. Therefore, an alternative method of weed control is necessary, as competition from weeds pose a significant problem to organic farmers. Even farmers that rely on chemicals for weed control can take advantage of alternative methods. Intercropping is one such method which could be used. Thus, wheat, barley, canola, and peas were planted as monocrops, and in all combinations that included wheat. Because planting several crops together combines their respective competitive traits, such as leaf cover and height, we anticipated lower weed biomass in the intercropped systems. The obvious weed suppression benefits we observed when barley was combined with other crop species in both the organic and conventional systems prompted us to quantify those benefits.

We found that all combinations that included barley had much lower percent weed biomass than the other intercrops tested. In the conventional system, weeds represented 1% of the total biomass in barley plots, while weeds comprised 5 to 22% of the biomass of the other monocrops and the intercrops without barley. In the organic system, the influence of barley was even greater. The barley monocrop and barley-containing intercrops had up to 23% of the total biomass as weeds. This compared to 42-85% of the total biomass as weeds for all the non-barley monocrops and intercrops. Peas did not improve the weed suppression of any combination, but this may be due to low (30 %) emergence in both systems

There are obvious harvest problems still to be worked out with annual intercrops, However, intercropping with wheat, especially when the intercrops include barley, can effectively reduce weed biomass. Organic and conventional farmers may use this technique to effectively manage weeds. The same study will be repeated next summer to facilitate more precise and repeatable results.


This article was guest authored by Alana Kornelsen, Alison Nelson and Dean Spaner. Alana is a grade 12 student at Scona High School in Edmonton, Alison and Dean are from the Department of Agricultural, Food and Nutritional Science at the University of Alberta.


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Posted March 2007