Water resilience and soil health: Undergrad research at UofM

Summer 2023 Research Experience by Grace Thomson, University of Manitoba (supervised by Dr. Martin Entz)

This summer I had the opportunity to work in Dr. Entz’s Natural Systems Agriculture lab at the University of Manitoba. My project focused on assessing the role that soil health plays in water resilience within a perennial cropping system. In this case, when we say a perennial cropping system, we mean a crop rotation that has two years of alfalfa, followed by one year of wheat and then one year of flax.

Understanding the water resilience that different systems offer helps us to know which systems may be able to withstand longer periods of drought. Soil that is healthier tends to have the ability to hold onto more water.

My experiment was conducted in Glenlea, MB, at the long-term trial that is run by Dr. Entz. I examined spring wheat under three different management systems that have various levels of soil health: a conventional system, where nutrients are added using synthetic fertilizers; an organic with composted manure, where manure is added every four years; and finally, the organic without composted manure system, which has had no supplemental nutrients added to it for over 32 years. Therefore, there were three different treatments within this trial, and each treatment had three repetitions. Each plot was 2m x 1m. I also had an irrigated plot and a non-irrigated plot for each repetition of this trial.

Every week, each irrigated experimental plot received roughly 2cm (40L) of supplemental water. The first day I watered the plots was on May 29, and the last day I watered the plots was on July 7. In that time, I watered each irrigated experimental plot with over 14cm of water. In total, I put more than 270L of water on each of the irrigated plots, for a grand total of 2,430L of water on all plots! I used a watering can with marks indicating water amounts, and would do each half of the plot one at a time. I determined exactly half of each plot by using a meter stick (since my total plot length was 2m). Each half of the plot received half of the pre-determined amount of water.

At the beginning of July, I collected 1.5m of biomass from all of my plots. Biomass from the conventional plots was taken on July 6, and the organic plots on July 10. Biomass was collected when the plants were at flowering. I collected final biomass on Aug. 16, taking 2 rows of 2m, for a total of 4m from each plot. This biomass will be threshed and weighed in the fall, and then used to determine final yield.

Following is an infographic that describes the procedure for irrigated vs. non-irrigated wheat trials that I followed for this experiment:

Pictured above: A watered organic plot on May 31 (left) and a meter stick being used to measure half a plot on May 29 (right).

Pictured above: A watered conventional plot on July 5 (left) and a watered conventional plot on August 9 (right).

I collected data on Normalized Difference Vegeta4on Index (NDVI) using a greenseeker, which is a handheld sensor that measures the density of greenness in a certain area. Healthier plants may appear greener than unhealthy plants, and healthier plants are more likely to be better yielding. I also measured plant height, and took biomass during the growing season and again during the end of the season. This data will be used to determine final yields.