| ||Field experiments should be monitored regularly. The frequency of monitoring will depend on the observations required to meet the project's objectives. Different types of experiments require different types of measurements. For example, in field crop studies, crop yields would be appropriate measurements. For weed control experiments, measurements could be made of weed populations before and after the experimental treatments. In livestock projects, measurements could be live weights of the individual animals at pre-determined times.
Crop yields can be measured using a weigh wagon (harvesting the plot strips with a combine) or from square metre samples. Harvesting strip plots with combines and weigh wagons is a quick and easy way to measure crop yields. Several points should be kept in mind to ensure reliable and consistent results with this method:
Crop residue levels may be measured using the knotted rope method or square metre weights (for heavy residue). Soil moisture measurements may be carried out in the fall or before planting or both. Gravimetric soil moisture sampling needs a core sampler, weigh scale, containers and oven. Decide on depth increments. For example, use increments of 0-15, 15-30, 30-45, 45-60, 60-90 and 90-120 cm for measuring moisture within the typical rooting zone (1.2 m).
- keep in touch with the cooperators as harvest approaches so you can help them swath the plots correctly and be there when they do the threshing.
- explain to the cooperators about the need to take a full width swath out of the centre of each treatment plot.
- take samples at least one metre from the end of the plot to avoid edge effects that could confound results.
- install marker flags to guide the operator down each strip.
Weather information, especially temperature and rainfall, should be recorded during the growing season. Rainfall should be measured at the site. Temperatures measured at a nearby weather station may be adequate if the station is located near the experiment. Wind speed and direction should be recorded on days when chemicals are applied.
Photographs taken during the course of the growing season provide excellent records of visual responses. They are also very useful if you are asked to give a presentation about the project at an extension meeting or to prepare an article for a local newspaper or bulletin.
Contact:Tom Goddard, Alberta Agriculture and Food.