b'Nurse Crops inPotato ProductionWhat nurse crops assist potato production? An AAFC team investigates nurse crops that boost seedling success and yields.BY: TREENA HEINAS WITH ANY FIELD crop, young potato plants face many threats. Erosion, wind, drought and competition from weeds are a few of the factors that can impede the plants optimal growth.This is why a team at Agriculture and Agri-Food Canada (AAFC) in the Mari-times has been looking into nurse cropswhat they describe as fast-growing companion crops planted during the potato-growing season that help draw water to root systems, provide shade and shelter, and keep weeds at bay.Building on the knowledge that cover crops provide benefits such as reduced soil erosion when planted after harvest, the scientists wanted to investigate how intercropping nurse crops with potatoes might have a beneficial effect on potato plant growth and production during the growing season.Pre-hillingIn North America, intercropping practices are common in grass, legume, andbiomass sampling cereal or forage production, says biologist Sheldon Hann, AAFC Fredericton. Theand aerial image use of nurse crops in potato production has been shown to be promising in high- capture set-up. PHOTO: AAFCly-mechanized large-scale monocropping systems like potatoes, but intercropping is not very common in these crops. It generally requires an increase in time and labour investment.In addition to Hann, the team for the three-year study (which ended in 2017)killing them included Bernie Zebarth and Jose Owen, also at AAFC Fredericton, Sherry Fillmorewere compared. at AAFC Kentville and Judith Nyiraneza at AAFC Charlottetown. Field pea and winterWith field peas, rye were chosen as nurse crops for their ability to be seeded early, germinate quick- mechanical hilling termination ly and become established reliably. In the study, the nurse crops were intercroppedresulted in higher potato yields compared to the method of with potatoes at two seeding rates at a site in New Brunswick. The winter rye washerbicide followed by mechanical hilling. Hann says in this seeded at 150 pounds per acre (high rate) and 100 lb/ac (low rate) while the fieldcase, it seems the action of hilling the nurse crop was adequate pea was seeded at 140 lb/ac (high rate) and 75 lb/ac (low rate). enough to terminate its growth and hilling field peas in their green form (alive) compared to desiccated form (dead) may have provid- Field pea as aSTUDY RESULTS ed a resource for the potato plant. In winter rye, a herbicide wasnurse crop. Hann and his colleagues found potato yields responded better with the high seed- needed to ensure the nurse crop did not compete for resources.PHOTO: AAFCing rate of field pea compared to the low rate, and better with the low rate of winterNyiraneza says the field pea results also might be due to how rye compared with the high.their root architecture and decomposition rate differ from winter rye. In We are currently analyzing the soil and plant data and are optimistic that theaddition, field pea is a legume which fixes nitrogen from the atmosphere and its analysis will provide some insight into why there were different yield responses,nitrogen content may therefore provide benefits to the potato crop.Hann reports. The low seeding rate in winter rye may have provided increasedIn a paired study, Hann and Nyiraneza evaluated spring barley and winter rye soil moisture without having a competitive effect that a high seeding rate mayas nurse crops using a single seeding rate for each crop. We also evaluated the have had on the potato crop. The high seeding rate for field pea may have providedeffect of two herbicide treatments (non-selective and selective) against a control, increased soil moisture and an enrichment of nutrients after termination withoutand yield increased with the non-selective herbicide, Hann explains. The results having the competitive effect expressed in the high rate of winter rye. The resultswere mixed using mechanical control or a selective herbicide.also may be due to the vegetative and root structure of the nurse crops, and furtherHann also measured the total nitrogen and carbon content of the soil as well evaluation of the soil and plant data may provide insights to this. as samples of the nurse crop and potato plants (both in the above-ground vege-In addition, the effectiveness of how the winter rye was terminated may matter.tation and the roots) as plant decomposition (in this case, the nurse plants) can All nurse plants were terminated 20 days after planting and different methods ofaffect these measurements. This data is currently under analysis.12 SPUDSMART.COM WINTER 2020'