Young potato shoots are up against many environmental factors, such as drought, wind and water erosion, all of which are mainly due to a large decrease in soil organic matter.
Now, researchers from Agriculture and Agri-Food Canada (AAFC) have found that nurse crops may be able to help potatoes by adding green manure to the soil and by helping to draw water to the root zone, provide shade and shelter, and keep weeds at bay.
Why it matters: Potatoes are challenging from a soil health perspective due to the time the soil is free of growth.
Sheldon Hann, biologist with AAFC at the Fredericton Research and Development Centre, said researchers wanted to see if planting a nurse crop would have a beneficial effect on potato growth and production.
“We know that cover crops are advantageous to intercepting rainfall and minimizing erosion and we wanted to see how companion planting of nurse crops fill these roles throughout the growing season as you have 20 to 30 days with little soil cover from planting to hilling.”
The findings are particularly beneficial to Eastern Canada where many areas are experiencing a decline in soil organic matter.
The study, partnered with fellow AAFC researchers Bernie Zebarth and Josée Owen at the Fredericton centre, Sherry Fillmore at the Kentville Research and Development Centre, and Judith Nyiraneza at the Charlottetown Research and Development Centre, focused on the effects of field pea, winter rye, and spring barley as nurse crops in potatoes.
Hann found that tilling the winter rye and field pea in the soil helped retain soil moisture in the potato hill throughout the growing season, increasing the ability to survive drought.
“Nurse crops can be part of the solution because they keep the ground covered during the critical window when the potato seeds have been planted and haven’t emerged,” Nyieranzea said.
Three trials have been completed with another expected to be completed this year.
“We placed temperature and moisture sensors at two different depths of the hill, 15 and 30 centimetres,” said Hann.
“At 15 cm, there is more moisture retention and it is present for a longer period throughout the growing season. We want to be able to better understand and see what exactly is going on, measure the infiltration, measure the permeability and the runoff with the added infiltration.”
Winter rye, field peas and spring barley were chosen based on their ability to be planted early, germinate quickly and establish good growth in the roots above the soil planted one to two days before the potatoes were planted.
The winter rye provided quick and aggressive top growth making it difficult for weed species to establish.
The field peas, when planted at a high rate performed well. With field peas’ ability to fix nitrogen, further research is going to look into the potential of nutrient stimulation for potatoes.
When compared to the control in the study, the winter rye and spring barley showed a yield increase. Although not a significant increase, the benefit of infiltration, permeability and season-long moisture is not showing a detrimental effect to potato yields.