The effects of companion cropping on potato production and soil

Potato cropping is reliant on large quantities of inputs (water, fertilizer, pesticides) and has adverse effects on soil structure and composition due to its sowing and harvest methods. This can increase the risk of soil and nutrient erosion and make the effect of droughts consequential. Companion cropping may be a way of helping to address these issues by increasing canopy cover and root density, while providing other benefits like enhanced biodiversity and pest and virus suppression.

A two-year field study at the Centre for Sustainable Cropping was conducted to evaluate the effects of companion cropping in potatoes. Potatoes were grown with and without a companion crop mixture of buckwheat, vetch, and peas, where various measurements were taken to assess soil fertility and water availability. Plant root simulator (PRS) probes were buried in the soil (ridges and furrows) to measure nutrient availability. Soil moisture, SPAD measurements, and yield were also taken.

Results over the two years show that nutrient availability is overall higher in the companion cropped potatoes. In 2025, nutrient availability was assessed in both the ridge and furrows, where differences appeared. Nutrient availability on the ridges did not follow the overarching pattern of greater nutrient availably where companion crops are present. This may be due to lower moisture levels in the ridges. The companion crop had little to no effect on soil moisture or yields in 2024. This may be explained by the poor establishment of the mixture. In 2025, companion crops resulted in a slight increase in yield but had lower soil moisture levels and SPAD results.

Companion cropping may be a viable method for reducing inputs and stabilising soil while providing other benefits; however, a third year of data is needed to explain variations between year 1 and year 2.