Can perennial grain crops combine the soil ecosystem services of grassland with starch production on sandy soils?

Perennial crops, like permanent grassland, provide soil ecosystem services such as carbon storage and water regulation. Novel perennial grain crops, like Kernza (Intermediate wheatgrass; Thynopyrum intermedium) combine these services with the production of grain, providing a more sustainable alternative for starch production compared to annual crops such as corn and cereals. A trial was established in 2020–2022 on a sandy soil in The Netherlands. Yields of Kernza were compared to triticale grain and grass-clover. Kernza generally yielded less then triticale grain and grass-clover, and the yields of Kernza decreased over three years. Other studies have shown that Kernza is able to form a deep and extensive root system which is capable of extending the depth of nutrient and water uptake, therefore needing fewer external inputs. However, in the current trial the root zone was only 85 cm deep, and deeper layers consisted of compacted sand that were impenetrable to the roots. We conclude that Kernza did not develop its deeprooting potential on this shallow sandy soil, which likely resulted in lower-than-expected crop yields from Kernza during our trial.