Insights into Beneficial Effects of an Agroforestry System on Soil Properties and Crop Yields: A Case Study from the Experimental Farm at University of Copenhagen, Denmark

Agroforestry systems are sustainable farming practices with multiple benefits like enhanced biodiversity, soil nutrient cycling, soil physical properties, and carbon sequestration. Investigating these multiple beneficial effects of agroforestry systems compared to monoculture cropping systems under diverse pedo-climatic zones and crop-tree combinations is required to gather robust field evidence for agroforestry performance. Hence, the objective was to investigate the beneficial effects of agroforestry systems on soil properties and crop yields in a combined food and energy production (CFE) agroforestry system compared to the conventional winter wheat (CWW) production system in Denmark. The field methods consisted of soil and crop cut sampling, soil moisture measurement, earthworm abundance count in CFE compared to the CWW fields, and climate data for 2023. The study demonstrated that an agroforestry system viz CFEmean and natural forest (NF) had a lower bulk density viz. 1.48 and 1.01 g cm−3, respectively compared to CWW (1.74 g cm−3) with intensive use of fertilizers and chemicals. CFEmean and NF had higher soil organic matter, total nitrogen %, available potassium (K), potentially mineralizable nitrogen, soil moisture retention, and earthworm count under drought conditions compared to CWW. The study demonstrated that alley cropped winter wheat (CFE WW) recorded similar grain yields and significantly higher straw and aboveground biomass accumulation compared to CWW with intensive use of chemical and fertilizer inputs. The biomass belt (BB) effects on alley crop yield varied with the distance with negative effects on grain, straw, and aboveground biomass yields in CFE WW at the nearest points from the BB, and yields increased gradually in the alley fields further away from the BB with maximum grain yields at 62.83 m away from the BB. The study provided a robust field evidence on the beneficial effects of agroforestry on soil properties and crop and biomass yields compared to CWW for informed decision-making by land managers for the adoption of agroforestry practice.