Effect of Vegetation Cover and Height on Soil and Plant Properties Across Managed and Unmanaged Agricultural Land in a Temperate Climate

Frequent monitoring of fresh soil and plant properties in the same location and timepoint is now possible using real-time near infrared spectroscopy (NIRS). The aim of the study was to investigate the effect of vegetation cover and height on soil and plant nutrients across managed and unmanaged agricultural land in a temperate climate. A total of 803 soil and 803 fresh vegetation samples were collected between the years 2023 and 2024 from 125 different land parcels in the southwest of the UK, which were either managed for grazing and/or feed production or not managed for agricultural use. The land had a range of grass, crops, legume, herb and flower species, across temporary grass, arable and permanent grass areas. A linear mixed model was used to assess the effect of vegetation height (in cm) and cover (tonnes dry matter per hectare) on soil and plant nutrients. The results showed that the ratio of soil to plant organic matter (OM) reduced with increased vegetation height and cover. Plant dry matter (DM) digestibility, acid detergent fibre (ADF), water soluble carbohydrate and oil contents increased with vegetation height, and DM and neutral detergent fibre (NDF) decreased with vegetation height. Ratio of soil to plant OM reduced and ADF increased with increasing vegetation cover. Interactions between vegetation height and cover (i.e. density) were found for ratio of soil to plant OM, ADF, NDF, DM, DM digestibility, oil, and crude protein nutrients. The real-time measurement of soil and plant nutrients with NIRS allowed changes in vegetation cover across the agricultural landscape to be investigated.