Quantifying seasonal changes in plant and soil properties associated with diverse grasslands

Different grassland types may interact with the soil depending on the season. The study, therefore, aimed to investigate seasonal changes in plant and soil properties associated with diverse grasslands. A randomised block design with four blocks of six plots containing grass types of ryegrass and clover, herbal ley, wildflower, brassica and native grass species at Hartpury University Farm was sampled in two replicates. A total of 288 individual samples were collected, each for soil and plant. The samples were collected at the same time and location during spring and autumn, from 24 grassland plots over a three-year period from 2022 to 2024. Samples collected were scanned using mobile near-infrared spectroscopy (NIRS) as soon as possible after collection. A linear mixed model was used to assess the effects of season and grass type on soil and plant properties. The study found that season affected more of the plant and soil properties studied compared to the grass type. Autumn conditions led to shorter swards with higher plant herbage mass and density, plant dry matter, neutral detergent fibre (NDF), crude protein contents, soil organic matter, moisture and carbon to nitrogen ratio compared to the spring. Plant properties of sward height, dry density, oil, crude protein contents and soil total nitrogen were different among the grass types studied.