Design of riparian buffer strips affects soil quality parameters

Vegetated buffer strips alongside watercourses are commonly used to counteract diffuse pollution from agricultural activities. If properly designed, they can provide multiple environmental benefits by increasing wildlife habitats and biodiversity. Little attention has been paid to the effects of buffer strips on soil quality. This study was conducted to determine the impact of different buffer designs on soil biochemical parameters and to define relevant quality parameters for soil monitoring. We compared four buffer arrangements: 3 m wide grass buffer; 3 m grass with one tree row; 6 m grass with one tree row; 6 m grass with two tree rows; plus two controls: an adjacent maize crop field and a plot without buffer. Buffers were established 13 years ago at the Padua University Experimental Farm in the Po Valley, north-east Italy. Studied parameters included soil organic matter composition and soil microbial and enzymatic assays. As expected, control plots showed the lowest values for all the studied parameters. Among buffer designs, 3 m grass and 3 m grass with 1 tree row buffers gave the highest values. Multivariate analysis demonstrated that the increase of soil organic carbon content distinguished buffers from controls, whereas soil humic carbon quality parameters such as humic compounds apparent molecular weight, together with acetyl esterase (fluorescein test) enzyme activity, were discriminatory in separating buffer designs. These results are an important contribution to the knowledge base and can help to improve the management of these systems.