Changes in soil organic matter forms after the conversion of a meadow into a rainfed forage maize-ley grassland rotation cropland

Agricultural management deeply affects soil properties, with soil organic matter (SOM) being among those most impacted. Nowadays, the importance of adopting agricultural management systems and practices that enhance the storage and stabilization of organic matter in the soil is widely accepted. In this context, the analysis of different SOM fractions is essential for evaluating its stability and obtaining valuable information about its potential long-term persistence. In the present study 0-10 cm and 10-20 cm soil samples were collected 2 months and 2 years after the conversion of an old meadow into a rainfed forage maize-ley grassland rotation system. Similar reference soil samples were taken from an undisturbed area of the meadow. The SOM in samples collected was analysed using different chemical extractants and particulate organic matter (POM) and mineral associated organic matter (MAOM) were studied using a physical fractionation method (Lopez-Sangil and Rovira, 2013 with unpublished modifications suggested by P. Rovira). The conversion of the meadow into the rotation cropland induced a reduction of soil organic C content and modifications of SOM fractions. Generally, the changes were detected in the first sampling and persisted two years after the implementation of the rotation system. The modification induced by the agricultural management were more pronounced in the 0-10 cm layer than in the 10-20 cm layer. Lopez-Sangil L., Rovira P. 2013. Soil Biol. Biochem. 62, 57–67