Spent Mushroom Substrates Influence Soil Quality and Nitrogen Availability in a Semiarid Vineyard Soil

Resumen

Two spent mushroom substrates (fresh, F-SMS, and composted in aerobic conditions, C-SMS) were annually applied for 4 yr at two different rates (8 and 25 Mg ha(-1) as dry matter) to a vineyard soil (Typic Haploxerept) located near Logrono (Ebro Valley, La Rioja, Spain). Soil samples were collected at three depths (0-5, 5-15 and 15-25 cm), and analyzed for soil organic carbon (SOC), water-soluble carbon (WSC), potentially mineralizable nitrogen (PMN), N-NO3- and exchangeable N-NH4+, microbial biomass carbon (MBC), soil CO2 evolution (SR), beta-glucosidase activity (GLU) and soil mean weight diameter (MWD) of aggregates and water-stable aggregates (WSA). The highest rate of F-SMS and C-SMS (25 Mg ha(-1)) increased SOC, total nitrogen (Total N), and labile organic forms (WSC and PMN) at 0- to 5- and 5- to 15-cm soil depth and microbiological activity (MBC and GLU) at 5- to 15-cm soil depth. There were no differences in soil CO2 emissions between F-SMS and C-SMS amendments. Applications of SMS did not increase the soil aggregation but increased the content of inorganic N in the soil surface (0- to 5-cm depth) layer. Factor analysis showed the positive relationship between labile organic matter fractions and N availability. Finally, application of SMS to semiarid vineyard soils facilities SMS recycling with simultaneous improvement in soil quality indicators related to labile organic matter and microbiologic activity. However, increased PMN and soil N-NO3- indicate a potential risks for N leaching from SMS amendments that should be further evaluated.