Intercropping kura clover with prairie cordgrass grown on a marginal land enhanced soil carbon and nitrogen fractions

Prairie cordgrass (PCG) ( Spartina pectinata Link) has been the focus of much scientific attention recently for use in biofuel applications, as it grows well on marginal lands that are unsuitable for row crops. This study investigated how the intercropping of kura clover (KC) ( Trifolium ambiguum M. Bieb) with PCG for 8 yr affects soil carbon (C) and nitrogen (N) fractions compared with N fertilization on marginally yielding croplands in South Dakota. This study was initiated in 2011 with five treatments: intercropping PCG with KC (PCG‐KC), and PCG with N fertilizer at four levels: 0 kg N ha –1 (PCG‐0N), 75 kg N ha –1 (PCG‐75N), 150 kg N ha –1 (PCG‐150N), and 225 kg N ha –1 (PCG‐225N). Soil samples were collected in 2018 and analyzed for permanganate oxidizable C and N, stable C and N, mineralized C and N, dissolved organic C and N, and particulate organic C and N. Further, C and N management indices were calculated from these data. Results showed that permanganate oxidizable C and N and particulate organic C and N were generally higher under PCG‐KC than under PCG‐0N and PCG‐75N but similar to PCG‐150N and PCG‐225N. Dissolved organic C and N and C mineralization were higher under PCG‐KC compared with fertilized and unfertilized PCG. Prairie cordgrass–kura clover (190.10) recorded a 91% higher N management index than PCG‐75N (99.66) but was similar to PCG‐150N (165.70) and PCG‐225N (163.10). This study concludes that growing KC–PCG mixture rather than using N fertilizers would have an overall positive effect on marginally yielding cropland soils.