Soil carbon and nitrogen pools under long-term productivity of rhizoma peanut and perennial weeds management systems

Abstract

The effects of a 10-year-old rhizoma peanut (RP) (Arachis glabrata Benth.), a perennial legume forage, and perennial weeds (PW) management systems on soil organic C (SOC), total N (STN), NH4-N, NO3-N, potential C and N mineralization (PCM and PNM), microbial biomass C and N (MBC and MBN), and particulate organic C and N (POC and PON) were evaluated in a Norfolk loamy fine sand (fine-loamy, siliceous, thermic Typic Kandiudult) in 2000 and 2001 in Georgia, USA. Aboveground biomass yield and N accumulation increased from June to October in 2000 and 2001, were greater in RP than in PW from July to October, and were greater in 2000 than in 2001 in RP. Root length density increased from June to September, and was greater in RP than in PW in September. The SOC, STN, POC, PON, MBC, MBN, PCM, and PNM varied seasonally but in different trends than those of biomass yield and root length density. In contrast, soil NH4-N in 2001 and NO3-N contents in 2000 and 2001 increased from June to September similar to those of biomass yield and N accumulation. Averaged across sampling dates, SOC, STN, POC, PON, MBC, MBN, PCM, PNM, and NO3-N were greater in RP than in PW and greater in 2000 than in 2001. Short-term productivity of RP may enrich soil mineral N by supplying N from above- and belowground residues and long-term productivity may improve soil quality and productivity by increasing microbial activities, N mineralization, and C and N sequestrations compared with PW.