Submitted to: North American Agroforestry Conference
Publication Type: Proceedings
Publication Acceptance Date: 8/22/2003
Publication Date: 3/10/2004
Citation: Mungai, N.W., Motavalli, P.P., Kremer, R.J. 2004. Soil organic C and N fraction in long-term temperate alley cropping practices. In: Sparrow, S.H., edior. Proceedngs of the 8th North American Agroforestry Conference, August 17-19, 2003, Oregon State University, Corvallis, Oregon. p. 196-205. CD-ROM.
Technical Abstract: Increasing public concerns over the enviromental effects of global warming have stimulated an interest in land use practices, such as agroforestry, which may promote greater sequestration of soil organic carbon. However, information on soil organic C and N distribution and accumultation in long-term temperate alley cropping practices is limited. The objective of this study was to examine spatial variability of soil organic C and N fractions in relation to tree rows in established alley cropping practices in north central Missouri. Soils were collected to a depth of 30 cm from two sites, a 19-year old pecan (Carya illinoinensis) bluegrass (Poa trivialis) intercrop (Pecan site) and an 11-year old silver maple (Acer saccharimum)/soybean-corn rotation (Maple site). Soil sampling was done at the tree row and at the middle of the alley at each site, and in two seasons, fall 2001 and summer 2002. Total organic C (TOC) was not significantly different at all depths in the tree row compared to the middle of the alley at the Pecan site for both seasons. At Maple site, TOC was significantly higher only at the 30 cm depth at the tree row in 2001; no differences were observed at any depth in 2002. Particulate organic matter C for surface soil comprised 19-42% of TOC and was generally higher at the tree row than at the middle of the alley. Soluble N was significantly higher at the tree row at the Pecan site. No significant differences were observed for microbial biomass C and N at both sites. In general, consistent differences were not observed between the tree row and middle of the alley at either site. The results suggest that trees did not influence soil organic C and N levels that contrasted with alley soils sufficient to be detectable with the methods used in this study.