 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.plant-soil.com J. Plant Nutr. Soil Sci. 2011, 174, 93–102 DOI: 10.1002/jpln.200900249 93 Long-term changes in the floristic composition and soil characteristics of reclaimed sodic land during eco-restoration Pankaj Kumar Srivastava 1 *, Baleshwar 1 , Soumit Kumar Behera 1 , Nandita Singh 1 , and Radhey Shyam Tripathi 1 1 National Botanical Research Institute, Rana Pratap Marg, Lucknow–226001, India Abstract The study was conducted under the “Uttar Pradesh Sodic Lands Reclamation Project” to exam- ine changes that occurred in the reclaimed sodic land in two districts of Uttar Pradesh, India. The study focuses on long-term seasonal changes in the floral diversity and soil characteristics of the reclaimed sodic land over a period of 10 y. The changes in the floristic composition, plant density, and soil characteristics (microbial biomass carbon [MBC], pH, exchangeable-sodium percentage (ESP), and electrical conductivity) were compared among the different study plots after different years of sodic-land reclamation. The study plots comprised reclaimed land with rice–wheat cultivation; semireclaimed land under rice cultivation only and nonreclaimed barren sodic land. There was a significant variation in the floristic composition of the three study plots. Dominance in the floristic composition was shifted from monocotyledonous weeds in the nonre- claimed sodic land to dicotyledonous weeds in the reclaimed land after 10 y of reclamation. Among the soil characteristics, the most remarkable changes were observed in soil MBC and ESP during the course of sodic-land reclamation. Soil MBC increased up to 480% and ESP val- ues decreased up to 79% in the reclaimed plots with reference to the nonreclaimed plots. The soil amelioration was more pronounced in the upper layer (0–30 cm) as compared to the lower layer (below 30 cm depth). A positive significant correlation was revealed between soil MBC and floristic composition of the reclaimed plots. These changes in floristic composition and soil char- acteristics could be used as good indicators of the eco-restoration of the sodic lands. The pre- sent study provides useful insights in understanding the temporal progress of eco-restoration in the reclaimed sodic lands. Key words: sodic-land reclamation; restoration / floristic composition / soil microbial biomass carbon / agro-ecosystem Accepted January 4, 2010 1 Introduction Sodic soils are widespread in arid and semiarid regions of the world covering 30% of the total land area (Rengasamy, 2006). Out of 329 million ha geographical area of India, 6.9 million ha is sodic, and 1.3 million ha of sodic land occur in the state of Uttar Pradesh alone. These sodic lands are unfit for agriculture because of high concentration of exchange- able Na + . However, such soils can be used for crop produc- tion after their reclamation. Transformation of sodic lands into agricultural landscapes is a challenge, and it has been accorded high priority in many regions of the world (Abens- perg-Traun et al., 2004). Sodic soils must be improved through reclamation to support productive land-use systems in order to meet the challenges of global food security (Qadir et al., 2007). The amelioration of these soils has been achieved through the application of gypsum in top 20 cm soil. The cultivation of salt-tolerant agricultural crops on such soils has been found effective in bringing about sustainable recla- mation of sodic soils after gypsum treatment (Qadir and Oster, 2004). Role of organic amendments has also been emphasized in the reclamation of sodic soils (Clark et al., 2007). The success of reclamation of sodic soils requires a greater understanding of the processes promoting agro-ecosystem restoration, changes in soil-sodicity levels, and the dynamics of floral diversity. The relationships between species diversity and ecosystem functioning have substantial implications for economically and ecologically sustainable cropping systems in reclaimed soils (Liebman and Davis, 2000). Plant-species diversity may play a significant role in agro-ecosystem func- tioning and restoration (Trenbath, 1999; Hooper et al., 2005). Similarly, farming practices also influence species richness and abundance of taxa (Petit et al., 2001; Firbank et al., 2003). Rather, most biodiversity changes are responses to agricultural changes and further agricultural intensification (Matson et al., 1997; Dauber et al., 2003). It influences the composition and abundance of the associated biota. The reduction in plant-species richness that accompanies agricul- tural intensification leads to changes in the community com- position of the weed–crop complex (Klimek et al., 2007). Activities of soil microorganisms tend to increase as the soil changes from sodic to normal agricultural soil. Organic-mat- * Correspondence: Dr. P. K. Srivastava; e-mail: drpankajk@gmail.com