Rehabilitation of Sodic Waste Land through Agro-Forestry System

Abstract

Sodic soils are widely distributed in arid and semi arid regions of the world and suffer from high values of pH, exchangeable sodium percentage (ESP), sodium absorption ratio (SAR) and low fertility. In north India, Uttar Pradesh, which is a major contributor to the national food grain stock, due to its large arable land, is occupying about 1.6 Mha of this type of sodic waste land. To alleviate the pressure of fulfilling the demand of wood, timber, fodder and food for the enormous population of human and cattle, the vast sodic soil area has to be rehabilitated by planting trees or adopting agro-forestry system. In this context, an attempt has been made to rehabilitate sodic waste land through the establishment of green cover, with diverse plant communities at Distant Research Centre of CSIR-National Botanical Research Institute, Lucknow during last few decades. A rehabilitated forest ecosystem was developed consisting of a number of herbs, shrubs and trees. Derris indica, Dalbergia sisso, Azadirachta indica, Cassia siamea, Terminalia arjuna, Syzigium cumini were the dominant species in this rehabilitated forest, resulting in significant amelioration process, influenced greatly by diversity of species and their productivity. A combined effect of both biomass productivity and species diversity contributed about 92% towards amelioration. There was reduction in soil pH and ESP and an increase in organic C and N contents showing that sodicity has receded in the forest soil. To meet the increasing demand of medicinal, aromatic, dye, gum, fibre, fodder yielding plants in the present scenario, the shade loving plants of these categories can be grown successfully in between the rows of economic trees like teak, poplar, Eucalyptus etc. Such agro-forestry models have been tried with various inter-crops like Curcuma longa, Rauvolfia serpentina, Zingiber officinale, Desmodium gangeticum and Asparagus racemosus etc. The findings of such studies are very useful for fulfilling the demand of economic plants by utilizing the waste land and free spaces of trees cultivated in such lands.