| Abstract: | Prolonged occupation of sodic soils by trees results in the latters' amelioration in terms of decreased pH and electrical conductivity and improved organic matter and fertility status. To assess whether sodic soils reclaimed by tree plantations can be used for growing agricultural crops, a greenhouse pot trial was conducted during winter of 1994–95 (November–April) at the Central Soil Salinity Research Institute, Karnal, India. Wheat (Triticum aestivum, L; cultivar HD 2329) and oat (Avena sativa, L. cultivar local) plants were grown in topsoils (30 cm) collected from 24-year-old plantations of Prosopis juliflora, Acacia nilotica, Eucalpytus tereticornis, Terminalia arjuna and Albizia lebbek that had been established in 1970 on a highly sodic soil (pH2 10·2–10·5), and a reclaimed sodic soil from a farm field adjacent to the plantations. The organic carbon content and nutrient status of the soil under the 24-year-old plantations was much higher than that of a reference farm soil reclaimed through gypsum in 1974. Soil amelioration was highest under Prosopis canopies (pH 7·4 and organic carbon 0·89 per cent) in topsoil and minimum in Eucalpytus canopies (pH 8·6 and organic carbon 0·56 per cent). Reduced sodicity and improved fertility resulted in much better growth reference and productivity of the wheat and oat test crops grown on the five plantation soils, than in the reference farm soil. Grain and straw yields of wheat and oats were maximum in Prosopis soil (wheat 61·7 g grains and 87·5 g straw and oats 87·9 g grains and 111·1 g straw per pot) and minimum in Eucalpytus soil (32·3 and 25·3 g, and 42·7 and 58·5 g per pot). Grain yields of both wheat and oats obtained in the Prosopis soil were 4·5 and 3·5 times more, respectively, than obtained in the reference farm soil. The phosphorus concentration in whole plant tissues of wheat and oats was highest in Prosopis soils reflecting the prevailing phosphorus status and better restoration processes of the soils. Potassium concentration was little affected due to different soil treatments. The study clearly indicated that prolonged afforestation of sodic soils by tree plantations, particularly by Prosopis and Acacia trees, may restore the productivity of abandoned soils to much above the present agricultural production levels. The results further suggest that 24 years' occupation of sodic soils by trees, such as Prosopis, Acacia, Eucalyptus, Terminalia and Albizia, did not result in a build-up or accumulation of toxic allelochemicals which could be injurious to wheat and oats cultivation on such soils. © 1998 John Wiley & Sons, Ltd. |
