Nutrient dynamics in Leucaena, Acacia and Eucalyptus, short rotation, high density (‘energy’) plantations in arid India

The nutrient budget in soil and vegetation, and the rates of nutrient recycling in high density (‘energy’) plantations in arid climate of north-western India (29°10′N latitude, 75°46′E longitude, 215 m.a.s.l.) were estimated. The amounts of nutrients were highest in the vegetation of 4-year-old stand of Leucaena leucocephala: N, 1159; P, 62; K, 563; Ca, 478 and Mg, 134 kg ha−1; the values were two-fold greater than the stand of Acacia nilotica and three-fold higher than that of Eucalyptus tereticornis. Leaves had the highest concentrations of nutrients followed by fruit and bark. Maximum amounts of nutrients were stored in the branches of A. nilotica and L. leucocephala, and in boles of E. tereticornis. The transfer of nutrients through litterfall in the stand of L. leucocephala was significantly (p<0.05) higher than in the remaining two species. In 8-year-old stands, nutrient contents in vegetation and their recycling rates through litterfall increased markedly, while rates of nutrients accumulated as the vegetation decreased. The enrichment quotients of vegetation were maximum for N, P and Mg in L. leucocephala and for K and Ca in E. tereticornis. Greater quantities of nutrients in the stands were in the soil compartment except phosphorus. Soil phosphorus may become a limiting factor in maintaining high productivity in subsequent rotations because boles and branches are completely removed from the ecosystem. The results are important in soil fertility in short-rotation energy plantations in arid climates