An evaluation of agriculture, forestry and agroforestry practices in a moderately alkali soil in northwestern India

Productivity, sustainability and economics of agriculture, forestry and agroforestry land use practices were compared over a six year period in a split plot experiment on a moderately alkali soil of the Central Soil Salinity Research Institute, Karnal, India. Three commercial trees of the area formed the main plot treatments and four crop sequences were the sub-plots. The trees were: poplar (Populus deltoides), Acacia (Acacia nilotica) and Eucalyptus (Eucalyptus tereticornis), and the crop sequences were (1) rice (Oryza sativa)-wheat (Triticum aestivum) for four years followed by guinea grass (Panicum maximum)-oats (Avena saliva) for two years; (2) rice-Berseem (Trifolium alexandrium) for four years followed by cowpea (Vigna unquiculata)-Berseem for two years; (3) pigeonpea (Cajanus cajan)/sorghum (Sorghum bicolor)mustard (Brassica juncea) for three years followed by turmeric (Curcuma longa) for three years and (4) no intercrops (only trees). Eucalyptus and poplar gained maximum height, girth and woody biomass in six years when they were intercropped with rice crops in sequences 1 and 2. Acacia attained maximum growth in the absence of intercrops. Protein content in guinea grass was more under tree canopies than in the open. Soil amelioration during five years followed the order: Acacia based system > poplar > Eucalyptus > sole crops. The benefit-cost ratio was highest (2.88) in poplar based system and minimum (1.86) in Acacia based system. The study indicated that growing trees and agricultural crops together is a better land use option in terms of productivity, maintenance of soil conditions and economics.