LONG-TERM EFFECTS OF AMENDMENTS ON <em>PROSOPIS</em> <em>JULIFLORA</em> AND SOIL PROPERTIES OF A HIGHLY ALKALI SOIL

Abstract

This study was conducted for 8 y at the Gudha experimental farm of the Central Soil Salinity Research Institute, Karnal on a highly alkali soil with an initial pH of 10.3. The effect of four treatments of amendment [no amendments; 3kg gypsum; 3 kg gypsum + rice husk (RH) in 1:2 ratio of rice husk: soil on volume basis; and 3 kg gypsum + 8 kg farm yard manure (FYM) plant ^-1] was evaluated in a field experiment in a randomized block design with four replications. Results indicated that during the initial 4 y, 50% Prosopis died without amendments while only 19% died when 3 kg gypsum plant ^-1 was used. Prosopis survival after 4 y was 100% when RH and FYM were applied with gypsum. Height and girth of Prosopis recorded at 2-y intervals from planting up to 8 y were maximum in plots with gypsum + FYM, followed closely by those receiving gypsum + RH, gypsum and no amendment treatment. Similarly, the biomass accumulated in different parts of Prosopis in a growth period of 6 y was 2.5, 29.6, 42.4 and 44.2 Mg ha^-1 in control, gypsum, gypsum + RH and gypsum + FYM treatments respectively. The mean concentrations of Ca, K and Mg in the leaf, stem and branch of 6-y-old Prosopis were less and that of Na was more when no amendment was used compared to the treatments where amendments were used. Uptake of N, P, K, Ca, Mg, S and Na by Prosopis in 6 y was higher in plots that received gypsum + FYM (1277.2 kg ha^-1) , followed by gypsum + RH (1198.3 kg ha^-1), gypsum (689.4 kg ha^-1) and in the control (58.5 kg ha^-1). Mean litter and pod yields of Prosopis recorded during the study period were markedly higher in amended soil than those without amendments. Total amounts of N, P, K, Ca, Mg, S and Na added to the site through Prosopis litter during the study period were 71.8, 937.9, 1557.6 and 1656.7 kg ha^-1 in no amendment, gypsum, gypsum + RH, and gypsum + FYM treatments respectively. The reduction in pH and EC and improvement in organic carbon and available N status of the soil were maximum in gypsum + FYM (probably due to better tree growth and higher litter fall in this treatment) and least in the no amendment treatment. A rough estimate about the likely effects of amendments on the soil nutrient balance showed again of 13, 40,93, and 121 kg of N, P and K to the site in the control, gypsum, gypsum + RH, and gypsum + FYM treatments respectively.