Abstract

In North-Eastern region of India, soilposes a great problem for crop production, particularly in Manipur state whereabout 90 % of soils are acidic. The present research entitled “Characterizationof Soil Acidity in Soils of Manipur” was undertaken with the followingobjectives viz. i) To characterize the nature of acidity in soils ii) To studythe relationship between the different forms of acidity and the soil propertiesiii) To study the lime requirement assessments. Depth wise 0-15 cm and 15-30 cm(surface and sub-surface) soil samples were collected from Thoubal districtcovering all blocks i.e. 1. Thoubal 2.Lilong and 3. Kakching,from each block 10 villages and 3 respondent farmers per village was selectedwith the help of stratified random sampling (proportional allocation). Thetotal numbers of soil samples collected from Thoubal district are 180. Processed soil samples were used foranalysis. The soils were found tobe of heavy in texture and ranged from clay loam to clay while the pH rangedbetween 4.86 to 6.19 which wereconsidered as strongly acidic to slightly acidic. The cation exchange capacityof the studied samples varied from 7.61 to 20.61 cmol (p+) kg^-1soil and organic carbon contents werehigh and ranged between 3.40 to 20.30 g kg^-1. Extractable Al and Exchangeable Al ranged from 0.60 to 3.30 Cmol (p+) kg^-1 and 0.10 to 2.16 Cmol (p+) kg^-1, respectively. Total Potential Acidity rangedfrom 4.11-12.00 Cmol (p+) kg^-1,Exchangeable Acidity from 0.24-2.97Cmol (p+) kg^-1 and pHDependent Acidity from 2.81 to 9.23 Cmol (p+) kg-1. Lime requirement (LR) was estimated by threemethods i.e. BaCl₂ –TEA method (7.00 to 18.70 t/ha), DunnEquilibrium method (1.40 to 5.28 t/ha) and 1N KCl method (0.17 to 3.50 t/ha).Among the methods, highest quantity of LR was recorded by BaCl₂ –TEAmethod and lowest by 1N KCl method. Further, it is observed that the majorcontributing factors for producing exchange acidity are pH, exchangeable Al,extractable Al & clay whereas soil properties responsible for pH- dependentacidity are organic matter, extractable Al & clay. Therefore, it isadvisable to supply the required doses of lime requirement to the soil tosustain its fertility as well as productivity. Also suitable remedial countermeasures other than liming may be adopted to enhance crop production.

Keywords: TotalPotential acidity, Exchangeable acidity, pH dependent acidity and LR.