Characterization and Lime Requirement Estimation of Acid Soils of Nagaland

One soil profile belonging to Monguya I series in Zunheboto district and three soil profiles of Mokakchang, Longsamtang and Monguya II series in Mokakchang district of Nagaland, were studied for lime requirement as influenced by the nature of acidity. The electrostatically bonded, EB–H⁺ and EB–Al³⁺ acidities constituted 90.1 and 9.6% of exchangeable acidity while EB–H⁺, EB–Al³⁺, exchangeable and pH-dependent acidities comprised 1.3, 12.5, 13.7 and 85.5% of total potential acidity. Grand mean of lime requirement determined by different methods as expressed in Mg CaCO3 ha^–1 was in the order: SMP 24.5 > New Woodruff 15.5 > Woodruff 11.2. Correlation analysis among different forms of acidity and lime requirement methods with selected soil properties showed that pH in both water and 1M KCl had a significant negative correlation with different forms of acidity and lime requirement methods. Significant positive correlations existed between lime requirements and different forms of acidity of the soils. The nature of soil acidity was mostly pHdependent. Statistically, the Woodruff did slightly better than New Woodruff and SMP methods in estimating lime requirement and hence the Woodruff procedure may be recommended for routine soil testing because of its speed and simplicity.