Effect of long term application of fertilizer and manure on passive pool of organic carbon under maize-wheat sequence in Heplustepts

Abstract

A field study entitled “Effect of long term application of fertilizer and manure on passive pool of organic carbon under maize-wheat sequence in Heplustepts” was conducted during Kharif 2013-14 and 2014-15 in the Long Term Fertilizer Experiments initiated in Kharif, 1997 at the Instructional Farm of the Rajasthan College of Agriculture, Udaipur. The soil of the experimental site was sandy clay loam in texture, slightly alkaline in reaction, medium in available nitrogen and phosphorus, while high in potassium and zinc. The objective of study was to assess the effect of continuous application of plant nutrients through organic and inorganic sources and its combination on passive fractions of soil organic carbon. Twelve treatments i.e. control, 100 % N, 100 % NP, 100 % NPK, 100 % NPK + Zn, 100 % NPK + S, 100 % NPK + Zn + S, 100 % NPK + Azotobacter, 100 % NPK + FYM 10 t ha-1, FYM 10 t ha-1 + 100 % NPK (-NPK of FYM), 150 % NPK and FYM 20 t ha-1 were evaluated under randomized block design (RBD) with four replications. The results of the present investigation revealed that the highest Humin, Humic and Fulvic acid were obtained under the application of FYM 20 t ha-1.