Effect of different organic manures on build-up of soil organic carbon and dtpa-extractable micronutrients in soil profile under basmati rice-wheat system

The application of organic materials is one of the most effective ways of increasing soil organic carbon (SOC) levels and availability of micronutrients in soil. In order to assess the build-up of SOC and DTPA extractable micronutrients in soil profile with the application of different manures under basmati rice-wheat system, soil samples were collected depth-wise from ongoing experiment since rabi 2006–07, at Research Farm, Punjab Agricultural University, Ludhiana. The experiment comprised of 10 treatments i.e. T1: Control, T2: Recommended fertilizer, T3: 75%RF+N200 FYM, T4: RF+N200 FYM, T5: N300 FYM, T6: N400 FYM, T7: N300 VC, T8: N400 VC, T9: N300 RSC and T10: N400 RSC. The results indicated that soil pH decreased significantly with the addition of different manures and values of soil pH increased along the profile. The SOC content increased from 2.9–6.3 g kg-1 with the application of different organic manures and declined with increase in depth in profile. The application of different organic manures increased the status of micronutrients cations in soil i.e. DTPA-Zn, DTPA-Fe, DTPA-Mn and DTPA-Cu from 0.48 to 7.55 mg kg-1, 50.8 to 156.7 mg kg-1, 8.5 to 22.6 mg kg-1 and 1.35 and 3.30 mg kg-1, respectively. The status of micronutrient cations decreases with the increase in soil depth. Among different treatments, T6: N400 FYM and T8: N400 VC performed better in SOC build-up as well as on improvement in availability of micronutrients in soil.