Soil carbon pools, carbon and nitrogen storage pattern in a soybeanwheat cropping system based on 21-year field experiment of Indian mid-Himalayas

Abstract

Long-term organic and mineral fertilization can bring in changes in the different pools of soil carbon (C) and nitrogen (N), and sequestration under irrigated soybean-wheat cropping system (SW). Results showed that long-term mineral and organic fertilization (NPK + FYM) significantly (P < 0.05) increased soil reaction (5.96, 6.41 and 6.56) as compared to unfertilized control (CK), however, it was 0.24, 0.11 and 0.12 units lower than FYM in all three soil depths. NPK + FYM fertilization clearly indicated that ~54, 51 and 52% higher total organic carbon (TOC) and ~46, 56 and 55% higher total nitrogen (TN) as compared to CK in 0–15 cm, 15–30 cm and 30–45 cm soil depths, respectively. Average values for TOC and TN with different treated plots were 9.89, 9.23 and 8.57 g kg-1 and 0.80, 0.74 and 0.68 g kg–1 under all three soil depths. We conclude that, significantly higher C (~22, 20 and 19 Mg C ha–1) and N (1.79, 1.67 and 1.53 Mg N ha–1) storage was recorded with NPK + FYM as compared to CK in 0–15 cm, 15–30 cm and 30–45 cm soil depths, respectively. Nevertheless, higher total C and N sequestration rate in 0-45 cm soil depth was noted under NPK + FYM (~1153 and 91 kg ha–1 year–1) treated plot, followed by N + FYM (~981 and 78 kg ha–1 year-1) and FYM alone (~873 and 63 kg C ha–1 year–1). These results clearly indicated that combined organic and mineral fertilization have its positive effect on soil C and N pools, and sequestration in the long-run, and thus, help in maintaining long-term soil sustainability.