Long-term Effect of Different Cropping Systems on Carbon Sequestration in a Sandy Loam Soil of Telangana

Abstract

Background: Rice, maize and Bt cotton are the predominant crops which are either grown solely or in rotation with other crops in Telangana state. As all these crops are exhaustive, non leguminous in nature and may lead to fast soil degradation. Therefore, a major agricultural research priority is needed to sustain soil productivity through carbon sequestration by including legume component in cropping systems. The present study was undertaken to investigate effect of cropping systems on carbon sequestration in the ongoing long-term field trial. Methods: This field investigation was initiated during the year 2017 at an experimental farm located at College of Agriculture, Rajendranagar, Hyderabad. The surface soil samples were collected at 0-15 cm depth in various treatments within different cropping systems after harvest of Kharif and Rabi crops, 2019-2020 at the completion of third year of the experiment and analysed for soil organic carbon (SOC) and soil inorganic carbon (SIC) status by following standard procedures. Data were subjected to statistical analysis by adopting RBD statistical tool and analysis of variance was worked by adopting operational statistics (OP STAT) software programme. Result: The results indicated the improvement in soil organic carbon over the initial status due to the effect of efficient cropping systems. Significantly highest build-up of organic carbon was noticed in the following cropping sequence: CS5: maize + pigeon pea (1:3) (1.25 Mg ha-1) and CS4: pigeon pea + green gram (1:3) - sesame (1.22 Mg ha-1) but the lowest value of SOC was recorded in CS1: rice-maize (7.51 Mg ha-1) and CS2: Bt cotton-fallow (7.24 Mg ha-1), respectively. During the study, it was also observed that in one of the cropping systems i.e., CS10: bhendi-marigold-beetroot showed the negative impact on the level of SOC stock (6.77 Mg ha-1) fell below the initial value (7.53 Mg ha-1) after third year of trial. However, the highest carbon sequestration rate was recorded in CS5: maize + pigeon pea (0.42 Mg ha-1 yr-1) and CS4: pigeon pea + green gram (1:3) - sesame (0.41 Mg ha-1 yr-1). The salient findings of this study showed that cropping systems involving legumes and fodder crops had improved soil organic carbon on long term basis.