Exploration of Soil Carbon Sequestrationin Relation to C:N:P:S Stoichiometryunder Dynamic Cropping Systems

Climate change impacts soil carbon storage by increasing temperatures, which accelerate organic matter decomposition and reduce soil carbon retention.Elevated temperatures and extreme weather events affect organic matter stability and carbon storage by disrupting C:N:P balance.Soil carbon storage is dependent on nitrogen, phosphorus, and sulfur, which help its stabilization in soil.However, there is limited information on how C:N:P:S stoichiometry affects soil carbon storage under prevailing climatic scenarios in different cropping systems.To address this gap, a two-year field experiment was conducted at the National Agricultural Research Centre in Islamabad.The study investigated maize-wheat (cereal-cereal) and fallow-wheat (fallow-cereal) cropping systems.Results showed that the highest concentrations of soil organic carbon (SOC), carbon fractions, and available nitrogen, phosphorus, and sulfur were found in the optimum humification treatment (based on 30% of humus C:N:P:S stoichiometry) for both cropping systems.This treatment resulted in an 8% increase in maize yield under the maize-wheat system and a 13-17% increase in wheat grain yield compared to the recommended dose treatment in both systems.Additionally, soil organic carbon sequestration increased by 34-36% in the maize-wheat system and 27-33% in the fallow-wheat system under the optimum humification treatment compared to sole straw incorporation.The study concludes that optimal humification practices enhance soil carbon storage by increasing microbial activity through higher organic matter inputs, thereby boosting the agricultural productivity of major cropping systems in Punjab, Pakistan.