Long-Term Fertilizer Experiments: Strategies for Efficient Carbon Sequestration

Soil carbon is an important indicator of soil quality and productivity, and it is influenced by various agricultural practices such as tillage, mulching, fertilization, and cropping sequence. The long-term accumulation of soil carbon, or sequestration, is essential for sustaining agricultural production and the mitigation of climate change. Soil carbon sequestration is a complex process which involves various physical, chemical, and biological processes. Judicious or balanced fertilization is crucial for soil carbon management, but the effects of balanced fertilization on carbon sequestration can only be predicted over the long term. Long-term fertilizer experiments (LTFEs) provide an opportunity to understand and predict the changes in SOC pool and carbon sequestration potential of soil systems. LTFEs conducted in India have shown that the combined application of chemical and organic manure (NPK + FYM) has a sequestration potential of 2.73 and 4.93 Mg C ha−1, respectively, compared to NPK and control plots. Similarly, continuous use of NPK + FYM has increased SOC content from 26% to 52% compared to NPK and control plots, respectively. However, long-term studies have clearly shown that the use of organic manure increases soil carbon sequestration, but its feasibility and availability to resource-poor farmers need to be promoted through various technological and policy interventions.