Is the Period of 18 Years Sufficient for an Evaluation of Changes in Soil Organic Carbon under a Variety of Different Soil Management Practices?

ABSTRACT

The influence of differing soil management practices on changes seen in soil organic carbon (SOC) content of loamy Haplic Luvisol was evaluated. The field experiment included two types of soil tillage: 1. conventional tillage (CT) and 2. reduced tillage (RT) and two treatments of fertilization: 1. crop residues with nitrogen, phosphorus, and potassium (NPK) fertilizers (PR+NPK) and 2. NPK fertilizers (NPK). The results of SOC fluctuated from 9.8 to 14.5 g kg⁻¹ and the tillage systems employed and fertilization status did not have a statistically significant influence on SOC. The SOC content was higher in RT (12.4 ± 0.86 g kg⁻¹) than in CT (12.2 ± 0.90 g kg⁻¹). On average, there was a smaller higher value of SOC in PR+NPK (12.4 ± 1.02 g kg⁻¹) than in NPK (12.3 ± 0.88 g kg⁻¹). During a period of 18 years, reduced tillage and application of NPK fertilizers together with crop residues build up a SOC at an average speed of 7 and 16 mg kg⁻¹ year⁻¹, respectively, however conventional tillage and NPK fertilizer applications caused a SOC decline at an average speed of 104 and 40 mg kg⁻¹ year⁻¹, respectively.

KEYWORDS:

• Fertilization
• soil organic carbon
• soil tillage

Acknowledgments

The author thanks Matthew Evans (Brackley, England) for improving the English text and also the editor and reviewers, for constructive comments.