Assessment of Lettuce Yield and Soil Organic Carbon Fraction Distribution under Different Types of Organic Matter in South Korea

Abstract

In this study, we evaluated the effect of applying different types of organic matter on yield, soil chemical properties, and soil carbon fraction in lettuce cultivation. The experiment consisted of six different fertilizations; no fertilizer (NF), inorganic fertilizer (IF), mixed expeller cake (MEC), mixed organic fertilizer (MOF), NPK+ Cow manure compost (NPKCC), NPK+Pig manure compost (NPKPC). The yield of lettuce under NPKCC (2,962 kg 10a -1 ) was higher than NF (1,157 kg 10a -1 ), IF (1,990 kg 10a -1 ), MEC (2,173 kg 10a -1 ), MOF (2,398 kg 10a -1 ), and NPKPC (2,810 kg 10a -1 ). In the soil chemical analysis, the pH showed no significant difference between treatment, whereas both EC and available phosphate demonstrated statistically significant increases in response to the application of inorganic fertilizer and cow manure compost. The concentration of fulvic acid (FA) was high in the following order: NPKCC (776 mg kg -1 ) > MOF (684 mg kg -1 ) > NPKPC (652 mg kg -1 ) > MEC (623 mg kg -1 ) > IF (577 mg kg -1 ) ≒ NF (555 mg kg -1 ). The concentration of humic acid (HA) was high in the following order: NPKCC (1,868 mg kg -1 ) > NPKPC (1,403 mg kg -1 ) > MOF (1,346 mg kg -1 ) > MEC (1,304 mg kg -1 ) > IF (1,273 mg kg -1 ) > NF (1,206 mg kg -1 ). In conclusion, application of cow manure compost with inorganic fertilizer can increase lettuce yield and stable carbon (fulvic acid, humic acid) concentration. Therefore, it is recommendable for suitable soil management strategy to improve soil carbon and increase crop yield in upland soil. Furthermore, in order to provide a comprehensive evaluation of the enduring effects of organic matter application on crop yields, soil chemical properties, and soil organic carbon stocks, it is strongly recommended that further studies be undertaken.