PJB-2018-896
Long term fertilization altered labile soil organic carbon fractions in upland soils of China
Rais Nazia
Abstract
The labile soil organic carbon (SOC) plays key roles in assessment to improve soil fertility, but how the labile fractions change at the depths with long-term fertilizations remains unknown. In this study, the labile SOC fractions were extracted by 333, 167, and 33 mM potassium permanganate oxidizable C (KMnO4–C) named total, mid and highly labile SOC fraction at three long-term fertilization experimental sites in typical Chinese croplands representing black soil in Gongzhuling (GZL), Chao soil in Zhengzhou (ZZ), and red soil in Qiyang (QY) selected 0-40cm soil depth at GZL and 0-100cm soil depth at ZZ and QY. The four fertilization treatments including cropping without fertilization (CK), inorganic fertilizer nitrogen, phosphorus and potassium (NPK), inorganic fertilizer with manure (NPKM), and inorganic fertilizer with straw (NPKS). Results showed that SOC storage in 0-20cm soil layer increased under NPKM > NPKS > NPK relative to CK at all sites except GZL i.e NPKM > NPKS, NPK. The SOC storage in whole soil profile (0-100cm) was higher under NPKM >NPKS, NPK relative to CK at GZL, ZZ and QY. Long-term fertilization experiment also increased labile SOC storage pool in 0-20cm soil layer but it was sharply decline with increasing soil depth in each site. The average storage of total, mid and highly labile fraction in manure with balanced fertilizer (NPKM) in 0-40cm depth of GZL were increased 113.3, 183.7 and 274.5%, 153.4, 76.0 and 67.6 in 0-100cm of ZZ and in QY 105.5, 129.8 and 118.7% respectively, compared to CK. The study indicated the need to implement application of integrated NPK with manure or straw for improvement of soil fertility and productivity across various croplands and soils. This study could conduct to examine the labile fraction of SOC in different soils, much less along further soil profile or under long-term application of manure and fertilizers. Thus, in the present study, evaluate the effects of long-term fertilization on labile organic carbon fraction in typical upland soils of China across the soil profile.
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