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Updated: Jan 10, 2026

Measuring Phosphorus Release in Laboratory Microcosms for Water Quality Assessment
Published on: July 22, 2019
Microbial-derived carbon indirectly drives soil phosphorus availability via microbial mechanisms in reddish paddy
Jian Xiao1, Peng Li2, Yanhong Lu3
1Longping Agricultural College, Hunan University, Changsha, 410017, China; Hunan Institute of Agricultural Soil and Eco-Environment, Hunan Academy of Agricultural Sciences, Changsha, 410125, China.
Abstract:
The long-term addition of organic resources can improve soil phosphorus (P) availability by increasing soil organic carbon (SOC). However, the mechanisms by which different C sources influence P availability have not been explored. To address this, five fertilizer treatments with four replications per treatment from a 43-year field trial were selected: no inorganic fertilizer (CK), inorganic fertilizer with nitrogen (N) and potassium (K) (NK), inorganic NK fertilizer with pig manure (15 t ha-1) (NKM), inorganic fertilizer with N, P (38.7 kg ha-1), and K (NPK), and inorganic NPK fertilizer combined with rice straw (2.1 t ha-1) (NPKS). The results indicated that the long-term addition of pig manure and straw enhanced SOC by 14.97 % and 14.98 %, particulate organic C (POC) by 33.63 % and 60.98 %, microbial biomass C by 47.15 % and 22.10 %, available P (Olsen-P) by 106.04 % and 21.35 %, microbial biomass P by 64.17 % and 62.34 %, total P by 22.45 % and 4.42 %, and P activation coefficient contents by 68.23 % and 16.23 %, and increased plant and microbial necromass C by 30.76 %-32.41 % and 18.93 %-25.75 %, respectively. POC and SOC were the most critical factors affecting the plant and microbial necromass C. A structural equation model revealed that plant necromass C content directly predicted changes in P availability, whereas microbial necromass C content indirectly predicted changes in P availability through microbial biomass and the phoD gene. In conclusion, this study enhances our understanding of the mechanisms by which microbial necromass C indirectly drives soil P availability via microbial mechanisms through the input of organic materials.
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