This study aimed to understand the effect of long-term fertilisation of nitrogen (N)-phosphorus (P)-potassium (K) additions alone and in combination with organic manure in relation to a control in a 30-year-old
hydromorphic paddy soil of China.
The forests are on generally flat to undulating terrain that is predominantly underlain by deep unconsolidated Kalahari sand deposits with small patches of
hydromorphic black clay mainly in the vlei areas.
Yellow Acrisol, Fluvic Neosol, and Indiscriminate
Hydromorphic Soils are also present (Valente et al.
The soil in the experimental field is dark-yellow
hydromorphic paddy soil.
Intra-zonal soils occupy a significant portion of the vineyard soil (>30%), the former being represented by regosols and erodisols on the more eroded slopes, and azonal, alluvial and/or
hydromorphic soils on the valley meadows.
The streams and rivers in the study area are formed mostly of
hydromorphic zones, in which surface runoff near the headwaters is intermittent.
The
hydromorphic structure combined with current precipitation controlling factors influence runoff and flash flood in the study area.
According to the French classification of soils (CPCS, 1967) the soils found in the study area are included into six classes: isohumic soils, vertisols, calcimagnesic soils, slightly developed soils, iron sesquioxides soils and
hydromorphic soils (Badraoui & al., 1993).
Mudrocks record suspension deposition on the floodplain; blocky textures and roots within these beds record the development of immature
hydromorphic paleosols and colonization by vegetation.
The development of the crusts and globule irons could have resulted from a
hydromorphic process because of seasonal variations of the phreatic water (Astibia et al., 1999c; Elorza et al., 1999).
Soils are of sedimentary origin, occurring in clayey and sandy phases alternately and discontinuously, with a dominance of
hydromorphic soils (CORINGA et al., 2012).
Overwetting of upper layers of soils and severe thermal conditions are limiting factors for earthworms functioning in soils of
hydromorphic type.