Soil organic carbon, nitrogen, and phosphorus distribution in stable aggregates of an Ultisol under contrasting land use and management history

Abstract

Different land-use affects the organization of mineral soil particles and soil organic components into aggregates and the consequent arrangement of the aggregates will influence essential ecosystem functions. We investigated a continuous rubber plantation (forested), land fallowed for 10 y (fallow), 10-y continuous arable cropping land and cropped land with top soil removed (TSR) for concentrations of C, N, and P in bulk soil and dry aggregates. Results showed that a high level of soil disturbance decreased the proportion of surface (0-15 cm) soil aggregate stability (low mean weight diameter) in TSR by 149% and arable cropping by 125% compared with the forested. Aggregate associated SOC was higher in aggregate-size fractions of forested land-use when compared with that in 10-y fallow, continuous arable cropping, and TSR. For aggregate associated N, fallow and forested land-use types concentrated higher proportion across aggregate sizes than the arable cropping and TSR. Macro aggregate fractions generally contained higher concentrations of C, N, and P compared with the micro-aggregates. Water transmission indicators like total porosity and saturated hydraulic conductivity recorded higher values with forested and fallow land-use than the others. We can thus conclude that long-term soil disturbance due to cultivation and removal of top soil reduces the accumulation of soil C, N, and P in bulk soil and decreases water transmission properties. On the other hand, aggregate-associated C, N and P accumulations are dependent on the level of soil surface disturbance and aggregate sizes.

Changes in Soil Aggregate Stability Induced by Mineral Nitrogen Fertilizer Application

“…I.e., adding lignohumate into compost reduced the decrease in the stability of soil aggregates (N50 + K; N50 + C), in comparison with the variants fertilized only with mineral fertilizer. The same phenomenon was observed in the study of Udom (2015). However, variant N100 + C did not reveal improvement of the stability of soil aggregates.…”

Enhanced soil aggregate stability limits colloidal phosphorus loss potentials in agricultural systems

“…Notably, P has a relatively closed cycle, with most of the mineralized and dissolved P from microaggregates adsorbed onto unaggregated clay-sized particles (< 53 μm) or utilized by plants [26]. Reportedly, some studies have shown that the soil aggregate stability and size affect the soil P distribution [27][28][29]. Higher percentages of both waterextractable and Mehlich III-extractable P were observed in both the 0.50-0.25 and 0.25-0.125 mm aggregate fractions [30].…”

Organic Carbon and Nitrogen Distribution in Particle-size Fractions of Soils Under Cassava, Plantain and Rubber Based Land Use

“…This is because organic litter fall from the cassava may have contributed to lower the soil bulk density. Kou et al (2012) and Udom and Ogunwole (2015) have agreed that, the volume of organic matter in the soil usually improved soil structure and consequently, the bulk density. Total porosity and permeability of the soils were higher in cassava and plantain soils, an indication of great input of organic residues which enhanced these soil physical properties.…”

“…This method can provide useful information on SOC dynamics under natural conditions or short-term management practices (Shrestha et al, 2007). Previous research has indicated that changes in land use (or management practices) have a marked impact on the amount of Organic Carbon (OC) in particle-size fractions, which could serve as an early indicator to identify the impact of land-use change on SOC storage (Leifeld and Kogel-Knabner, 2005;Udom and Ogunwole, 2015).…”

“…Cropping pattern and the integration of anthropogenic disturbances on farm lands can significantly affect agricultural soil carbon pool. Results from many studies showed that rubber plantation decreased soil organic carbon (Yang et al, 2004;Udom and Ogunwole, 2015). In contrast, studies by Wang and Li (2003) and Yang et al (2007) have demonstrated that rubber plantation could potentially enhance SOC sequestration.…”