Fractal Characteristics of Stagnic Anthrosols and the Relationship with Soil Micro-Structure

The Stagnic Anthrosols developed from quaternary yellow sedimentary parent material occupied an important position in Southwest China. Fractal dimensions of particle size and micro-aggregate size distributions of Stagnie Anthrosols and their relationship to soil micro-structure had been probed. Results showed that the soil particle size distributions were dominated by clay, the fractal dimensions of particle size distributions （Ds） were high and between 2.676-2.925, as the fractal dimensions of micro-aggregate size distributions （Da） were between 2.354-2.853. The fractal dimensions of particlesize distributions were preferably related with the ratio of coarse particles and fine particles （c/f20 ,m） and the micromorphological feature of skeleton grains. The evolution degree of micro-structure among horizons were reflected by the coefficient of variation of Ds within the profile. The fractal dimensions of micro-aggregate size distributions were related with the quantities, distributions of micro-aggregates and micro-pores. Results revealed that the soil micro-structures could be quantified by fractal dimensions preliminarily.

Changes in N,P and K Contents in Eum-orthic Anthrosols at Different Moisture Contents

[Objectives]This study aimed to provide a basis for the management of nitrogen,phosphorus and potassium nutrients in eum-orthic anthrosols and the fertilization of crops.[Methods]Using the indoor culture method,the contents of total nitrogen,available phosphorus and available potassium in eum-orthic anthrosols under three different moisture conditions:long-term drying,long-term logging and alternate drying and logging were analyzed and compared.[Results]The total nitrogen content was higher under the moisture condition of long-term drying.The minimum(0.60 g/kg)appeared on day 30,and the maximum(0.74 g/kg)appeared on day 120,increased by 8.8%compared with the minimum.The available phosphorus content was also higher under the moisture condition of long-term drying.The minimum(16.9 mg/kg)appeared on day 60,and the maximum(22.5 mg/kg)appeared on day 120,increased by 33.1%compared to the minimum.The available potassium content showed a downward trend under long-term logging,and was higher than those under the other two moisture conditions.The maximum(150 mg/kg)appeared on day 30,and the minimum(136 mg/kg)appeared on days 75 and 90,reduced by 9.3%compared with the maximum.[Conclusions]Water plays a positive role in activating nutrients.Different nutrients have different responses to different moisture conditions.

Human-altered soils–Signatures of Anthrosols and their potential for arable lands

The fertility of human-altered soils,Anthrosols,developed from past settlement activities for crop production is scarcely studied.The study evaluated the fertility of Anthrosols developed from the 15th to mid-20th century AD settlement in Old Buipe,Savanna region,Ghana,to determine whether abandoned localities are suitable for arable fields.Human activities enhanced the physical attributes of the Anthrosols:brown to dark brown intergrain fine soil,15%−35%organic matter,15%−30%potsherd,and 5%−15%charred materials.The Anthrosols were slightly acidic to neutral reactions(pH_([H_(2)O])5.67−6.83,pH_([cacl_(2)])5.83−6.95),high cation exchange capacity(CEC;18.77−45.31me/100 g),electric conductivity(EC=0.28−0.36 dS m^(−1)),accumulation,and distribution of organic C,total N,P,Mn,Cu,Zn,K,and Fe,and available P,K,Ca,Mg,S,Mn,Fe,Cu,and Zn.Plant-available nutrients were comparatively higher than concentrations in non-anthropogenic soils.The level of releasability(bioavailable fractions of total concentrations)of P,K,Ca,Mn,Fe,Cu,and Zn partly compensates for low plant-available portions.Enrichment of chemical and physical properties of Anthrosols make them fertile for arable fields.The signatures of settlement activities are strong and can remain in soils for a long time,even under harsh environmental conditions.