Watersoluble phosphorus in Finnish mineral soils and its dependence on soil properties

Abstract

Abstract. Water soluble phosphorus ranged from 0.2 mg to 117.8 mg/kg in 104 surface soil samples studied. On the average, water extracted less P from the heavy clay soils (4.8 ± 2.2 mg/kg) than from the coarser clays (12.8 ± 4.6 mg/kg) and non-clay soils (13.3 + 7.2 mg/kg).Water extraction seemed to illustrate ''the effective" P status, it is that determined by the quantity and quality of sorption components in soil, soil pH and the content of organic carbon. These factors did not affect the amounts of P dissolved in water directly but inderectly by controlling the nature of P bonding which, in turn, seems to be of decisive importance in the extractability of P into water.The P supplying power of a given fraction is obviously controlled by the quantity of corresponding sorption agent. Water extractable P correlated most closely with the molar ratio of NH,F soluble P to oxalate extractable A 1 (r=o.93***, n= 103). However, according to the theory presented, with progressing desorption, P starts to mobilize also from the NaOH soluble fraction, its significance being the more apparent the greater the corresponding molar ratio NaOH-P/Fe is. In addition, the role and significance of other inorganic P fractions were discussed.

Relationship between phosphorus intensity and capacity parameters in Finnish mineral soils: II Sorption-desorption isotherms and their relation to soil characteristics

“…Water extraction has been shown to illustrate the P status determined by the quantity and quality of sorption components in soil, soil pH, and the content of organic carbon (HARTIKAINEN 1982 a Further, it can be concluded from the equations of the isotherms B that a given desorption decreases the P concentration in a solution the more markedly the lower the buffer power of the soil is. Also HOLFORD and MATTINGLY (1976) have emphasized the importance of the buffering factor.…”

“…The means and range of other properties in various soil groups as well as the methods of soil analyses are presented in a previous study (HARTIKAINEN 1982 a). The method for preparing the isotherms is described in the first part of this study (HARTIKAINEN 1982 b).…”

The multifunctional roles of vegetated strips around and within agricultural fields

“…The efficiency of vegetated strips in reducing dissolved phosphorus is dependent on the dynamic equilibrium between soil and dissolved phosphorus. Phosphorus is adsorbed by soil when the phosphorus concentration in soil water is higher than the equilibrium level and vice versa [27]. Generally, the effectiveness of vegetated strips in controlling transport of soluble contaminants is less than for strongly-sorbed chemicals because the reduction in water transfer across the buffer is generally smaller than the reduction in sediment transfer [28].…”

Effects of applications of lime, wood ash, manure and mineral P fertilizer on the inorganic P fractions and other selected soil chemical properties on acid soil of Farta District, Northwestern highland of Ethiopia

“…This result indicated that Al-P and the Fe-P are the most important sources of easily soluble P which are important for plant growth by supplying P to the soil solution. However, Hartikainen (1982) stated that Al-P has a dominant influence over Fe-P in maintaining P concentration in the soil solution in the first place. The contribution of Fe-P to maintain P concentration in the soil solution can be expected to become source of available P with decreasing Al-P content.…”