scholarly journals Redox potential of bulk soil and soil solution concentration of nitrate, manganese, iron, and sulfate in two Gleysols

2004 ◽  
Vol 167 (1) ◽  
pp. 7-16 ◽  
Author(s):  
Tim Mansfeldt
Keyword(s):  
Redox Potential ◽  
Soil Solution ◽  
Solution Concentration ◽  
Bulk Soil

scholarly journals The impact of four decades of annual nitrogen addition on dissolved organic matter in a boreal forest soil

2013 ◽  
Vol 10 (3) ◽  
pp. 1365-1377 ◽  
Author(s):  
M. O. Rappe-George ◽  
A. I. Gärdenäs ◽  
D. B. Kleja
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Soil Solution ◽  
Mineral Soil ◽  
Solution Concentration ◽  
Oxidative Enzymes ◽  
N Saturation ◽  
N Addition ◽  
Mineral N ◽  
The Impact

Abstract. Addition of mineral nitrogen (N) can alter the concentration and quality of dissolved organic matter (DOM) in forest soils. The aim of this study was to assess the effect of long-term mineral N addition on soil solution concentration of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in Stråsan experimental forest (Norway spruce) in central Sweden. N was added yearly at two levels of intensity and duration: the N1 treatment represented a lower intensity but a longer duration (43 yr) of N addition than the shorter N2 treatment (24 yr). N additions were terminated in the N2 treatment in 1991. The N treatments began in 1967 when the spruce stands were 9 yr old. Soil solution in the forest floor O, and soil mineral B, horizons were sampled during the growing seasons of 1995 and 2009. Tension and non-tension lysimeters were installed in the O horizon (n = 6), and tension lysimeters were installed in the underlying B horizon (n = 4): soil solution was sampled at two-week intervals. Although tree growth and O horizon carbon (C) and N stock increased in treatments N1 and N2, the concentration of DOC in O horizon leachates was similar in both N treatments and control. This suggests an inhibitory direct effect of N addition on O horizon DOC. Elevated DON and nitrate in O horizon leachates in the ongoing N1 treatment indicated a move towards N saturation. In B horizon leachates, the N1 treatment approximately doubled leachate concentrations of DOC and DON. DON returned to control levels, but DOC remained elevated in B horizon leachates in N2 plots nineteen years after termination of N addition. We propose three possible explanations for the increased DOC in mineral soil: (i) the result of decomposition of a larger amount of root litter, either directly producing DOC or (ii) indirectly via priming of old SOM, and/or (iii) a suppression of extracellular oxidative enzymes.

scholarly journals Low, Controlled Nutrient Availability Provided by Organic Waste Materials for Chrysanthemum

1992 ◽  
Vol 117 (3) ◽  
pp. 422-429 ◽  
Author(s):  
Kimberly A. Williams ◽  
Paul V. Nelson
Keyword(s):  
Soil Solution ◽  
Release Rate ◽  
Waste Water Treatment ◽  
Poultry Manure ◽  
Solution Concentration ◽  
Application Rate ◽  
Liquid Fertilizer ◽  
Brevibacterium Lactofermentum ◽  
N Release ◽  
Poultry Feathers

Seven organic materials including 1) the bacterium Brevibacterium lactofermentum (Okumura et al.) in a nonviable state, 2) a mixture of two bacteria, Bacillus licheniformis (Weigmann) and Bacillus subtilis (Ehrenberg), plus the fungus Aspergillus niger (van Tieghem) in a nonviable state, 3) an activated microbial sludge from waste-water treatment, 4) sludge from a poultry manure methane generator, 5) unsteamed bonemeal, 6) aged pine needles, and 7) poultry feathers were evaluated to determine their pattern and term of N release and the possibility of using them as an integral part of root media releasing N at a steady, low rate over 10 to 12 weeks for production of Dendranthema × grandiflorum (Ramat.) Kitamura `Sunny Mandalay'. These were compared to the inorganic slow-release fertilizer micro Osmocote (17N-3.9P-10.8K) and a weekly liquid fertilizer control. All organic sources released N most rapidly during the first 2 weeks, followed by a decline, which ended at 6 to 7 weeks. Brevibacterium lactofermentum, bonemeal, and micro Osmocote treatments resulted in about equal growth, which was similar to growth of a weekly liquid fertilizer control for 9 weeks in the first and for 12 weeks in the second experiment. The period of N release could not be extended through increased application rate of source due to the high initial release rate. It was not possible to lower source application rates to achieve an effective, low soil solution concentration due to the large variation in release rate over time. Efficiency of N use varied among plants grown in media treated with various microorganismal sources and was highest in those treated with B. lactofermentum. Nitrogen release from ground poultry feathers was inadequate, and additions of the viable hydrolyzing bacterium B. licheniformis to feathers failed to increase soil solution N levels. Attempts to retard mineralization of B. lactofermentum by cross-linking proteins contained within the bacterium by means of heat treatment at 116C vs. 82C failed. While anaerobic poultry manure sludge proved to be an inefficient source of N, it provided large amounts of P. Organic sources released primarily ammoniacal N, which raised the medium pH by as much as one unit, necessitating the use of less limestone in the medium formulation.

Solute Transport in the Soil near Root Surfaces

2000 ◽  
Author(s):  
Peter B. Tinker ◽  
Peter Nye
Keyword(s):  
Soil Solution ◽  
Dynamic Equilibrium ◽  
Pore Solution ◽  
Plant Root ◽  
Unit Length ◽  
Solution Concentration ◽  
Root Surface ◽  
Transport Processes ◽  
Soil Pores ◽  
Intact Root

We discussed in chapter 4 the movement of solute between small volumes of soil, and in chapter 5 some properties of plant roots and associated hairs, particularly the relation between the rate of uptake at the root surface and the concentration of solute in the ambient solution. In the chapters to follow, we consider the plant root in contact with the soil, and deal with their association in increasingly complex situations; first, when the root acts merely as a sink and, second, when it modifies its relations with the surrounding soil by changing its pH, excreting ions, stimulating microorganisms, or developing mycorrhizas. In this chapter, we take the simplest situation that can be studied in detail, namely, a single intact root alone in a volume of soil so large that it can be considered infinite. The essential transport processes occurring near the root surface are illustrated in figure 6.1. We have examined in chapter 3 the rapid dynamic equilibrium between solutes in the soil pore solution and those sorbed on the immediately adjacent solid surfaces. These sorbed solutes tend to buffer the soil solution against changes in concentration induced by root uptake. At the root surface, solutes are absorbed at a rate related to their concentration in the soil solution at the boundary (section 5.3.2); and the root demand coefficient, αa, is defined by the equation . . . I = 2παaCLa (6.1) . . . where I = inflow (rate of uptake per unit length), a = root radius, CLa = concentration in solution at the root surface. To calculate the inflow, we have to know CLa, and the main topic of this chapter is the relation between CLa, and the soil pore solution concentration CL. The root also absorbs water at its surface due to transpiration (chapter 2) so that the soil solution flows through the soil pores, thus carrying solutes to the root surface by mass flow (convection). Barber et al. (1962) calculated whether the nutrients in maize could be acquired solely by this process, by multiplying the composition of the soil solution by the amount of water the maize had transpired.

TDR estimation of the resident concentration of electrolyte in the soil solution

Soil Research ◽  
1997 ◽  
Vol 35 (3) ◽  
pp. 515 ◽  
Author(s):  
I. Vogeler ◽  
B. E. Clothier ◽  
S. R. Green
Keyword(s):  
Electrical Conductivity ◽  
Soil Solution ◽  
Electrolyte Concentration ◽  
Time Domain Reflectometry ◽  
The Other ◽  
Bulk Soil ◽  
Small Scale ◽  
Soil Electrical Conductivity ◽  
Soil Columns ◽  
Leaching Experiments

In order to examine whether the electrolyte concentration in the soil solution can be estimated by time domain reflectometry (TDR) measured bulk soil electrical conductivity, column leaching experiments were performed using undisturbed soil columns during unsaturated steady-state water flow. The leaching experiments were carried out on 2 soils with contrasting pedological structure. One was the strongly structured Ramiha silt loam, and the other the weakly structured Manawatu fine sandy loam. Transport parameters obtained from the effluent data were used to predict the transient pattern in the resident electrolyte concentration measured by TDR. The electrolyte concentration was inferred from the TDR-measured bulk soil electrical conductivity using 2 different calibration approaches: one resulting from continuous solute application, and the other by direct calibration. Prior to these, calibration on repacked soil columns related TDR measurements to both the volumetric water content and the electrolyte concentration that is resident in the soil solution. The former calibration technique could be used successfully to describe solute transport in both soils, but without predicting the absolute levels of solute. The direct calibration method only provided good estimates of the resident concentration, or electrolyte concentration, in the strongly structured top layer of the Ramiha soil. This soil possessed no immobile water. For the less-structured layer of the Ramiha, and the weakly structured Manawatu soil, only crude approximations of the solute concentration in the soil were found, with measurement errors of up to 50%. The small-scale pattern of electrolyte movement of these weakly structured soils appears to be quite complex.

EFFECT OF pH ON PLANT UPTAKE AND SOIL ADSORPTION OF 14C-FLURIDONE

1990 ◽  
Vol 70 (3) ◽  
pp. 435-444 ◽  
Author(s):  
N. MALIK ◽  
D. S. H. DRENNAN
Keyword(s):  
Soil Solution ◽  
Plant Uptake ◽  
Sandy Loam ◽  
Organic Soil ◽  
Solution Concentration ◽  
Silty Clay ◽  
Clay Loam ◽  
Silty Clay Loam ◽  
Solution Ph ◽  
Soil Adsorption

Experiments were conducted to obtain a better understanding of the role of pH on the availability of fluridone (1-methyl-3-phenyl-5-[3-(trifluoromethyl) phenyl]-4(1 H)-pyridinone) in soil solution when used as a selective herbicide and the partitioning into aqueous and sediment phases when employed for aquatic plant control. Phytotoxicity of fluridone to seedling sorghum (Sorghum bicolor L.) plants increased with increasing pH of the sand-nutrient solution medium. Since stability and plant uptake of fluridone by bioassay plants were not affected by solution pH, the increasing phytotoxicity at basic pH was attributed to less adsorption and hence higher availability of the herbicide in solution. Soil adsorption studies with 14C-fluridone confirmed this trend, as the soil solution concentration at equilibrium increased from 0.091 to 0.258 μg mL−1 and from 0.216 to 0.354 μg mL−1, respectively, as pH of a sandy loam and silty clay loam increased from 3 to 9. In contrast, adsorption on the sandy loam and silty clay loam for the same pH range decreased from 4.108 to 2.435 μg g−1 and from 2.850 to 1.484 μg g−1, respectively. Smaller but significant changes in adsorption were also observed for an organic soil over this range. Key words: Herbicide, fluridone, pH, uptake, soil adsorption

scholarly journals 256 Evaluation of Phosphate Desorption Characteristics of Clay Minerals for Soilless Root Media

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 486C-486
Author(s):  
Young-Mi Oh ◽  
Paul V. Nelson ◽  
Dean L. Hesterberg
Keyword(s):  
Clay Minerals ◽  
Soil Solution ◽  
Equilibrium Concentration ◽  
Solution Concentration ◽  
Reaction Chamber ◽  
Maximum Adsorption Capacity ◽  
Commercial Alumina ◽  
Root Media ◽  
Phosphate Leaching ◽  
Phosphate Desorption

Soilless root media retain very little phosphate. This characteristic necessitates continual application of phosphate, which leads to excessive application and leaching. The phosphate desorption characteristics of synthetic hematite (a-Fe2O3), goethite (a-FeOOH), allophane (Si3Al4O12*nH2O), and a commercial alumina (Al2O3), previously determined for their maximum adsorption capacities, were evaluated to determine their potential for providing a low, constant soil solution phosphate supply with low phosphate leaching from soilless root media. The desorption isotherms of the clay minerals were obtained by introducing 10 mM KCl solution at 0.2 ml/min flow rate into a stirred flow reaction chamber loaded with clay adsorbed with phosphate at maximum adsorption capacity. The suspension in the reaction chamber was held at pH 6.4 during desorption. Effluent solutions were collected for phosphorus analysis until the equilibrium concentration of phosphorus in solution reached 0.05 mg•L-1. Adsorbed phosphorus at 0.05 mg•L-1 equilibrium concentration in solution was in the order allophane (19 mg•g-1) > alumina™ goethite (8 mg•g-1) > hematite (1.3 mg•g-1). The equilibrium concentration of phosphorus in solution over time showed that allophane releases phosphate for a longer time than the other clay minerals at a desirable soil solution concentration for plants, less than 5 mg•L-1. Among the clay minerals tested, allophane showed the most favorable potential to supply phosphate to plants in soilless root media.

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