SOIL WATER CONTENT AFFECTS THE AVAILABILITY OF PHOSPHATE

1985 ◽  
pp. 185-189
Author(s):  
M.C.H.Mouat Pieter Nes
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Solution ◽  
Equivalent Reduction

Reduction in water content of a soil increased the concentration of ammonium and nitrate in solution, but had no effect on the concentration of phosphate. The corresponding reduction in the quantity of phosphate in solution caused an equivalent reduction in the response of ryegrass to applied phosphate. Keywords: soil solution, soil water content, phosphate, ryegrass, nutrition.

Solution concentrations of nutrient ions below the rooting zone of a sugar maple stand: relations to soil moisture, temperature, and season

1993 ◽  
Vol 23 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Xiwei Yin ◽  
Neil W. Foster ◽  
Paul A. Arp
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Solution ◽  
Sugar Maple ◽  
Temporal Variations ◽  
Solution Chemistry ◽  
Rooting Zone ◽  
Temperature Solution ◽  
Turkey Lakes Watershed

Temporal variations of ion concentrations in soil solution were analyzed in relation to soil percolate volume, soil water content, soil temperature, solution chemistry, and season. The study site was an uneven-aged, mature northern tolerant hardwoods dominated by sugar maple (Acersaccharum Marsh.) within the Turkey Lakes Watershed, Ontario. Six ions were investigated: nitrate (NO3−), sulfate (SO42−), calcium (Ca2+), magnesium (Mg2+), potassium (K+), and ammonium (NH4+). Nitrate concentrations in the soil solution depended on season during the nonfoliage period and responded directly to forest floor percolation, soil water content, and season during the foliage period. Variations of SO42−, Ca2+, and Mg2+ concentrations were mostly attributable to NO3− concentration, and to season to a lesser extent. Concentrations of K+ and NH4+ correlated only weakly to any of the "independent" variables included in the analysis, reflecting a high affinity between these ions and the soil colloids.

ESTIMATING SPATIAL VARIATIONS OF SOIL WATER CONTENT USING NONCONTACTING ELECTROMAGNETIC INDUCTIVE METHODS

1988 ◽  
Vol 68 (4) ◽  
pp. 715-722 ◽  
Author(s):  
R. G. KACHANOSKI ◽  
I. J. VAN WESENBEECK ◽  
E. G. GREGORICH
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Solution ◽  
Soil Texture ◽  
Spatial Variations ◽  
Bulk Soil ◽  
Soil Electrical Conductivity ◽  
Solution Conductivity

The relationships among the spatial variations of soil water content, soil texture, soil solution electrical conductivity, and bulk soil electrical conductivity were examined for a field characterized by net drainage and low concentrations of dissolved electrolytes. Bulk soil electrical conductivity was measured over various depths at 52 locations within a 1.8-ha field using noncontacting electromagnetic inductive meters. Soil water content (0–0.5 m depth) was measured at the same locations using the time domain reflectometry method. Measurements of soil texture and soil solution conductivity were obtained from core samples from 37 of the sampling locations. Soil water content at the site ranged from 0.06 to 0.36 m3 m−3. Clay content ranged from 2.5 to 44% percent and bulk soil electrical conductivity ranged from 0.0 to 0.21 S m−1. Significant correlation existed among almost all of the measured variables. Regression analysis indicated soil solution conductivity had no effect on measured bulk soil electrical conductivity for soil water contents less than 0.25 m3 m−3. Bulk soil electrical conductivity explained 96% of the spatial variation of soil water content independent of a wide range of soil texture. Autocorrelations of soil water content were similar to autocorrelations for bulk soil electrical conductivity. Under conditions similar to those in the study area, it should be possible to infer spatial variations in soil water content quickly by measuring bulk electrical conductivity using noncontacting electromagnetic inductive meters. Key words: Spatial variability, soil water, electrical conductivity, soil texture

Káliumföldpát, savkezelés és száradás-nedvesedés hatása a talajoldat káliumkoncentrációjára

2005 ◽  
Vol 54 (1-2) ◽  
pp. 121-138
Author(s):  
Julianna Csillag ◽  
András Lukács ◽  
Géza Pártay ◽  
Krisztina Rajkainé Végh
Keyword(s):  
Liquid Phase ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Solution ◽  
Potassium Concentration ◽  
Field Capacity ◽  
Soil Samples ◽  
Acid Load ◽  
Water Contents

Experiments were carried out on an acidic, clay loam soil (Ragály) to study the release of potassium into the soil solution as affected by soil acidification and soil water content. Two replicates of air-dried samples were acidified with HCl solutions to various water contents: soil suspensions (at 1:10, 1:5, 1:2.5 and 1:1 soil:water ratios) and wet soil samples having water potentials of -0.1 kPa, -20 kPa and -100 kPa were prepared. Constant acid loads, corresponding to 0, 5, 12.5, 25, 37.5, 50 and 62.5 mmol H+/kg soil were applied to each soil water content series. At field capacity acid loads of 75, 87.5 and 100 mmol H+/kg soil were also applied. After one week of incubation the liquid phases were extracted by centrifugation with a rotor speed corresponding to -1500 kPa (equal to the conventional wilting point of plants). At constant soil water content, the potassium concentration in the liquid phase of the soil (cK) increased with decreasing pH according to an exponential relationship (cK = a e-bpH). The slope (b) was higher at low soil water contents. At constant acid load, the potassium concentration in the liquid phase increased with decreasing soil water content (q) according to a hyperbolic relationship cK = a' + b' {1 / (qq-qq')}, where q' denotes the gravimetric soil water content at -1500 kPa water potential. The slope (b') was higher at lower pH values. The combined effect of the matrix of changing acid load and soil water content gave a three-dimensional surface characterizing the plant available potassium concentration over a wide range of these parameters: ln cK (mg/L) = 4.79 - 0.66 pH + 9.79 {1/(qq-qq'); R2 = 0.87. A finely ground (<100 mmm) feldspar mixture (80% orthoclase + 20% albite) was added as potassium source to the air-dried samples of a slightly acidic sandy soil in 0:1, 1:3 and 1:1 feldspar:soil ratios (Somogysárd). Two replicates of the control and feldspar-enriched soil samples were moistened to field capacity with HNO3 solutions of 0, 0.25, 0.50, 0.75 and 1.0 mol/L concentrations (equal to acid loads of 0, 50, 100, 150 and 200 mmol H+/kg soil). The soil solution was extracted with the above centrifugation method. After feldspar application, the potassium concentration in the soil solution increased many times as compared with the control. Due to acid treatment the soil pH decreased by three units and the potassium concentration in the soil solution increased according to a saturation curve. Due to a two-unit decrease in soil pH, the potassium concentration increased threefold in the control and sixfold in feldspar-enriched (1:3) soil. This decrease in pH may take place due to root activity, promoting the dissolution of potassium minerals, and increasing potassium availability in the rhizosphere. The impact of drying-rewetting was also studied at the above feldspar:soil ratios. After one week of incubation the samples were kept in open vessels for one year, irrigated weekly with distilled water to field capacity, then the soil solution was extracted by centrifugation. The concentrations were compared to those measured in a soil solution obtained from soil not subjected to the drying-rewetting procedure. The potassium concentration decreased in the liquid phase of the soil with no added feldspar: presumably it entered more strongly bounded forms during the drying-rewetting cycles. In the feldspar-enriched soil, however, the potassium concentration in the soil solution increased, which may be the consequence of the slow dissolution of the feldspar mineral.

scholarly journals Potassium estimation in the soil solution based on electrical conductivity and soil water content

2012 ◽  
Vol 16 (6) ◽  
pp. 618-623 ◽  
Author(s):  
Torquato M. de Andrade Neto ◽  
Eugênio F. Coelho ◽  
José A. do V. Santana ◽  
Edvaldo B. Santana Júnior ◽  
Márcio da S. Alves
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Solution ◽  
Potassium Concentration ◽  
Time Domain Reflectometry ◽  
Trickle Irrigation ◽  
Bulk Electrical Conductivity ◽  
Crop Cycle

The objective of this work was to evaluate and to validate models for estimating potassium in the soil solution as a function of bulk electrical conductivity (ECw), soil water content (q) and a soil solution electrical conductivity (ECss). Treatments consisted of using three concentrations of injecting solution of potassium chloride (1.0, 2.5 and 4.0 g L-1) which were applied by two trickle irrigation systems (microsprinkler and drip) during the first cycle of the banana crop cv. Terra Maranhão. Results showed that it is feasible to estimate potassium concentration in the soil solution from data of ECss and q obtained by time domain reflectometry (TDR) using an equation that combined a linear and a potential model. The estimated values of potassium concentration were close to the ones measured along the crop cycle under field conditions, with a mean normalized deviation of 10.0%, maximum and minimum deviation of 5.0 and 13.0%, respectively.

scholarly journals CONDUTIVIDADE ELÉTRICA DA SOLUÇÃO DE SOLO EM FUNÇÃO DA CONDUTIVIDADE ELÉTRICA APARENTE E DA UMIDADE DO SOLO SOB APLICAÇÃO DE CLORETO DE POTÁSSIO COM USO DA REFLECTOMETRIA NO DOMINIO DO TEMPO

Irriga ◽  
2005 ◽  
Vol 10 (2) ◽  
pp. 174-183
Author(s):  
Tibério Santos Martins da Silva ◽  
Vital Pedro da Silva Paz ◽  
Eugênio Ferreira Coelho ◽  
Maurício Antônio Coelho Filho ◽  
Gessionei Da Silva Santana
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Solution ◽  
Time Domain ◽  
Linear Models ◽  
Time Domain Reflectometry ◽  
Soil Electrical Conductivity ◽  
Bulk Electrical Conductivity

CONDUTIVIDADE ELÉTRICA DA SOLUÇÃO DE SOLO EM FUNÇÃO DA CONDUTIVIDADE ELÉTRICA APARENTE E DA UMIDADE DO SOLO SOB APLICAÇÃO DE CLORETO DE POTÁSSIO COM USO DA REFLECTOMETRIA NO DOMINIO DO TEMPO  Tibério Santos Martins da Silva1; Vital Pedro da Silva Paz2; Eugênio Ferreira Coelho3; Maurício Antônio Coelho Filho3; Gessionei da Silva Santana41Universidade Federal da Bahia,  Cruz das Almas, BA, tibé[email protected] de Engenharia Agrícola, Universidade Federal da Bahia, Cruz das Almas-BA, 3Embrapa Mandioca e Fruticultura, Cruz das Almas-BA4Universidade Federal de Viçosa, Viçosa, MG,   1 RESUMO O trabalho teve como objetivo definir, em campo e em laboratório, modelos matemáticos que melhor relacionam a condutividade elétrica aparente (CEa), a umidade do solo (q) e a condutividade elétrica da solução do solo (CEw) sob aplicação de cloreto de potássio, via água de irrigação por gotejamento. O experimento consistiu de leituras de CEa e q com um analisador de umidade de reflectometria no domínio do tempo (TDR) em colunas de solo em laboratório e em várias posições de uma malha retangular de um perfil do solo, em condições de campo, seguido da extração de solução iônica nas respectivas posições. Foram ajustados modelos lineares e não lineares relacionando CEa, q e CEw. O resultados permitiram concluir que a CEw da solução do solo pode ser monitorada a partir de leituras de CEa pela TDR para fins de distribuição de solutos no solo sob fertirrigação, com uso dos modelos de Rhoades et al. (1976), Vogeler et al. (1996), Nadler et al. (1984) e empírico em condições de campo e laboratório. O modelo de Rhoades et al. (1989) e Rhoades et al. (1976) mostraram-se adequados apenas para os estudos em laboratório. UNITERMOS: fertirrigação, TDR  SILVA, T. S. M. DA; PAZ, V. P. DA S.; COELHO, E. F.; COELHO FILHO, M. A.; SANTANA, G. DA S. SOIL SOLUTION ELECTRICAL CONDUCTIVITY AS A FUNCTION OF BULK ELECTRICAL CONDUCTIVITY AND SOIL WATER CONTENT UNDER POTASSIUM CLORIDE APPLICATION USING TIME DOMAIN REFLECTOMETRY  2 ABSTRACT This study aimed to define mathematical models that suitably relate bulk electrical conductivity (CEa), soil water content (q) and soil solution electrical conductivity (CEw) under potassium chloride application by drip irrigation. The experiment consisted of readings of CEa and q using a Time Domain Reflectometry analyzer (TDR) in soil columns in laboratory and on several positions of rectangular soil profile grid under field conditions. Ionic solution was extracted in all positions of TDR readings. Linear and non-linear models relating CEa, q and CEw were adjusted to laboratory and field data. Results allowed to conclude that CEw may be monitored by readings of CEa from TDR for soil solute distribution under fertirrigation, using models of Rhoades et al. (1976), Vogeler et al. (1996), Nadler et al. (1984) and an empirical model in lab and in field. The models of de Rhoades et al. (1989) e Rhoades et al. (1976) were suitable only for laboratory studies. KEYWORDS: fertirrigation, soil electrical conductivity, TDR

Herbicide Equilibrium in Soils in Relation to Soil Water Content

Weed Science ◽  
1969 ◽  
Vol 17 (4) ◽  
pp. 514-519 ◽  
Author(s):  
R. E. Green ◽  
S. R. Obien
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Solution ◽  
Partition Coefficients ◽  
Reasonable Accuracy ◽  
Principal Effect ◽  
Herbicide Transport ◽  
Herbicide Concentration ◽  
Water Contents

The concept of herbicide partition into adsorbed and solution phases in the soil was utilized to predict the effect of soil water content on the concentration of herbicide in solution. Calculated predictions based on measured partition coefficients and water contents were tested experimentally by equilibrating 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) with soil from three horizons of a latosolic soil at four water contents (45 to 60%). The effects of adsorption and water content were predicted with reasonable accuracy when only that water held at tensions less than 15 bars was considered available for equilibration with the applied herbicide. Only on low adsorption soils will water content variations alter significantly herbicide concentration in the soil solution. The principal effect of soil water content on herbicide phytotoxicity probably is associated with herbicide transport, which is more sensitive to changes in water content than is the concentration of herbicide in soil solution.

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