Potassium Quantity–Intensity Parameters and Their Correlation with Bean Plant Indices in Some Calcareous Soils

Plant availability of potassium (K) in soils is controlled by dynamic interactions among its different pools. Potassium quantity–intensity (Q/I) parameters were determined to relate them to bean plant indices in a pot experiment. The results showed that the activity ratio at equilibrium (AR^k) ranged from 0.015 to 0.358 (mmol L^?1)^0.50, the potential buffering capacity (PBC) ranged from 7.54 to 26.32 mmol kg^?1/(mmol L^?1)^0.50, the labile K (Δk°) ranged from 9.1 to 112.2 mg kg^?1, and the K adsorbed at specific sites (Kx) ranged from 6.51 to 69.69 mg kg^?1. The results of pot experiment showed that some K Q/I parameters were significantly correlated with some plant indices. Also, the correlation study showed that readily exchangeable K was significantly correlated with K Q/I parameters except K_x. The results of this research show that the K Q/I method can be used for estimating of soil K availability for bean.     

Evaluation of Extractants and Quantity–Intensity Relationship for Estimation of Available Potassium in Some Calcareous Soils of Western Iran

Accurate estimation of the available potassium (K⁺) supplied by calcareous soils in arid and semi‐arid regions is becoming more important. Exchangeable K⁺, determined by ammonium acetate (NH₄OAc), might not be the best predictor of the soil K⁺ available to crops in soils containing micaceous minerals. The effectiveness of different extraction methods for the prediction of K‐supplying capacities and quantity–intensity relationships was studied in 10 calcareous soils in western Iran. Total K⁺ uptake by wheat grown in the greenhouse was used to measure plant‐available soil K⁺. The following methods extracted increasingly higher average amounts of soil K⁺: 0.025 M H₂SO₄ (45 mg K⁺ kg^?1), 1 M NaCl (92 mg K⁺ kg^?1), 0.01 M CaCl₂ (104 mg K⁺ kg^?1), 0.1 M BaCl₂ (126 mg K⁺ kg^?1), and 1 M NH₄OAc (312 mg K⁺ kg^?1). Potassium extracted by 0.01 M CaCl₂, 1 M NaCl, 0.1 M BaCl₂, and 0.025 M H₂SO₄ showed higher correlation with K⁺ uptake by the crop (P < 0.01) than did NH₄OAc (P < 0.05), which is used to extract K⁺ in the soils of the studied area. There were significant correlations among exchangeable K⁺ adsorbed on the planar surfaces of soils (labile K⁺) and K⁺ plant uptake and K⁺ extracted by all extractants. It would appear that both 0.01 M CaCl₂ and 1 M NaCl extractants and labile K⁺ may provide the most useful prediction of K⁺ uptake by plants in these calcareous soils containing micaceous minerals.     

Assessment of Soil Potassium Sufficiency as Related to Quantity‐Intensity in Montmorillonitic Soils

Abstract

No studies have been conducted to evaluate the potassium (K) quantity‐intensity (Q/I) relationships that exist in eastern South Dakota soils and how that may affect K fertility interpretations. The objectives of this study were to i) evaluate the K status of smectite‐dominant soils through quantity‐intensity relationships and (ii) relate the findings to current research on soil K release and plant availability. Soil and plant tissue samples were collected from eight different corn production fields across east‐central South Dakota. Samples were collected from areas where corn plants did or did not exhibit K deficiency symptoms. Quantity‐intensity plots were developed and used to derive the typical Q/I parameters. Little difference existed in Q/I parameters and the form of Q/I plots among field sites. The AR_e ^K and ΔK⁰ values ranged from 0.0013 to 0.0113, and ?0.47 to 0.18 cmol_c kg^?1, respectively, and most sites were considered K insufficient. The predominant phyllosilicate present in the clay‐sized fraction was montmorillonite with an estimated 17% tetrahedral charge. These soils would not be expected to contribute much plant‐available, nonexchangeable K and would be in need of frequent K fertilization. Presumably, these and similar soils, upon K exhaustion, rely heavily on K released from K‐bearing silt‐sized particles and may be highly dependent on surface‐controlled dissolution processes for labile K replenishment. Additional research needs to be conducted concerning the release kinetics of K from K‐bearing minerals of these soils.     

Effect of Potassium Nutrition of Different Varieties of Rice on the Redox Status in Microzone Rhizosphere Soils

Being divided into three groups-strong,moderate and weak-according to the different kinetic parameters (Fmax,km,Cmin) of potassium uptake by crops,21 cultivars of rice have been studied to find out the relationships between their potassium nutrition and the oxidation-reduction status in the rhizosphere soils. Results show that,with no application of K fertilizer,there were higher contents of active reducing substances and ferrous iron in rhizosphere soils planted with cultivars,such as Zhongguo 91,week in absorbing potassium than in soils cropped with cultivars,Shanyou 64,stronger in absorbing potassium.As a result of K application,however,these toxic substances were decreased appreciably in the soil,particularly in the root zone where weakly K-absorbing sultivars were growing,and the parameter of soil redox (pH pE) was increased,the most striking example of this being found in the rhizosphere soil where the more strongly K-absorbing sultivars were growing.On and close to the root surface in soils where rice plants were supplied with potassium fertilizer,rather more iron oxide had been accumulated compared with rice receiving no potash,and even greater amounts of red iron oxide precipitated on the rice root in neutral paddy soils.As shown by the concentration distribution of active reducing substances and ferrous iron in a microzone of the profile,the redox range of rice roots supplied with potassium may extend as far as several centimeters from the root surface.It can thus be seen that potassium nutrition exerts its effect first on the morphological properties of rice roots and their exudation of oxygen,then on the content of soluble oxygen and the count and species of oxygen-consuming microbes in the rhizosphere soil,and finally on the redox status of the soil.     

Comparative Study on the Kinetic Equations of Potassium Release from Soils

Elovich,two-constant,parabolic diffusion,exponential,second-order,first-order and zero-order equations were used to describe the kinetic characteristics of potassium desorption from six paddy soils of Zhejiang Province in a constant electric field (44.4V/cm) of EUF.Results showed that the second-order and Elovich equations could describe the potassium desorption kinetics best,as evidenced by the highest correlation coefficients (r) and the lowest standard errors (SE).The first-order,two-constant and parabolic diffusion equations also described the K desorption kinetics well,as showed by the relatively high correlation coefficients and relatively low standard errors.The zero-order equation did not describe the K desorption satisfactorily with a relatively low correlation coefficient and relatively high standard error.However,the exponential equation could not be used to describe the K desorption kinetics,due to the lowest correlation coefficient and the highest standarderror.     

Adsorption of Acrylonitrile on Some Soils and Minerals from Aqueous Solutions

Equilibrium and kinetic studies have been made on the adsorption of acrylonitrile(CH2=CHCN) on three soils and four minerals from aqueous solutions.It was shown that the organic matter was the major factor affecting the adsorption process in the soils.The conformity of the equilibrium data to linear type(one soil) and Langmuir type(two soils) isotherms indicated that different mechanisms were involved in the adsorption.This behavior appears bo be related to the hydrophobicity of soil organic matter due to their composition and E4/E6 ratio of humic acids.The adsorption kinetics were also different among the soils,indicating the difference in porosity of organic matter among the soils,and the kinetics strongly affected the adsorption capacity of soils for acrylonitrile.Acrylonitrile was slightly adsorbed from aqueous solutions on pyrophyllite with electrically neutral and hydrophobic nature,and practically not on montmorillonite and kaolinite saturated with Ca.However,much higher adsorption occurred on the zeolitized coal ash,probably caused by high organic carbon content(107g/kg).     

Potassium Fixation and Release Characteristics of Some Benchmark Soil Series under Rice–Wheat Cropping System in the Indo‐Gangetic Plains of Northwestern India

Abstract

Potassium (K) fixation and release in soil are important issues in long‐term sustainability of a cropping system. Fixation and release behavior of potassium were studied in the surface and subsurface horizons in five benchmark soil series, viz. Dhar, Gurdaspur, Naura, Ladowal, and Nabha, under rice–wheat cropping system in the Indo‐Gangetic plains of India. Potassium fixation was noted by adding six rates of K varying from 0 to 500 mg kg^?1 soil in plastic beakers while K release characteristics were studied by repeated extractions with 1 M HNO₃ and 1 M NH₄OAc extractants. The initial status of K was satisfactory to adequate. Potassium fixation of added K increased with the rate of added K irrespective of soil mineralogy and soil depth. Soils rich in K (Ladowal and Nabha) fixed lower amounts (18–42%) of added K as compared to Gurdaspur, Dhar, and Naura (44.6–86.4%) soils low in K. The unit fertilizer requirement for unit increase in available K was more in low‐K soils. The study highlights the need for more studies on K fixation in relation to the associated minerals in a particular soil. Potassium‐release parameters such as total extractable K, total step K, and CR‐K varied widely in different soil series, indicating wide variation in the K‐supplying capacity of these soils. K released with 1 M NH₄OAc extractant was 20–33% of that obtained with 1 M HNO₃. Total extractable K using 1 M HNO₃ varied from 213 to 528 mg kg^?1 and NH₄OAc‐extractable K ranged from 71 to 312 mg kg^?1 soil in surface and subsurface layers of different soil series. The Ladowal and Nabha series showed higher rates of K release than Gurdaspur, Dhar, and Naura series, indicating their greater K‐supplying capacity.     

Soil Organic Carbon,Phosphorous, and Potassium Status in Rice–Wheat Soils of Different Agro-climatic Zones in Indo-Gangetic Plains of India

The status of available macronutrients [phosphorus (P) and potassium (K)] and soil organic carbon (SOC) of the surface soil under a rice–wheat cropping system was studied in 40 districts of the Indo-Gangetic Plains (IGP) of India. The soil samples were collected from the farmers' fields in four transects (Trans-, Upper, Middle, and Lower Gangetic Plains) of the IGP. The selection of farmers, villages, blocks, and districts within an agro-climatic zone (ACZ) was done on the basis of a multistage statistical approach. The available macronutrients were characterized as low, medium, and high. In Trans-Gangetic Plains, SOC, available P, and available K were in the ranges of 0.06–0.86%, 6.7–85.1 kg ha^?1, and 50–347 kg ha^?1, respectively. In Upper Gangetic Plains, the respective values were in the ranges of 0.05–2.55%, 4.5–155.0 kg ha^?1, and 45 to 560 kg ha^?1. Similarly, in Middle Gangetic Plains, these values were in the ranges of 0.04–2.01%, 4.7–183.7 kg ha^?1, and 72–554 kg ha^?1, respectively. In Lower Gangetic Plains, respective values were 0.12–1.78%, 2.2–112.0 kg ha^?1, and 83–553 kg ha^?1. In Trans-Gangetic plains, the majority of the soils in the midplains ACZ representing intensively cultivated rice–wheat system area were low to medium in SOC and available P, whereas available K status was medium to high. Irrespective of the agroclimatic variations, more than 90% of the soils were low to medium in SOC and available P with a marginal deficiency of K. The majority of the coarse-textured soils in Shiwaliks were found to have low to medium SOC and available P, whereas less intensively cultivated arid zone soils were high in SOC, available P, and available K. In Upper and Middle Gangetic Plains, the majority of the soils tested medium for SOC and medium to high in available P and K. The dominance of medium status of available P in these soils could be due to mining of soil P by the rice–wheat cropping system practiced in these regions for more than 300 years. In Lower Gangetic Plains, the SOC was medium to high in most of the soils, whereas available P and K were high. Recent introduction of the rice–wheat system on intensive scale in these traditionally rice-growing areas resulted in less mining of SOC, P, and K.     

Effect of pH on Zinc Sorption–Desorption by Soils

The objective of this study was to examine the effect of soil pH on zinc (Zn) sorption and desorption for four surface soils from the Canterbury Plains region of New Zealand. Zinc sorption by the soils, adjusted to different pH values, was measured from various initial solution Zn concentrations in the presence of 0.01 M calcium nitrate [Ca(NO₃)₂]. Zinc desorption isotherms were derived from the cumulative Zn desorbed (µg g^?1 soil) after each of 10 desorption periods by sequentially suspending the same soil samples in fresh Zn‐free 0.01 M Ca(NO₃)₂. Zinc sorption and desorption varied widely with soil pH. Desorption of both native and added Zn decreased continuously with rising pH and became very low at pH values greater than 6.5. The proportion of sorbed Zn that could be desorbed back into solution decreased substantially as pH increased to more than 5.5. However, there were differences between soils regarding the extent of the hysteresis effect.     

Spectrophotometric and Inductively Coupled Plasma–Optical Emission Spectroscopy Determination of Gallium in Natural Soils and Soils Polluted by Industry: Relationships between Elements

The aim of this work was to determine gallium contents in different soils of Poland using a sensitive spectrophotometric method based on the complex of Ga(III) with chrome azurol S and benzyldodecyldimethylammonium bromide and inductively coupled plasma–optical emission spectrometry technique. The total content of gallium in the soils clearly depends on the soil location and properties and ranged from 41.7 to 437 μg g^–1. The contents of gallium determined in 10% nitric acid and 1 M of magnesium chloride extract ranges respectively from 38.0 to 81.9% and 20–40% of the total content of this element. A strong correlation has been found between gallium and zinc, cadmium, lead, and copper. The high Pearson correlation coefficient values and the proportional relationship between the concentrations of Ga and these metals may make it possible to treat gallium as an indicator of soil contamination with heavy metals.     

pH Effect on kinetics of Heavy Metal Sorption in Soils

The pH effect on the sorption kinetics of heavy metals in soils was studied using a constant flow leaching method.The soil samples were red soil collected from Yingtan,Jiangxi,and yellow-brown soil from Nanjing,Jiansu,The heavy metals tested were zinc and cadmium.Assuming that the experimental data diffed to the following kinetic rate equation:1/c.dx/dt=kx∞-kx,the rate constant k of sorption could be determined from the slope of the straight line by plotting of 1/c,dx/dt vs.x.The results showed that the pH effect on the rate constants of heavy mental sorption in soils was very significant.The values of k decreased with increasing pH.The sorptions were more sensitive to pH in red soil than in yellow-brown soil.     

Influence of Organic Manure on Organic Phosphorus Fraction in Soils

The transformation of organic P(Po) from organic manures in two types of soils (ultisol and entisol) and the influences of external addition of organic substance or inorganic P(Pi) on Po under the condition of the 60% maximum water capacity were investigated.The results obtained from Po fractionation experiments indicated that all the Po fractions except for the highly resistant Po fraction decreased during incubation.Application of pig feces and cow feces could largely increase each fraction of Po in the soils.Immediately after application of organic manure into the soils a large part of labile and moderately labile Po from organic manure was transferred into moderately resistant Po,which might be due to the fact that Ca-or Mg-inositol P was precipitated into Fe-inositol P.However,the availability of Po from organic manure in the soils would increase again after incubation because of the transformation of moderately labile and resistant Po fractions into labile Po fractions.Addition of cellulose or Pi into the soils showed a good effect on increasing all the Po fractions except for the highly resistant Po,and this effect was much more pronounced when cellulose was applied in combination with Pi.Therefore,in view of the effect of organic manure on improving P nutrition to plant,attention should be paid to both the Po and the organic substances from organic manure,It is suggested that application of Pi fertilizer combined with organic manure may be referred to as an effective means of protecting Pi from chemical fixation in soil.     

Potential of Carbon Dioxide Biosequestration of Saline–Sodic Soils during Amelioration under Rice–Wheat Land Use

Potential for carbon dioxide (CO₂) biosequestration was determined during the reclamation of highly saline–sodic soils (Aridisols) after rice (2003) and wheat (2003–2004) crops at two sites in District Faisalabad, Pakistan. Two treatments were assessed: T₁, tube-well brackish water only; and T₂, soil-applied gypsum at 25% soil gypsum requirement?+?tube-well brackish water. The irrigation water used at both sites had different levels of salinity (EC 3.9–4.5 dS m^?1), sodicity (SAR 21.7–28.8), and residual sodium carbonate (14.9 mmol_c L^?1). Composite soil samples were collected from soil depths of 0–15 and 15–30 cm at presowing and postharvest stages and analyzed for pH, EC_e, and sodium adsorption ratio (SAR). After rice harvest, there was no significant effect of gypsum application on EC_e, pH, and SAR at both sites, except pH at 0–15 cm depth decreased significantly with gypsum at site 1. After wheat harvest, EC_e, pH, and SAR decreased significantly with gypsum at site 1, whereas the effect of gypsum on these parameters was not significant at site 2. Compared to initial soil, EC_e and SAR in soil decreased considerably after rice or wheat cultivation, particularly at site 1, whereas pH increased slightly due to cultivation of these crops. For rice, the total CO₂ sequestration was significantly increased with gypsum application at both sites and ranged from 1499 to 2801 kg ha^?1. The total sequestration of CO₂ was also significantly increased with gypsum application in wheat at both sites and ranged from 2230 to 3646 kg ha^?1. The amounts of CO₂ sequestered by crops due to gypsum application were related to seed and straw yield responses of rice and wheat to gypsum, which were greater at site 1 than site 2. Also, the yield response to applied gypsum was greater for rice than wheat at site 1, whereas the opposite was true at site 2. Overall, the combined application of gypsum with brackish water reduced soil EC_e and SAR compared to brackish water alone, particularly at site 1. Our findings also suggest that the reclamation strategies should be site specific, depending on soil type and quality of brackish water used for irrigation of crops. In conclusion, the use of gypsum is recommended on brackish water–irrigated salt-prone soils to improve their quality, and for enhancing C biosequestration and crop production for efficient resource management.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Crop Response to Long‐Term Potassium Application as Affected by Potassium‐Supplying Power of the Selected Soils in Northern China

Potash resources in China are very scarce. It is especially important to correctly evaluate the potential potassium‐supplying power of soils in northern China in order to use soil potassium sufficiently and potash fertilizer properly. Regional differences in crop yield responses to long‐term potassium application in northern China were determined in this study. Twenty‐five representative soil samples from 13 provinces, municipalities, and autonomous regions of major agricultural regions in northern China were collected from the surface layer (0–20 cm) before crop seeding in 1993. A soil potassium‐depletion study was carried out in a pot experiment with successive planting of corn seedlings for 10 harvests in the 25 soils. Since 1993, field trials on wheat and corn response to long‐term potassium application were conducted at the fixed sites of HLJ‐SC (Shuangcheng of Heilongjiang), JL‐LFZ (Liufangzi of Jilin), HB‐XJ (Xinji of Hebei), SX‐LF (Linfen of Shanxi), QH‐NKY (Nongkeyuan of Qinghai), and XJ‐CJ (Changji of Xinjiang). Soil‐available potassium, slowly available potassium, total potassium, main clay minerals, cation exchange capacity, particle size, other available nutrients, and potassium concentration in plants were measured. The results showed that potential potassium‐supplying powers of the 25 tested soils, which were respectively evaluated by the contents of slowly available potassium in soils and the amount of total net potassium uptake in the pot experiment, generally tended to increase from eastern to western regions in northern China. Significant wheat yield responses to long‐term potassium application in the field trials were found since 2000 in the north‐central region but not observed until 2004 in the northwestern region. Significant corn yield responses to long‐term potassium application in the field trials were found starting in soils of the northeastern region, following in soils of the north‐central region, and then in soils of the northwestern region. These were consistent with potential potassium‐supplying power of the soils, which tended to increase from east to west regions.     

Aggregate Stability and Its Relationship with Some ChemicalProperties of Red Soils in Subtropical China

The stability of aggregates in the surface soil is crucial to soil erosion and runoff generation. Thus, to understand the stability and the breakdown mechanisms of soil aggregates as well as the relationship between aggregate stability and selected soil chemical properties, such as different forms of Fe and A1 oxides, organic matter, CEC and clay content, the aggregates of slightly and severely eroded red soils derived from Quaternary red clay in subtropical China were analyzed using the routine wet sieving and the Le Bissonnais methods. The results indicated that the aggregates of the severely eroded soils were more stable than those of the slightly eroded soils. Different aggregate breakdown mechanisms resulted in different particle size distribution. The slaking from entrapped air in aggregates severely destroyed the soil aggregates,especially in the slightly eroded soils. Meanwhile, mechanical breakdown and microcracking had little effect on the aggregates compared to slaking. The fragments resulting from slaking were mainly microaggregates that increased in size with increasing clay content. The main fragment size of the slightly eroded soils was 1.0-0.2 mm, while for the severely eroded soils it was 5.0-2.0 mm and 1.0-0.5 mm. Overall, more than 20% of the fragments were smaller than 0.2 mm.In addition, aggregate stability was positively and often significantly correlated with Fed, Ald, Feo and clay content, but significantly and negatively correlated to SOC.     

Vermiculite-Type Clay Minerals in Some “Kuroboku” Soils Distributed in Mie Prefecture of West Japan

In the past several years, the occurrence of vermiculite-type clay minerals and the problem of the formation of Al-interlayers have attracted the intensive attention of soil clay mineralogists. A number of papers have appeared in Japan, in Which the identification data of the vermiculite-type minerals with stable 14 Å spacing were given. (Matsui 1959, 1960; Kanno 1961b, Kato 1961, 1962a, 1962b; Egawa 1963).     

Effect of Synergism and Antagonism between Metals on Toxicity in Soils

Synergism and antagonism of cadmium(Cd),copper (Cu) and selenium (Se) to biological toxicities in red soil,yellow brown soil and black soil were evaluated by MICROTOX method.The relation between forms of the tested metals in soil and the synergism or antagonism between them was also studied.Results showed that owing to the difference of soil chemical properties,toxicity of these metals in soils was different.In red soil with acid reaction and low in cation exchange capacity,antagonism occurred significantly between metals when they coexisted at high concentrations,while synergism occurred only under low concentrations.It is indicated that in red soil,toxicity of metals affected by synergism or antagonism depends on concentration of the metals present.For yellow brown soil and black soil with larger cation exchange capacity and lower exchangeable aluminium(Al),no toxicity of metals was observed even if metals were added to soil in high concentrations.Synergism and antagonism between Cd,Cu and Se were controlled by the forms of metals present.The amount of water-soluble metals was the most important factor in determining synergism and antagonism. In this paper,comparisons of synergism and antagkonism between metals in soils and in water solutions were made.There occurred the synergism of metal toxicity in water solutions when the concentration of coexisting metals was high.This is just opposite to the case in soils.