Potassium release by some delaware soils

Abstract

The A and B horizons of 29 Delaware soils were extensively cropped to sudan grass (Sorghum vulgare Pers. Piper) and corn (Zea mays L. Pioneer Brand Hybrid No. 3958) to evaluate the K release characteristics of these soils.

Various chemical analyses were made on these soils. The double acid North Carolina extractant (NCE) was good at predicting K uptake during the early stages of the experiment and was most sensitive with A horizon soils. However, this extractant was not suitable for predicting K uptake in the latter part of the experiment when nonexchangeable K was more important. Boiling IN HNO₃ was a good extractant in the latter part of the experiment when nonexchangeable K was being released and it also predicted K uptake from the B horizon well. Soils leached with 0.025M MgCl₂ and incubated 25 days to determine K released were also highly correlated with plant uptake.     

Mercury intrusion porosimetry of some New Zealand soils in relation to clay mineralogy and texture

Pore size distributions in the 10/10⁴ nm e.c.d. range in aggregates from three New Zealand soils with largely monomineralic clay fractions, were determined by mercury porosimetry after oven drying and also after critical point drying following methanol and then CO² exchange from a range of water contents. A soil containing halloysite showed considerable porosity in the fine pores (10–30 nm) regardless of the method of drying. A smectitic soil showed virtually no porosity in the 10²–10⁴ nm range when oven dry. A soil containing allophane was dominated by large pores (> 10³ nm). The change from a fine (clayey) to a coarser (clay loam) texture within the profile of one soil was reflected in an increase in large pores.     

Potassium replenishment capacity of illitic soils at their minimal exchangeable K in relation to clay mineralogy

Potassium replenishment capacity of eight soil series with varying illite content of their clay fraction were studied at their minimal exchangeable K through green house experiments. Higher minimal K levels were found in soils with high initial K status. Maximum K uptake values were associated with high minimal K. The % illite also had a significant relationship with minimum K levels. Average daily rates of K replenishment of soils varied between 0.25 and 0.67 mg kg^?1 soil after reaching minimum K. The K replenishment rates were found highly correlated with minimal exchangeable K (0.96^**). Amount of clay failed to attain the level of significance with K replenishment rate. Soils with higher illite content in their clay showed high K replenishment rates.     

Potassium fixation capacity of some highly calcareous soils as a function of clay minerals and alternately wetting-drying

ABSTRACT

The current research was done to investigate the effect of wetting-drying cycles, time, and clay mineralogy on K fixation capacity of highly calcareous soils. In order to conduct the study, eight soil samples were collected. The samples were treated with different concentrations of K including 200 (K1), 400 (K2) and 800 mg kg^?1 (K3) and 8 different incubation time including 6 h (t1), 24 h (t2), 72 h (t3), one week (t4), two weeks (t5), one month (t6), two months (t7) and three months (t8). Also, a wetting-drying treatment was done (td) in order to simulate the effect of irrigation and soil drying on K fixation. The results showed that for all K levels addition, the percentage of fixed K was increased with time. The K fixation content was increased with the increase in the added K from K1 to K3, while K fixation percentage was decreased. The results also showed that there was a significant difference between soils with wetting-drying treatment (td) and soils with three-month incubation (t8) in K fixation capacity, so that the fixation of K by the soils was increased with wetting-drying cycles.     

Effects of biochar application on soil potassium dynamics and crop uptake

Biochar has been suggested as a possible means for enhancing soil fertility, including soil potassium (K). However, understanding of the effects of biochar on soil K dynamics remains limited. In this study, a pot trial was conducted to investigate the influence of biochar application (0, 5, 10, and 25 g kg^?1 soil) on soil K dynamics and crop K uptake under a winter wheat–maize rotation in two types of soil (an Alfisol, which contained a high initial available K and an Entisol, which contained a high abundance of 2 : 1 K‐bearing minerals). Changes in soil K in various forms following biochar application and cropping were determined, and their contributions to plant K uptake were evaluated. Soil microbial activity, especially the development of K‐dissolving bacteria (KDB), was evaluated to obtain insights into its effects on the weathering of K‐bearing minerals in the soils. During the wheat growth period, crop K uptake was more enhanced (13.6–40.5% higher) in the Alfisol than in the Entisol due to the higher availability of water‐soluble and exchangeable K, while K fixation occurred in the Entisol because of the higher content of 2 : 1 K‐bearing minerals. During the maize period, crop K uptake was generally higher in the Entisol soil due to the release of non‐exchangeable K. In addition, biochar application enhanced the growth of KDB in both soils, which was associated with changes in soil pH and water‐soluble K. However, improved mineral K release was observed only in the Entisol. It is concluded that biochar application could be a feasible soil amendment to improve soil K availability, but crop K uptake responses may vary depending on soil types. Soils abundant in 2 : 1 K‐bearing minerals tend to prolong biochar effects on crop K uptake. Biochar application enhanced the growth of KDB, which may facilitate mineral K weathering in soils with abundant K‐bearing minerals.     

Extraction of potassium from some kaolinitic soils of the tropics

Abstract

Three methods for soil potassium extraction (M NH₄OAc pH 7, 0.01 M AgTU and 30 % hot H₂SO₄) were compared for a variety of kaolinitic soils of the tropics. The AgTU‐extractable K was much higher than the M NH₄OAc‐extractable K when vermiculite clay was present in the soil. The correlation between both was given by an R value of 0.937. The amounts of K extracted by 0.01 M AgTU and by hot H₂SO₄ were approximately the same. The R value for these two methods was 0.843.

It is suggested that the AgTU extractant could be used for determination of plant‐available K in soil and for testing for the presence or absence of vermiculite clay in soils.     

Potassium fertilization on sandy soils in relation to soil test,crop yield and K-leaching

To study the influence of potassium (K) fertilizer rate on soil test K values, crop yield, and K-leaching in sandy soils, four long-term fertilizer experiments (0–60–120–180 kg K ha^?1 a^?1) were initiated in 1988 in northern Germany on farmers fields. Clay content of the plow layer was about 4%, and organic matter between 2% and 5%. Plant available soil K was estimated with the double lactate (DL) method. Small grain cereals (rye and barley) did not respond to K fertilization in the 7-year period even though the soil test value of the K-0 plots decreased from ca. 90 to ca. 30 mg K_DL kg^?1 within 3 years. This value remained almost constant thereafter. Crop removal (including straw) of 75 kg K ha^?1 a^?1 was therefore apparently supplied from nonexchangeable K fractions. Compared to the optimum, no K application reduced the yield of potato by up to 21%, and that of white sugar yield up to 10%. Maximum potato yield was obtained by annually applying 60 kg K ha^?1 which resulted in a test value of 60 mg K_DL kg^?1 soil. Maximum potato yield was also obtained at 40 mg K_DL kg^?1 soil, however, with a single application of 200 kg K ha^?1. Similar results were obtained with sugar beet. This indicates that for maximum yield, even for K demanding crops, it is not necessary to maintain K_DL values above 40 mg K kg^?1 soil throughout the entire crop rotation. Soil test values increased roughly proportional to the K fertilizer level. About 120 kg fertilizer K ha^?1 a^?1, markedly more than crop K removal, was required to maintain the initial K_DL of 90 mg kg^?1. The K concentration of the soil solution in the top soil measured after harvest was increased exponentially by K fertilizer level and so was K leaching from the plow layer into the rooted subsoil. The leached quantity increased from 22 kg K ha_?1 a_?1 in the plot without K application to 42.79 and 133 kg Kha^?1 a^?1 in plots supplied with 60, 120 and 180 kg K ha^?1 a^?1 respectively. Soil test values around 100 mg K_DL kg^?1 on sandy soils, as often found in the plow layer of farmers fields, lead to K leaching below the root zone that may exceed the critical K concentration of 12 mg K T^?1 for drinking water.     

Potassium release characteristics and mineralogical characteristics of some delaware soils

Abstract

Twenty‐eight agriculturally important Delaware soils were cropped intensively in a greenhouse experiment. There was no consistent positive correlation between K uptake and percent sand, silt, clay, clay minerals of the clay fraction, K‐feld‐spars of the sand fraction or K‐feldspar weathering of the soils from the A horizon. Only potassium feldspar from the sand fraction and K‐feldspar weathering correlated with K uptake in the soils of the B horizon. This correlation was only significant at the latter part of the experiment when nonexchangeable K was probably the source of plant available K.     

Boron adsorption characteristics of some acidic alluvial soils in relation to soil properties

Abstract

We investigated boron (B) adsorption characteristics for 16 acid alluvial soils as a function of equilibrium B concentration (0–80 μg/mL) and the effect of soil properties on such adsorption. The adsorption data for the soils could be described by Freundlich, Temkin, and BET isotherm equations over the entire concentration ranges studied, and by Langmuir and Eadie‐Hofstee equations only over a limited range. In general, the B adsorption capacity and the energy of retention of the soils calculated from different equations are low, the average Langmuir adsorption maxima and bonding energy constant being 21.47 μg/g and 0.113 mL/μg, respectively, making B susceptible to leaching losses. Simple and multiple regression analysis show that the adsorption capacities are significantly influenced by organic carbon (C), cation exchange capacity (CEC), and different forms of aluminium (Al) content in soils. The energy related constants are also influenced by the forms of Al in soils. Existence of significant correlations between constants obtained from different equations confirmed the adsorption characteristics of the soils.     

Changes in the carbon concentrations and other soil properties of some Scottish agricultural soils: Evidence from a resampling campaign

The change in soil carbon (C) concentration, soil pH and major nutrients for approximately 1,000 topsoil sampled from on-farm experimental sites over a thirty-year period from 1950 to 1980 in north-east Scotland are summarized. This period coincided with increased agricultural intensification, which included regular liming and fertilizer additions. During 2017, 37 of these sites were resampled and reanlaysed. While pH and extractable phosphorus (P) and potassium (K) increased over this period, there was no detectable change in the percentage loss on ignition. Composite soil samples were taken by auger from a depth of 0–15 cm and compared with the corresponding archived samples collected at the initiation of each experiment. Analysis of these resampled soils indicated no significant change in soil carbon (C), although soil pH, extractable magnesium (Mg) and K and Nitrogen (N) concentrations were significantly greater (p < .001) but extractable soil P concentration was significantly less (p = .015) compared with the original samples. Even though measuring C concentration alone is a poor indicator of overall changes in soil C stocks, it does provide a relative quick “early warning” of C losses that would justify a more comprehensive measure of stocks.     

Ability of different soil extraction methods to predict potassium release from soil in ley over three consecutive years

To avoid over‐fertilization of potassium (K) and thereby a mineral composition in the grass crop not optimal for animal health, estimation of K release from soil is important. The analytical methods should therefore predict the total K release. Furthermore, to minimize costs for the farmers they should provide information which remains valid over a period of several years. The relationship between different soil extraction procedures for K and K uptake in ley for three subsequent years after soil sampling was studied in 19 field experiments on a range of mineral soil types in Norway. Potassium determined with solutions that extracted exchangeable K or parts of exchangeable K (0.01 M CaCl₂, 0.5 M NaHCO₃, 1 M NH₄oAc, or ammonium acetate lactate) was significantly (p < 0.05) related to the K yield only in the 1st yr after soil sampling. Potassium extracted with boiling in 1 M or 2 M HNO₃ was significantly related to the K yield only in the 2nd and 3rd yr. Potassium extracted with cold 2 M HCl, boiling 0.1 M HNO₃ or 0.5 M HNO₃ was significantly related to the K yield in all 3 yr after soil sampling. Among these extractants, 0.1 M and 0.5 M HNO₃‐extractable K were better predictors of K uptake than 2 M HCl‐extractable K. These three extractants release some non‐exchangeable K in addition to exchangeable K. The fraction of 1 M HNO₃‐K extractable with 0.1 M HNO₃ varied from 4% to 45%, whereas from 15% to 78% of 1 M HNO₃‐K was extractable with 0.5 M HNO₃. Consequently, the more easily releasable fraction of K extracted by boiling with 1 M HNO₃ varied considerably between different sites.     

Zinc and copper in some soils of Egypt as related to other soil properties

Total Zn in alluvial and calcareous soils (average 138 and 70 ppm respectively) was significantly related to their contents of CaCO₃ (negatively), O.M. and clay (positively). Extracting Zn by Na₂EDTA gave the highest values for both soil types. Total Cu contents varied widely from 26 to 111 ppm in alluvial and from 15 to 30 ppm in calcareous soils. They were negatively correlated with the CaCO₃ contents. The pot experiments showed that EDTA(NH₄)₂CO₃, Na₂EDTA and DTPA are reasonable extractants for available Zn from both soil types. DTPA was efficient for all soils investigated, while Na₂ EDTA and EDTA-citrate were specific for extracting Cu from calcareous soils.     

Shrinkage of clay soils: A statistical correlation with other soil properties

The hypothesis that the shrinkage of soils is greater when expansible minerals are dominant was tested with 63 soils containing between 40 and 64% clay. Shrinkage between pF 2 and 4 (0.1 and 10 bar) correlated significantly with the expansible mineral content (measured by ethylene glycol retention) for remoulded but not for dried and rewetted specimens. Shrinkage between pF 4 and 6 (10 and 10³ bar) was strongly correlated with the expansible mineral content for both kinds of specimens. The physical significance of the results is discussed, and it is concluded that interlamellar shrinkage is not the principal component of bulk shrinkage.     

Distribution and mobility of radiocesium in relation to the clay fraction mineralogy and soil properties in the Iput River floodplain

The role of the mineralogy of the clay fraction and the physicochemical properties of alluvial soils in the floodplain of the Iput River and its tributary the Buldynka River (in the region of the settlement of Starye Bobovichi in Bryansk oblast) in the distribution and immobilization of radioactive isotope ¹³⁷Cs from the atmospheric fallout after the Chernobyl accident was studied. The soils had a sandy texture; a significant variation in the content of amorphous iron oxides (0.1–0.77%) and labile manganese (11.2–193 mg/kg), the cation exchange capacity (6.1–54.2 meq/100 g soil), and the base saturation (29–100%) was common; an appreciable content of X-ray amorphous mineral substances in the clay fraction (<1 μm) enriched with organic carbon (7.7–13.1%); the predominance of trioctahedral hydromicas (Me=50%) in the clay fraction; and the presence of fine-disperse quartz and lepidocrocite. The specific activity of the ¹³⁷Cs in the clay fraction of the moderately and strongly contaminated layers increased with the increasing portion of smectite formations and (or) hydromicas. On the whole, the presence of the clay fraction favored a decrease in the ¹³⁷Cs mobility (the correlation between its content and that of exchangeable cesium was r=?0.608, n=17). However, the portion of exchangeable radiocesium (extracted with 1 M CH₃COONH₄, 1:10) had a tendency toward an increase with increasing content of hydromicas in the clay fraction. Thus, the minerals of this group were a potential source of exchangeable ¹³⁷Cs in the soils. The significant role of amorphous and mobile iron forms in the immobilization and migration of radiocesium in the secondary contaminated horizons of the alluvial soils was revealed.     

Potassium behavior and clay mineral composition in the soil with low effectiveness of potassium application

ABSTRACT

Increasing exchangeable potassium (ExK) content in soil to an appropriate level is important to mitigate the transfer of radioactive cesium to crops. We focused on a buckwheat (Fagopyrum esculentum Moench) field with a low ExK content, despite the application of K, in Fukushima Prefecture, Japan (Field A), following the Tokyo Electric Power Company Fukushima Dai-ichi (No. 1) Nuclear Power Plant accident in March 2011. We examined the relationship between K concentration and clay mineral composition in the soil of Field A and compared the findings with another field in Fukushima Prefecture (Field B) to clarify whether K applied to the soil was leached or remaining fixed. Pot experiments showed that K concentration in water seepage from pots following irrigation was significantly lower in pots from Field A than in those from Field B. Soil ExK content after soybean cultivation was lower in soils of Field A than those of Field B. These results indicate that K applied to Field A was fixed in the soil. Analysis of clay mineral composition confirmed the distinctive vermiculitic nature of Field A soils. This clay mineralogy would be associated with the higher K fixation ability of Field A than Field B soils. This study demonstrated that K fixation in vermiculite was a factor preventing the increase in ExK content from K application to Field A.     

长期定位施肥对夏玉米钾素吸收及土壤钾素动态变化的影响

以长期定位试验为平台,夏玉米品种郑单136为材料,设置CK（不施肥）,NP（施氮、 磷肥）,NPK（施氮、 磷、 钾肥）和1.5MNPK（小麦季施高量氮、 磷、 钾肥+有机肥,玉米季仅施用化肥）4个处理,研究夏玉米钾素吸收规律及生育期内土壤钾素动态变化。结果表明,生育期内施钾与不施钾处理夏玉米干物质积累量均一直增加,在成熟期达到最大值; 在施用氮、 磷肥的基础上增施钾肥不但可以提高夏玉米地上部干物质积累量,同时也可以提高叶片及茎秆中的钾素含量,进而提高夏玉米整个地上部吸钾量;而在氮、 磷、 钾肥基础上增施有机肥,对夏玉米干物质积累无显著影响,但可显著提高茎秆及叶片的钾素含量和地上部钾素吸收总量。夏玉米钾素吸收主要集中在灌浆期之前,在灌浆期达到最大值,之后钾素出现回流现象。夏玉米收获后与播种前相比,土壤水溶性钾和交换性钾含量无明显下降或者略有增加,而非交换性钾明显下降,非交换性钾是夏玉米钾素吸收的主要形式。夏玉米吸钾量与播种前土壤3种形态的钾素含量呈显著正相关。因此,增施钾肥对于改善夏玉米生产,维持土壤钾素平衡及实现农业可持续发展具有深远意义。     

Effects of liming on soil magnesium on some soils in New Zealand

Abstract

Results from 2 pastoral field lime trials showed that liming reduced exchangeable Mg. This effect increased with increasing rate of lime and with time following lime application, and was greatest in the top 0–50 mm depth. Soil solutions, sampled 2 years after liming, showed that solution Mg increased in increasing rate of lime. This effect was greatest in the top 20 mm of soil.

Lime incubation studies indicated that Mg fixation did occur on some of the soil studied, at pH >6.2. However, this did not account for the size of the observed effects of liming on exchangeable Mg in the field or explain the observed effects of liming at pH <6.2.

It is suggested therefore, that the major mechanism by which liming reduces exchangeable Mg, on these soils, is through displacement of exchangeable Mg into solution by the added Ca in lime, and subsequent leaching.

Results from other field trials suggest that liming will decrease exchangeable Mg if the change in pH‐dependent CEC (?ECEC) per unit change in soil pH is <15 me 100 g‐¹.     

Potassium isotherm partitioning based on modified quantity‐intensity relation and potassium buffering characterization of soils of North India

Background : Potassium (K) availability in soil and plant uptake is restrained by the dynamic interactions among the different pools of K. Aims : To understand these interactions, a study was undertaken to assess the quantity–intensity (Q/I) and buffering characteristics of rainfed maize (Zea mays L.) growing soils. Ten contrasting soils were evaluated for K partitioning changes in exchangeable K (ΔEK) and non‐exchangeable K (ΔNEK) pools in the soil‐solution phase and buffering characteristics using a modified version of Q/I approach. Results : The partitioned Q/I isotherms showed strong adsorption with the increase in K concentration ratio (CR^K) and the changes due to ΔEK were higher than changes due to ΔNEK. Total buffering capacity (PBC^K) significantly correlated (r = 0.92, p <0.01) with clay content with a major share contributed by buffering capacity owing to non‐exchangeable K ( ${\mathrm{PBC}}_{\Delta \mathrm{NEK}}^K$) rather than exchangeable K ( ${\mathrm{PBC}}_{\Delta \mathrm{EK}}^K$). The fixation capacity (β) factor, the magnitude of added K converted into a non‐exchangeable pool, ranged from 41 to 63%, whereas release (α) factor, the magnitude of added K converted to the exchangeable pool, ranged from 19 to 36%. Both threshold solution K (CK_r) and threshold exchangeable K (EK_r) values were found to be high in Satran clay loam (S2) and lower in Doon silty clay loam (S3) soils. The equilibrium exchangeable K (EK_o) was found close to minimum exchangeable K (E_min) in Doon silty clay loam (S3) and Babaweyl sandy clay loam (S1) soils and overall E_min constituted about 8.94 to 0.57% of the EK_o. Conclusion : It may be concluded that K Q/I isotherm partitioning provides a valuable insight to assess the dynamic relations. The ratio of α/β (K recharge index) could be used to evaluate the K enrichment capacity of soil to K additions while EK_r and E_min can be potentially useful in the elucidation of exchangeable K as K fertility index especially in soils with poor K fertilizer management.     

The mineralogy and potassium supplying power of some loessial and related soils of New Zealand

Sixteen Pallic (Aqualfs, Ustalfs, Aquepts, Ochrepts) and related soils collected from the North and South Islands of New Zealand were studied to determine if variations in nonexchangeable K supply could be explained by mineralogical composition. A strong relationship was found which indicates that mica is weathering to vermiculite. Proportions of vermiculite and kandite are generally higher in the North Island than in the South Island. Dominance of either micas or vermiculite or kandite is determined by the stage of weathering and/or the nature of parent materials. Soils that supplied more nonexchangeable K (K_nex) to ryegrass plants contained more mica in the clay fraction than soils that supplied less K_nex. The results confirmed that use of a soil test that includes a measure of K_nex (i.e. acid-extractable K) may be a vital part of identifying variations in plant available K status of the soils. It is concluded that the K supplying power of the Pallic and related soils is related directly to the amounts of mica present in clay fraction and that good K supplying soils will be transformed to K depleted soils as a result of increased weathering and leaching (pedogenic factors) and K exploitation in intensive farming systems.     

Potassium status and clay mineralogy in ordinary chernozems treated with different rates of potassium fertilizers

The effect of a single instance of potassium fertilization at rates of 0, 70, 140, and 280 kg/ha on the potassium status and clay mineralogy was studied in a field experiment on ordinary chernozems. The content of exchangeable potassium determined by the Maslova method and the potassium potential vary with greatest reliability in response to increasing fertilizer rates. The content of easily exchangeable potassium and the potassium-buffering capacity are insignificantly affected by the application rate of potassium fertilizers. The chernozems under study without fertilization are characterized by a low supply of available potassium. When potassium fertilizers are applied at rates of 70 and 140 kg/ha, the soils pass into the category of unstable or high supply according to different gradation systems. The lower limit of the high or optimal supply category is reached only at the application of 280 kg/ha of potassium fertilizer. However, even in this case, chernozems are characterized by a low potassium supply according to the value of potassium potential and the content of nonexchangeable potassium. A single application of potassium fertilizers does not cause significant changes in the contents of illites in the clay fraction.