Differential potassium buffer behavior of individual soils related to potassium corrective treatments

Abstract

Although the basic chemistry and behavior of potassium in the soil is well understood, little of this knowledge is used in soil testing and practical soil fertility mangement. In this study the K buffer behavior of three individual soils (Hagerstown silt loam (Typic Hapludalf), Gatesburg sand (Entic Haplorthod) and Gilpin channery silt loam (Typic Hapludult)) was investigated. The buffer relationships determined indicated very different K behavior for these soils even though exchangeable K soil tests indicated similar K levels. It was also determined that for these soils the buffer relationship was apparently independent of previous K management, indicating that the K buffer behavior could be included as part of soil characterization data.

The role of nonexchangeable K in determining K buffer behavior was also investigated. It was found that the levels of solution K where the release of nonexchangeable K becomes measurable (0.27 ‐ 0.83 × 10^‐4 M) are similar to solution K levels reportedly required for crop growth (0.02 ‐ 0.95 × 10^‐4 M). It was also found that these soils were capable of maintaining a relatively high level of exchangeable K even after extraction of significant amounts of nonexchangeable K with sodium tetraphenyl boron.

It was concluded that K buffering behavior of individual soils could and should be included in K management decisions involving corrective soil treatments and/or crop removal estimation. Otherwise, based on current soil tests, soils with very different K buffer behavior will be treated similarly.     

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.     

土壤供钾状况及土壤湿度对我国北方烤烟烟叶含钾量的影响研究

田间采样统计分析和框栽试验结果表明 ,土壤钾素状况及土壤的供钾能力是影响我国北方烟区烤烟烟叶含钾量的主要因子之一 ,合理施用钾肥和改善土壤的钾素状况是提高烟叶含钾量的有效措施 ;土壤湿度是保证土壤钾素向烟株根系运动的必要条件 ,在烟株生长期间 ,特别是在烟株移栽 4 0— 50天期间 ,保持土壤的相对含水量 6 0— 70 % ,是促进烟叶吸钾 ,提高烟叶含钾量的重要手段     

Use of intensity and capacity measurements to assess the potassium supplying power of soils

Abstract

For depletions of soil exchangeable potassium of between 15 and 50%, potassium concentrations in ryegrass and strawberry leaf were linearly related to pAR^O _K√BC^O where AR^O _K is the equilibrium potassium activity ratio and BC^O is the slope, measured at AR^O _K of the curve relating the quantity of labile potassium and the activity ratio. Potassium supplying power as measured by pAR^O _K√BC^O could also be expressed as a function of the equilibrium activity ratio and the mineral component of the cation exchange capacity of the soil.     

Kinetics of nonexchangeable‐potassium release and plant response in some calcareous soils

Nonexchangeable K⁺ constitutes a slowly available reserve that may significantly influence K⁺ fertility of soils. Laboratory and greenhouse experiments were conducted to characterize the K⁺ supply and nonexchangeable K⁺–release kinetics in 10 calcareous soils using 0.01 M CaCl₂ and 0.01 M oxalic acid extractions. Total K⁺ uptake by wheat (Triticum aestivum L.) grown in the greenhouse was used to measure plant‐available K⁺. The release of K⁺ was characterized by an initial fast rate followed by a slower rate. The nonlinear relationship in the early stages of the K⁺ release may be attributed to the edge sites, and release of K⁺ from interlayer exchange sites may be responsible for the second part of the K⁺ release. Kinetics of K⁺ release was described best with power function, which showed the best fit of the four models tested. Parameters of kinetics models in 0.01 M CaCl₂ were significantly related to K⁺ uptake by wheat. Potassium release was also correlated to initial NH₄OAc‐extratable K⁺ and to HNO₃‐extractable K⁺.     

Long-term consequences of topsoil mining on select biological and physical characteristics of two New Zealand loessial soils under grazed pasture

Soil chemical, biochemical, biological and structural properties were measured in two New Zealand loessial soils that were topsoil-mined 10 and 25 years ago respectively. Measurements at the 10-year site were compared to some earlier measurements made at this site and the data combined in a chronological sequence for analysis. Topsoil mining had a large, detrimental impact on the soil microbial biomass, the earthworm populations, easily mineralizable N and soil enzyme activities. However, most of these properties substantially recovered, to 80-90 per cent of the levels in unmined soils, within 10-25 years of restoration under pasture. In contrast, while total soil C and N were less affected by topsoil mining, their recovery was much slower. Stabilities of macro-aggregates of soil had fully recovered within 10-25 years after topsoil mining. The apparent changes in all the measured properties between 10 and 25 years of restoration were small in comparison with changes between 0-10 years of restoration after topsoil mining. The total C content of both soils under pasture appeared unlikely to attain the levels present in unmined soils. In soils undergoing restoration, the ratio of microbial C/total soil C may be a useful index of soil ‘biological stability’. Sulphatase activity may reflect the recovery of pasture production.     

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.     

Decomposition in five woodland soils: relationships with some invertebrate populations and with weather

Summary In two alluvial forests, a beech forest, an oakhazel-wood and a spruce forest, correlations between abiotic factors and the different groups of soil animals on the one hand and the decomposition rate (mean rate of disappearance) on the other hand have been the subject of investigation. There is a positive correlation between Lumbricidae and Brachycera imagines and the pH and the decomposition rate, but a negative one with Enchytraeidae and Nematocera imagines.Varying weather conditions are of great importance for decomposition processes. The influence of temperature seems to be insignificant. In the deciduous forests fluctuations of precipitation correlate fairly well with fluctuations in rates of decomposition, because of the high abundance of lumbricids. The spruce forest has very few lumbricids and the influence of weather on the course of decomposition is insignificant. Yet there is only a very loose relationship with the annual fluctuations of weather conditions. Only a major event such as the relatively low temperature and precipitation of 1980 is capable of inhibiting the development of sciarid larvae and enchytraeids and hence reducing the ensuing decomposition rate in 1981 and possibly even in 1982. The reason for this is that sciarid larvae and imagines, for example, go through critical periods during their development, which are influenced by the weather, frequently with a time lag of 1 year.Long-term investigations in the spruce forest have established a high correlation between sciarid larvae and enchytraeids and the decomposition rate.Dedicated to the late Prof.Dr. M.S. Ghilarov     

Isolation and characterization of potassium solubilizing bacteria in some Iranian soils

The ability of a few soil bacteria to transform unavailable forms of potassium (K) to an available form is an important feature in plant growth-promoting bacteria for increasing plant yields of high-K-demand crops. In this research, isolation, screening, and characterization of six isolates of K solubilizing bacteria (KSB) from some Iranian soils were carried out. The ability of all isolates were tested in three treatments including acid-leached soil, biotite, and muscovite by analyzing the soluble K content after 5 days of incubation at 28 ± 2°C. Identification and phylogenetic analyses were also carried out by morphological, biochemical, and 16S rDNA analyses. Among the six efficient isolates, five isolates belonged to Bacillus megaterium (JK3, JK4, JK5, JK6, and JK7), while isolate JK2 belonged to Arthrobacter sp. The soluble K contents in all isolated-treatments were significantly (p < 0.01) higher than the contents in nonbacteria treatment. Herein, isolate JK2 had lower potential for K solubilization (910 mg kg^?1) compared with other isolates in acid-leached soils. The six bacterial strains showed higher solubilized K in biotite treatment than other two treatments. Overall, it can be concluded that the isolates belong to B. megaterium are the most efficient KSB under in vitro condition.     

Phosphorus and potassium fertility of some riceland soils in Indonesia

Abstract

Contents of soil phosphorus and potassium vary appreciably in different localities of the Indonesian Archipelago. Data collected for riceland soils from seven irrigation areas (five on Java and one each on Sumatra and Sulawesi) show that average available phosphorus contents in the tilled layer may range from 23 ppm P at the Sumatra location to 203 ppm Pat the Sulawesi location. Average exchangeable potassium contents ranged from less than 0.2 meq/100g. K in the Sumatran soils to over 1.0 meq/100g. in potash‐rich soils of Java. Distinct regional differences in soil fertility of the magnitude observed indicate that blanket fertilizer recommendations cannot be made if rice production is to be increased without wasting chemical fertilizers which are relatively scarce and expensive in Indonesia. Increased emphasis must be placed on soil testing and soil fertility research in order to achieve the national goal of self‐sufficiency in food stuffs.     

Effects of drying on the ion exchange capacity and cation adsorption properties of some New Zealand soils

Abstract

The effect of drying on the cation (CEC) and anion (AEC) exchange capacity, and on potassium (K) and magnesium (Mg) adsorption by three New Zealand soils was investigated. Air‐drying resulted in no significant changes in these properties compared with the field‐moist samples. Oven‐drying at 105°C significantly decreased the CEC and increased the AEC of most soils compared with air‐dried samples. The decrease in CEC was related to increased solubility of organic matter and a decrease in surface area on which charge could be developed. The increase in AEC was attributed to a decrease in soil pH.

Potassium and Mg adsorption by two soils decreased following oven‐drying. This was consistent with the effect of drying on CEC. For the remaining soil, K adsorption increased following oven‐drying. This was attributed to K fixation.     

草酸对土壤和矿物中钾素的释放规律研究

Oxalic acid plays an important role in improving the bioavailability of soil nutrients. Batch experiments were employed to examine the influences of oxalic acid on extraction and release kinetics of potassium （K） from soils and minerals along with the adsorption and desorption of soil K^＋. The soils and minerals used were three typical Chinese soils, black soil （Mollisol）, red soil （Ultisol）, and calcareous alluvial soil （Entisol）, and four K-bearing minerals, biotite, phlogopite, muscovite, and microcline. The results showed that soil K extracted using 0.2 mol L^-1 oxalic acid was similar to that using 1 mol L^-1 boiling HNO3. The relation between K release （y） and concentrations of oxalic acid （c） could be best described logarithmically as y = a ＋ blogc, while the best-fit kinetic equation of K release was y = a ＋ b√t, where a and b are the constants and t is the elapsed time. The K release for minerals was ranked as biotite 〉 phlogopite 〉〉 muscovite 〉 microcline and for soils it was in the order： black soil 〉 calcareous alluvial soil 〉 red soil. An oxalic acid solution with low pH was able to release more K from weathered minerals and alkaline soils. Oxalic acid decreased the soil K^＋ adsorption and increased the soil K^＋ desorption, the effect of which tended to be greater at lower solution pH, especially in the red soil.     

Amounts and forms of micronutrient cations in a group of loessial grassland soils of New Zealand

The status of micronutrient cations Fe, Mn, Zn, Cu and Co was examined in a group of soils from beneath undisturbed grassland sites. The soils were selected such that factors of soil formation besides loess accumulation and rainfall remained relatively constant. In a previous study these two factors were found to have a large effect on the K status of the soils, but results from this study showed that there had been little effect on micronutrient content. With decreasing loess accumulation the total and HCl- and EDTA-extractable micronutrient content of soils tended to decrease, but rainfall had no consistent effect. Extractable levels of Cu and Co in A horizons tended to decrease from high to potentially deficient values with decreasing loess accumulation.HCl- and EDTA-extractable Fe, Mn, Zn and Cu were clearly higher in A than B horizons although total contents tended to be lower in A horizons. A chemical fractionation procedure demonstrated that there were greater quantities of pyrophosphate- and oxalate-extractable Zn and Cu and acetic acid-extractable Zn in the A than B horizons.With the exception of HCl-extractable Cu, extractable micronutrients were significantly correlated with the organic matter content of the HCl or EDTA extracts. There were no significant correlations between extractable micronutrients and soil pH or oxalate-extractable Al or Fe.Acetic acid-extractable Co was not significantly correlated with any measured soil property. It is concluded that the cycling of nutrients and the build-up of organic matter, which characteristically occur under grassland conditions in New Zealand, were the major factors influencing the micronutrient status of the soils.     

Sorption isotherms for predicting potassium requirements of some Iowa soils

Abstract

The sorption isotherm technique was used in predicting potassium requirements of some Iowa soils for growing tomatoes, potatoes, celery and beans. Based on previous comparisons, all of these soils would require additional amounts of K for optimum yields of celery, potatoes, tomatoes and beans. According to Woodruff's energy of exchange concept of K availability, all the soils used in this study are potassium deficient. Amounts of K needed to maintain a specific level of K in sorption equilibrium solution appeared to be largely a function of physicochemical characteristics of the soil. Predicted K requirements of these soils for optimum yields of these crops are reported.     

苏南地区两种土壤钾素供应状况及其调节

苏南地区黄刚土和白土供钾潜力较低 ,加之复种指数较高、雨水过多 ,致使土壤钾素亏缺严重 ,而我国钾矿资源贫乏 ,钾肥生产量有限 ,因此如何充分利用有限的钾肥资源 ,就显得尤为迫切和重要 .本文主要从钾肥的供需现状、作物的需钾特征和土壤的供钾规律等方面探讨了钾肥的合理投向及其调节 ,以提高钾肥的利用效率和增产效益     

The zinc status of some Nova Scotia soils and crops

Abstract

Ranges for total, 0.1N HCl and EDTA‐(NH₄)₂CO₃ extractable Zn in 69 samples of surface soil (0–15 cm), representing nine soil series, were 14–108, 0.9–10.5 and 0.5–8.0 ppm respectively. Total Zn in barley (Hordeum vulgare), carrot (Daucus carata sativa), corn (Zea mays L), grape (Vitis spp.), onion (Allium cepa), pea (Pisum sativum, strawberry (Fragaria spp.), and wheat (Triticum spp.) leaves and in barley and wheat grain ranged from 13.5 to 80.6 ppm.

The results suggest that, with the possible exception of corn leaf samples from one location, Zn levels in plant tissue were adequate. However, the results also indicate that liming strongly acid sandy soils reduces Zn availability and may induce a deficiency in Zn sensitive crops.     

磷的吸附和表面电荷特征及其与华南地区某些土壤矿物的关系

The phosphate adsorption and surface charge characteristics of the tropical and subtropical soils derived from different parent materials in China were determined, and their relations to soil mineralogy were analysed. The results showed that all soil phosphate adsorption curves were well fitted by Freundlich equation and Langmuir equation. The maximum buffering capacity of P ranged from 66 to 9 880 mg kg^-1, with an increasing order of purple soil, skeletal soil, red soil, lateritic red soil, yellow soil and latosol; and the highest value was 149 times the lowest value, which indicated great differences among these soils in phosphate adsorption and supplying characteristics. The pH₀ (zero point of charge) values obtained by salt titration-potential titration varied from 3.03 to 5.49, and the highest value was found in the latosol derived from basalt whereas the lowest value was found in the purple soil. The correlation analysis indicated that the main minerals responsible for phosphate adsorption in the soils were gibbsite, amorphous iron oxide and kaolinite; and the pH₀ was mainly controlled by kaolinite, gibbsite and oxides.     

Short‐term potassium release and fixation in some calcareous soils

Potassium (K⁺) directly released from primary K‐bearing minerals can contribute to plant nutrition. The objective of this research was to assess short‐term K⁺ release and fixation on a range of intensively cropped calcareous soils. Potassium sorption and desorption properties and the contributions of exchangeable‐K⁺ (EK) and nonexchangeable‐K⁺ (NEK) pools to K⁺ dynamics of the soil‐solution system was measured using a modified quantity‐to‐intensity (Q : I) experiment. Release and fixation of K⁺ were varied among soils. The relation between the change in the amount of NEK during the experiment and the initial constrain was linear, and soil ability for K⁺ release and fixation (β) for all soils varied from 0.041 to 0.183, indicating that 4% to 18% of added K⁺ converted to NEK when fixation occurred. The equilibrium potential buffering capacity (PBC) for K⁺ derived from Q : I experiments had significant correlation (r = 0.75, p < 0.01) with β, indicating that PBC depends not only on exchange properties but also on release and fixation properties. The depleted soils showed higher β value than the other soils, indicating much of the added K⁺ was converted to NEK in case of positive constraint. The range of the amount of EK which was not in exchange equilibrium with Ca (E_min) in the experimental conditions was large and varied from 0.68 to 9.00 mmol kg^–1. On average, E_min amounted to 64% of EK. This fraction of EK may not be available to the plant. The parameters obtained from these short‐term K⁺ release and fixation experiments can be used in plant nutrition.     

Hydrolytic enzyme activities in agricultural and forest soils. Some implications for their use as indicators of soil quality

Although a great deal of information exists about the effect of land use on soil enzyme activities, much of this is contradictory and brings into question the suitability of soil enzyme activities as indicators of how land use affects soil quality. The purpose of this study was to investigate the effect of land use on different soil biochemical properties, especially hydrolytic enzyme activities, with the aim of providing knowledge about the problems related to the use of enzymes as indicators of soil quality. The data presented derive from various studies in which a large number of soils under different types of forest or agricultural management were analysed by the same methods. All of the soil samples were characterized in terms of their main physical and chemical properties, the activity of several hydrolases, microbial biomass C and soil basal respiration. The results indicate that soil use causes a large reduction in organic matter content and that the effect on enzyme activity varies depending on the type of land use or management and the type of enzyme. Furthermore, the enzyme activities per carbon unit (specific activities) in soils affected by land use are almost always higher than in maximum quality soils (climax soils under oak vegetation or oak soils), and land use also generates greater increases in the specific activity as the C content decreases. The mechanism responsible for these increases probably involves loss of the most labile organic matter. Enzyme enrichment is not always produced to the same degree, as it varies as a function of the enzyme and the type of land use under consideration. It is concluded that the complexity of the behaviour of the soil enzymes raises doubts about the use of enzyme activities as indicators of soil degradation brought about by land use.