Effects of Different Application Amounts of Potassium Fulvate on Yield and Quality of Tomato and Soil Physical and Chemical Properties

This study was conducted to study the optimum dosage of potassium ful- vate （PF） on greenhouse tomato, the effects of different amounts of PF on yield and quality of greenhouse tomato and soil physical and chemical properties were investigated by a field plot experiment. The results showed that the bottom applica- tion of PF increased tomato yield, plant dry matter weight and root dry matter weight by 14.0%, 14.4 and 50.6%, respectively; Vc and soluble sugar content of tomato increased by 1＆5% and 10.0%, respectively; and soil bulk density de- creased by 3.6%, and CEC increased by 5.0%. All the indexes increased with the increase of PF application amount, and reached the maximum value when the PF application rate was 4 500 kg/hm2. In consideration of the cost of fertilizer and all indexes, the optimum dosaqe of PF fertilizer was 4 500 kg/hm2.

Effects of Straw Covering and Different Types of Potassium Fertilizer on Salinity Accumulation in Surface Layer of Tobacco-planted Paddy Soil

[Objective] This study aimed to investigation the effects of straw covering and different types of potassium fertilizer on salinity accumulation in surface layer of tobacco-planted paddy soil in southern China. [Method] Tobacco variety ‘Yunyan87’ was used as the experimental material to investigate the effects of salinity accumulation in surface layer of tobacco-planted paddy soil on the growth and development of flue-cured tobacco using different types of potassium fertilizer and mulching cultivation methods. [Result] The results showed that K＋ , Ca2＋ , SO42and NO3-were the major salt ions in topsoil at different growth stages of flue-cured tobacco, Na ＋ and Mg2＋ contents were also relatively high at vigorous growth stage, indicating that these salt ions were easily accumulated in surface layer of soil; to be specific, the absolute increase of salt ion concentration showed a decreasing order of K＋ SO42- NO3-Ca2＋ Mg2＋ Na＋ Cl-, while the relative increase of salt ion concentration showed a decreasing order of Ca2＋ K＋ Na＋ NO3-SO42-Mg2＋ Cl-. At 60 d posttransplanting, total salt content in topsoil reached the minimum of 359.1 mg/kg in Treatment 2, total salt content in topsoil reached the maximum of 536.1 mg/kg in Treatment 5 （CK）, which was significantly higher than that in other treatments. At 90 d post-transplanting, no significant difference was observed in total salt content among various treatments. At harvesting period, total salt content in topsoil reached the maximum of 3 278.4 mg/kg in Treatment 1, which was significantly higher than that in other treatments. Topsoil pH showed no significant differences among various treatments at three different periods, ranging from 5.39 to 5.59. Straw covering could effectively reduce salt content in topsoil, accelerate vigorous growth of tobacco, shorten vigorous growth period and increase plant height, leaf number and lead area; at vigorous growth stage, root vitality and root volume of tobacco were improved, but the yield and output value were relatively low. Major agronomic traits and yield of tobacco showed no significant difference among various treatments. Output value of tobacco reached the maximum of 24 196.8 yuan/hm2 in Treatment 3, which was significantly higher than that in other treatments. [Conclusion] Appropriate types and proportions of potassium fertilizer and straw covering can effectively reduce the total salt content in tobacco-planted paddy soil and increase the effective supply amount of K＋ , Ca2＋ , SO42-and NO3-, thereby promoting and improving the root vitality of tobacco, which is conducive to the growth and development of tobacco and will eventually enhance the yield, quality and economic benefits of flue-cured tobacco.

Semi-analytical solution for drained expansion analysis of a hollow cylinder of critical state soils

The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by the common self-similar-based similarity techniques.This paper proposes a novel,exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils.Considering stress-dependent elastic moduli of soils,new analytical stress and displacement solutions for the nonself-similar problem are developed taking the small strain assumption in the elastic zone.In the plastic zone,the cavity expansion response is formulated into a set of first-order partial differential equations(PDEs)with the combination use of Eulerian and Lagrangian descriptions,and a novel solution algorithm is developed to efficiently solve this complex boundary value problem.The solution is presented in a general form and thus can be useful for a wide range of soils.With the new solution,the non-self-similar nature induced by the finite outer boundary is clearly demonstrated and highlighted,which is found to be greatly different to the behaviour of cavity expansion in infinite soil mass.The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small-sized calibration chambers.

Long-Term Effect of Fertilizer and Rice Straw on Mineral Composition and Potassium Adsorption in a Reddish Paddy Soil

Increasing K＋ adsorption can be an effective alternative in building an available K pool in soils to optimize crop recovery and minimize losses into the environment. We hypothesized that long-term fertilization might change K＋ adsorption because of changes in the chemical and mineralogical properties of a rice （Oryza sativa L.）. The aims of this study were （i） to determine clay minerals in paddy soil clay size fractions using X-ray diffraction methods and a numerical diagramdecomposition method; （ii） to measure K＋ adsorption isotherms before and after H202 oxidation of organic matter, and （iii） to investigate whether K＋ adsorption is correlated with changes in soil chemical and mineral properties. The 30-yr longterm fertilization treatments caused little change in soil organic C （SOC） but a large variation in soil mineral composition. The whole-clay fraction （〈5 Jam） corresponded more to the fertilization treatment than the fine-clay fraction （〈1 gin） in terms of percentage of illite peak area. The total percentage of vermiculite-chlorite peak area was significantly negatively correlated with the total percentage ofillite peak area in the 〈5 lam soil particles （R=-0.946, P〈0.0006）. Different fertilization treatments gave significantly different results in K＋ adsorption. The SOC oxidation test showed positive effects of SOC on K＋ adsorption at lower K＋ concentration （≤120 mg L-0 and negative effects at higher K＋ concentration （240 mg L-l）. The K＋ adsorption by soil clay minerals after SOC oxidization accounted for 60-158% of that by unoxidized soils, suggesting a more important role of soil minerals than SOC on K＋ adsorption. The K＋ adsorption potential was significantly correlated to the amount of poorly crystallized illite present （R--0.879, P=0.012）. The availability of adsorbed K＋ for plant growth needs further study.

Effects of a new nitrification inhibitor 3,4-dimethylpyrazole phosphate(DMPP) on nitrate and potassium leaching in two soils

In this study, soil column was used to study the new nitrification inhibitor 3,4-dimethylpyrazole phosphate （DMPP） on nitrate （NO3^-- N） and potassium （K） leaching in the sandy loam soil and clay loam soil. The results showed that DMPP with ammonium sulphate nitrate （ASN） （（NH4）2SO4 and NHaNO3） or urea could reduce NO3^--N leaching significantly, whereas ammonium （NH4^＋-N） leaching increased slightly. In case of total N （NO3^--N＋NH4^＋-N）, losses by leaching during the experimental period （40 d） were 37.93 mg （urea）, 31.61 mg （urea＋DMPP）, 108.10 mg （ASN）, 60.70 mg （ASN＋DMPP） in the sandy loam soil, and 30.54 mg （urea）, 21.05 mg （urea＋DMPP）, 37.86 mg （ASN）, 31.09 mg （ASN＋DMPP） in the clay loam soil, respectively. DMPP-amended soil led to the maintenance of relatively high levels of NH4^＋ -N and low levels of NO3^--N in soil, and nitrification was slower. DMPP supplementation also resulted in less potassium leached, but the difference was not significant except the treatment of ASN and ASN＋DMPP in the sandy loam soil. Above results indicate that DMPP is a good nitrification inhibitor, the efficiency of DMPP seems better in the sandy loam soil than in the clay loam soil and lasts longer.

Adsorption of Potassium and Sodium Ions by Variable Charge Soils

Adsorption of potassium and sodium ions by four typical variable charge soils of South China was studied. The results indicated that the variable charge soils saturated with H and Al showed a much higher preference for potassium ions relative to sodium ions, and this tendency could not be changed by such factors as the pH, the concentration of the cations, the dielectric constant of solvent, the accompanying anions and the iron oxide content etc., suggesting that this difference in affinity is caused by the difference in the nature of the two cations. It was observed that a negative adsorption of sodium ions by latosol and lateritic red soil in a mixed system containing equal amount of potassium and sodium ions at low pH, which is caused by a competitive adsorption of potassium and sodium ions and repulsion of positive charge on the surfaces of soil particles for cations. The adsorption of potassium and sodium ions increased with the decreases in the dielectric constant of solvent and the iron oxide content. Sulfate affected the adsorption of potassium and sodium ions through changing the surface properties of the soils.

Preferential Fixation of Ammonium to Potassium by Soils

Ten soils collected from different parts of China were used in a series of experiments to study fixation of NH￣+_4 and K￣+ by soils. When K￣+ was added concurrently with or prior to NH￣+_4, the soils were found to fix more moles of NH￣+_4 than those of K￣+, irrespective of the mole ratios of NH￣+_4 to K￣+ that were added.

Adsorption of Potassium and Calcium Ions by Variable Charge Soils

Interactions of potassium and calcium ions with four typical variable charge soils in South China were examined by measuring pK-0.5pCa value with a potassium ion-selective electrode and a calcium ion-selective electrode,and pK value with a potassium ion-selective electrode.The results showed that adsorption of potassium and calcium ions increased with soil suspension pH,and the tendency of the pK-0.5pCa value changing with pH differed with respect to pH range and potassium to calcium ratio.Adsorption of equal amount of calcium and potassium ions led to release of an identical number of protons,suggesting similar adsorption characteristics of these two ions when adsorbed by variable charge soils.Compared with red soil,latosol and lateritic red soil had higher adsorption selectivities for calcium ion.The red soil had a greater affinity for potassium ion than that for calcium ion at low concentration,which seems to result from its possession of 2:1 type minerals,such as vermiculite and mica with a high affinity for potassium ion.The results indicated that adsorption of potassium and calcium ions by the variable charge soils was chiefly caused by the electrostatic attraction between the cations and the soil surfaces.Moreover,it was found that sulfate could affect the adsorption by changing soil surface properties and by forming ion-pair.

Effect of CO_(2)exposure on the mechanical strength of geopolymerstabilized sandy soils

In recent years,there has been growing interest in developing methods for mitigating greenhouse effect,as greenhouse gas emissions continue to contribute to global temperature rise.On the other hand,investigating geopolymers as environmentally friendly binders to mitigate the greenhouse effect using soil stabilization has been widely conducted.However,the effect of CO_(2)exposure on the mechanical properties of geopolymer-stabilized soils is rarely reported.In this context,the effect of CO_(2)exposure on the mechanical and microstructural features of sandy soil stabilized with volcanic ash-based geopolymer was investigated.Several factors were concerned,for example the binder content,relative density,CO_(2)pressure,curing condition,curing time,and carbonate content.The results showed that the compressive strength of the stabilized sandy soil specimens with 20%volcanic ash increased from 3 MPa to 11 MPa.It was also observed that 100 kPa CO_(2)pressure was the optimal pressure for strength development among the other pressures.The mechanical strength showed a direct relationship with binder content and carbonate content.Additionally,in the ambient curing(AC)condition,the mechanical strength and carbonate content increased with the curing time.However,the required water for carbonation evaporated after 7 d of oven curing(OC)condition and as a result,the 14-d cured samples showed lower mechanical strength and carbonate content in comparison with 7-d cured samples.Moreover,the rate of strength development was higher in OC cured samples than AC cured samples until 7 d due to higher geopolymerization and carbonation rate.

Comparative Study on the Kinetic Equations of Potassium Release from Soils

Elovicb, 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 df Zhejiang Province in a constant electric field (44.4 V/ 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 standard error.

The effect of seismic action on stability of saline soil subgrade in cold region based on isothermal stratification method

With the change of seasons, the shear strength of saline soil subgrade filler will change with the change of external temperature, which will aggravate the adverse effects of seismic on the subgrade. To explore the influence of seismic action on the stability of saline soil subgrade under the influence of temperature on the strength of saline soil subgrade filler, this paper first carried out saline soil shear tests at different temperatures to obtain the influence of temperature on the shear strength of saline soil. Then, the temperature field of the saline soil subgrade was simulated, and then based on the subgrade isothermal stratification model and FLAC3D, the displacement and acceleration amplification effects of seismic action on the shady slope, sunny slope and subgrade of saline soil subgrade in different months were analyzed. The following conclusions were finally drawn: under the action of seismic, In the process of the change of subgrade temperature of Qarhan-Golmud Expressway between 7.7°C and 27°C, the change of saline soil cohesion is the main factor affecting the stability of subgrade slope, and the maximum and minimum values of subgrade surface settlement appear in September and June of each year,respectively. In August, the differences of settlement between the shady slope and the sunny slope shoulder of the subgrade were the largest, and the acceleration of the shady slope and the sunny slope and the inside of the subgrade changed most significantly in the vertical direction. Special attention should be paid to the seismic early warning in the above key months;In the range from both sides of the shoulder to the centerline of the roadbed,the acceleration amplification effect starts to increase significantly from about 3m from the centerline of the roadbed to the centerline, so it is necessary to pay attention to the seismic design of this range.

Effect of Soil Fertility and Planting Density on the Partitioning of the Above-Ground Biomass of Eucalyptus in a Plantation (Pointe-Noire, Republic of Congo)

Afforestation and reforestation are useful approaches to improve carbon sequestration. With the advent of forest plantations, growing environment conditions have become increasingly restrictive for light, soil nutrients, and interactions between trees to acquire available resources. Tree biomass data are essential for understanding the forest carbon cycle and plant adaptations to the environment. The distribution of tree biomass depends on the sum of multiple stand conditions. The data are from a dedicated experiment with two very contrasting areas of fertility, and two planting densities, including a high density at planting in order to achieve thinning. The plant material consists of the high-performance clones of Eucalyptus urophylla × E. grandis and the reference clone E. PF1. We hypothesize that the distribution of biomass changes as the intensity of competition changes and that this is accelerated by the fertility of the sites in time. The results indicate that fertilization, planting density and clones have an impact on biomass partitioning.

Evaluation of Soil Potassium Test to Improve Fertilizer Recommendations for Corn

The soil potassium (K) test methodology is under increased evaluation due to the soil sample drying effect, temporal variations of test results and inconsistent crop response to applied K fertilizers. Ten on-farm trials were conducted in 2014 in eastern North Dakota to determine the corn response to different K-fertilizer rates and to assess the variation of soil K test levels between air-dried (KDry) and field moist (KMoist) soil samples during the corn growing season. Significant differences were observed between KDry and KMoist soil K test results. The ratio of KDry/KMoist showed high correlation with cation exchange capacity (r = 0.63, p < 0.10), Organic matter (r = 0.61, p < 0.10) and (Ca + Mg)/K ratio (r = 0.64, p < 0.10) from the 1 M ammonium acetate extractant, while pH, electrical conductivity, clay (%), and soil moisture showed non-significant correlation. On average, KDry resulted in higher soil K test levels than KMoist and pattern of deviation was different for surface and sub-surface soil samples. Soil K analysis of samples collected during the fall and spring showed large enough variations to affect the soil test interpretation category which was used to make fertilizer recommendations. Corn yield increased significantly with applied K fertilizer at only three out of 8 sites with beginning K levels below the current critical level of 150 ppm, and one response was at a site with K level above the critical level. Therefore, use of either the KDry or KMoist method alone may not be adequate to predict K response in some North Dakota soils.

Treatment of Phenol-Contaminated Soil by Potassium Ferrate Based on pH Control

This study aims to optimize the treatment of phenol-contaminated soil by potassium ferrate. Variations in pH value can accurately reflect the state and reaction status of the entire treatment process. Therefore, the pH value could be an important variable for optimizing the reaction conditions and achieving the automatic control of the process. About 99.89% of phenol was removed after 10 min of the pH-contxolled reaction at a rotational speed of 40-70 r/min, with the initial phenol concentration equating to 10.0 g/kg and the total water consumption reaching 2.72 L （at a soil/water ratio of 1：0.68）. The test results could provide a basis for practical application of automatic reaction control by pH value.

Effect of potassium on soil conservation and productivity of maize/cowpea based crop rotations in the north-west Indian Himalayas

Plots under conservation tillage may require higher amount of potassium(K) application for augmenting productivity due to its stratification in upper soil layers, thereby reducing K supplying capacity in a medium or long-term period. To test this hypothesis, a field experiment was performed in 2002-2003 and 2006-2007 to study the effect of K and several crop rotations on yield, water productivity, carbon sequestration, grain quality, soil K status and economic benefits derived in maize(Zea mays L)/cowpea(Vigna sinensis L.) based cropping system under minimum tillage(MT). All crops recorded higher grain yield with a higher dose of K(120 kg K2 O ha-1) than recommended K(40 kg K2 O ha-1). The five years' average yield data showed that higher K application(120 kg K2 O ha-1) produced 16.4%(P<0.05)more maize equivalent yield. Cowpea based rotation yielded 14.2%(P<0.05) higher production than maize based rotation. The maximum enhancement was found in cowpea-mustard rotation. Relationship between yield and sustainable indices revealed that only agronomic efficiency of fertilizer input was significantly correlated with yield. Similarly, higherdoses of K application not only increased the water use efficiency(WUE) of all crops, but also reduced runoff and soil loss by 16.5% and 15.8% under maize and 23.3% and 19.7% under cowpea cover, respectively. This study also revealed that on an average 16.5% of left over carbon input contributed to soil organic carbon(SOC). Here, cowpea based rotation with the higher K application increased carbon sequestration in soil. Potassium fertilization also significantly improved the nutritional value of harvested grain by increasing the protein content for maize(by 9.5%) and cowpea(by 10.6%). The oil content in mustard increased by 5.0% and 6.0% after maize and cowpea, respectively. Net return also increased with the application of the higher K than recommended K and the trend was similar to yield. Hence, the present study demonstrated the potential yield and profit gains along with resource conservation in the Indian Himalayas due to annual additions of higher amount of K than the recommended dose. The impact of high K application was maximum in the cowpea-mustard rotation.

The Characters and Effect of Potassium in the Aeolian Sand Soil on Growth and Quality of Wine-Grapes in Ningxia

The paper reports the study on validity, absorbing and using in potassium of wine-grapes grown on aeolian sandy soil in Ningxia. The result shows that the content of slow release potassium and available potassium is low. The amount of available potassium and fixed potassium increases with raising amount of applied potash. Slow release potassium can be quickly replenished when available potassium is depleted, but slow release potassium is exhausted too, and the buffering capacity of supplying potassium is low. The content of potassium in grains and plants increases with the increasing amount of applied K in different treatments. The sequence of potassium recovery rate in different soil is as follows: sand-loam>fine-sand>coarse-sand. The capacity of supplying potassium in high-fertility soil is better than that in low-fertility soil, and rate of potassium recovery is high. Potassium nutrient affects growth and quality of wine-grapes.

Potassium Supplying Power of Soils in Heilongjiang Province and the Effect of Potassium Application on Resistance of Crops to Adverse Conditions

The total potassium (K) content of soils in Heilongjiang was relatively high in general and the available potassium content in soils was quite different for different soil types. The results of electro - ultra- filtration (EUF) analysis showed that the dark brown forest soils and the black soils in the northern part contained relatively high EUF-K, ranged from 12.5 to 15.7 mg per 100 g soil. In the black soils in the southern part, the EUF-K ranged from 8 to 9 mg per 100 g soil. The albic and aeolian sandy soils contained low EUF-K, ranged from 3.2 to 4.8 mg per 100 g soil. Field experiment in 1982 indicated that potassium fertilizer in soils with medium or low EUF-K, increased soybean yield by 17%-34%, and obviously prevented the epidemic of meadow moth and soybean mosaic virus. Application of potassium fertilizer increased the protein and total sugar content of the plants, promoted transportation of nutrients, speeded up the growth of the plants, improved the resistance of crops to adverse conditions. Application of potassium fertilizer resulted in early maturity of crops (4 - 7 days earlier than control), which had great significance for preventing crops from early frost damage. Hence, in order to keep nutrients balance in the soil and to increase soil fertility, potassium fertilizer or materials containing potassium must be applied to soils with medium and low EUF- K, such as black soils in the south part, ablic soils and aeolian sandy soils in Heilongjiang province.

Effects of soil potassium levels on dry matter and nutrient accumulation and distribution in cotton

Background Potassium(K)is an essential nutrient for plant growth and development.However,plant fertilization ignoring the soil K level is very likely to cause excessive fertilizer use,and further arouse a series of side effects.This study investigated the response of cotton growth to different soil K levels and the uptake of major nutrients,aiming to evaluate the appropriate K supply level for cotton growth.Using a random block design with 6 soil K levels,we conducted 18 micro-zones field experiments over two continuous years.The soil available K concentration of each treatment was K1(99.77-100.90 mg·kg^(-1)),K2(110.90-111.26 mg·kg^(-1)),K3(123.48-128.88 mg·kg^(-1)),K4(140.13-145.10 mg·kg^(-1)),K5(154.43-155.38 mg·kg^(-1)),and K6(165.77-168.75 mg·kg^(-1)).Cotton nutrient contents,soil nutrient contents,accumulation and distribution of dry matter in cotton were determined,and the relationships between K content in soil and plants and dry matter accumulation were analyzed.Results The soil K content had a significantly positive relationship with dry matter and K accumulation in cotton plants.There were significant differences in dry matter accumulation,single-plant seed cotton yield,mineral nutrient uptake and the proportion of K accumulation in reproductive organs among different soil K levels.The results showed that there was significant difference between K4 and lower K level treatments(K1 and K2),but no significant difference between K4 and higher K level treatments(K5 and K6)in dry matter,single-plant seed cotton yield,or accumulation,distribution and seed cotton production efficiency of N,P and K.Conclusion The soil K level of K4 was able to provide sufficient K for cotton growth in our experiment.Therefore,when the soil K level reached 140.13 mg·kg^(-1),further increasing the soil K concentration no longer had a significant positive effect on cotton growth.

Effect of nitrogen fertilizer on the uptake and utilization of potassium by various rice varieties in purple soil

Nitrogen and potassium are important nutrientelements for rice.Besides supplied by the or- ganic manure,potassium nutrition of ricecomes dominantly from purple soils in Sichuanbasin.Potassium exists abundantly in mineralforms in the purple soils.Availability of soilpotassium for crop depends on the potassiumforms,the uptake ability of crops,and fertiliz-er practices.A pot culture experiment wasconducted to study the kinetics of potassiumuptake in the purple soil(total N 22.64g·kg,total K 24.36g·kg,available N 102.6mg·kg,available K 140.6mg·kg,acidsoluble K 936.0mg·kg,and pH 6.8).Ma-terials used were three Fhybrid rices,Eryou

Study on regulation of potassium loss and its balance characteristics from typical paddy soils in Dongting Lake area

Potassium loss due to runoff and leaching, crop uptake, and K-fertilizer input, irrigation and wet deposition was studied, subsequently potassium balance characteristics was analyzed using lysimeter modeled two typical paddy soils from double rice field in Dongting Lake area. K losses due to runoff and leaching in Alluvial Sandy Loamy Paddy Soil （ASL） with lower cation exchange content （CEC） and clayey granule content were increased significantly compared with those in Reddish Yellow Loamy Paddy Soil （RYL） with higher CEC and clayey granule content. Compared with RYL, lower economic and biological yield due to lower capacity of nutrient and water keeping in ASL resulted in lower K uptake. So potassium deficit in double rice field of RYL was more serious than that of ASL because main K proportion was accounted by crop uptake. Available K in soil of surface layer （0-15 cm） was decreased significantly due to long term nutrient management of K deficit in double rice field. The straw return paddy field was suggested as an effective way to increase soil K and balance K deficit in double rice field because large amount of potassium was enriched in rice straw at harvest.