Coarse Mineral Soils Research Articles

Gypsum amendment influences soil and plant chemical composition temporarily

Field application of gypsum (CaSO4 × 2H2O) is a tool to decrease phosphorus (P) load to watercourses. Effects of gypsum application (4 tons ha-1) on soil and crop composition were monitored up to four years after the treatment in the Savijoki catchment, southwestern Finland. Eleven amended fields and 17 control fields were analyzed for easily soluble P, Ca, Mg, K, S, pH(H2O), electrical conductivity (EC) and loss-on-ignition. Plant samples were analyzed for most nutrients and Se. Downward S transport was monitored in two fields. In the first spring after gypsum application, but not later, S concentrations and EC were substantially but not harmfully elevated in the plough layer, with no other significant effects on soil composition. Sulfur leached out slightly less rapidly from clay than from the coarse mineral soil. Plant S concentration increased for the first and the second year. In conclusion, gypsum application did not have adverse effects on soil or crop chemical composition in this survey of predominantly clay soils.

Erratum: Nutrition and mycorrhizae affect interspecific patterns of seedling growth on coarse wood and mineral soil substrates

Erratum: Nutrition and mycorrhizae affect interspecific patterns of seedling growth on coarse wood and mineral soil substrates

Shifts in soil–climate combination deserve attention

In addition to causing shifts in regional climate, climate change will also affect the combination of climatic conditions and dominant soil type. This may be reflected in crop responses; however, currently, empirical knowledge in this regard is limited. We hypothesised that 1) the weather patterns most influencing forage crop yield variation vary among soil types 2) the yield responses of forage crop species and cultivars to agro-climatic variables depend on soil type, and 3) response diversity of the forage crop species and cultivars to agro-climatic factors depends on soil type. To assess these assumptions, we utilized the Finnish long-term multi-location Official Variety Trial and weather data for 1979–2012 as a case study. The yield responses of timothy (Phleum pratense L.), meadow fescue (Festuca pratensis Huds.), tall fescue (Lolium arundinaceum (Schreb)/Festuca arundinacea (Schreb)), Festulolium (Festuca sp.×Lolium sp.), red clover (Trifolium pratense L.), and Italian ryegrass (Lolium multiflorum L.) to the critical agro-climatic variables depended in most cases on whether the trials were located on clay, coarse mineral, or organic soils. The average yield response to weather was 10% in clay and organic soils and 8% in coarse mineral soils. The diversity of forage crop responses was also dependent on soil type. The demonstrated dependency of crop responses to climate change on soil type emphasizes that attention should be paid to the plausible shifts in soil–climate combinations when planning adaptation.

35-year trends of acidity and soluble nutrients in cultivated soils of Finland

Nutrient status of arable soils is linked to food production potential and environmental risks. The use of nutrients is affected by policy measures, which formulation calls for data on the long-term development of soil fertility. In Finland, the chemical status (pH4.65 ammonium acetate-extractable nutrients and pHw) of cultivated topsoils has been surveyed at the same sites in 1974 (n=1835), 1987, 1998 and 2009 (n=524). The aims of this study were to determine the temporal trends in P, S, macro nutrient cations and pH utilizing the monitoring data, to find explanations for the trends, and to assess the current status of fertility in the Finnish cultivated soils. The mean soil P concentrations continuously increased with time in clay, fine-textured and mull soils, or first increased but later turned to a decrease in coarse mineral soils, and exhibited no trend in peat soils. Between 1998 and 2009, high P concentrations tended to decrease whereas low P increased, the magnitude of the change being dependent on cropping system (if >80% of the time planted with annual crops, perennial crops, or under rotation of the two). The trends of the other nutrients mostly reflected the balances of the elements in agricultural soils. The trend for S was generally increasing between 1987 and 1998, but turned to a decline after 1998. The general trends in the mean Ca, Mg and pH were increasing, whereas the initial upward trend for K leveled off after 1987. Based on the 2009 sampling, the current soil fertility is sufficient, but attention is to be paid on S and K status, and the overall fertility of coarse mineral soils.

A Simple Dynamic Model of Soil Test Phosphorus Responses to Phosphorus Balances.

Soil test P (STP) concentration indicates whether annual P applications can be expected to give yield increases and can also indicate an elevated risk of P mobilization and potential for P transfer to surface waters and groundwater from a particular field. Changes in STP with time thus project agronomic benefits and environmental risks of different P use strategies. To predict STP changes with time, we constructed a simple dynamic model for which the input variables are P balance and initial STP. The model parameters (soil type-specific constants) were fitted using data originating from 44 P fertilizer experiments with different P rates. Model performance was evaluated using independent data sets that either had reasonably accurate input values ( = 103) or were obtained from farmers through interviews ( = 638). The simulations were in agreement with measured STP changes for both evaluation data sets when fittings were performed separately for four main soil types (clays, silts, coarse mineral soils, and organic soils). Statistical analysis confirmed that the model captured the trends in STP (NHOAc test) with acceptable accuracy and precision, with of 0.83 and 0.66 for the data with more accurate input and for farmer interview data, respectively; the corresponding model efficiency statistics were 0.88 and 0.66. The model is not restricted to use with one soil test, as fittings for several different types of soil tests can be generated. In this study, we fitted the model for Olsen P data retrieved from the literature. Agronomic use of the model includes evaluation of P use strategies, e.g., when a certain STP level is targeted or when long-term economy of P use is calculated. In an environmental context, the model can be used to predict STP changes with time under variable P balance regimes, which is essential for realistic assessment of changes in the potential for dissolved P losses.

Impact of soil pH and organic matter on the chemical bioavailability of vanadium species: The underlying basis for risk assessment

The main objective of this study was to unravel the chemical reactions and processes dictating the potential bioavailability of vanadium (V). In environmental solutions V exists in two stable oxidation states, +IV and +V, of which + V is considered to be more toxic. In this study, the effect of speciation and soil pH on the chemical accessibility of V was investigated with two soils: 1) field soil rather rich in soil organic matter (SOM) and 2) coarse mineral soil low in SOM. Fresh soil samples treated with V(+V) (added as NaVO3) or V(+IV) (added as VOSO4) (pH adjusted to the range 4.0–6.9) were incubated for 3 months at 22 °C. The adsorption tendency of V species was explored by water extraction (Milli-Q water, 1:50 dw/V) and by sequential extraction (0.25 M KCl; 0.1 M KH2/K2HPO4; 0.1 M NaOH; 0.25 M H2SO4, 1:10 dw/V). The potential bioavailability of V was found to be dictated by soil properties. SOM reduced V(+V) to V(+IV) and acted as a sorbent for both species, which lowered the bioaccessibility of V. A high pH, in turn, favored the predominance of the V(+V) species and thus increased the chemical accessibility of V.

Using Selected Structural Indices to Pinpoint the Field Moisture Capacity of Some Coarse-Textured Agricultural Soils in Southeastern Nigeria

Over- or underestimation of field capacity (FC) of agricultural soils could misguide soil and water management and this might have negative agronomic and environmental impacts. The study sought to identify the moisture tension for reliably estimating in the laboratory the FC of some sandy soils with low-activity clay minerals and at different levels of structure development in Nsukka agroecological zone in southeastern Nigeria. Fifty-four samples of topand subsoils under contrasting vegetation cover at three locations in the zone were analyzed for texture, organicmatter contents, bulk density and total porosity. Saturated hydraulic conductivities (Ksat) of the samples were equallydetermined. Water-conducting and water-filled porosities at each of 0.06-, 0.10- and 0.33-bar tensions were implied from water retention data at the respective tensions. The soils were categorized based on their levels of structure development using a structural stability index [(organic matter: silt+clay) %] as follows: very low (< 4%), low (4-7.5%) and moderate to high (> 7.5%) stability soils. Series of simple correlation tests were run among the waterconducting porosities at the various tensions and the Ksat of the soils. In each case, the soil was assumed to have attained FC at that moisture tension which the associated water-conducting porosity showed significant positive correlation with the Ksat. Our results revealed that the 0.06-bar tension overestimated the FC of the soils. The 0.10-bar tension, the commonly used moisture tension for the purpose in the study area, proved suitable only for soils within the moderate to high structural stability category. From all indications, the 0.33-bar tension best corresponded to the FC of the less structurally developed soils in the other two categories. The level of soil structure development should therefore be considered before deciding the suitable moisture tension for the determination of FC of these and similar soils in other tropical locations.Keywords: Coarse mineral soils, field moisture capacity, saturated hydraulic conductivity, structural stability,water-conducting pores

Land Use Planning of Way Betung Watershed for Sustainable Water Resources Development of Bandar Lampung City

Over- or underestimation of field capacity (FC) of agricultural soils could misguide soil and water management and this might have negative agronomic and environmental impacts. The study sought to identify the moisture tension for reliably estimating in the laboratory the FC of some sandy soils with low-activity clay minerals and at different levels of structure development in Nsukka agroecological zone in southeastern Nigeria. Fifty-four samples of topand subsoils under contrasting vegetation cover at three locations in the zone were analyzed for texture, organic matter contents, bulk density and total porosity. Saturated hydraulic conductivities (Ksat) of the samples were equally determined. Water-conducting and water-filled porosities at each of 0.06-, 0.10- and 0.33-bar tensions were implied from water retention data at the respective tensions. The soils were categorized based on their levels of structure development using a structural stability index [(organic matter: silt+clay) %] as follows: very low (< 4%), low (4-7.5%) and moderate to high (> 7.5%) stability soils. Series of simple correlation tests were run among the waterconducting porosities at the various tensions and the Ksat of the soils. In each case, the soil was assumed to have attained FC at that moisture tension which the associated water-conducting porosity showed significant positive correlation with the Ksat. Our results revealed that the 0.06-bar tension overestimated the FC of the soils. The 0.10-bar tension, the commonly used moisture tension for the purpose in the study area, proved suitable only for soils within the moderate to high structural stability category. From all indications, the 0.33-bar tension best corresponded to the FC of the less structurally developed soils in the other two categories. The level of soil structure development should therefore be considered before deciding the suitable moisture tension for the determination of FC of these and similar soils in other tropical locations. Keywords: Coarse mineral soils, field moisture capacity, saturated hydraulic conductivity, structural stability, water-conducting pores

Deriving hillslope sediment budgets in wildfire-affected forests using fallout radionuclide tracers

Information on post-fire sediment and nutrient redistribution is required to underpin post-fire catchment management decisions. Fallout radionuclide budgets ( 210Pb xs, 137Cs and 7Be) were derived to quantify soil redistribution and sediment yield in forested terrain following a moderately severe wildfire in a small (89 ha) water supply catchment in SE Australia. Application of these techniques in burnt terrain requires careful consideration of the partitioning of radionuclides between organic and mineral soil components. Beryllium-7 and 210Pb xs were shown to be closely associated with ash, litter and soil organic matter whereas 137Cs was more closely associated with subsurface coarse mineral soil. Comparison of the three tracer budgets indicated that the dominant sediment source areas were ridgetops and steep valley sideslopes, from which burnt surface material was conveyed to the stream network via pre-existing gullies. Erosion was predominantly driven by sheetwash, enhanced by soil water repellency, and modified by bioturbation which both supplies subsurface sediment and provides sinks for erosive overland flow. Footslope and riparian zones were not important sediment source areas. The estimated event-based (wildfire and subsequent rainfall) sediment yield is 58 ± 25 t km − 2 , based on fallout 7Be measurements. The upper estimate of total particulate phosphorus yield (0.70 kg ha − 1 ) is more than 10 times that at equivalent unburnt sites. This illustrates that, soon after fire, burnt eucalypt forest can produce nutrient loads similar to those of agricultural catchments. The tracer budgets indicate that wildfire is an important control on sediment and phosphorus inputs to the stream network over the decadal timeframe and the pulsed nature of this release is an important concern for water quality management.

The FORWARD Project: Objectives, framework and initial integration into a Detailed Forest Management Plan in Alberta

The Forest Watershed and Riparian Disturbance (FORWARD) project input into the Millar Western Forest Products Ltd. Detailed Forest Management Plan consists of three main components: 1) watershed and stream layer maps and associated datasets; 2) soil and wetland layer maps and associated datasets; and 3) a lookup table that permits planners to determine runoff coefficients (the variable selected for hydrological modelling) for functional first order watersheds, based upon various site factors and time since disturbance. The watershed and stream layer component includes a hydrological network, a Digital Elevation Model, and Strahler classified streams and watersheds for functional first and third order watersheds in the entire Millar Western Forest Management Agreement area. Relatively coarse mineral soils (which drain quickly) and wetlands (which retain water) were the key features that needed to be identified for the FORWARD modelling effort; therefore, the soil and wetland layers represent a combined soil texture and wetland coverage. The runoff coefficient lookup table integrates predictions of hydrologic impacts of harvest into planning. Key words: forest management, watershed, hydrology, stream, soils, wetlands, modelling

Concentrations of heavy metals in fly ash from a coal-fired power plant with respect to the new Finnish limit values

In Finland, the new limit values for heavy metals in fertilizers used in agriculture and in forestry came into force in March 2007, and for materials used as earth construction agents, in June 2006. From the utilization point of view, it was notable that the total heavy metal concentrations (Cd, Cu, Pb, Cr, Mo, Zn, As, Ni, Ba, and Hg) in fly ash from a coal-fired power plant were lower than those limit values. The concentrations of the easily soluble elements Ca, Mg, Na, P, and Zn in the fly ash were between 3.5 and 35 times higher than those found in the coarse mineral soils of Finland. Fly ash is a potential agent for soil remediation and for improving soil fertility. If inorganic materials and by-products are utilized in earthworks, the content of harmful compounds must be low and the harmful components must be tightly bound to the matrix. Therefore, a five-stage sequential extraction procedure was used to evaluate the extractability of different elements in fly ash into the following fractions: (1) the water-soluble fraction, (2) the exchangeable fraction (CH3COOH), (3) the easily reduced fraction (NH2OH-HCl), (4) the oxidizable fraction (H2O2 + CH3COONH4), and (5) the residual fraction (HF + HNO3 + HCl).

Extractability of trace elements in precipitated calcium carbonate (PCC) waste from an integrated pulp and paper mill complex

From the utilization point of view, it is notable that the total element concentrations in the precipitated calcium carbonate (PCC) waste were significantly lower than the maximal allowable heavy metal concentrations for fertilizers used in agriculture and in forestry, set on the basis of the EU and Finnish legislation. The easily soluble Ca concentration of 168.5 g kg −1 (d.w.) in PCC waste was 105 times higher than the typical value of 1.6 g kg −1 (d.w.) in the coarse mineral soil in Finland indicates that the PCC waste is a potential agent for soil remediation and for improving soil fertility if it is used as fertilizer. According to a five-stage sequential extraction procedure, the highest concentrations of most of the elements occurred either in HF + HNO 3 + HCl or H 2O 2 + CH 3COONH 4 fraction. This means that the major part of the elements retained in the PCC waste are not easy to extract (leach) under conditions normally found in nature. This is beneficial since, if inorganic materials and by-products are utilized in earth construction, the content of harmful compounds must be low and the harmful components must be tightly bound to the matrix.

Effects of de-icing chemicals sodium chloride and potassium formate on cadmium solubility in a coarse mineral soil

Excessive use of sodium chloride (NaCl) as de-icing chemical causes environmental problems, such as elevated chloride concentrations in groundwater. On vulnerable sites, this can be avoided by using alternative organic de-icing chemicals, such as potassium formate (KHCOO). The environmental impacts of KCHOO are, however, not well known. This study reports the potential effects of NaCl and KCHOO on mechanisms controlling the mobility of cadmium (Cd) in roadside soils as a result of vehicular traffic. Changes in the solubility of Cd in a coarse mineral soil treated with these two de-icing chemicals were studied in a 50-day incubation experiment under four different moisture and temperature combinations and an initial soil Cd concentration of 3 mg kg − 1 . After incubation, the distribution of soil Cd into different fractions was analyzed using a sequential extraction method. Soil pH and soil redox potential were recorded and the occurrence of Cd–Cl complexes in the soil was estimated using published stability constants. During incubation, KCHOO lowered the soil redox potential, but this was not accompanied by a decrease in the sorption capacity of oxides and the release of oxide-bound Cd into soil solution. On the other hand, elevated pH (from 4.3 to 6.7–8.5) in the formate treatments increased the sorption of Cd onto the oxide surfaces (up to 80% of total sorbed Cd). In the NaCl treatments, cation competition and formation of Cd–Cl complexes increased the water-soluble Cd fraction. Consequently, the amount of bioavailable Cd was 3.5 times smaller in the KCHOO than in the NaCl treatments.

The influence of waterlogging and variations in pedology and ignition upon resultant susceptibilities: a series of laboratory reconstructions

AbstractMagnetic survey techniques, such as fluxgate gradiometry, depend greatly on bodies of soil developing enhanced magnetic susceptibilities. Coarse mineral soils, especially those subject to a high groundwater table, often fail to develop enhanced susceptibilities and gradiometry. An example of this is Easingwold, in the Vale of York, UK. Gradiometry detected very little, however, subsequent excavation uncovered a complex of features suggesting multiphase activity and evidence for industry. This non‐detection is attributed to the coarse mineral soils and the high watertable. Several laboratory reconstructions were made to investigate the influence of specific characteristics of soil and ignition episode upon susceptibility. It was found that variations in soil texture had marked impacts on the levels of susceptibility attained, as did waterlogging. Leaching had a limited effect upon soil magnetic susceptibility, but there was variation according to texture. Copyright © 2004 John Wiley & Sons, Ltd.

The transfer of cesium-137 and strontium-90 from soil to food crops after the Chernobyl accident

The soil to plant transfer of 137Cs and 90Sr was studied at seven locations in Finland over 4 and 2 years, respectively. The plant/soil concentration ratio of 137Cs for field crops in the southern area (60°–63°N) ranged from 0.001 to 0.26 and in the northern area (64°–67°N) from 0.01 to 2.29, and that of 90Sr in the whole area from 0.02 to 2.44. The mean concentration ratio of 90Sr was about nine times higher than that of 137Cs in the southern area. The concentration ratio of 137Cs for leaf vegetables fluctuated between years, and that for carrot, potato and especially cereals decreased gradually after the first year. In the fourth year, the mean concentration ratio of 137Cs in the southern area was about 60% of the first year value for coarse mineral soils and 80% of that for clay and silt soils. There was no difference in the average 90Sr ratios between the 2 years studied. The concentration ratio of 137Cs was lower for clay and silt soils than for coarse mineral soils, and the 90Sr ratio was lowest for organic soils. The concentration ratio of 137Cs for vegetables and grain decreased in the order: lettuce, cabbage > carrot, potato > cereals, onion; for fruits in the order: blackcurrant > strawberry > apple, and the concentration ratio of 90Sr decreased in the order: lettuce, cabbage > carrot, anion > cereals > potato.

Soil properties affecting weed distribution in spring cereal and vegetable fields

The incidence of weed species in 482 cereal and 224 vegetable field plots in southern and central Finland was investigated. The occurrence of the 16 most common weed species was related to soil properties. Chenopodium album L., Lamium spp. L. and Fallopio convolvulus (L.) Löve were more abundant in clay than in coarse mineral or organic soils. Elymus repens (L.) Gould, Erysimum cheiranthoides L., Lapsana communis L., Myosolis arvensis (L.) Hill and Poa annua L. thrived better in coarse than in clay soils. Polygonum lapalhifolium L. and Rumex spp. L. were more abundant in organic than in mineral soils, and Lamium spp. was not found at all in organic soils. Rumex spp., Poa annua and Polygonum lapalhifolium had higher densities at the lowest pH level, < 5.2. Lamium spp. and Myosolis spp. thrived at the highest pH levels. Poa annua and Spergula arvensis were most common in soils where the extractable calcium concentration was below 1000 mg l-1 soil.

Weed infestation and factors affecting weed incidence in spring cereals in Finland - a multivariate approach

Weed vegetation of spring cereal fields in southern and central Finland was analyzed by ordination methods to provide a community level description of weed populations. Attention was paid particularly to the relative importance of environmental factors affecting weed incidence such as crop management, soil properties and weather conditions. A data set of 33 weed taxa from 252 fields was subjected to both indirect and direct gradient analysis. Indirect ordination was obtained with correspondence analysis (CA), and direct gradient analyses were performed with redundancy analysis (RDA) and with canonical correspondence analysis (CCA) relating environmental factors to the occurrence of weeds. Among several management factors, continuous herbicide use explained best the variation in the species composition of weed flora. Weed vegetation was also associated with soil type, moisture conditions and soil pHH2O. Ordination diagrams visualized the species-environment interactions and detected characteristic weed species for different geographical regions. In addition to ordination analyses of weed flora, the level and structure of weed infestation are described. The density of weeds averaged 170 plants m2 (median=124) and the air-dry weight of weeds 320 kg ha-1 (median=183). The average weed density was the same in different soil types, but the weed biomass was lower in clay soils than in coarse mineral and organic soils

Micronutrient concentration of Italian ryegrass (Lolium multiflorum L.) grown on different soils in a pot experiment

The uptake of micronutrients, B, Co, Cu, Mn, Mo and Zn, was studied in a pot experiment. The micronutrient concentrations of Italian ryegrass (Lolium multiflorum L.) ranged as follows: B 4.9-11.1, Co 0.01-2.30, Cu 2-15, Mn 29-225, Mo 0.01-1.79 and Zn 23-75 mg kg-1 DM. The micronutrient concentration of plant was compared with the AAAc+EDTA-extractable concentration in soil by soil type. The copper and zinc concentrations of ryegrass correlated stongly with the respective concentrations of all four soil type groups. The respective correlations of boron and manganese were good except in the silt soil group. Cobalt correlated best in coarse mineral and clay soils and molybdenum in clay and organic soils. Boron, cobalt, manganese and zinc concentrations of ryegrass were the higher the lower the soil pH was. In the whole material the following correlations were found between the micronutrient concentrations of ryegrass and soil: boron 0.58***, cobalt 0.68***, copper 0.70***, manganese 0.19**, molybdenum 0.69*** and zinc 0.90***. The results indicate that interpretation of micronutrient soil test data may be more accurate when soil type is considered.

Requirement for magnesium fertilization in Finland

More magnesium, on average, is removed annually from agricultural soils in Finland in yields (10 kg/ha) and through leaching (20kg/ha) than is replaced as fertilizers (4 kg/ha), manure (7 kg/ha) and as wet or dry depositions from the atmosphere (1 kg/ha). The amount of magnesium which is applied in assosiation with liming agents (at the most 25 kg/ha) has a decisie effect on the magnesium balance of the soils, although liming itself reduces those magnesium reserves of the soil which are extractable in neutral ammonium acetate(1 M) or in calcium chloride (0,01 M). The effect of two amounts of nitrogen and potassium fertilizers on the spring cereal and cultivated ley yields, on the magnesium uptake and nutrient contents of the yields, and the effect of liming on the magnesium status of the soil was studied using field, pot and incubation experiments in order to gain an estimate of requirement for magnesium fertilization. The results obtained with magnesium sulphate fertilizer in the same experiments were also used as an indicator of requirement for magnesium fertilization. The ammonium acetate (1 M, pH 7) extractable magnesium in the soil appeared to be the most important source of magnesium for the plants and the best indicator of requirement for magnesium fertilization. For the intensive cultivation of grassland crops, the soil should contain about 15 mg/100g of this type of magnesium. In pot experiments, the plants took up only small amounts of not extractable magnesium. Increasing the nitrogen fertilizer dosage (pot experiments, 4,5 l soil: N1=1500 mg, N2=3000mg N per year, field experiments: N1=50 kg/ha, N2=100 kg/ha N per year) generally brought about an increase in the magnesium uptake and in the magnesium content of the grasses. When the experiments were carried out using coarse mineral soils, the magnesium uptake and magnesium content of the plants decreased during the second and third year as the amount of nitrogen fertilizer increased. This was caused by the low magnesium content of the soil (pot experiments: below 12 mg/100 g soil in neutral ammonium acetate extractable magnesium, field experiments: below 100 mg/l soil in acid ammonium acetate extractable magnesium). In these soils, magnesium fertilization (200 mg Mg for 4,5 l soil per year or 57 kg/ha per year) appeared to have a positive effect on the supply of magnesium to the plants. The heavy clay and sandy clays used in the pot experiment did not require magnesium fertilization. The magnesium in silty clays, which contain a high proportion of the silt fraction (0,02—0,2 mm), may be liberated too slowly for intensively cultivated grasses and it may be necessary to give additional magnesium as fertilizer. Increasing the potassium fertilizer level from 60 kg/ha to 240 kg/ha K per year significantly decreased the magnesium content of the plants. Judging by the quality of the crops, a high potassium fertilizer level appeared to increase the requirement for magnesium fertilization. In the case of muddy very finesand the yield and magnesium uptake of timothy decreased with an increase in the amount of potassium applied. Liming (90, 180 or 360 mg/100g soil Ca as CaCO3) decreased the amount of neutral ammonium acetate extractable magnesium, in seven mineral soils out of nine, by 2—24 % in comparison to the magnesium content of unlimed soils. Part of the fertilizer magnesium became not extractable, too.

Effect of liming on the magnesium status of some mineral soils and on the fate of fertilizer magnesium

Nine mineral soils were incubated in laboratory without lime (Ca0) or limed (Ca1) with calcium carbonate (lab.reag.), and without magnesium fertilizer (Mg0) or fertilized with MgSO4*7H20 (Mg1 = 4 mg/100 g soil Mg). The incubation covered a period of seven weeks in aerobic conditions at constant 20 °C temperature. The relative increase in the effective cation exchange capacity (ECEC) caused by liming seemed to be in coarse mineral soils greater than in clay soils. The differences in pH (CaCl2) values between soil types was not so evident. In seven soils of the nine, liming decreased the 0,01 M CaCl2 extractable magnesium content more than in 1 M KCI or in 1 M neutral ammonium acetate extractable magnesium contents. The limed soils contained ammonium acetate extractable magnesium 2—24 % less than the unlimed soils. The decrease in magnesium content was greatest in acid muddy silt (Littorina soil) and in acid silty clay. Without lime the I M KCI extractable (Al+H) contents of these soils were 6,6 and 2,2 me/100 g soil and pH (CaCl2) 3,9 and 4,5, respectively. In finesand soils liming seemed to increase the magnesium content although not significantly. In limed soils 17—73 %of the fertilizer magnesium was extractable in 0,01 M CaCl2, 67—100 % extractable in 1 M KCI and 57—100 % extractable in 1 M neutral ammonium acetate. The equivalent ratio of exchangeable (1 M ammonium acetate, pH 7) calcium to magnesium in the soils may give pointers to the choice of liming agents, especially in the liming of low cation exchange capacity soils.