Ion mass budgets for small forested catchments in Finland

Ion mass and H⁺ budgets were calculated for three pristine forested catchments using bulk deposition, throughfall and runoff data. The catchments have different soil and forest type characteristics. A forest canopy filtering factor for each catchment was estimated for base cations, H⁺, Cl^? and SO ₄ ^2? by taking into account the specific filtering abilities of different stands based on the throughfall quality and the distribution of forest types. Output fluxes from the catchments were calculated from the quality and quantity of the runoff water. Deposition, weathering, ion exchange, retention and biological accumulation processes were taken into account to calculate catchment H⁺ budgets, and the ratio between external (anthropogenic) and internal H⁺ sources. In general, output exceeded input for Na⁺, K⁺, Ca²⁺, Mg²⁺, HCO ₃ ^? (if present) and A^? (organic anions), whereas retention was observed in the case of H⁺, NH ₄ ⁺ , NO ₃ ^? and SO ₄ ^2? . The range in the annual input of H⁺ was 22.8–26.3 meq m^?2 yr^?1, and in the annual output, 0.3–3.9 meq m^?2 yr^?1. Compared with some forested sites located in high acid deposition areas in southern Scandinavia, Scotland and Canada, the catchments receive rather moderate loads of acidic deposition. The consumption of H⁺ was dominated by base cation exchange plus weathering reactions (41–79 %), and by the retention of SO ₄ ^2? (17–49 %). The maximum net retention of SO ₄ ^2? was 87% in the HietajÄrvi 2 catchment, having the highest proportion of peatlands. Nitrogen transformations played a rather minor role in the H⁺ budgets. The ratio between external and internal H⁺ sources (excluding net base cation uptake by forests) varied between 0.74 and 2.62, depending on catchment characteristics and acidic deposition loads. The impact of the acidic deposition was most evident for the southern Valkeakotinen catchment, where the anthropogenic acidification has been documented also by palaeolimnological methods.     

Effect of Environmental Conditions on Chemical Profile of Stream Water in Sanctuary Forest Area

This study reports the evaluation of chemical composition of a Black Vistula and White Vistula streams’ waters taking into consideration both geological conditions of the stream’s catchment area and different water’ level related to seasonal variations in particular catchment ecosystem (high stage: beginning of the vegetation period; medium stage: vegetation period; low stage: final time of vegetation period). The complex data matrix (744 observations), obtained by the determination of major inorganic analytes (Cl^?, NO₃ ^?, SO₄ ^2?, NH₄ ⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺) in water samples by ion chromatography was treated by linear discriminant analysis and non-parametrical testing. In case of both streams obtained results indicate presence of two discriminant functions (DFs). The data variance explained by DFs is as follows: Black Vistula stream—first DF: 93.5%, second DF: 6.5%; White Vistula stream—first DF: 66.3%, second DF: 33.7%. In case of Black Vistula stream first DF allows distinction of medium, high and low waterstage related samples while second DF between high/low and medium water stage related samples. In case of White Vistula stream first DF allowed to distinguish between medium/high and low water stage related samples while second DF between medium and high water level samples. In case of both streams, the most informative DFs were related to geological conditions of investigated catchments (contents of Cl^?, Na⁺, K⁺, Mg²⁺, Ca²⁺, SO₄ ^2?), while the second to nutrient biocycle (mainly NH₄ ⁺ and NO₃ ^?) related to slope’s exposition and inclination.     

Randomized intervention analysis of the response of the West Bear Brook Watershed,Maine to chemical manipulation

A paired watershed manipulation study was conducted to study the qualitative and quantitative impacts of elevated acidic precipitation on the chemistry of soils, soil water, and stream water. The Bear Brook Watershed, Maine (BBWM) is drained by two first order streams, East Bear Brook and West Bear Brook. The streams were chemically and hydrologically monitored for two years (1987–1989) and exhibited similar behavior. The West Bear watershed was then chemically manipulated with the bimonthly addition of (NH₄)₂SO₄ (150 mol ha^?1 per application). To assess whether changes in stream water chemistry occurred following the chemical manipulation, and if so when, Randomized Intervention Analysis (RIA) was performed using time-paired data from the two watersheds. RIA, along with autocorrelation analysis, statistically evaluates the behavior of the various analytes under the influence of artificial acidification and therefore provided an objective basis for determining whether changes in the geochemical behavior of West Bear Brook were temporally associated with the chemical manipulation. RIA analysis using weekly data yielded higher probabilities of stream water chemistry effects being temporally linked with the manipulation than RIA analysis using monthly data. Using monthly data, there is a lower probability that short-term excursions in water chemistry related to hydrology can be detected. According to RIA analysis of weekly data for three years of manipulation (1989–1992), the statistically-determined order of impact on water chemistry was (K⁺, Mg²⁺, Na⁺, Ca²⁺, total Al, pH, SO ₄ ^2? , NO ₃ ^? , DOC)>Si>Cl^?. Autocorrelation analysis indicated that several analytes exhibited increasingly deterministic behavior, including SO ₄ ^2? , base cations, and DOC. Both RIA and autocorrelation analysis indicated no temporal relationship between the manipulation and hydrology.     

Three-component model of runoff generation,Lysina catchment,Czech Republic

The forested Lysina catchment is situated in an area very susceptible to acid deposition. The stream water is characterized by extremely high concentrations of total dissolved Al (volume weighted mean 66 Μmol L^?1) and H⁺ (average pH=3.87). In a simple two-component model, the surface runoff component contributes only 6% of runoff in winter and 4% of runoff in summer. During flood episodes, the direct runoff contributes up to 20% of streamflow. There is a strong positive correlation between stream acidity and stream discharge. The observed exponential increase in streamwater acidity with discharge during high flow periods cannot be explained by the simple two-component model. A three-component model used for hydrograph separation is based on chemical and¹⁸O analysis of precipitation, soil water and runoff. It incorporates a soil water component along with groundwater and rainfall components in streamwater generation. Dissociated organic acids leached during the flow of water through the uppermost soil horizon help to balance an apparent anion deficit. The apparent anion deficit was found to increase exponentially with flow rate. Low variability in streamwaterδ ¹⁸O corresponds to a high contribution of indirect components (i.e., soil and ground water) in the runoff. The soil water contribution to indirect runoff calculated from the apparent anion deficit of streamwater, varied from 0 at base flow up to 80% during floods. On average, 40% of the streamwater is derived from soil water (from 31 to 39% in winter and from 47 to 54% in summer).     

Chemical Composition of Precipitation, Throughfall and Soil Solutions at Two Forested Sites in Guangzhou, South China

Rain water at two forested sites in Guangzhou (south China) show high concentrations of SO₄ ^2?, NO₃ ^? and Ca²⁺ and display a remarkable seasonal variation, with acid rain being more important during the spring and summer than during the autumn and winter. The amount of acid rain represents about 95% of total precipitation. The sources of pollutants from which acid rain developed includes both locally derived and long-middle distance transferred atmosphere pollutants. The seasonal variation in precipitation chemistry was largely related to the increasing neutralizing capacity of base cations in rainwater in winter. Soil acidification is highlighted by high H⁺ and Al³⁺ concentrations in soil solutions. The variation in elemental concentration in soil solution was related to nitrification (H⁺, NH₄ ⁺ and NO₃ ^?) and cation exchange reaction (H⁺, Al³⁺) in soil. The negative effect of soil acidification is partly dampened by substantial deposition of base cations (Ca²⁺, Mg²⁺ and K⁺) in this area.     

Simulated effects of acid deposition on podzolic soils: Consequences of process and parameter aggregation

Solution cation concentrations and base cation leaching were simulated for a homogenous soil block and a soil showing five horizons of a podzolic forest soil. The dynamic model ACIDIC simulated water flow, nutrient uptake for tree growth, and cation exchange between H⁺, Al³⁺, Ca²⁺, Mg²⁺ and K⁺ in forest soil. In the multi-layer simulations exchangeable base cation concentrations changed most in the O horizon. The subsoil had a decisive effect on the pH of the runoff and base cation leaching from the soil. The one-layer model underestimated Ca and Mg leaching and overestimated H⁺ and Al concentrations in the runoff. In the eluvial and the top of illuvial horizon the solution Al / (Ca + Mg) ratio exceeded that in one-layer structure more than 10-fold. Cases with the horizon-specific cation exchange coefficient values and mean coefficient values for all layers showed only minor differences in Al / (Ca + Mg) ratio. The vertical variation in the soil chemical properties should be accounted for even if some details of processes and parameters were unavailable.     

Solute Release from Weathering of Spent Mushroom Substrate under Controlled Conditions

Weathering of piled material in the field is a popular method to treat spent mushroom substrate (SMS) before reuse. During the weathering process, rainfall and snowmelt pass through SMS piles and a large amount of solutes is released in the leachate. To investigate solute release patterns, the field weathering process was simulated under controlled conditions in the laboratory. Fresh SMS was packed in an acrylic column (20 cm i.d.) to 150 cm height and leached intermittently with a cumulative total of 230 cm of deionized water over 180 days. Leachate was collected and analyzed for dissolved organic carbon (DOC), dissolved organic nitrogen (DON), electrical conductivity (EC), and inorganic salts. Solute release patterns were described using first order models, and total released solutes were calculated. The SMS leachate had DOC, DON and EC values ranging from 450 to 15,500 mg L^?1, 50 to 1,700 mg L^?1, and 3 to 50 dS m^?1, respectively. The major inorganic cations were K⁺, Na⁺, Ca²⁺, Mg²⁺ and NH₄⁺, and anions were Cl^? and SO₄^2?. Release of DOC, DON, and bivalent cations Ca²⁺ and Mg²⁺ were described by a first order Exponential Rise to Maximum model, while releases of monovalent ions Cl^?, K⁺, Na⁺ and NH₄⁺ were described as a first order Sigmoidal Logistic process, and SO₄^2? release was best modeled by a Sigmoidal Chapman equation. Following six months and 230 cm applied water, 3.1 kg of DOC, 0.58 kg of dissolved N, and 8.6 kg of inorganic salts were leached per cubic meter of bulk SMS (220 kg oven dry mass). Weathering of SMS involves a significant removal of nutrients from the composted material, which can contribute to pollution of soil and groundwater.     

Aluminium Mobility at an Acid Sensitive Site with High S-Deposition

Soil water at an acid-sensitive forested catchment in southwestern Poland has been studied for four years. Median base saturation (BS) is only 5% in the podzol B-horizons. Very low pH values in the soil water from the O-horizons (10- and 90 percentiles pH 3.5 and 4.3) increased to a typical median pH in the B-horizons of 4.4, mainly by release of inorganic labile aluminium (Al_i). Median concentrations in the B horizons were 3.4mg Al_i L^?1. Al-soil/soilwater interactions were studied over a large span of sulphate concentrations resulting from both a generally decreasing S-deposition during the last decades and an increase in precipitation during the study period. These changes led sulphate to leach from the mineral soil. Aluminium mobilisation is better described by jurbanite- than by gibbsite solubility. For the soils with aluminium saturation (AlS) >90%, there is a tendency that the concentration of Al³⁺ decreases less than divalent base cations with a decrease in SO₄ ^2? concentration. This causes the critical load molar ratio (R_CL={Al³⁺}/{Ca²⁺+Mg²⁺}) to increase with a decrease in the sulphate concentration in soil water, which is not in agreement with a simple cation-exchange model.     

Trends of Major Inorganic Species at the Small Watershed Ecosystem in Northern Tama Hills, the Western Tokyo Metropolitan Area, Japan

Acid rain impacts on the small forested watershed in northern Tama Hills in the western Tokyo metropolitan area Japan were investigated by surveying the trends of major inorganic species in rain and spring water during the years from 1991 to 1997. The ecosystem had been stressed by the annual H⁺-deposition of around 0.43 kmol/ha. The spring water outflow corresponded to ca. 27% of the precipitation. Budgets for the precipitation input and spring water output gave good balance for Cl^?,?0.01 ±0.09 kmol/ha, net gains for H⁺, NO₃ ^? and SO₄ ^2?, and to the contrary, relatively large net losses for Na⁺, Mg²⁺, Ca²⁺, Si(as H₄SiO₄) and HCO₃ ^?, thus suggesting the dissolution of chemical weathered products of silicate minerals. Further, in spring water, some concentration relationships were found: CNa⁺ = 376.5?2.05CCl^? (R²=0.748), CNa⁺=12.69+0.5556CHCO₃ ^? (R²=0.872) and CH₄SiO₄=130.0 + 1.108CHCO₃ ^? (R²=0.816). Evidently, the spring water chemistry reflected probable geochemical changes in the soil layer of the watershed. Mass balance in the ecosystem and estimation of the spring water output of chemical weathered products were investigated     

Influence of Catchment Characteristics and Flood Type on Relationship Between Streamwater Chemistry and Streamflow: Case Study from Carpathian Foothills in Poland

The study aimed to determine the influence of catchment characteristics and flood type on the relationship between streamflow and a number of chemical characteristics of streamwater. These were specific electrical conductivity (SC), pH, the concentrations of main ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO ₃ ^? , SO ₄ ^2? , and Cl^?), and nutrients (NH ₄ ⁺ , NO ₂ ^? , NO ₃ ^? , and PO ₄ ^3? ). These relationships were studied in three small catchments with different geological structure and land use. Several flood types were distinguished based on the factors that initiate flooding and specific conditions during events. Geological factors led to a lower SC and main ion concentrations at a given specific runoff in catchments built of resistant sandstone versus those built of less resistant sediments. A lower concentration of nutrients was detected in the semi-natural woodland catchment versus agricultural and mixed-use catchments, which are strongly impacted by human activity. The strongest correlation between streamflow and the chemical characteristics of water was found in the woodland catchment. Different types of floods were characterized by different ion concentrations. In the woodland catchment, higher SC and higher concentrations of most main ions were noted during storm-induced floods than during floods induced by prolonged rainfall. The opposite was true for the agricultural and mixed-use catchments. During snowmelt floods, SC, NO ₃ ^? , and most main ion concentrations were higher when the soil was unfrozen in the agricultural and mixed-use catchments versus when the soil was frozen. In the case of the remaining nutrients, lower concentrations of NH ₄ ⁺ were detected during rain-induced floods than during snowmelt floods. The opposite was true of PO ₄ ^3? .     

Sources of Nitrate in Snowmelt Discharge: Evidence From Water Chemistry and Stable Isotopes of Nitrate

To determine whether NO₃ ^? concentration pulses in surface water in early spring snowmelt discharge are due to atmospheric NO₃ ^?, we analyzed stream δ¹⁵N-NO₃ ^? and δ¹⁸O-NO₃ ^? values between February and June of 2001 and 2002 and compared them to those of throughfall, bulk precipitation, snow, and groundwater. Stream total Al, DOC and Si concentrations were used to indicate preferential water flow through the forest floor, mineral soil, and ground water. The study was conducted in a 135-ha subcatchment of the Arbutus Watershed in the Huntington Wildlife Forest in the Adirondack Region of New York State, U.S.A. Stream discharge in 2001 increased from 0.6 before to 32.4 mm day^?1 during snowmelt, and element concentrations increased from 33 to 71 μmol L^?1 for NO₃ ^?, 3 to 9 μmol L^?1 for total Al, and 330 to 570 μmol L^?1 for DOC. Discharge in 2002 was variable, with a maximum of 30 mm day^?1 during snowmelt. The highest NO₃ ^?, Al, and DOC concentrations were 52, 10, and 630 μmol L^?1, respectively, and dissolved Si decreased from 148 μmol L^?1 before to 96 μmol L^?1 during snowmelt. Values of δ¹⁵N and δ¹⁸O of NO₃ ^? in stream water were similar in both years. Stream water, atmospherically-derived solutions, and groundwaters had overlapping δ¹⁵N-NO₃ ^? values. In stream and ground water, δ¹⁸O-NO₃ ^? values ranged from +5.9 to +12.9‰ and were significantly lower than the +58.3 to +78.7‰ values in atmospheric solutions. Values of δ¹⁸O-NO₃ ^? indicating nitrification, increase in Al and DOC, and decrease in dissolved Si concentrations indicating water flow through the soil suggested a dilution of groundwater NO₃ ^? by increasing contributions of forest floor and mineral soil NO₃ ^? during snowmelt.     

Simulation of flow patterns and ion-exchange in soil percolation experiments

An increased understanding of ion-exchange processes in raw-humus was obtained by simulations using quantitative mathematical models. The work is based on a series of percolation experiments with a water flow of about 1 mm min^?1 through raw-humus samples of 4 cm thickness. For the input solutions consisting of 10^?3 N H₂SO₄, HNO₃, HCl and NaCl the results indicate that cation-exchange reactions are the most important processes for the chemical composition of the run-off. Since a large part of the water flows quickly through the soil, both the water residence time and the ion-exchange kinetics must be taken into account. As a basis for the chemical model, a hydrologic sub-model reproducing the residence time distribution of the flow in the soil is used. Considering the ions H⁺, M⁺ (monovalent metal ions) and M²⁺ (divalent metal ions), four different chemical models were tried but only one of them gave satisfactory agreement with the experimental results. This model has 5 independent parameters and consists of first and second order chemical processes.     

Variation in Stream Water Quality in an Urban Headwater Stream in the Southern Appalachians

We examined the influence of a forested landscape on the quality of water in a stream originating on an urban landscape and flowing through National Forest lands. Sample sites included an urban stream (URB), a site on the same stream but within a National Forest (FOR) and 2 km downstream from the URB site, and a small, undisturbed, forested reference tributary of the main stream (REF). We monitored stream water quality from March 2002 through June 2003. Average base flows for the three stream sites were URB = 184 L s^?1, FOR = 420 L s^?1, and REF = 17 L s^?1. We analyzed weekly stream water samples for NO₃ ^?, NH₄ ⁺, PO₄ ⁺, Cl^?, K, Ca, Mg, SO₄, SiO₂, pH, conductivity, total suspended solids (TSS), and bacteria on a monthly basis. Most solutes were higher in concentration at the URB site, as were conductivity, TSS, and bacteria counts. Reductions in NO₃ ^?, NH₄ ⁺, and PO₄ ⁺ concentrations between the URB and FOR sites were inferred from changes in nutrient:chloride ratios. Bacteria populations were greater and more responsive to stream temperature at the URB site. Water quality responses to changes in stream discharge varied among sites but were greater at the URB site. By all measures, water quality was consistently higher at the FOR site than at the URB site.     

Biogeochemistry of aluminum in a forest catchment in the Czech Republic impacted by atmospheric inputs of strong acids

The Lysina catchment in the Czech Republic was studied to investigate the biogeochemical response of Al to high loadings of acidic deposition. The catchment supports Norway spruce plantations and is underlain by granite and podzolic soil. Atmospheric deposition to the site was characterized by high H⁺ and SO₄ ^2– fluxes in throughfall. The volume-weighted average concentration of total Al (Al_t) was 28 mol L^–1 in the O horizon soil solution. About 50% of Al_t in the O horizon was in the form of potentially-toxic inorganic monomeric Al (Al_i). In the E horizon, Al_t increased to 71 mol L^–1, and Al_i comprised 80% of Al_t. The concentration of Al_t (120 mol L^–1) and the fraction of Al_i (85%) increased in the lower mineral soil due to increases in Al_i and decreases in organic monomeric Al (Al_o). Shallow ground water was less acidic and had lower Al_t concentration (29 mol L^–1). The volume-weighted average concentration of Al_t was extremely high in stream water (60 mol L^–1) with Al_i accounting for about 60% of Al_t. The major species of Al_i in stream water were fluorocomplexes (Al-F) and aquo Al³⁺. Soil solutions in the root zone were undersaturated with respect to all Al-bearing mineral phases. However, stream water exhibited Al_i concentrations close to solubility with jurbanite. Acidic waters and elevated Al concentrations reflected the limited supply of basic cations on the soil exchange complex and slow weathering, which was unable to neutralize atmospheric inputs of strong acids.     

Ermittlung der Gesamtsäuredeposition in nordrheinwestfälischen Fichten- und Buchenbeständen

Measurement of total acid deposition into spruce and beech forests in Northrhine-Westfalia During one year the deposition of H⁺, NH₄⁺, Al³⁺, Fe³⁺ and the acidity (BNC_8,2) in bulk precipitation and throughfall of spruce and beech stands was measured in Northrhine-Westfalia. It is shown that the calculation of acid deposition as the sum of the H⁺-equivalents of (H⁺ + NH₄⁺ + Al³⁺ + Fe³⁺ + Mn²⁺) underestimates total deposition of acidity. A simple and useful alternative is the calculation of H⁺-equivalents from (BNC_8,2 + 0.9 NH₄⁺ + Mn²⁺).     

Nutrient Fluxes in Planted Norway Spruce Stands of Different Age in Southern Poland

The fluxes of N–NO ₃ ^? , N–NH ₄ ⁺ , S–SO ₄ ^2? , Na⁺, K⁺, Ca²⁺ and Mg²⁺ from bulk precipitation to throughfall, stemflow and soil water surface flows were studied during 1999–2003 in planted Norway spruce forest stands of different ages (11, 24, 91 and 116 years in 1999). Also, runoff from the corresponding Potok Dupniański Catchment in the Silesian Beskid Mts was studied. N deposition was above the critical load for coniferous trees. The interception increased with stand age as well as leaf area index and so did the leaching from the canopy of almost all the analysed elements, but especially S–SO ₄ ^2? , H⁺ and K⁺. The nutrient fluxes varied with age of the spruce stands. Throughfall showed a high amount of S and of the strong acids (S–SO ₄ ^2? and N–NO ₃ ^? ) deposited to the soil, especially in older spruce age classes. Decomposition of organic matter caused a rise in water acidity and an increase in the concentrations of all the analysed ions; the leaching of minerals, however, was low (under 1%). The horizontal soil water flow showed an increase in the amount of water and amount of ions and contributed to a further decrease of pH at the soil depth of 20 cm. Element concentrations and their amounts increased with water penetrating vertically and horizontally on the slopes. Considerable amounts of ions, especially S and alkaline cations, were carried beyond the reach of the root system and then left the catchment. In the long term, these mineral losses will adversely affect health and growth of the spruce stands, and the increased acidity with stand age will presumably have negative effects on the runoff water ecosystem.     

Chemistry of the Urauchi River Water in Iriomote Island National Park, Okinawa, Japan

The chemical characteristics of the Urauchi River water in Iriomote Island National park, Okinawa, Japan have been studied. Concentrations of PO₄ ^3?, NO₂ ^?, and NH₄ ⁺ were barely detectable. We compared the concentration ratios of Mg²⁺/Na⁺, HCO₃ ^?/Na⁺, and Ca²⁺/Na⁺ in the Urauchi River to those of 60 large rivers in the world and indicated that the chemical composition of the river is most likely formed by the binary mixing of sea salt components and silicate rock weathering components. Although rock weathering in the catchments area is driven by both H₂CO₃ and H₂SO₄, the role of H₂CO₃ is dominant. The percentages of the concentration of each cation in the river water are almost the same as those of other rivers with drainage areas consisting of silicate rock and sandstone. Thus, the Urauchi River shows the typical chemical characteristics of a river in a silicate rock area that includes sandstone.     

Chemical input/output balance for a moderately polluted forest catchment in southern Poland

A four-year study in a forest catchment exposed to a moderate level of anthropogenic pollution indicated heavy accumulation of hydrogen (H⁺), manganese (Mn), zinc (Zn), copper (Cu) and lead (Pb) in the ecosystem and phosphorous (P), potassium (K) and cadmium (Cd) to a lesser extent. Nitrogen, which is also accumulated, is leached mainly as NO₃ ^–, even though the input is dominated by NH₄ ⁺. Magnesium (Mg), calcium (Ca) and sodium (Na) are leached from the catchment, presumably due to intensive weathering processes in deeper layers of mineral soil. Chloride ion (Cl^–) is also lost from the ecosystem. The output of sulphate (SO₄ ^2–) with stream water exceeds its input only slightly. Although it appears that the catchment as a whole has a large buffering capacity (average stream water pH=7.43, rainfall pH=4.33), the upper biologically active soil layers are probably more susceptible to acidification and pollution. With constant accumulation of H⁺ and heavy metal ions this may lead to degradation of forest health.     

Yield,Nutrient Uptake,and Soil Chemical Properties as Influenced by Liming and Boron Application in Common Bean in a No‐Tillage System

Abstract

In Oxisols, acidity is the principal limiting factor for crop production. In recent years, because of intensive cropping on these soils, deficiency of micronutrients is increasing. A field experiment was conducted on an Oxisol during three consecutive years to assess the response of common bean (Phaseolus vulgaris L.) under a no‐tillage system to varying rates of lime (0, 12, and 24 Mg ha^?1) and boron (0, 2, 4, 8, 12, 16, and 24 kg ha^?1) application. Both time and boron (B) were applied as broadcast and incorporated into the soil at the beginning of the study. Changes in selected soil chemical properties in the soil profile (0- to 10‐ and 10- to 20‐cm depths) with liming were also determined. During all three years, gain yields increased significantly with the application of lime. However, B application significantly increased common bean yield in only the first crop. Only lime application significantly affected the soil chemical properties [pH; calcium (Ca²⁺); magnesium (Mg²⁺); hydrogen (H⁺)+ aluminum (Al³⁺); base saturation; acidity saturation; cation exchange capacity (CEC); percent saturation of Ca²⁺, Mg²⁺, and potassium (K⁺); and ratios of exchangeable Ca/Mg, Ca/K, and Mg/K] at both soil depths (0–10 cm and 10–20 cm). A positive significant association was observed between grain yield and soil chemical properties. Averaged across two depths and three crops, common bean produced maximum grain yield at soil pH_w of 6.7, exchangeable (cmol_c kg^?1) of Ca²⁺ 4.9, Mg²⁺ 2.2, H⁺+Al³⁺ 2.6, acidity saturation of 27.6%, CEC of 4.1 cmol_c kg^?1, base saturation of 72%, Ca saturation of 53.2%, Mg saturation of 17.6%, K saturation of 2.7%, Ca/Mg ratio of 2.8, Ca/K ratio of 25.7, and Mg/K ratio of 8.6. Soil organic matter did not change significantly with addition of lime.     

Comparing Two Extraction Methods to Evaluate the Composition of Substrate Solution of a Burnt Rice Husk Substrate Used for Carnation Crops

Substrates have been increasingly used in recent years for carnation crops. Burnt rice husk (BRH) is widely available and used as a substrate in Colombia. The present work aims to compare the effects of two aqueous extraction methods on the chemical contents. Saturated and 1:1 (v/v) extractions were performed in three replications. Ionic forms of the macronutrients (NO₃^?, NH₄⁺, PO₄H₂^?, K⁺, Ca²⁺, Mg²⁺, and SO₄^2?, in meq L^?1), micronutrients (Fe, Mn, Zn, Cu, and B, in mg L^?1), Cl^?, CO₃ H^? in meq L^?1, electrical conductivity in dS m^?1, and pH were analyzed. Except for NH₄⁺, Cl^?, and B the determination coefficient R² was greater than 95 percent. Average values and standard errors of data have been used to define suitable intervals for 1:1 extractions. Proposed intervals for 1:1 extracts are consistent with the saturated extract and therefore are a good tool to optimize the management of fertigation in those crops.