Relationship between EUF-K contents,K uptake and sugar yield of sugar beet in deep loess soils

Summary In field experiments with varying K fertilization (1981 and 1982) changes in EUF-K contents were studied in deep loess soils of Southern Lower Saxony under sugar beet. A significant positive linear relationship was found between EUF-K contents at 20°C and 200 V (15 mA) of the topsoils and quantities of K absorbed by sugar beet in both years. The corresponding regression lines for 1981 and 1982 are almost parallel, the only difference being the yield level which was higher in 1982.The relationship between EUF-K contents at 20°C of topsoils and sugar yields showed the same parallelism for the two years. Not much increase in sugar yield was found at EUF-K contents over 12 mg/100 g soil at EUF-K 80°C/EUF-K 20°C ratios between 0.5 and 0.7. To attain a sugar yield of 10 t/ha an EUF-K 20°C value of at least 12 mg/100 g soil is required for these deep soils at the beginning of the K uptake period. This finding confirms experiences gained over an 8-year period at the Tulln Sugar Factory (Austria) with fertilizer recommendations based on EUF.     

Relationships between EUF-N fractions,N uptake and quality of sugar beet in deep loess soils of Southern Lower Saxony

Summary In field experiments conducted in 1981 on deep loess soils a significant correlation was obtained between EUF-N content in the topsoil and N in sugar beet roots as well as in whole plants. A very close correlation was found to exist between EUF-N values in June 1981 and -amino N in sugar beet roots at harvest. Also other quality criteria such as the contents of sugar, K and Na in roots and yield parameters correlated with EUF-N contents in topsoils.The inorganic and organic EUF-N fractions changed during the vegetation period due to both N uptake by the crop and mineralization. Therefore it appears to be expedient to use both fractions when calculating N fertilizer requirements.The correlation between EUF-N (topsoil samples drawn in the year preceding sugar beet) and sugar yield increases obtained by N fertilization that was found in Austria¹² was confirmed in our experiments with soils from Southern Lower Saxony.     

Effects of 60-year N,P, K and Ca fertilization on EUF-nutrient fractions in the soil and on yields of rye and potato crops

Summary In field experiments carried out uninterruptedly since 1923 on a sandy, grey-brown luvisol (8% clay) the EUF-nutrient fractions were determined after potato and rye crops in 1982 had been harvested.Annual applications of N fertilizer (90 kg N/ha) over a 60-year period raised both the organic and inorganic EUF-N fractions (Table 1). EUF-N_org values increased depending on crop rotation from 1.1–1.9 to 2.4–3.6 mg/100 g. This increase in EUF-N amounts was higher under rye monoculture than under potato monoculture. N leaching was more intensive under potato monoculture than under rye monoculture.Application of P, K and Ca fertilizers raised the EUF-P, EUF-K and EUF-Ca values at 20°C as well as at 80°C (Figs. 1, 2, 3). Analyses of soil samples from the 25–75 cm layer showed that the contents of EUF-Ca and EUF-K in this layer are as high as in the topsoil or even higher (Table 3).High yields of rye (>4 t/ha) and of potatoes (>30 t/ha) were obtained when in samples taken after harvest EUF-amounts of 3.5 mg N, 2 mg P, 3 mg K (in both topsoil and subsoil), 1.7 mg Mg and 20 mg Ca/100 g were released within 35 min. These levels were obtained with annual fertilizer application rates of 90 kg N, 60 kg P₂O₅ and 110 kg K₂O/ha.Applications of 1.6 t CaO/ha every 4 years were sufficient to maintain the soil pH at 6.0–6.5. Calculated on the basis of EUF-Ca contents, with the amounts of K-selective minerals being taken into account, this rate of liming corresponds with the needs of acid sandy soils.     

Newly Isolated Bacillus gibsonii S-2 Capable of using Sugar Beet Pulp for Alkaline Pectinase Production

Summary A Bacillus strain capable of growing under highly alkaline conditions was isolated from a sample of alkaline soil. The isolate was a Gram-positive, spore-forming, aerobic, alkaliphilic bacterium and was designated as strain S-2. Growth of the strain was observed in the pH range of 7–12 and temperature range of 4–40 °C. Sequence analysis of the 16S rDNA of the strain revealed more than 99% homology with the strains of Bacillus gibsonii. The S-2 strain was confirmed as B. gibsonii by comparing its physiological and biochemical characteristics with the B. gibsonii DSM 8722 strain. The S-2 strain could use sugar beet pulp as the carbon source as well as the pectinase inducer to produce extracellular alkaline pectinase by solid-state fermentation. The maximum polygalacturonase yield of 3600 U/g dry sugar beet pulp was obtained at 35 °C after 48 h of incubation.     

Methods of short-term storage of cultures of the blowfly <Emphasis Type="Italic">Calliphora Vicina</Emphasis> R.-D. (Diptera,Calliphoridae)

Three methods of short-term storage of the blowfly Calliphora vicina strains are considered based on the experimental study of 21 strains originating from different parts of the species range. The colony can be preserved as diapausing adults at 6° and darkness for 2–3 months or more, depending on the geographical origin of the population. During the first five days of adult life the flies should be kept at 12° and short day on a sugar diet, after which they should be transferred into a refrigerator. During artificial hibernation the flies also require periodic sugar feeding every 20 days (3–4 h at 20°C) to maintain their vital functions. The combination of temperatures of 20–23°C and a protein diet terminates reproductive diapause, and oviposition starts in 10–17 days. The fly strain may be preserved as reproductive females at 6°C and darkness with sugar feeding. Flies also require periodic sugar feeding at 20°C (3–4 hours). In this case the flies start laying eggs 2–3 days after being transferred to 20–23°C. The preservation of diapausing larvae is a more reliable method of prolonged strain storage. In this case the flies of maternal generation are maintained at 20–23°C on sugar and protein diet. The egg rafts laid during 5–6 hours are then transferred into 12°C and short day until hatchment. The hatched larvae should be immediately placed into a refrigerator (2–3 or 5–6°C), where they feed during 1–1.5 months and enter diapause. For strain restoration, the diapausing larvae should be transferred into 20–25°C, where they pupariate in 3–5 days and the flies emerge in nearly 10 days.     

Production of <Emphasis Type="SmallCaps">d</Emphasis>-lactic acid from sugarcane molasses,sugarcane juice and sugar beet juice by <Emphasis Type="Italic">Lactobacillus delbrueckii</Emphasis>

Lactobacillus delbrueckii was grown on sugarcane molasses, sugarcane juice and sugar beet juice in batch fermentation at pH 6 and at 40°C. After 72 h, the lactic acid from 13% (w/v) sugarcane molasses (119 g total sugar l⁻¹) and sugarcane juice (133 g total sugar l⁻¹) was 107 g l⁻¹ and 120 g l⁻¹, respectively. With 10% (w/v) sugar beet juice (105 g total sugar l⁻¹), 84 g lactic acid l⁻¹ was produced. The optical purities of d-lactic acid from the feedstocks ranged from 97.2 to 98.3%.     

Application of the EUF procedure in grape production

Summary The relationships between the nutrient contents in vine leaves and grape yield on the one hand and the nutrient contents in the soil on the other are described on the basis of results from pot and field experiments conducted over several years. The soils were analysed by means of conventional methods as well as by electro-ultrafiltration (EUF). The following results were obtained: The application of high K and P fertilizer amounts in pot experiments increased the availability of Mg, Mn and Fe. A marked rise in the Mg, Mn and Fe contents was observed in the vine leaves. The exchange processes due to fertilizer addition were well indicated by the EUF method, whereas the results obtained by extraction with ammonium lactate (AL) and CaCl₂ were unsatisfactory. Close and highly significant correlations were found between the EUF-P, EUF-K and EUF-Mg contents on the one hand and the P, K and Mg contents in vine leaves on the other. A close correlation also exists (r=0.91^***) between grape yield and EUF-K contents. Grape yield increases with increasing EUF-K values up to 25 mg/100 g/30 min at 20°C in pot experiments (30 cm rooting depth) and only up to 12 mg/100 g/30 min at 20°C in field experiments. The soil in this field experiment had, however, EUF-K values of 12 mg/100 g in the topsoil as well as in the subsoil. When assessing the limit values, it is therefore important to consider the depth of the horizon in which the nutrients are present. After addition of very high amounts of P fertilizer the P contents in vine leaves markedly decrease after one year, as there is a decline in the availability of phosphates. The EUF-P values measured immediately after the application of high doses of P fertilizer can only characterize the P supply status of a soil for a period of one or two years. The P availability after application of different forms of phosphate fertilizers (superphosphate, hyperphosphate) is well indicated by means of EUF, but not by means of the AL method. When assessing the required K and Mg values in the soil (whatever the method) the vine variety has also to be taken into account, whereas the utilization of soil phosphates depends less on the varietal differences.     

Acetylene reduction byDaviesia mimosoides under Eucalyptus

Summary Daviesia mimosoides is a common understorey legume in Eucalyptus forests of the Brindabella Range in southeastern Australia, capable of fixing atmospheric nitrogen. Rates of N fixation were measured by the acetylene-reduction technique over a growing season in the field. Pot trials under controlled conditions were also carried out to elucidate effects of soil moisture, temperature, and light. Average rates in the field varied from about 1–5 μ mol C₂H₄/g/h (wet weight of nodule), but rates up to 14 μ mol C₂H₄/g/h were measured in optimum controlled conditions. Annual N-fixation rates approximate 4.5–7.0 kg/ha. In pot trials, rate of acetylene reduction decreased with soil moisture to about−10 MPa tension, with a marked depression at about−6 MPa, but within the normal field range of soil moisture there was little correlation of moisture with average acetylene reduction rate. Rates were similar in the temperature range of 20–30°C, but were depressed by either low or high temperature (<10 or >30°C). Diurnal fluctuations in acetylene reduction rates were not correlated with solar radiation, but rates were limited by high mid-day temperatures.     

阔叶红松林生态化学计量学特征及其对纬度梯度的响应

为研究红松叶片的养分及生态化学计量学特征的空间分布及其影响因素,依据我国温带阔叶红松林的分布特点,沿纬度梯度,选取长白山(42°27'N)、张广才岭(44°16'N)和小兴安岭(48°05'N)等3个地区的典型阔叶红松老龄林,测定红松叶片碳(C)、氮(N)、磷(P)含量,及表层土壤(0—15 cm)、中层土壤(15—30 cm)的有机碳(SOC)、全氮(TN)和全磷(TP)含量,分析了其分布特征及其相互关系。结果表明:1)红松叶片C、N、P含量显著高于土壤。表层土壤C、N、P含量变化范围分别为27.6—87.4,2.0—7.2 mg/g和0.26—0.92 mg/g;中层土壤为8.1—59.7,0.7—4.6 mg/g和0.2—0.82 mg/g;而叶片为495.5—507.4,12.7—172.5 mg/g和1.1—2.1 mg/g。2)土壤中的SOC、C/N、C/P均随纬度升高极显著增加,而叶片各元素计量特征随纬度的变化不显著。3)叶片N、P含量分别与土壤N、P含量显著正相关,同时,叶片N与土壤C/N、P与土壤N/P显著相关。相比较而言,红松叶片N、P含量较低,这可能说明阔叶红松林土壤N、P供应不足,而叶片N/P仅为9.9,说明东北阔叶红松林N限制更加明显。本研究为阐明东北温带阔叶红松林的养分供应状况和限制因素,为阔叶红松林区提高红松生产力的管理措施的提出奠定了基础。     

Identification and characterization of fermentation inhibitors formed during hydrothermal treatment and following SSF of wheat straw

A pilot plant for hydrothermal treatment of wheat straw was compared in reactor systems of two steps (first, 80°C; second, 190–205°C) and of three steps (first, 80°C; second, 170–180°C; third, 195°C). Fermentation (SSF) with Sacharomyces cerevisiae of the pretreated fibers and hydrolysate from the two-step system gave higher ethanol yield (64–75%) than that obtained from the three-step system (61–65%), due to higher enzymatic cellulose convertibility. At the optimal conditions (two steps, 195°C for 6 min), 69% of available C6-sugar could be fermented into ethanol with a high hemicellulose recovery (65%). The concentration of furfural obtained during the pretreatment process increased versus temperature from 50 mg/l at 190°C to 1,200 mg/l at 205°C as a result of xylose degradation. S. cerevisiae detoxified the hydrolysates by degradation of several toxic compounds such as 90–99% furfural and 80–100% phenolic aldehydes, which extended the lag phase to 5 h. Acetic acid concentration increased by 0.2–1 g/l during enzymatic hydrolysis and 0–3.4 g/l during fermentation due to hydrolysis of acetyl groups and minor xylose degradation. Formic acid concentration increased by 0.5–1.5 g/l probably due to degradation of furfural. Phenolic aldehydes were oxidized to the corresponding acids during fermentation reducing the inhibition level.     

Rapid determination of EUF-extractable nitrogen and boron

Summary A procedure for the rapid determination of EUF-extractable nitrogen (NH₄ ⁺, NO₃ ⁻ and easily soluble organic N compounds) is described. In this procedure the EUF-N fractions are oxidized to NO₃. The oxidation with peroxodisulfate is accelerated by ultraviolet (UV) radiation. This reduces the time of digestion to about 15 minutes. The contents of EUF-extractable N are on the average only between 2–8 mg/100 g soil. Their determination by the new procedure in the form of NO₃ is more precise than the results obtained by digestion according to Kjeldahl. The sum of EUF-extractable N fractions obtained by the new procedure allows to assess the N fertilizer requirements more precisely than is possible when using the EUF-NO₃ fractions alone. Therefore this new procedure constitutes a considerable advantage when working out fertilizer recommendations for agricultural practice.     

Overgrazing and soil carbon dynamics in eastern Inner Mongolia of China

Eastern Inner Mongolia of China is a typical ecotone between sandy forests and steppe. Little is known about the effect of overgrazing on carbon loss from soil in semiarid steppe and sandy forests of the north of China. The soil carbon parameters were measured in a 10,000 ha natural reserve in eastern Inner Mongolia of China (43°30′–43°36′N, 117°06′–117°16′E). Three situations were compared: primary protected (PP), moderately protected (MP) and highly degraded (HD). Soil and litter samples were recovered in spring and summer. Soil organic carbon (SOC) and CO₂–C values decreased from the PP (9.23 kg m⁻² and 157 g m⁻²) to the HD (1.69 kg m⁻² and 57 g m⁻²) sites whereas the C mineralization rate increased toward the less restored sites (1.06–2.37). Surface-litter C was different in both sites under protection (PP 648 and MP 408 g m⁻²), an was low at the HD site (17 g m⁻²). Leaves from woody species dominated the surface litter at the PP site, whereas grass material was predominant at the MP site. During summer, both CO₂–C and SOC decreased, whereas the C mineralization rate increased. We calculated that C loss since the introduction of cattle into the forest was 77 M g ha⁻¹, reaching a total of 1.1×10¹⁵ g for eastern Inner Mongolia. These values are higher than those caused by the conversion of steppe and other ecosystems into agriculture or cultivated pastures. The amount of C fixed at the PP site (650 g ha⁻¹year⁻¹) indicates that the sandy soils have a significant potential as atmospheric carbon sinks. Foundation item: The National Natural Science Foundation of China (No. 39900019, 30070129).     

Effects of atmospheric CO2 enrichment on δ 13C, δ 15N values and turnover times of soil organic matter pools isolated by thermal techniques

CO₂ applied for Free-Air CO₂ Enrichment (FACE) experiments is strongly depleted in ¹³C and thus provides an opportunity to study C turnover in soil organic matter (SOM) based on its δ ¹³C value. Simultaneous use of ¹⁵N labeled fertilizers allows N turnover to be studied. Various SOM fractionation approaches (fractionation by density, particle size, chemical extractability etc.) have been applied to estimate C and N turnover rates in SOM pools. The thermal stability of SOM coupled with C and N isotopic analyses has never been studied in experiments with FACE. We tested the hypothesis that the mean residence time (MRT) of SOM pools is inversely proportional to its thermal stability. Soil samples from FACE plots under ambient (380 ppm) and elevated CO₂ (540 ppm; for 3 years) treatments were analyzed by thermogravimetry coupled with differential scanning calorimetry (TG-DSC). Based on differential weight losses (TG) and energy release or consumption (DSC), five SOM pools were distinguished. Soil samples were heated up to the respective temperature and the remaining soil was analyzed for δ ¹³C and δ ¹⁵N by IRMS. Energy consumption and mass losses in the temperature range 20–200°C were mainly connected with water volatilization. The maximum weight losses occurred from 200–310°C. This pool contained the largest amount of carbon: 61% of the total soil organic carbon in soil under ambient treatment and 63% in soil under elevated CO₂, respectively. δ ¹³C values of SOM pools under elevated CO₂ treatment showed an increase from −34.3‰ of the pool decomposed between 20–200°C to −18.1‰ above 480°C. The incorporation of new C and N into SOM pools was not inversely proportional to its thermal stability. SOM pools that decomposed between 20–200 and 200–310°C contained 2 and 3% of the new C, with a MRT of 149 and 92 years, respectively. The pool decomposed between 310–400°C contained the largest proportion of new C (22%), with a MRT of 12 years. The amount of fertilizer-derived N after 2 years of application in ambient and elevated CO₂ treatments was not significantly different in SOM pools decomposed up to 480°C having MRT of about 60 years. In contrast, the pool decomposed above 480°C contained only 0.5% of new N, with a MRT of more than 400 years in soils under both treatments. Thus, the separation of SOM based on its thermal stability was not sufficient to reveal pools with contrasting turnover rates of C and N. Responsible Editor: Bernard Nicolardot.     

EUF-analysis of tea soils of Southern India and tea productivity

Summary The relationship between EUF extractable nutrients and conventional soil test extractable nutrients in the acid soils of Southern India on one hand and that between EUF values and tea productivity on the other are described. Close correlation exists between EUF-NO₃–N at 20°C and CuSO₄–Ag₂SO₄-extractable NO₃–N (r=0.98^***), EUF-N_org and Morgan's reagent extractable NH₄–N (r=0.97^***), total EUF-N and CuSO₄–Ag₂SO₄-extractable NO₃–N plus Morgan's reagent NH₄–N (r=0.96^***), EUF-P at 20°C and modified Bray II-P (r=0.93^***) and EUF-P at 20°C plus that at 80°C and modified Bray II-P (r=0.91^***). The EUF-K at 20°C shows close correlation with NH₄OAc–K (r=0.80^***), Ag-thiourea-K (r=0.86^***) and Morgan's reagent-K (r=0.84^***) whereas the EUF-K at 80°C shows close correlation with the difference in K contents of NH₄OAc–K and Ag-thiourea-K (r=0.92^***) or of NH₄OAc–K and Morgan's reagent-K (r=0.93^***) and fixed NH₄–N (r=0.89^***). EUF-Ca, EUF-Mg and EUF-Mn do not show any relationship with conventional soil test values. Tea productivity is strongly associated with EUF-N and EUF-P extracted at 20°C.     

Cryopreservation of in vitro sugar beet (Beta vulgaris L.) shoot tips by a vitrification technique

 Sugar beet shoot tips from cold-acclimated plants were successfully cryopreserved using a vitrification technique. Dissected shoot tips were precultured for 1 day at 5  °C on solidified DGJ0 medium with 0.3 M sucrose. After loading for 20 min with a mixture of 2 M glycerol and 0.4 M sucrose (20  °C), shoot tips were dehydrated with PVS2 (0  °C) for 20 min prior to immersion in liquid nitrogen. Both cold acclimation and loading enhanced the dehydration tolerance of shoot tips to PVS2. After thawing, shoot tips were deloaded for 15 min in liquid DGJ0 medium with 1.2 M sucrose (20  °C). The optimal exposure time to both loading solution and PVS2 depended on the in vitro morphology of the clone. With tetraploid clones a higher sucrose concentration during cold acclimation and preculture further enhanced survival after cryopreservation. Survival rates ranged between 60% and 100% depending on the clone. Since only 10–50% of the surviving shoot tips developed into non-hyperhydric shoots, regrowth was optimized. Received: 13 September 1999 / Revision received: 2 March 2000 / Accepted: 16 March 2000     

Effect of low temperature on the activity of phosphofructokinase from potato tubers

The aim of this work was to compare the coldlability of phosphofructokinase (EC 2.7.1.11) from tubers of potato cultivars (cvs.) known to differ in their propensity to accumulate sugars at low temperature. When stored at 4°C for six weeks, the sugar content of tubers ofSolanum tuberosum L. cv. Record doubled whereas the amount of sugar in tubers of cv. Brodick and an advanced breeding clone (13676) decreased slightly. Tubers from each line contained four forms of phophofructokinase. Over the range 12°–16°C the temperature coefficients of the four forms of phosphofructokinase from cvs. Record and Brodick were similar. In cv. Record the temperature coefficients of three of the enzyme forms were significantly higher at 2°–6°C than at 12°–16°C, whereas those from cv. Brodick were unchanged. These results are consistent with the proposal that inactivation of phosphofructokinase at low temperature results in the accumulation of hexose phosphates leading to increased sucrose synthesis.     

Microtuberization in potato (Solanum tuberosum L.)

Twenty-two genotypes of potato (Solanum tuberosum L.) were induced to form microtubers under six in vitro culture conditions. Cultures maintained under a short photoperiod (10 h of 6–12 μmol m^–2 s^–1) and low temperatures (day 20°±2°C and night 18°±2°C) had both a higher yield (255 mg/plantlet) and a greater number (2/plantlet) of microtubers than those maintained under long days (16 h of 38–50 μmol m^–2 s^–1) combined with high temperatures (day 28°±2°C and night 25°±2°C) (yield 207 mg/plantlet; microtuber number, 0.9/plantlet), over a wide range of genotypes. After the plantlets had been cultured under long days for an initial period of 60 days, continuous darkness advanced microtuberization by 2–3 months in various genotypes. Under short-day and low-temperature conditions the addition of 6-benzylaminopurine increased microtuber yield from 255 mg/plantlet to 645 mg/plantlet and average microtuber weight from 115 mg to 364 mg. A similar pattern was observed under conditions of long days and high temperature, and continuous darkness and low-temperature. Microtubers produced under light had a greater number of eyes (maximum average: 5.96/microtuber) than those produced in the dark (maximum average: 3.50/plantlet). The genotype × cultural conditions interactions were significant indicating the importance of developing genotype-specific protocols to maximize microtuberization. Received: 17 September 1997 / Revision received: 12 December 1997 / Accepted: 1 January 1998     

Transport of Carbon and Nitrogen Between Litter and Soil Organic Matter in a Northern Hardwood Forest

We used sugar maple litter double-labeled with ¹³C and ¹⁵N to quantify fluxes of carbon (C) and nitrogen (N) between litter and soil in a northern hardwood forest and the retention of litter C and N in soil. Two cohorts of litter were compared, one in which the label was preferentially incorporated into non-structural tissue and the other structural tissue. Loss of ¹³C from this litter generally followed dry mass and total C loss whereas loss of ¹⁵N (20–30% in 1 year) was accompanied by large increases of total N content of this decaying litter (26–32%). Enrichment of ¹³C and ¹⁵N was detected in soil down to 10–15 cm depth. After 6 months of decay (November–May) 36–43% of the ¹³C released from the litter was recovered in the soil, with no differences between the structural and non-structural labeled litter. By October the percentage recovery of litter ¹³C in soil was much lower (16%). The C released from litter and remaining in soil organic matter (SOM) after 1 year represented over 30 g C m⁻² y⁻¹ of SOM accumulation. Recovery of litter ¹⁵N in soil was much higher than for C (over 90%) and in May ¹⁵N was mostly in organic horizons whereas by October it was mostly in 0–10 cm mineral soil. A small proportion of this N was recovered as inorganic N (2–6%). Recovery of ¹⁵N in microbial biomass was higher in May (13–15%) than in October (about 5%). The C:N ratio of the SOM and microbial biomass derived from the labeled litter was much higher for the structural than the non-structural litter and for the forest floor than mineral SOM, illustrating the interactive role of substrates and microbial activity in regulating the C:N stoichiometry of forest SOM formation. These results for a forest ecosystem long exposed to chronically high atmospheric N deposition (ca. 10 kg N ha⁻¹ y⁻¹) suggest possible mechanisms of N retention in soil: increased organic N leaching from fresh litter and reduced fungal transport of N from soil to decaying litter may promote N stabilization in mineral SOM even at a relatively low C:N ratio.     

Differential medium for revelation of bacterial producer strains of L-asparaginases

A specific, fast, and easy method for revelation of active plate producers of L-asparaginase using differential medium on the basis of LB or M9 with 1.5% agar was developed. Each 100 ml of LB or M9 medium additionally contained 6–7 ml of glycerol, 4 g of L-asparagine, 0.2 g of CaCO₃, and diagnostic components: 3 ml of 0.2 M CuSO₄ · 5H₂O and 2.5 ml of 0.1 M K₃Fe(CN)₆, pH 7.6–7.8. The results were counted 12–20 or 24–48 h after strain growth at 37°C in corresponding mediums. Red color of colonies and colored zone around them showed the ability of the strain under study to destroy asparaginic complexes. The recommended method allows revealing bacterial strains producing L-asparaginase with specific activity of not less than 0.1–3.0 MU/mg of protein.     

Peat accretion and phosphorus accumulation along a eutrophication gradient in the northern Everglades

Recent rates of peat accretion (as determined by¹³⁷Cs) and N, P, organic C, Ca and Na accumulation were measured along a 10 km eutrophication gradient in the northern Everglades area of Water Conservation Area 2A (WCA 2A) that has received agricultural drainage from the Hillsboro canal for the past 25–30 yrs. Rates of peat accretion were highest at sampling locations closest to the Hillsboro canal, 1.6 km downstream, (5.67 ± 0.50 mm/yr) and decreased to 2.01 ± 0.31 mm/yr at distances of 7.1 to 10.7 km downstream. Phosphorus and Na accumulation were a function of both peat accretion and soil P and Na concentrations. The concentration and accumulation of P in peat deposited in the past 26 years was highest near the Hillsboro canal (1478 ± 67 ug/g, 0.66 ± 0.06 g/m²/yr) and decreased to 560 ± 20 ug/g and 0.10 ± 0.02 g/m²/yr at distances of 8.8 to 10.7 km downstream. Like phosphorus, the concentration and rate of Na accumulation was highest near the Hillsboro canal (3205 ± 1021 ug/g, 1.48 ± 0.53 g/m²/yr). Although sodium enrichment of the peat was limited to 1.6 km downstream of the Hillsboro canal, increased rates of Na accumulation penetrated 5.2 km downstream of the Hillsboro canal, the extent of the area of enhanced peat accretion. In contrast to P and Na, there was no difference in the concentration of soil organic C, N and Ca along the eutrophication gradient. However, there was a gradient of organic C, N and Ca accumulation corresponding to the area of enhanced peat accretion. The highest rates occurred 1.6 km south of the Hillsboro canal (212 ± 5 g organic C/m²/yr, 14.1 ± 0.4 g N/m²/yr, 22.1 ± 5.2 g Ca/m²/yr). Accumulation of organic C, N and Ca at distances of 7.1–10.7 km downstream averaged 87 ± 11, 6.3 ± 0.7 and 6.5 ± 0.9 g/m²/yr, respectively. The areal extent of enhanced peat accretion and organic C, N, Ca and Na accumulation encompasses approximately 7700 ha of the northern part of WCA 2A. The area of enhanced P accumulation is larger, covering 11,500 ha or 26% of the total area of WCA 2A. The 11,500 ha area has functioned as a sink for P for the past 25–30 yr removing 74% (49.3 MT/yr) of the 67 MT/yr that enters via agricultural drainage and rainfall. Moreover, P accumulation along the gradient was related to mean (1989–1990) surface water P concentration, decreasing as surface water P decreases. These findings suggest that P accumulation is dependent on the P concentration in the water column and that decreasing P loadings per unit area result in less P storage per unit area. The potential longterm equilibrium of the 11,500 ha area as a sink for P is based on a mean annual loading of 67 metric tons P/yr. Input rates exceeding this loading rate could result in an expansion of the 11,500 ha area until a new equilibrium size is reached.