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1.
Abstract

Copper (Cu) can be toxic to creeping bentgrass (Agrostis palustris ’Penncross') grown in sand‐based systems. Plant analysis is not always a reliable predictor of toxic levels of Cu in these sand‐based systems. Therefore, there is need for soil analysis to detect potentially toxic Cu concentrations in soil. The objective of this research was to determine the effectiveness of AB‐DTPA and Mehlich III soil tests to assess Cu availability to ‘Penncross’ creeping bentgrass grown in calcareous and silica sand/peat media. Samples of sand/ peat were removed from greenhouse pots, air dried, and Cu was analyzed by inductively coupled argon plasma spectrometry (ICAP/IRIS). Correlations were made between extracted Cu and Cu in the shoot and root tissue of the plant. The AB‐DTPA‐extractable Cu was 24% and 42% higher for the calcareous sand at the 400 and 600 mg kg‐1 Cu treatments, respectively, when compared with Cu extracted from the silica sand. The Mehlich III soil test extracted 25% more Cu at the 400 mg kg‐1 Cu treatment and 37% more Cu at the 600 mg kg‐1 Cu treatment from the calcareous as compared to the silica medium. Shoot and root tissue Cu concentrations were higher at all Cu treatment levels for plants grown in silica sand. Although correlations were significant between Cu extracted from both sands by the AB‐DTPA and Mehlich III soil tests and Cu in the shoot and root tissue of plants, these extractants were unsuccessful in determining Cu availability from the two sand medium. This research indicates a need for a soil test which can be effectively used to extract plant‐available Cu from sand‐based systems.  相似文献   

2.
This study was designed to determine and compare root growth and nutritional responses of creeping bentgrass cultivars that differ in heat tolerance to differential, supraoptimal, shoot and root temperatures. Shoots and roots of ‘Penncross’ (heat sensitive) and ‘L‐93’ (heat tolerant) were exposed to four air/soil temperature regimes (20/20°C‐control, 20/35°C, 35/20°C, and 35/35°C) in water baths and growth chambers. Exposing roots to supraoptimal root temperature (35°C) while maintaining shoots at normal temperature (20°C) or particularly at 35°C reduced root fresh weight, root number, and contents of nitrogen (N), phosphorus (P), and potassium (K) in shoots and roots and accelerated root death for both cultivars. High root temperature had greater detrimental effects on root growth and nutrient element accumulation than high shoot temperature for both cultivars. A low root temperature at supraoptimal shoot temperature improved root growth, reduced root mortality; and increased N, P, and K contents in shoots and roots. Among the three nutrient elements, K was the most sensitive to changes in root temperature. L‐93 generally maintained higher fresh weight and number of roots and higher N, P, and K contents in shoots and roots, particularly K in roots, under high root (20/35°C) or shoot/root (35/35°C) temperatures. The results indicated that root growth and nutrient element accumulation, particularly of K, played an important role in creeping bentgrass tolerance to heat stress imposed on shoots by high air temperature or to roots by high soil temperatures. The enhanced root growth and nutrient element relations with a low root temperature at supraoptimal ambient temperatures could lead to the improved shoot growth in cool‐season grasses observed under these conditions.  相似文献   

3.
Abstract

Two greenhouse studies were conducted to evaluate the effect of B, Mn and Zn on nodulation and N2‐fixation of southernpea (Vigna unguiculata (L.) Halp.) cultivars ‘Freezegreen’, ‘Mississippi Silver’ and ‘Pinkeye Purple Hull’. The cultivars were grown in plastic pots with a Norfolk sandy loam (fine, loamy siliceous thermic, Typic Paleudult) soil treated with B, Mn and Zn at rates of 0, 5, 10 and 20 kg/ha each at pH levels 5.5, 6.0 and 6.5. At pH 6.5 all micronutrient treatments significantly increased nodulation and N2‐fixation over the control (no micronutrient applied). The effects of B, Mn and Zn on nodulation and N2‐fixation depended on the cultivar and soil pH. For plants given the 5 kg/ha B and Mn treatments, ‘Mississippi Silver’ produced the highest number of nodules and ‘Pinkeye Purple Hull’ the least. At 20 kg/ha Zn, nodulation of ‘Freezegreen’ was highest and ‘Pinkeye Purple Hull’ the lowest. As a whole, maximum nodulation was at 5 kg/ha B and Mn and 20 kg/ha for Zn. Nitrogen fixation rates responded similarly except that the optimum rate for Zn was 10 kg/ha. Seed yield of plants peaked at 5 kg/ha for B and 10 kg/ha for Zn, indicating a possible relation of N2‐fixation to seed yield.  相似文献   

4.
St. Augustinegrass [Stenotaphrum secondatum (Walt.) Kuntze] is a home lawn grass widely used in the southern United States. At present, phosphorus (P) fertilization of St. Augustinegrass is based primarily on Mehlich 1 P test. One criticism of Mehlich 1 extractant is that it extracts some fraction of soil P pool that is not available to plants, whereas, iron (Fe) oxide P and water‐extractable P methods are reported to be better related to plant growth in some cases. Literature relative to the soil test procedure comparison for St. Augustinegrass was not found. The objective of this study was to evaluate Mehlich 1 P, Fe oxide P, and water‐extractable P to identify the most suitable soil test method for St. Augustinegrass growth. Established pots of ‘Floratam’ were subjected to P application of 0, 0.14, 0.27, 0.54, and 1.07 g m?2 every 4 wk for 12 wk. Measurements included tissue growth rates, tissue P concentration, soil Mehlich 1 P, Fe oxide P, and water‐extractable P concentrations. Phosphorus application increased soil test P concentrations. Soil Mehlich 1 P, Fe oxide P, and water‐extractable P concentrations were closely correlated to each other. Three soil test P levels and tissue P concentrations were highly correlated with Mehlich 1 P, which best predicted tissue P levels. Three soil test P levels were also closely correlated to the St. Augustinegrass top growth rate. Critical minimum Fe oxide P and water‐extractable P concentration was 3 mg kg?1. Overall, Mehlich 1 P was the best soil P test for St. Augustinegrass among the three extractants tested.  相似文献   

5.
Abstract

This research evaluated effects of nitrogen fertilizers on availability of zinc (Zn) in soils. Two slit loams of the Hadley series (Typic Udifluvents) were used. Zinc sulfate was mixed with the soils to give Zn at 125, 250, 500, or 1,000 mg/kg and incubated for 14 days. Fertilizers (compost, cow manure, urea) were mixed with the soils to supply N at 200 mg/kg. Fourteen days after the fertilizers were mixed with the Zn‐treated soils, soil samples were taken for analysis of plant‐available Zn by extraction with Morgan's solution or water. After the soil samples were taken, fescue (Festuca arundinacea Schreb.) seeds were placed into pots to assess germination, growth, and Zn accumulation. Higher concentrations of Morgan's extractable Zn were detected in soils treated with compost (201 mg/kg) than with calcium nitrate (179 mg/kg), manure (153 mg/kg), or urea (152 mg/kg). However, with water extraction, higher Zn concentrations were detected in soils treated with calcium nitrate (36 mg/kg) with the lowest concentrations being extracted from soils treated with urea (8 mg/kg). Extraction of Zn by Morgan's solution or water increased as the soil‐Zn levels increased. Fescue germinated and grew at all of the soil‐Zn levels. The highest concentration of Zn occurred in plants grown in soils amended with calcium nitrate or urea, and the lowest concentration was in plants grown in soils amended with compost or manure. Fescue grown in soils amended with urea had the largest dry mass, and plants grown with compost or manure had the smallest. Zinc concentration and accumulation for fescue shoots increased as the soil‐Zn levels increased. These results suggest that accumulation of Zn in fescue can be enhanced by selection of nitrogen‐containing fertilizers that affect the solubility of Zn in soils.  相似文献   

6.
The effect of elemental sulphur (S) and S containing waste applications on soil pH treated with 0–2,000 kg ha‐l elemental S, and 0–100 tons ha‐1 of waste was determined in the field and the pots. Sorghum (Sorghum bicolor L.) was grown in a Lithic Xerorthent soil which was taken from where the field experiment was conducted in pots receiving 5 kg soil. Plants were harvested 20 weeks after planting or 30 weeks after the applications for determination of dry matter yield and phosphorus (P), iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) uptake by shoots. EC, NaHCO3‐extractable P, and DTPA‐extractable Fe, Zn, Mn, Cu also were measured in pot soil at the 5th, 10th, and 30th weeks. All treatments led to a decrease in soil pH though pH tended to increase again during course of time in both field and pot experiments. The both elemental S and waste applications in pot experiment caused an increase in dry matter yield and P, Fe, zinc (Zn), Mn and Cu uptake (mg pot‐1) by shoots in sorghum plant. There was also an increase in EC of soil due to both applications of S. The concentration of available P extracted by NaHCO3 in the pot soil, though not significantly different, was slightly higher compared with the control. Waste applications increased DTPA‐extractable Fe content of the soil, DTPA‐extractable Mn and DTPA‐extractable Cu. DTPA‐extractable Zn content, however, was reduced by the same applications.  相似文献   

7.
Abstract

A glasshouse study was conducted to determine effects of lime and Mn applied to three Florida soils on plant Mn, growth, and chlorophyll concentration of ‘Tifway II’ bermudagrass (Cynodon dactylon x Cynodon transvaalensis). Four replications of three lime rates (0, 1000, and 2000 mg CaCO3/kg as dolomite and Ca(OH)2 for Astatula fine sand (Typic Quartzipsamment, hyperthermic, uncoated) and Pompano fine sand (Typic Psammaquent, siliceous, hyperthermic); 0, 2000, and 4000 mg CaCO3/kg as dolomite and Ca(OH)2 for Myakka fine sand (Aeric Haplaquod, sandy siliceous, hyperthermic) and three Mn applications (none, 10 mg Mn/kg as MnSO4, and 5 mg Mn/kg as MnEDTA) were used in a randomized, complete block, factorial design. A wide range of plant Mn concentrations existed across treatments for each soil. Differences in plant Mn concentration did not cause significant differences in growth or chlorophyll concentration. The critical plant Mn concentration was not reached, but it appeared to be below 20 mg Mn kg for bermudagrass. Models for prediction of plant Mn concentration using soil pH and extractable soil Mn (Mehlich I, Mehlich II, DTPA‐TEA) were obtained. The applications of MnSO, and MnEDTA each resulted in increased plant Mn under acidic soil conditions. Neither Mn application resulted in increased plant Mn concentration in grass grown on Pompano fine sand with soil pH values of 7.0 or above.  相似文献   

8.
In greenhouse studies, corn (Zea mays L.) growth increased with Zn fertilization of two alkaline calcareous soils. Zinc concentration and total uptake increased with Zn application. Very high correlations were recorded between plant tissue Zn concentration, total Zn uptake and soil Zn levels determined by DTPA and AB-DTPA soil tests. Correlation between Zn concentration in plants and relative yield was poor. However, close relationships were revealed between extractable soil Zn and relative yield. Near maximum dry matter yield of corn was associated with a fertilizer rate of 2 mg Zn/kg soil. Plant tissue Zn-requirement was 27 mg/kg in 15 days old plants and 32 mg/kg in corn shoots of 40 day age. Critical soil test Zn level was 1.2 mg/kg by DTPA and 1.7 mg/kg by AB-DTPA method. Use of AB-DTPA soil test is suggested for evaluating Zn status of calcareous soils.  相似文献   

9.
Abstract

A field investigation was conducted to compare the efficacy of plowed‐down and disked‐in Zn as ZnSO4.H2O in correcting Zn deficiency of corn (Zea mays L.). The soil, Buchanan fine sandy loam, was nearneutral in pH and contained 0.7 ppm of EDTA‐extractable Zn and 1.4 ppm of dilute HCl‐H2SO4 extractable P. Application of 6.72 kg Zn/ha as ZnSO4.H2O corrected Zn deficiency of corn plants on the soil. Corn grain yields and Zn concentrations in tissue samples indicated that the plowed‐down and disked‐in Zn were about equally effective in correcting Zn deficiency where the level of Zn application was 6.72 kg/ha.  相似文献   

10.
Abstract

Zinc toxicity of peanuts (Arachis hypogaea L.), resulting from excessive amounts of Zn applied to previous crops, has been observed for many years in a limited number of peanut fields in Georgia. A tentative critical value of 12 mg/kg of Mehlich No.1 extractable soil Zn has been reported, but soil pH should be considered in establishing a more precise critical value since availability of soil Zn is affected greatly by soil acidity. A 3‐year study was conducted on a Tifton loamy sand (thermic, Plinthic Paleudults) to evaluate the relationship between soil pH and soil Zn on concentration of Zn in peanut leaves. Factorial treatments were 0, residual, medium, and high rates of Zn and soil pH levels near 5.5, 5.9, 6.2, and 6.8. Pod yields were not affected by treatments and Zn toxicity was not observed. Leaf Zn was affected more by soil pH than by soil Zn, but correlation coefficients were highest where both soil pH and soil Zn were included in the determination. A regression equation, based on soil pH and soil Zn, showed that an increase in soil Zn from 1.0 to 10.0 mg/kg increased leaf Zn 202 mg/kg at soil pH 4.6 and only 9 mg/kg at pH 6.6. Data from growers’ fields, in which samples were collected from eight healthy and toxic areas, indicated that a leaf Ca:Zn ratio of 50 or less was required for Zn toxicity of peanuts rather than high concentrations of leaf Zn per se.  相似文献   

11.
The sensitivity of creeping bentgrass (Agrostis palustris Huds.) to the extreme heat found in the southeastern United States has led to the development of new greens-management methods. The purpose of this study was to examine the effects of subsurface aeration and growth regulator applications on soil microbial communities and mycorrhizal colonization rates in a creeping bentgrass putting green. Two cultivars (Crenshaw and Penncross), a growth regulator (trinexapac-ethyl), and subsurface aeration were evaluated in cool and warm seasons. Total bacterial counts were higher in whole (unsieved) soils than in sieved soils, indicating a richer rhizosphere soil environment. Mycorrhizal infection rates were higher in trinexapac-ethyl (TE) treated plants. High levels of hyphal colonization and relatively low arbuscule and vesicle occurrence were observed. Principal components analysis of whole-soil fatty acid methyl ester (FAME) profiles indicated that warm-season microbial populations in whole and sieved soils had similar constituents, but the populations differed in the cool season. FAME profiles did not indicate that subsurface aeration and TE application affected soil microbial community structure. This is the first reported study investigating the influences of subsurface aeration and TE application on soil microorganisms in a turfgrass putting green soil.  相似文献   

12.
Crambe (Crambe abyssinica Hochist.) is an oilseed crop high in euricic acid with industrial applications in production of nylon, plasticizers, and lubricants. Little information is available on crambe response to phosphorus (P) and zinc (Zn) fertilization. This glasshouse study was conducted to evaluate the response of crambe to four rates of P and five rates of Zn fertilizer application to a soil with 10 mg/kg NaHCO3‐extractable P and 0.6 mg/kg DTPA‐extractable Zn. Phosphorus fertilizer, but not Zn fertilizer, increased the dry matter yield of plant tops. Phosphorus response was consistent in both 35‐ and 62‐day‐old plants. Zinc response was most consistent in 35 day‐old plants. Significant interactions were observed between P and Zn for dry matter weight, P:Zn ratio, and Zn uptake at 35 days. No significant interactions were observed at 62 days. Analysis of the data showed a negative correlation coefficient between P or Zn treatment and tissue concentration or uptake for the opposite element.  相似文献   

13.
The zinc (Zn) requirements of subterranean clover (Trifolium subteraneaum L.) are well known for the predominantly marginally acidic to neutral sandy soils of southwestern Australia, but the Zn requirements of French serradella (Ornithopus sativus Brot.) and biserrula (Biserrula pelecinus L.), now also grown on these soils, is not known and were investigated in a glasshouse pot experiment. Soil was collected from field plots never treated with Zn or treated once only with 0.5 and 1.0 kg Zn/ha as Zn oxide either in 1983, 1984, 1986, 1990, 1992, 1996, 1997, or 2000. In the pot experiment, six levels of Zn were freshly-applied to samples of soil collected from each Zn treatment of the field experiment, and pots were sown either with subterranean clover cv. ‘Dalkeith’, French serradella cv. ‘Margurita’, or biserrula cv. ‘Casbah’. The pasture species were defoliated by cutting pasture herbage 3 cm above the soil surface for up to 4 consecutive defoliations. The approximate linear relationship between the level of freshly-applied Zn in the pot experiment required to produce 90% of the maximum yield of dried defoliated herbage (y-axis) and the number of years since Zn was applied in the field (x-axis) was used to project the number of years it took for the 0.5 or 1.0 kg Zn/ha treatments applied in the field to require the same level of freshly-applied Zn to produce 90% of the maximum yield of the nil-Zn treatment in the field. This was 18–19 years for the 0.5 kg Zn/ha treatment and 32–35 years for the 1.0 kg Zn/ha treatment. The range in values was due to differences between legume species and the defoliation treatments, which were not significant. When yields were measured, samples of young growth (YG) were separated from the rest of the defoliated herbage (ROH) and the concentration of Zn in YG and ROH was measured. The concentration of Zn in YG that was related to 90% of the maximum yield of defoliated dried herbage (critical tissue test value) was (mg/kg) 13 for subterranean clover, 17 for French serradella, and 19 for biserrula; respective critical tissue test values for ROH were 19, 24, and 21 mg/kg. The approximate linear relationship between critical Zn concentration in YG (y-axis) and the number of years since Zn was applied in the field (x-axis) was used to project the number of years it took for the 0.5 and 1.0 kg Zn/ha levels applied in the field to reach the same critical tissue test value as the nil-Zn treatment of the field experiment. This was 17–20 years for the 0.5 kg Zn/ha treatment and 31–37 years for the 1.0 kg/ha treatment, which was similar to the 18–19 and 32–35 years projected using yield data. Before sowing the legumes in the pot study soil samples were collected to measure soil test Zn using the DTPA procedure. The critical DTPA soil test Zn, the soil test value that was related to 90% of the maximum yield of defoliated dried herbage, was about 0.20 mg Zn/kg for the 3 pasture legume species and all Zn treatments in the field and pot studies.  相似文献   

14.
ABSTRACT

Zinc (Zn) deficiency is a global nutritional problem in crops grown in calcareous soils. However, plant analysis criteria, a good tool for interpreting crop Zn requirement, is scarcely reported in literature for onion (Allium cepa L.). In a greenhouse experiment, Zn requirement, critical concentrations in diagnostic parts and genotypic variation were assessed using four onion cultivars (‘Swat-1’, ‘Phulkara,’ ‘Sariab Red,’ and ‘Chilton-89’) grown in a Zn-deficient (AB-DTPA extractable, 0.44 Zn mg kg?1), calcareous soil of Gujranwala series (Typic Hapludalf). Five rates of Zn, ranging from 0 to 16 mg Zn kg?1 soil, were applied as zinc sulphate (ZnSO4·7H2O) along with adequate basal fertilization of nitrogen (N), phosphorus (P), potassium (K), and boron (B). Four onion seedlings were transplanted in each pot. Whole shoots of two plants and recently matured leaves of other two plants were sampled. Zinc application significantly increased dry bulb yield and maximum yield was produced with 8 mg Zn kg?1. Application of higher rates did not improve yield further. The cultivars differed significantly in Zn efficiency and cv. ‘Swat-1’ was most Zn-efficient. Fertilizer requirement for near-maximum dry bulb yield was 2.5 mg Zn kg?1. Plant tissue critical Zn concentrations were 30 mg kg?1 in young whole shoots, 25 mg kg?1 in matured leaves, 16 mg kg?1 in tops and 14 mg Zn kg?1 in bulb. Zinc content in mature bulb also appeared to be a good indicator of soil Zn availability status.  相似文献   

15.
Greenhouse and field experiments were conducted to determine the influence of nitrogen (N) fertilization and DTPA‐extractable soil zinc (Zn) on Zn concentration in wheat (Triticum aestivum L., cv. Pioneer 2375) grain. Application of zinc sulfate (ZnSO4) in the range of 0 to 8 mg Zn kg‐1 increased linearly DTPA‐extractable Zn in an incubated calcareous soil from 0.3 to 5.0 mg kg‐1. Application of these rates of ZnSO4 to the same soil under greenhouse conditions increased Zn concentration of wheat grain from 26 to 101 mg kg‐1. The influence of 134 kg urea‐N ha‐1 on Zn concentration in wheat grain at eight field sites, with DTPA‐extractable soil Zn levels ranging from 0.3 to 4.9 mg kg‐1, was studied. Nitrogen fertilizer increased wheat‐grain yields in four of the eight experiments but had little effect on grain‐Zn concentration. Grain‐Zn concentration ranged from 31 to 45 mg kg‐1 in N‐fertilized plots at the various sites and was related (r=0.74*) to DTPA‐extractable soil Zn.  相似文献   

16.
Abstract

Fifty soil samples (0–20 cm) with corresponding numbers of grain, potatoes, cabbage, and cauliflower crops were collected from soils developed on alum shale materials in Southeastern Norway to investigate the availability of [cadmium (Cd), copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), and manganese (Mn)] in the soil and the uptake of the metals by these crops. Both total (aqua regia soluble) and extractable [ammonium nitrate (NH4NO3) and DTPA] concentrations of metals in the soils were studied. The total concentration of all the heavy metals in the soils were higher compared to other soils found in this region. Forty‐four percent of the soil samples had higher Cd concentration than the limit for application of sewage sludge, whereas the corresponding values for Ni, Cu, and Zn were 60%, 38%, and 16%, respectively. About 70% the soil samples had a too high concentration of one or more of the heavy metals in relation to the limit for application of sewage sludge. Cadmium was the most soluble of the heavy metals, implying that it is more bioavailable than the other non‐essential metals, Pb and Ni. The total (aqua regia soluble) concentrations of Cd, Cu, Zn, and Ni and the concentrations of DTPA‐extractable Cd and Ni were significantly higher in the loam soils than in the sandy loam soils. The amount of NH4NCyextractable metals did not differ between the texture classes. The concentrations of DTPA‐extractable metals were positively and significantly correlated with the total concentrations of the same metals. Ammonium nitrate‐extractable metals, on the other hand, were not related to their total concentrations, but they were negatively and significantly correlated to soil pH. The average concentration of Cd (0.1 mg kg‐1 d.w.) in the plants was relatively high compared to the concentration previously found in plants grown on the other soils. The concentrations of the other heavy metals Cu, Zn, Mn, Ni, and Pb in the plants were considered to be within the normal range, except for some samples with relatively high concentrations of Ni and Mn (0–11.1 and 3.5 to 167 mg kg‘1 d.w., respectively). The concentrations of Cd, Cu, Zn, Ni, and Mn in grain were positively correlated to the concentrations of these respective metals in the soil extracted by NH4NO3. The plant concentrations were negatively correlated to pH. The DTPA‐extractable levels were not correlated with plant concentration and hence DTPA would not be a good extractant for determining plant availability in these soils.  相似文献   

17.
Elevated copper (Cu) concentrations have been shown to decrease the microbial activity in soils. Plants can have beneficial effects on the biological activity of soils mainly through their root exudates. In this study we investigated the impact of various plant species with different Cu tolerance levels on the microbial activity in two soils with low (10 mg/kg) and high (180 mg/kg) copper concentrations. The soil was a Kahangi Sandy Loam. Three different plants, Agrostis capillaris ‘Parys’ tolerant for Cu, Agrostis capillaris ‘Highland’ non-tolerant and Helianthus annuus tolerant and a hyper-accumulator for Cu were used. To increase the Cu availability to plants, EDTA was added to some of the pots 20 days after sowing. The effect of Cu contamination on the biological activity of soil in the presence and absence of plant growth was evaluated by measuring the dehydrogenase activity, the microbial biomass, the basal respiration, and the potential nitrification.Results show that plants increased the microbial activity in the low Cu soil. In the high Cu soil the microbial activity seemed to be related to the plant health. With the Cu-tolerant Agrostis capillaris ‘Parys’, the microbial activity increased faster than with the other plant species. Up to 50 days after sowing, the tolerant grass Agrostis capillaris ‘Parys’ had a higher plant biomass and was much healthier than the non-tolerant grass. Later on the growth of the non-tolerant Agrostis capillaris ‘Highland’ recovered, and the microbial activity of the soil reached close to those recorded for the soil treatments with the Cu-tolerant plant species. The addition of EDTA delayed the increase in microbial activity even further. The proportion of microbial biomass carbon in the organic fraction was higher in the low Cu soil than in the high Cu soil, with ratios ranging from 1.3 to 3.3 and from 0.5 to 1.7 respectively. The basal respiration rate in the original soil was significantly lower in the high Cu soil than in the low Cu soil, and was generally increased by the presence of plants.  相似文献   

18.
Abstract

Z1nc (Zn) deficiency of corn (Zea mays L.) has been detected in 20 or more states 1n the United States including Georgia. Since soil pH is a major factor in assessing the availability of soil Zn, this measurement has been included with acid extractable soil Zn in developing calibration Zn soil tests in North Carolina and Virginia. The objectives of this study were to develop a reliable soil test for Zn based on soil pH and Mehlich 1 soil Zn for corn gown on coarse‐textured soils and to compare our soil test values with those recently published from North Carolina where Mehlich 3 was the extractant. The study was conducted 1n 1979 to 1981 on a Tifton loamy sand (Plinthic Paleudult) site which had been used to study the influence of lime rates on micronutrient availability since 1970. Treatments consisted of four soil pH levels ranging from 5.3 to 6.6 and soil Zn levels ranging from 0.5 to 4.9 mg/kg. The Zn levels were established from the previous study where 5.6 kg Zn/ha had been applied annually for eight years (residual treatment) and by applying 3.36 or 6.72 kg Zn/ha during 1979, 1980 and 1981.

Soil Zn, corn shoot, and ear leaf Zn values were reflective of the amount of Zn applied except that the residual Zn treatment resulted in Zn concentrations > than the annual application of 3.36 kg Zn/ha. Zinc tended to accumulate in the soil and in corn leaf tissue more from the residual Zn than the recently applied Zn treatments, especially at the highest pH levels. Increasingly more soil Zn was required to increase corn shoot and ear leaf Zn one mg/kg as soil pH increased. In the initial year, each unit (kg/ha) of applied Zn increased corn shoot Zn approximately 4 units (mg/kg) at pH 5.3 and only 0.3 unit at pH 6.6. Zinc deficiency symptoms developed in corn shoots for the two highest soil pH levels in two of three years. Corn yields were increased by Zn only in 1980 and were increased by residual or applied Zn at pH levels of 6.2 and 6.6. Regression equations from these studies were utilized to develop predictive corn shoot and ear leaf Zn values over wide ranges in soil Zn and pH. Our field research data using Mehlich 1 extractant could possibly be used satisfactorily in North Carolina regression equations where Mehlich 3 was the extractant; however, certain limitations would need to be imposed in the North Carolina equations.  相似文献   

19.
Minimum tillage cropping systems and the use of animal manures on cropland are becoming more prevalent. An experiment was initiated to determine the effects of tillage and lime/gypsum variables on uptake of zinc (Zn), manganese (Mn), and copper (Cu) by corn (Zea mays L.) and to show correlations between plant uptake of these metals and soil pH and Mehlich 1‐extractable soil metals where poultry litter was used as a nitrogen (N) source. Surface soil samples were taken in the spring and fall for two years from a long‐term tillage experiment that had been in place for nine years. There were two tillage treatments [conventional (CT) and no‐tillage (NT)] and six lime/gypsum treatments (control, 8,960 kg gypsum ha‐1 every fourth year, 4,480 kg lime ha‐1 every fourth year, and three treatments of 8,960 kg lime ha‐1 in a four‐year period divided by application times into 1, 2, and 4 treatments). Poultry litter was applied each year of the two‐year experiment at a rate of 8.96 Mg ha‐1 on a dry weight basis. Soil samples were analyzed for pH and Mehlich 1‐extractable Zn, Mn, and Cu, and plant tissue (small plant, ear leaf, stalk, and grain) was analyzed for Zn, Mn, and Cu concentrations. Lime treatments resulted in lower Zn in the small plant and ear leaf for CT, but not for NT. Plant Mn was decreased by lime and gypsum rates for small plant, ear leaf, stalk and grain for both years for CT and NT. Correlations for plant Zn versus soil pH were generally non‐significant, except for one year for ear leaf Zn (R=‐0.413**). Correlations for soil pH and plant tissue Cu were all nonsignificant. Correlations for plant Mn and soil pH were strong with R values over 0.80. Plant Mn response to treatments was found at a pH range of 4.2 to 5.8 for ear leaf and pH 5.2 to 6.2 for stalks. Plant Mn and Zn versus Mehlich 1‐extractable soil Mn and Zn, respectively, were negative. This response was possibly due to oxidation‐reduction and non‐incorporation of the lime for Mn and non‐incorporation of the lime for Zn. Also, the poultry litter was high in Zn (447 mg kg‐1), which could have masked pH effects. It was concluded that soil sampling for plant micronutrients for NT, especially where a waste material high in micronutrients is applied, can give erratic and even erroneous results. However, lime and tillage treatments had a predictable effect on micronutrient uptake as related to soil pH.  相似文献   

20.
Abstract

Onion (Allium cepa) and fenugreek (Trigonella poenum‐graceum) growth was measured in glasshouse on a slightly alkaline clay‐loam soil from Northern India. Cadmium, Ni, Pb and Zn were applied at the rate of 0, 50, 100, 200 and 400 mg/kg of soil. The fresh and dry weights of onion and fenugreek were drastically reduced even at the 50 mg/kg soil addition of Cd and decreased further at higher applied levels. There was a slight decrease in the yield of both of the vegetables at 50 mg Ni/kg soil but at 100 mg Ni/kg soil and above yield decrease was significant. No growth was observed at 400 mg Ni/kg soil. The application of 50 mg Zn/kg soil slightly increased the yield of both of the vegetables, but the yield decreased at higher levels of applied Zn and more so for fenugreek. The threshold concentration, toxicity index and loading rate to produce ten percent yield reduction were also calculated. These values suggested that the toxicity of heavy metals varied with crop species. The concentrations of the elements in onion bulb and fenugreek root and leaves increased linearally with increasing levels of applied elements. The uptake of Zn was highest, followed by Cd, Ni and then Pb. The roots accumulated higher amounts of these elements than the leaves. Tissue concentrations of Cd, Ni, Pb and Zn associated with ten percent yield reduction for onion were 6, 3.2, 8 and 75 ppm, respectively, and for fenugreek, the concentrations were 1.5, 7.8, 11.5 and 54.5 ppm, respectively. In general, phytotoxicities were found to be in the order: Cd > Ni > Pb > Zn. The DTPA extractable elements in soil, after the harvest of crops, increased with increasing levels of applied elements in soil.  相似文献   

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