ISSN:0010-3624    

DOI:10.1080/00103629009368283

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103629009368284

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103629009368285

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The availability of chemical elements from soils to plants and ultimately to animals consuming them has been investigated by scientists for centuries. Evidence has accumulated to support the theory that plants respond directly to changes in the activities of ions in the soil solution and only indirectly to the quantities of each element in soil which maintains the respective activities within the soil solution. Soil management involves changes in the available forms of each element in order to obtain the required range of activity to meet plant requirements. The Baker Soil Test™ (BST) is a new approach to soil testing which provides an activity measurement (intensity), a quantity measurement (extensive), and for some samples the total sorbed quantity of metals.

ISSN:0010-3624    

DOI:10.1080/00103629009368286

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Five chemical soil‐P extractants were compared. Surface samples from 88 Ontario soils were collected and used to grow corn (Zea mays L.) in a greenhouse. Soil pH ranged from 5.0 to 7.6 and organic matter from 60 to 575 g kg‐1. The amount of P extracted by the five extractants was used to predict P availability to corn plants. The amounts of P extracted by the five extractants were highly correlated (r = 0.83 to 0.97). The correlation of extractable P to plant P uptake resulted in r2values of 0.74, 0.73, 0.54, 0.65, and 0.66 for the NaHC03, AB‐DTPA, Bray‐Kurtz P1, Bray‐Kurtz P2, and Mehlich 3 extractants respectively. Adding soil pH to the equations improved the prediction of plant P uptake resulting in R2values of 0.80, 0.80, 0.70, 0.73, and 0.75 for the NaHC03, AB‐DTPA, Bray‐Kurtz P1, Bray‐Kurtz P2 and Mehlich 3 extractants, respectively. The two alkaline extractants appeared to be equally effective and superior to the three acidic extractants with the Bray‐Kurtz P1 extractant being least effective.

ISSN:0010-3624    

DOI:10.1080/00103629009368287

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Because of both economic and environmental concerns, soil testing is becoming an increasingly important component of crop‐production systems. This increasing demand for soil testing will necessitate more efficient methods for routine soil testing. The Mehlich‐3 soil test has been proposed as an extractant that can be used for simultaneous extraction of several nutrients including both P and K. Before this extractant can be used in place of the current extractants, it must be evaluated in field calibration studies. This study was designed to compare the ability of the Mehlich‐3 extractant to predict corn(Zea maysL.) yield response to P and K with the Bray‐Kurtz P1 extractant for P and the neutral, 1N ammonium acetate extractant for K. A field study was conducted at 67 locations across Pennsylvania over 4 yr. A factorial arrangement of P (0 and 88 kg ha‐1) and K (0 and 168 kg ha‐1) was applied at each location. Corn‐grain yield was measured as the response parameter. The Mehlich‐3 extractant was highly correlated with the Bray‐Kurtz P1 extractant (r=0.99) and neutral, 1N ammonium acetate K extractant (r=0.96). The calibrations for the Mehlich‐3 P and Bray‐Kurtz P1 were similar. While there was a large amount of scatter in both data sets, a Cate‐Nelson partitioning of the data resulted in critical levels of 43 and 45 kg P ha‐1for the Bray‐Kurtz P1 and Mehlich‐3 P extractants, respectively. The calibrations for the Mehlich 3 and the neutral, 1N ammonium acetate extractants were also similar. Again there was considerable scatter in the data. The Cate‐Nelson critical levels for K were 0.20 and 0.24 cmol kg‐1for the Mehlich 3 and neutral, 1N ammonium acetate extractants, respectively. On this basis it appears that the Mehlich 3 is at least as good as the currently used extractants for P and K and could readily replace them in Pennsylvania. At the same time the large amount of scatter indicates the need for a more mechanistic approach to soil testing.

ISSN:0010-3624    

DOI:10.1080/00103629009368288

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The purpose of this research was to compare results of several solutions for the extraction of P, K, Ca, and Mg in Alabama soils. Fifty soils from each of three soil groups ranging from sands to clay loams were selected for analysis. The soils were analyzed by Mehlich 1, Mehlich 3, Bray‐Kurtz P1 and by the Mississippi method of Lancaster (modified for Alabama). Values for P, K, Ca, and Mg were plotted against Mehlich 1 results, the procedure presently used in Alabama. Also, all soils were extracted with ammonium acetate for cation comparisons with the other four methods. Good correlations were obtained for all comparisons among extractants.

ISSN:0010-3624    

DOI:10.1080/00103629009368289

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Mehlich 3, proposed as the “universal extractant”; for the Eastern U. S., has not been adequately evaluated for the major agricultural soils of the Coastal Plain of Georgia. A greenhouse study was conducted to compare soil P, K, Ca, and Mg extracted by Mehlich 3, Mehlich 1, and Bray/Kurtz P1. Rye (Secale cerealeL.) was grown oh six soil series with five P and five K rates to develop plant data for Mehlich 3 extractable P and K. Rye dry weight, P concentration, and P uptake were significantly related to applied and soil P. Extraction of soil P was significantly correlated among the extractants, but slopes varied from 1.22 to 1.84 in the order: Bray/Kurtz P1 > Mehlich 3 > Mehlich 1. Responses of soil tests to applied P were in the same order and for five of the soils were 0.87, 0.71, and 0.51 kg P extracted/kg P added for the three extractants, respectively. A sixth Coastal Plain soil with a relatively high clay content gave much smaller soil‐test responses of 0.32, 0.26, and 0.16 kg/kg for the three extractants, respectively. Sorption isotherms indicated a high P sorption for the high clay soil relative to the other soils. Isotherms or clay content may be useful in extrapolation among soils. Rye was less responsive to K than to P and its response to K was curvilinear. Mehlich 3‐K, ‐Ca and ‐Mg values were closely related to their respective Mehlich 1 values with slopes close to one. The results indicate that Mehlich 3 is a suitable extractant for P, K, Ca, and Mg in Coastal Plain soils. Samples stored for 27 mo under prevailing temperature conditions and then retested had increased Mehlich 1‐P and ‐K at low soil test levels and decreased Mehlich 1‐P and ‐K at high test levels.

ISSN:0010-3624    

DOI:10.1080/00103629009368290

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A four year study was planned and initiated in the fall of 1988 on a soil (Typic Pelloxerert) with a Bray‐Kurtz P1 of 8 mg/kg and a 2:1 water:soil pH of 5.2. Perennial ryegrass (Lolium Perenne L.) was seeded in 30.4 cm rows with P surface banded and broadcast at four rates (0, 26.5, 53 and 79.5 kg/ha) on limed (4.5 t/ha) and unlimed plots. Each plot was sampled at four intensities; 5, 10, 20 and 40 cores to a 0 to 15 cm depth. An additional sample from 0 to 2.5 cm was obtained for the 40 core intensity. A 6.1 m by 2.4 m area with lines every 30.4 cm was delineated and superimposed on each plot. For each plot the same spot for the 5, 10, 20 and 40 intensities were used and samples analyzed for P and pH. Where P was banded, an additional sample was taken with 50% of the cores in the band. No discernible differences were measured between banded and broadcast P in sampling error or P means.

ISSN:0010-3624    

DOI:10.1080/00103629009368291

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Universal extraction reagents are defined as a single extractant for use on a range of soils for the determination of both major elements and micronutrients. The first universal extractant, so named by its developer, was the Morgan Extraction Reagent which was introduced in 1941 for use on both mineral soils and organic soilless mixes. In 1954, Mehlich introduced an universal extractant, frequently referred to as the Double Acid extractant, for assaying acid sandy textured soils. The ammonium bicarbonate‐DTPA extraction reagent for use on alkaline soils was introduced by Soltanpour in 1977. In 1982, Wolf modified the Morgan extraction reagent by adding DTPA to it. In 1984, Mehlich described his Mehlich No. 3 extraction reagent for use on a wide range of acid soil types. All these extraction reagents can be assayed using a multielement analyzer such as the inductively coupled plasma emission specterometer for both the major elements and micronutrients in the obtained extractant.

ISSN:0010-3624    

DOI:10.1080/00103629009368292

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor