摘要:

Rice (Oryza sativaL. CV. Lemont) was grown on 19 soils, and eight extractants were evaluated for determining the availability of Cu to rice plants. Correlation analyses were employed as criteria for evaluating methods that would provide the best index of Cu availability. The order of removal of Cu from soils was: 0.5NHC1 + 0.05NA1C13> 0.5NHNO3> 0.5 N HC1 > EDTA + NH4OAc > 0.1NHC1 > EDTA + (NH4)2CO3≫ DTPA‐TEA, pH 7.3 >>> 1 N NH40Ac, pH 4.8.

ISSN:0010-3624    

DOI:10.1080/00103628809368055

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The Modified Olsen (MO) extracting reagent is used extensively as a soil test extractant in Latin America. Little correlation or calibration research hasbeenreportedonit, however, especially for the micronutrients. wheat, corn, and soybeans were grown successively in the greenhouse to evaluate Cu, Zn, and Mn, respectively. Lime and micronutrient variables (one micronutrient per crop) were imposed on six soils representing four orders. After each cropping the soils were extracted with MO and with three other extracting reagents for which there are referenced critical levels: Mehlich‐1 (Ml), Mehlich‐3 (M3) and Soltanpour‐Schwab (SS). The correlations between nutrient uptake and the concentrations extracted were fairly similar for the four solutions, but were better for Mn and Zn than Cu. The poor relationship for Cu occurred partly because a maximum wheat concentration of about 10 mg/kg was reached, creating a curvilinear function. The amounts of nutrients extracted by the four reagents were also well correlated except for that between MO and Ml for Cu. Using these relationships, along with critical levels previously determined with reference extractants, the MO critical levels for Cu, Zn, and Mn were estimated to be 0.3, 1.0, and 3.0 mg/L, respectively

ISSN:0010-3624    

DOI:10.1080/00103628809368056

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Evaporation rates and drying times of soil samples exposed to high fluxes of unipolar air ions of either polarity, produced by corona electrodes, were studied with a beta‐ray gauge. Ion‐treated soils dried more than three times faster than the control samples under the same laboratory conditions. An analysis of the experimental curves on Rideau clay showed evaporation rates of 2.96 x 10‐4and 8.84 x 10‐4g cm‐2min‐1for control and treated samples, respectively, when exposed to 4.39 x 1012negative air ions cm‐2s‐1. An objective criterion was defined for a state of soil dryness when the sample acquired a steady‐state value of transmission of beta particles with time. Electric wind caused by the ionic drag is proposed as the principal driving force for the enhancement of evaporation rates from soil samples used.

ISSN:0010-3624    

DOI:10.1080/00103628809368057

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Two experiments of 4 year duration were conducted on organic soil sites which had accumulated P and K from several years of previous fertilization. There were no adverse consequences to an onion crop (Allium cepaL.) when P and K were omitted from the fertilizer program until the third year in one experiment. In the other there was no response to P and K even after 4 years of omission. Soil test levels declined substantially when P and K were not applied and also, although to a lesser degree, when they were applied at 112 and 168 kg/ha as P2O5and K2O respectively In contrast there were yield responses to N in most years. Nitrogen stimulated early development and always accelerated maturity as measured by the percentage of onion tops down in middle or later August. Concentrations of N, P and K in leaves or immature bulbs at midseason were always higher when these nutrients were applied indicating increased uptake even though yield responses did not always occur. When soil tests are relatively high, there appears to be little risk in reducing P and K providing the resulting decline in soil tests are monitored yearly. Eliminating N, however, could be very risky for early planted onions, even though substantial quantities can be released from organic soils later in the season.

ISSN:0010-3624    

DOI:10.1080/00103628809368058

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Two digestion procedures, employing aqua regia‐HF (ARHF) and HNO3‐HCIO4‐HF (HHH), were used to analyze residual metals (following a chemical fractionation scheme) and total metal content of two soils, one moderately polluted by municipal sludge applications and the other a grossly‐contaminated sample (20.8% Pb) from a battery recycling site. Although commonly used in sequential extraction analyses, the ARHF method solubilized only 53% (significant at p = 0.05) of the HHH‐determined residual Pb in the battery soil. For the sludge‐amended soil, residual Cd, Pb, and Zn were not statistically different by the two methods. For the battery soil, a single ARHF extraction also underestimated total Pb and Cu relative to HHH, but both methods gave statistically‐similar total Cd, Cu, Pb, and Zn for the sludge‐amended soil. As the sample metal concentration increased, the ability of ARHF to solubilize HHH‐equivalent metal quantities generally decreased. Since the degree of contamination is often unknown for environmental samples, the HHH method is more reliable for assessing residual and total metals in polluted soils

ISSN:0010-3624    

DOI:10.1080/00103628809368059

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A technique is described for the correction of abnormally high iron concentrations measured by X‐ray fluorescence spectrometry in alfalfa tops contaminated with soil. By adding to alfalfa samples, known amounts of different soils representative of the textural types occurring in the sampling area, the concentration of iron and aluminium in the contaminating soil was determined by subtracting the concentrations of the elements in the uncontaminated controls. A single regression equation relating concentrations of iron in the contaminating soil as a function of soil aluminium was suitable for correcting iron concentrations measured in all plants contaminated with soils of a loamy texture. Another regression equation was derived to correct values of iron in plants contaminated with sandy soils.

ISSN:0010-3624    

DOI:10.1080/00103628809368060

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Changes in soil chemical properties were investigated in conjunction with an ongoing study of fertility and irrigation relationships of cotton. Four irrigation methods and five nitrogen fertilization rates were the primary focus of the study. The four irrigation regimes studied were: high frequency center pivot, low frequency center pivot, furrow irrigated, and unirrigated. Nitrogen rates were 0, 30, 60, 90, and 120 lb N/A. Soil samples were collected from each plot in 6‐in‐ increments to a depth of 24 in. in 1982 and again in 1986 after four years of continuous cotton production. The soil samples were analyzed for pH, organic matter (OM), P, K, electrical conductivity (EC), and NO3‐‐N. All background soil characteristics were found to vary with depth with the exception of NO3‐‐N. The follow‐up sampling and testing in 1986 showed significant differences in soil properties as a function of irrigation, N‐fertilization, depth, and their interactions. Nitrates were accumulated in the 18 to 24‐in. depth under high (120 lb N/A) fertilization, and in the 0 to 6‐in. depth under the four lower treatments (0, 30, 60, and 90 lb N/A). Soil pH was highest in the furrow and high frequency center pivot irrigated regimes and lowest in the unirrigated regime. Soil pH also decreased with depth. Electrical conductivity of the soil was highest in the high frequency regime and not significantly different among the other three irrigation methods. The 0M content of the soil was greatest in the high frequency regime but not significantly different in the low frequency, furrow, or unirrigated blocks. Soil 0M was found to decrease with depth through 18 in. in all cases. The P and K status of the soil was not changed as a result of the N fertilization or irrigation treatments.

ISSN:0010-3624    

DOI:10.1080/00103628809368061

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Studies with 41 soils selected to obtain a wide range in properties showed that air‐dry and moist soils have substantial capacities for sorption of SO2from air (averages, 1.80 and 9.98 g S kg‐1soil, respectively). Soil properties influencing the capacities of air‐dry soils for sorptlon of SO2included clay content, surface area, DCB‐soluble Mn, CaCO3equivalent, dpH, acid‐titratable basicity, and sulfate sorption capacity. The corresponding capacities of moist soils were influenced by surface area and soil properties associated with CaCO3equivalent. It was possible to closely predict the SO2sorption capacities of both air‐dry and moist soils (R2‐ 0.913 and 0.939, respectively) from consideration of their properties

ISSN:0010-3624    

DOI:10.1080/00103628809368062

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Three standard techniques (thermocouple psychrometry, cell sap extraction, and plasmolysis) and two novel methods (osmometer solution, and image analysis) were comparatively evaluated for estimation of leaf cell water and osmotic potentials invitroand invivo. The test plants, tomato (Lycopersicon) assessionsL. esculentum‘Chico III’,L. pennellii, L. peruvianum, andL. cheesmanii, were grown as whole plants under microculture and growth chamber cultural environments. Each of the methods for measuring total water potential (thermocouple psychrometry, osmometer solution, and image analysis) and osmotic potential (thermocouple psychrometry, cell sap extraction) yielded consistent results when applied to microculture test plants (from a highly controlled, uniform environment), but results from growth chamber grown plants were too variable (between methods) to be conclusive. Plasmolysis gave unrealistically high estimates of osmolarity in all cases. Tissue water potential and osmolarity estimates were higher for plants grown in microculture than their growth chamber counterparts. The osmometer solution and image analysis methods were practical methods for total water potential estimation, required only a fraction of the time needed for psychrometry, and could be used reliably for microcultured tissues

ISSN:0010-3624    

DOI:10.1080/00103628809368063

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628809368054

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor