摘要:

The soil and plant analyst of today has a wide variety of analytical tools to choose from compared to the analyst of just a few years ago. The development of new instrumentation and equipment that applies to soil testing and plant analysis, and their application to both the small and large laboratory will be discussed. Areas covered will include equipment for sample preparation using automated and microwave digestion, measurement techniques to include colorimetry, potentiometry, plasma atomic emission and atomic absorption spectrometry, ion chromatography, nitrogen and sulfur analyzers, robotics, instrument control and data handling.

ISSN:0010-3624    

DOI:10.1080/00103629009368343

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A practical limitation of nitrogen soil tests is large spatial variability. The object of this research was to compare the variability of several forms of soil nitrogen: total N, nitrate, nitrate + ammonium, ammonium released during a two‐week anaerobic incubation at 25° C, and ammonium released by distillation with alkaline permanganate. A second objective was to compare sensitivity of these measurements to presence of green manure legume residues. Samples were collected from a 6.1‐ha area of a Nueva loam soil in transects with a 33.5‐m spacing and over a shorter distance at a 5‐m spacing. Plots with and without purple vetch (Vicia benqhalensis) were established on the site and at one other site with clay soil. Soil samples were collected in the spring just before and just after the legume was disced under. Coefficients of variability for nitrate, incub. ammonium, total N, and alk. perman. ammonium were 29–36%, 9–15%, 5–6%, and 2–4%, respectively. All variables showed similar spatial dependence except for incub. ammonium. Alk. perman. ammonium was not different in control and legume plots, while anaerobic incubation ammonium was higher in legume plots.

ISSN:0010-3624    

DOI:10.1080/00103629009368344

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Between 1978/79 and 1987/88, not one summer season recorded more rainfall than the long term average (878mm) in the dry tropics of north eastern Australia (Bowen). Without significant recharge of the aquifers the electrical conductivity of some bore waters used for irrigation increased beyond 3dS/m. Experiments were conducted to assess the changes in anion and cation concentrations in a black fine sandy clay loam soil treated with various fertilizer rates and furrow irrigated to compare the effects of high and low conductivity waters. The interaction of the salinity status of the waters and the rates of fertilizer will be discussed. The greatest concentration of salts was found in the surface few centimetres of the beds, at the extremity of the wetting front. The implications for soil sampling will be discussed.

ISSN:0010-3624    

DOI:10.1080/00103629009368345

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

To characterize the degree of alteration of the lignin molecule during biodegradation, CuO oxidation has been used in litters and soils. Condensed lignin structures are not attacked by the relatively‐mild alkaline CuO oxidation, for this reason the oxidation degradation with CuO is considered a specific method for the characterization of intact lignin structures in forest litters and soils. In this paper we examine two natural lignins, one from a gymnosperm litter, the other from angiosperm litter and from respective soils under air pollution conditions. The sum of phenolic CuO oxidation products gives an overall pattern of lignin decomposition. The degree of alteration of remnant lignin is described by the acid‐to‐aldehyde ratio (AC:A1) of syringyl and vanillyl units (S:V) for angiosperm lignin. The air pollution conditions do not influenced the degree of lignin degradation.

ISSN:0010-3624    

DOI:10.1080/00103629009368346

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This paper summarizes the principles of soil electrical conductivity, the equipment and methods used for measuring it, and the means of interpreting field soil salinity without need for soil sampling and laboratory analysis. A new technique for determining the salinity of soil samples from the electrical conductivity of the saturated‐paste is also described.

ISSN:0010-3624    

DOI:10.1080/00103629009368347

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A plant extraction method, which measures the inorganic phosphorus (Pi) in leaves, and four different soil testing methods were studied as indicators of phosphorus availability. Analytical values were compared with the yield responses and P uptakes of pot‐grown barley and oats. The inorganic leaf phosporus test was a sensitive indicator for P availability. This simple plant extraction method appeared to be at least as reliable as the best soil tests. Of the four soil tests studied, the water extraction test (Pw) was the most accurate method for mineral soils, but the water method as well as its modification with CaCl‐ addition (P‐Cl) gave overly high relative values for acid organic soils. The acid ammonium acetate test (P‐AAc) which is currently used in Finland, indicated excessively high P availabilities in strongly acid mineral soils, and gave erroneously low relative values in clay soils. The acid ammonium acetate EDTA method (P‐EDTA), which is used for micronutrients and could possibly serve as a universal extraction method, was found to be inferior to the other tests studied.

ISSN:0010-3624    

DOI:10.1080/00103629009368348

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Efficient use of nitrogen (N) fertilizer is important to achieve optimum crop yields while avoiding potential contamination of surface and ground water. A major obstacle in achieving optimum N fertilization is the difficulty of predicting soil organic N mineralization under field conditions. Since soils differ in their N‐supplying capacity, there is need for a testing procedure that will enable producers to make an accurate assessment of soil N availability. The purpose of this study was to evaluate electro‐ultrafiltration (EUF) and autoclave techniques to estimate soil N mineralization relative to N uptake by corn from unfertilized plots. Five different geographical locations in Nebraska were selected to encompass climatic conditions and soil types typically encountered throughout the state. Soil organic N mineralized determined by plant N uptake varied between geographical locations and ranged from 13 to 131 kg ha‐1. Data from both laboratory procedures were poorly correlated with crop N uptake across geographic locations. However, multiple regression including potentially mineralizable N (PMN), residual soil N, and growing degree days as independent variables resulted in a high correlation (R2≥ 0.93) with total N uptake. The results indicated that mineralization of organic matter (OM) can represent an important source of N and that it may be feasible to quantify soil organic matter mineralization by laboratory testing procedures for a broad range of climatic conditions.

ISSN:0010-3624    

DOI:10.1080/00103629009368349

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Soil testing and plant analysis using standard procedures are widely used in Malaysia. Routine soil analysis include determination of CEC, exchangeable cations, pH, organic carbon, total N, acid flouride soluble P, total P and extractable cations. Other parameters carried out by some laboratories include water‐soluble sulphates and chlorides, conductivity, exchangeable Al, available micronutrients, and total Si, Al and Fe. Plant analysis is the most utilized tool for discriminatory fertilizer recommendation. Dry ashing is generally used for determination of P, K, Ca, Mg, Na, Fe, Cu, Zn and B, and wet ashing using nitric‐perchloric acid is used for S and Mo. Generally, N, P and K are determined by autoanalyser, Ca, Mg, Fe, Cu and Zn by atomic absorption spectrophotometer, S by turbidimetry, and UV‐visible spectrophotometer is used for B and Mo determinations. The data obtained from both soil and plant analyses are used for fertilizer recommendation and nutrient diagnosis. Detail descriptions of the soil and leaf analytical procedures and the utilization of these data for diagnosing nutrient status 1n plantation crops, namely rubber, oil palm and cocoa will be presented and discussed.

ISSN:0010-3624    

DOI:10.1080/00103629009368350

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Fertilizer prescription equations were developed for sorghum (Sorghum bicolor) and chickpea (Cicer arientinum) separately based on yield goal approach. The validity of these equations was tested by conducting yield goal field trials on sorghum‐chickpea in sequence. The results showed that sorghum and chickpea yield goals were achieved within reasonable limits by applying fertilizers based on yield goal approach. The output/input ratio for a crop sequence was highest under 50 q/ha of sorghum yield goal followed by 25 q/ha of chickpea treatment (9.41).

ISSN:0010-3624    

DOI:10.1080/00103629009368351

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Because soil organic matter (OM) influences preemergent herbicide performance, many herbicide rates are based on soil OM content. Recent studies have found large inter‐laboratory differences in OM values whether determined by either similar or different methods. Making herbicide rate recommendations can therefore be difficult. A NaOH extraction method for determining humic matter (HM) is used by only a few laboratories but is gaining acceptance. Previous studies have shown that soil HM content also correlates with herbicidal activity. This study with several sulfonylurea herbicides found that both adsorption and herbicidal activity correlated more strongly with soil HM content than soil OM content.

ISSN:0010-3624    

DOI:10.1080/00103629009368352

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor