摘要:

Cation exchange capacity of ten non‐calcareous and non‐saline soils from Queensland, Australia, has been determined by the ammonium acetate method using different procedures, by an ammonium chloride method at pH8.5, and by three methods which attempt to approximate field conditions. Procedural differences in the ammonium acetate method produced variation in results, and methods using approximate field conditions gave much lower values for those soils considered to have variable charge properties.

ISSN:0010-3624    

DOI:10.1080/00103628309367428

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Potassium in soils from selected plots of the Broadbalk Experiment at Rothamsted, and Rotation I experiment at Saxmundham, U.K. was measured by five methods: the boiling nitric acid extractions of Haylock and Maclean, electro‐ultrafiltration, release to Ca‐saturated ion exchange resin, and a new procedure using extraction by HCl under reflux. All. the methods showed clearly the Gifferences between the two soil types, and between the differently fertilized plots on the basis of amounts, and 1n some cases rates of release, of different categories of soil K (exchangeable, fixed and native). The quantity of exchangeable K measured by each method, except that by Ca‐resin, gave significant correlations with the K balance of the soils, and yield and/or K offtake of winter wheat grown on the plots. The new HCl ‐reflux method gave the closest correlations. The amount and rate of release of fixed (available but not exchangeable) K estimated by HCl‐reflux was also correlated with yield and offtake.

ISSN:0010-3624    

DOI:10.1080/00103628309367429

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Potassium availability was determined by growing corn (Zea maysL.) in pots of soil in a controlled environment chamber. Comparison of K uptake rate per unit root area indicated differing degrees of K availability. The differences in availability among soils were not predicted by differences in cation exchange capacities. The K concentration in solution and the average rate of diffusion more nearly reflected differences in K availability, particularly when the kinetic rate factors of diffusion and mass flow were integrated with root growth and uptake factors in the Cushman mathematical model of K uptake. Utilization of this model demonstrated the importance of using rate factors for ion movement in soil along with plant factors of root growth in predicting K availability.

ISSN:0010-3624    

DOI:10.1080/00103628309367430

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A method is described for the direct estimation of NH+4‐N in 2MKCl extracts of soils based on the emerald green color formed when NH3and salicylate react in the presence of NaOCl at high pH.‐The reagent concentration, solution pH, and time and temperature of color development specified are those giving maximum molar asorptivity. Precipitate formation observed when KCl extracts containing divalent cations were treated with color developing reagents was eliminated by addition of 1 mL of 6% EDTA to complex Ca2+and Mg2+. Free EDTA or complexed Ca2+or Mg2+did not markedly affect color development or molar absorptivity. The proposed method efficiently recovered NH+4‐N added to 2MKCl extracts of soils and studies showed that the proposed method and two other procedures differing in principle gave similar values for NH+4‐N in extracts of 5 soils. The proposed method is a simple, rapid, accurate, and precise technique for the colorimetric determination of NH+4‐N in KCl extracts of soils.

ISSN:0010-3624    

DOI:10.1080/00103628309367431

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Interrelations between soil pH and exchangeable sodium percentage (ESP) were examined using soils from the Burdekin River area in tropical Queensland. Highly significant correlations were found but the goodness of fit differed between groups of soil profile classes. In general, Typic Natrustalfs of the flood plains had better relationships (r2= 0.85) between these soil properties than did the Chromusterts (r2= 0.50). The regression ESP = 1.935 × 10‐5pH6.205 (r2 = 0.61; n= 288) for all soils and depths underestimated ESP in Typic Natrustalfs groupings and overestimated this soil property in the Chromusterts.

ISSN:0010-3624    

DOI:10.1080/00103628309367432

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

High soil acidity (low metal ion saturation) favours the absorption of Rb from natural soils by vascular plants and fungi, whereas the absorption of K is little or not influenced. The difference in Rb uptake may be as great as one order of magnitude between soils of high and low acidity. Results of several studies are presented and discussed.

ISSN:0010-3624    

DOI:10.1080/00103628309367433

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Cauliflower (Brassica oleraceaBotrytis cv. Snow Crown) was grown in field microplots of an organic soil containing residual fertilizer Cu varying from 81 to 1063 ppm (w/w) as a result of three levels of Cu applications made in the previous two seasons. The variation in soil‐Cu was found to have no significant influence on the yield, nutrition or copper status of the crop.

ISSN:0010-3624    

DOI:10.1080/00103628309367434

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Water supply is an important factor for high grain corn (Zea mays L.) yield and in nitrogen fertilizer management. It is the objective of this paper to develop a model for N‐rate forecasting based on yield‐increase (Yi) as related to plant available soil water (PAW) and precipitation.

ISSN:0010-3624    

DOI:10.1080/00103628309367435

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The effects of mixing lime and large quantities of phosphorus and potassium fertilizers with the subsoil were studied on 16 Maryland subsoils. These subsoils were covered with 10. cm of a fertile surface soil so the subsoils’ effect would be the major variable. Soybeans were grown on these soils in the greenhouse. These subsoils received 65.2 and 83.0 ug/g of phosphorus and potassium respectively. Two treated subsoils were also studied in the field. Simulated subsoiling in the field was accomplished by digging to a depth of 50.8 cm. Lime, 148 or 440 Kg P/ha, and 186 or 558 Kg K/ha were mixed with each 15 cm depth of subsoil. Soybeans and/or barley were planted on the field plots.

ISSN:0010-3624    

DOI:10.1080/00103628309367436

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Soybean (Glycine max(L.) Merril) production within Brazil is a major source of oil and meal exports for world markets. Vast underutilized areas within Brazil have favorable climates with potential for increased production. However, nonfavorable soil fertility factors and erosion losses are restraints for high yield soybean cropping within most neotropical regions. The objective of these studies was to determine influence of basic soil cations Ca, Mg and K with P amendment governing growth, nodulation, nitrogenase activity C2H2red.), ureide and associated nodule components of Forrest cultivar soybeans grown on a Typic Eutrustox (dark red latosol) of Jaiba, Minas Gerais, Brazil.

ISSN:0010-3624    

DOI:10.1080/00103628309367437

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor