摘要:

Four soils of wide range in exchangeable Al and basic cation status, two from Ohio and two from Bangladesh, were treated and equilibrated with five rates of P. Each soil and treatment was analyzed for “available”; P by the following methods: Bray‐1 and double acid (Mehlich No. 1) extractable, and pressure membrane (1/3 to 15 bar) and double field capacity water extractable (suction). The P‐treated soils were placed in pots and cropped with wheat in a growth chamber. The soil “available”; P data for Bray‐1, Mehlich, and pressure membrane extractions were all relatively highly correlated with that of each other and with both P concentration in and uptake of P by the crop. The Bray‐1 available P vs yield data evidently fit the Bray‐Mitscherlich equation well when the Ohio and Bangladesh soils are treated as different populations due to differences in: a) maximum yields, b) available P levels where maximum yields occurred, and c)c1values of the equation. These differences are partly due to marginal levels of Zn in the Bangladesh soils which evidently limited yields. Linear correlation of the yield function, log (A‐y) vs the soil available P function log A‐c1x for all soils gave r = 0.961. None of the other methods gave data which approached this degree of correlation between these two values. Also, in simple linear regressions of the various crop and soil parameters, correlations of data from the Bray‐1 method were generally slightly superior to those from the Mehlich and pressure membrane methods, while those from all three were definitely superior to those from the double field capacity water extractable method.

ISSN:0010-3624    

DOI:10.1080/00103628309367338

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The influence of delayed inoculation on N2(C2H2)‐fixation byPhaseolus vulgarisL. grown in minesoil is described. Fertilizer treatments included in the study were 0, 25, 50, and 100 kg N/ha applied at 21 days or at seeding. A peat culture ofRhizobium phaseoliwas inoculated at 21 days or at seeding. Nitrogenase activity was determined by reduction of C2H2to C2H4, at 7, 21, 35, and 49 days.

ISSN:0010-3624    

DOI:10.1080/00103628309367339

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Nitrogen mineralization of soils under both aerobic and anaerobic incubation procedure and urea hydrolysis were studied under laboratory conditions. Percentage nitrogen mineralization potential (No) of total soil N was 30.0 under anaerobic incubation and about one‐half of that under aerobic conditions. Two different procedures were used to compute nitrogen mineralization potential. The determination using No= Nt/(l‐10‐kt/2.303) appeared time consuming whereas No= (factor ×?Nt/?t1/2) was found to be relatively quick for accurate prediction and could be used as a basis for Nodetermination in any area. The results of 2‐week incubation were remarkably similar to those for all other incubation periods with the aerobic or anaerobic groups. The hydrolysis of urea under flooded condition was found to be complete within 11 days.

ISSN:0010-3624    

DOI:10.1080/00103628309367340

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The Berthelot reaction has been applied to an AutoAnalyzer method for the analysis of ammonium‐nitrogen. This method is suitable for the determination of total nitrogen in soils and plant material, and sufficiently stable and sensitive to determine levels of NH+4‐N in natural waters. Amino acids interfere, but only contribute a relatively small fraction (11%) in soil extracts and were not present in the soil solution examined. The inclusion of the generally used disodium hydrogen phosphate buffer was found to enhance interference from amino acids, and precipitate calcium phosphate from calcareous soil extracts.

ISSN:0010-3624    

DOI:10.1080/00103628309367341

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Growth response and nutrient levels in the foliage and growth medium were compared usingNephrolepsis exaltata(L.) Schott ‘Com‐pacta’ ferns grown in a peat‐perlite medium with 4 rates of dolo‐mitic limestone (0.0, 1.2, 2.4, and 6.0 kg/m3) and 2 rates of gypsum (0.0 and 1.2 kg/m3). Incorporation of dolomitic limestone and gypsum resulted in greater growth compared to treatments without dolomitic limestone and gypsum, but dolomitic limestone rates of 1.2, 2.4, or 6.0 kg/m3resulted in no difference in fern dry weight. Addition of gypsum resulted in higher foliar S levels. Suppressed fern growth was associated with lower foliar Ca and S levels. When 6.0 kg/m3of dolomitic limestone was added to the medium, foliar N was lower and nitrates in the medium were higher compared to ferns grown with no dolomitic limestone. Addition of gypsum and dolomitic limestone to the medium increased soluble salt levels.

ISSN:0010-3624    

DOI:10.1080/00103628309367342

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

In this publication, comparisons are made between the results of crop analyses obtained with the aid of dried material and plant sap. The crop samples used for the analyses were collected from experiments in which crops were grown in nutrient solutions with varying nutrient element contents. The experimental crops consisted of tomatoes, cucumbers, eggplants and lettuce. Of the first three crops, the leaf petioles and leaf laminae were used as samples and in the case of lettuce, midrib parts and leaf edges were sampled.

ISSN:0010-3624    

DOI:10.1080/00103628309367343

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The concentration and distribution of organic P and of the inorganic P fractions of Al, Fe and Ca were determined in forest soils derived from a range of parent materials and developed in different bioclimatic zones.

ISSN:0010-3624    

DOI:10.1080/00103628309367344

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628309367337

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor