摘要:

This paper summarizes recent work on the slow reactions between soil and phosphate or molybdate. These slow reactions are important in determining long‐term effectiveness and residual value. It was found that the rate of the reaction could be described by a simple equation, and that the rate was very sensitive to temperature, but not greatly affected by differences between soils or by a range of water contents. The proportion changed to an ineffective form was independent of the level of application. The differences between adsorption and desorption of phosphate could be explained by the continuing slow reactions.

ISSN:0010-3624    

DOI:10.1080/00103627409366515

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Accurate and reproducible determinations of total sulphur can be made following digestion of plant samples with a nitric/ perchloric acid mixture containing dichromate and metavanadate. Care should be taken to control digestion temperatures. The occurrence of dense fumes of perchloric acid and the deposition of red chromium trioxide are not satisfactory indicators of the digestion endpoint. Digestion for lh. beyond the change in colour of the digest from green to olive‐brown was necessary, in our work, for consistent results.

ISSN:0010-3624    

DOI:10.1080/00103627409366516

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Soil salinity increases when heavy rates of poultry manure are applied to sandy coastal plain soils. Analysis of soils involved in a poultry manure study during 1970, 1971 and 1972 has shown that soil salinity is primarily associated with a high concentration of ? in the soil solution. Although concentrations of other elements increased with the application of poultry manure also, the increases were not sufficient to account for the salinity in these soils.

ISSN:0010-3624    

DOI:10.1080/00103627409366517

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The effects of plow sole placement (30.5 cm deep) of dolomitic limestone and various P and K treatments on the chemical composition of soybean(Glycine max(L.) Merrill) leaves and on certain properties of a Tatum soil were determined. Rates of lime were 0, 22.4, and 44.8 mt/ha. Various rates of P and K were surface applied and disked in annually.

ISSN:0010-3624    

DOI:10.1080/00103627409366518

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The effect of two benzimidazole fungicides, 2‐(4‐thiazolyl) benzimidazole (thiabendazole) and methyl l‐(butylcarbamoyl)‐2‐benzimidazole carbamate (benomyl) on growth and foliar element accumulation of ‘Penncross’ and ‘Seaside’ cultiyars of.Agrostis palustrisHuds. and ‘Merion’ cultivar ofPoa pratensisL: was investigated ina series, of greenhouse and field plot experiments. In the greenhouse, soils.with varying concentrations of the materials were seeded. with ‘Penncross,’ and ‘Merion. In the field a 2 year old plant ing of the ‘Seaside’ cultivar (Agrostis palustris) was sprayed with thiabendazole, and benomyl formulations. Criteria employed for determining growth effectswere dry weight of foliage, dry weight of roots, and macro‐ and micro‐element accumulation by the. foliage,

ISSN:0010-3624    

DOI:10.1080/00103627409366519

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The absorption of Mn by excised rice roots was studied in the absence and presence of interfering cations like Ca, Mg, and Zn in the absorption medium. In the low concentrations of Mn, the uptake was competitively inhibited by 0.5 mM Ca or Mg, and Mg was slightly stimulatory on the absorption from high Mn concentrations. There was no significant interaction between Ca and Zn, Fe or Mg, on the absorption from 0.1 mM MnSO4, although these elements reduced the uptake, when present individually. The absorption of Mn from high concentration (5 mM) was enhanced by the presence of low amounts of ? or Mg (0.05 to 0.5 mM).

ISSN:0010-3624    

DOI:10.1080/00103627409366520

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The history of nitrogen usage on oranges in California shows that prior to about 1960 many growers were using more nitrogen than was needed to produce the crop. In some areas nitrogen usage is now less than half of what it was prior to 1960. The reduction was associated with increased commercial usage of leaf analysis as a guide to nitrogen fertilization. Also since 1960, as a result of the decrease in fertilizer applied, the annual per‐acre amounts of fertilizer nitrogen that were subject to leaching in the Santa Ana Watershed were reduced by an estimated 50 percent in Riverside County and about 80 percent in San Bernardino County.

ISSN:0010-3624    

DOI:10.1080/00103627409366521

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Grain sorghum plants were grown in nutritive solution culture under variable potassium concentrations from 0.5 to 6.0 meq/l, Na replacing K in deficient solutions. Leaves were analysed for K+, Na+, Ca++and Mg++.

ISSN:0010-3624    

DOI:10.1080/00103627409366522

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Grain sorghum plants were grown in nutritive solution culture under variable potassium concentrations from 0.5 to 6.0 meq/l, Na replacing ? in deficient solutions. The effect of potassium concentration in the nutrient medium on the organic acids content of leaves has been investigated. In sorghum leaves, aconitic, malic, citric, succinic acids are the most important (as evidenced by gas chromatography analysis).

ISSN:0010-3624    

DOI:10.1080/00103627409366523

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

No significant correlation was observed between the organic acids (citric, malic and aconitic acids) content and the total amount of inorganic cations (potassium, calcium and magnesium) in sorghum leaves. Whatever the level of ? nutrition was, approximati‐vely twice as much cations as organic acids were found. However, the total amount of organic acids is nearly balanced by the sum of the “free”; cations, i.e. those present in the water‐alcohol extracts. The data for these “free”; cations suggest that potassium (90 % of which in eluted) is more mobile than magnesium (55 %) and calcium (26 %). Other organic compounds involved in the buffer system of plant cells were investigated: there is evidence of a decrease in the free amino‐acids content in potassium‐deficient sorghum leaves.

ISSN:0010-3624    

DOI:10.1080/00103627409366524

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor