摘要:

A wet oxidation digestion previously developed for plant material has now been evaluated for a range of British soil types. The traditional Kjeldahl procedure using sulphuric acid, salt and catalyst was modified to include hydrogen peroxide as an additional oxidant. The method is suitable for estimating both nitrogen and phosphorus in soil and overcomes the need for separate digestion procedures for these elements. It compared favourably with a normal Kjeldahl method for nitrogen and with a mixed acid oxidation system for phosphorus and recovery was complete after two hours. Total phosphorus and organic nitrogen were recovered together with labile ammonium‐nitrogen. Nitrate‐nitrogen would require a further modification and the recovery of ‘fixed’ lattice ammonium‐nitrogen was not assessed. Samples had to be finely ground to achieve good precision and recovery.

ISSN:0010-3624    

DOI:10.1080/00103628509367628

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

In a study involving 212 samples of surface and sub‐surface soils derived from basaltic, granitic, and metamorphic parent materials in the high rainfall region of north Queensland, Australia, the Al extracted with 1 M KC1 has been compared with ‘exchangeable aluminium’, defined as the difference between CEC and sum of basic exchangeable cations. It was concluded that for these highly weathered soils KCl‐extractable Al is exchangeable, and therefore that the sum of basic and acidic cations (ECEC) is a reliable measure of CEC at field conditions.

ISSN:0010-3624    

DOI:10.1080/00103628509367629

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The availability of N to corn (Zea MaysL.) in soils previously amended with organic wastes was estimated by a number of chemical soil tests in 1982 and 1983. Availability indexes were correlated with yield and N uptake by the crop. Total soil N and June mineral N (N extracted by 2NKC1 from soil samples obtained when corn was 20 to 30 cm tall) proved to be good predictors of yield and N uptake for combined 1982 and 1983 data. Soil organic matter content and absorption of U.V. (260 nm) light by .01MNaHCO3and NH4OAc (pH 4.8) soil extracts were not well enough correlated with yield or N uptake to be useful in a soil testing program. Various combinations of log transformations of June mineral N, preplant mineral N, and Ap horizon depth proved to be good indexes of N availability and in some cases explained a significantly greater percentage of the variability in yield and N uptake than single‐variable indexes.

ISSN:0010-3624    

DOI:10.1080/00103628509367630

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

An investigation was conducted on an Olivier silt loam (fine‐silty, mixed, thermic aquic, Fragiudalfs) at two locations to determine the influence of 6 seasonal temperatures and 4 N rates on head diameter, head weight, tissue NO3concentration and crop yield of 4 head lettuce (Lactuca sativaL.) cultivars. An analysis of covariance was used to establish prediction equations for each dependent variable. Temperature was shown to have a significant curvilinear influence on all crop parameters. There was a significant cultivar X temperature interaction with respect to all dependent variables except tissue NO3concentration. Calculated optimum mean temperatures for maximum head diameters, head weights, and yields for all cultivars were found to range between 17.4° and 18.2°C.

ISSN:0010-3624    

DOI:10.1080/00103628509367631

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Because of widespread Zn deficiency in rice, an experiment was designed to evaluate the Zn fixing capacity of several clay minerals separated from tropical rice soils. The study involved the addition of 25 μg Zn per g of clay as zinc sulphate, incubation at an ambient temperature of 30 C±2 followed by alternate wetting and drying and extraction by 0.005MDTPA to assess the magnitude of Zn fixation.

ISSN:0010-3624    

DOI:10.1080/00103628509367632

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Fluidized bed combustion residue (FBCR), a by‐product of fossil fuel fired boilers, was evaluated as a liming material and a source of calcium for peaches (Prunus persicaI.L.J Batsch). Incubation studies involving a medium textured soil indicated that FBCR (calcitic [FBCRC] or dolomitic [FBCRD] sources) was as effective a liming amendment as the respective agricultural limestone. Maximum soil pH occurred after 26 days incubation with FBCRC, but soil pH increased continuously throughout 137 days incubation with dolomitic limestone. Ammonium acetate extractable Ca was not affected by calcitic source, but Mg concentration increased with rates with the two dolomitic sources, and was highest in the FBCRD source after 137 days incubation. In greenhouse studies with ‘Elberta’ peach seedlings, FBCRC was more effective in neutralizing soil acidity and increasing extractable soil Ca than calcitic limestone after 24 weeks of growth. Leaf and stem Mn, Zn, and Al concentrations were decreased linearly by the FBCRC for both growth periods. Calcitic limestone did not have any effect on the concentration of Mn, Zn, or Al in the leaves or stems for either growth period. No visual symptoms of toxicity or nutrient imbalance from heavy metal contained in the FBCRC were observed.

ISSN:0010-3624    

DOI:10.1080/00103628509367633

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Fluidized bed combustion residue from a calcitic limestone source (FBCRC), a by‐product of scrubbing SO2from fossil fuel fired boilers using the FBC technique was evaluated as a source of calcium for pecan (Carya illinoensis(Wang.) K. Koch) seedlings. Fluidized bed combustion residue produced following injection of calcitic limestone into the combustion chamber was more effective in neutralizing soil acidity and increasing extractable soil Ca levels than agricultural calcitic limestone. The Ca concentration in the pecan leaves was increased linearly by Ca rates for both 12‐ and 24‐week growth periods, but stem and petiole Ca concentration was increased linearly for the second 12‐week growth period. Macronutrient concentrations were affected by Ca rates for both 12‐ and 24‐week growth periods, but no effect was observed with Ca source. The primary difference was between the control and all other Ca rates. Leaf concentrations of Mn and Zn were decreased linearly by Ca rates and source for the first 12‐week growth period, but only by Ca rates for the second 12‐week growth period. Aluminum, Mn, and Zn concentrations in stems and petioles were generally reduced linearly during the second growth period by increasing Ca rates with r2values <0.4. Terminal shoot length was not affected by Ca rates or sources although cross‐sectional area was significantly increased by Ca sources for the first 12‐week growth period, and by Ca rates for both the 12‐ and 24‐week growth periods. FBCRC may be applied to pecan trees without any adverse affect on pecan nutrient or induced nutrient imbalances or toxicity from the heavy metals contained in the FBCRC.

ISSN:0010-3624    

DOI:10.1080/00103628509367634

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628509367627

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor