摘要:

Greenhouse and laboratory experiments were conducted to determine if redox, Zn fertilization and incubation time could help to explain the Increased Incidence of Zn deficiency in rice (Oryza sativaL.) in submerged soils through greater solubilization of Fe and Mn. Continuous flooding Increases DTPA‐extractable Fe and Mn, but when Zn was applied, extractable Fe and Mn decreased. Even when Irrigated to 30 kPa (0.3 bar), the addition of Zn lowered the amount of DTPA‐extractable Fe and Mn. Depth and duration of flooding affected redox (pe + pH). After 30 days of continuous flooding pe + pH approached to 4.3 at 2 cm below the soil‐water interface. The pe + pH decreased significantly with soil depth, reflecting greater accumulation of CO2and depletion of O2. Under controlled redox conditions in the laboratory, decreasing pe + pH from 14.48 to 4.00 decreased soluble Zn from 10‐5.50to <10‐6.80M, while Fe content Increased from 10‐5.59to 10‐4.91Hand that of Mn from 10‐5.73to 10‐4.82M.The findings reported herein support the hypothesis that Zn deficiency observed In submerged rice can be partially explained by Increased reduction and solubilization of Fe and Mn which have an antagonistic effect on the availability and uptake of Zn. It is hypothesized that Fe dissolved at reduced microsites subsequently reprecipitates as ferroslc hydroxide (Fe3(OH)8) In more oxidized zones. The higher solubility of Fe maintained by Fe3(OH)8can depress Zn2+solubility through formation of ZnFe2O4or a similar franklinite‐like solid.

ISSN:0010-3624    

DOI:10.1080/00103628809367915

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Seeds of four lisianthus (Eustoma grandiflorum) cultivars were germinated and transplanted into an equal volume of peat, perlite medium without fertilizer amendments. Plants were grown in the greenhouse and watered daily with a modified Hoagland's solution containing 0, 100, 200, or 400 mg N/l in a N experiment, and 0, 75, 150 or 300 mg Ca/l in a Ca experiment. Plants were harvested at the end of 8 weeks. Increasing N concentrations in the nutrient solution decreased stem length and number of flowers slightly while it increased the number of basal and lateral breaks, number of buds and chlorophyll content. Increasing Ca concentrations increased the number of buds and shoot dry weight, while Ca concentrations of 150 mg/l stimulated the greatest number of branches, within 3cm of the base of the plant, and chlorophyll content. Shoot N and Ca concentrations of from 3.2 to 5.1% (dw) basis and 0.8 to 1.2% (dw) respectively was associated with good plant growth and flower production. In a second N experiment, a soluble, commercially available fertilizer (20–8.8–16.6, N‐P‐K) was applied to plants growing in a peat, vermiculite, sand, perlite medium with fertilizer amendments. Nitrogen concentrations from 100 to 1900 mg/l were applied weekly. It was found that a weekly application of from 1000 to 1500 mg N/l from a soluble complete fertilizer maximized flowering and growth.

ISSN:0010-3624    

DOI:10.1080/00103628809367916

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The price of water in Israel, its availability, and the other options for its use, made it necessary to examine the amount of water actually required by banana. (Musa cavendishii Lamb.) Water amounts were fixed according to the evaporation factor from a Class A pan. The factor changed throughout the irrigation season. At the peak of the season, the rate of water application corresponded to f=0. 8, 1.0, 1.2 and 1.4. An additional treatment, with a constant factor of evaporation (f=1.0), was applied. Two fertilizer regimes were also tested: a fixed dose of fertilizer applied once a week, and a constant concentration of fertilizer injected into the irrigation water throughout the irrigation season. The water applied amounted to 8450–14470 m3/ha/year. The increased water amount led to an increase in sucker height, earlier flowering, more bunches, and a small increase in average bunch weight. Maximum effects were found in suckers irrigated at f=1.4, but any increase above f‐1.0 (10370 m3/ha) gave no significant advantage. The suckers irrigated at f=0.8 were inferior to all others. The weekly fertilizer application had a slight but nonsignificant advantage over the continuous fertilization regime.

ISSN:0010-3624    

DOI:10.1080/00103628809367917

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Inductively coupled plasma atomic‐emission spectrometry (ICP‐AES) parameters were optimized for the interference free determination of several elements (Ca, Hg, Ma, K, Mn and Si) in soil solutions. These solutions were extracted fron layers of two soils at different distances from bands of superphosphate fertilizer. Ranges of elemental levels determined in soil solutions were as follows: Ca, 22–1600; Mg, 4–270; Ma, 20–130; K, 6–132; Mn, 0–30; Si, 8–175 μg/ml, respectively. The higher levels were in solutions taken from soil close to the fertilizer band. Iron and Al could not be determined because of insufficient analyte response in the presence of large Ca and Mg spectral effects. Recovery estimates for all analytes were not significantly different from 100% (P = 0.05). Limits of quantitation were acceptably low, except for Mn in soil solutions with less than 0.05 μg/ml. Mn Coefficients of variation were all less than 2%.

ISSN:0010-3624    

DOI:10.1080/00103628809367918

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A procedure based on blade area changes was used for predicting the P status of young, field‐grown sugarbeet plants. Plants from two field P‐fertilizer experiments were removed and transferred to nutrient solutions with and without added P. Measurement of changes in blade area and total leaf length of selected leaves from seedlings transplanted to culture solution with and without P provided an index of the P status of field‐grown plants. Disadvantages of the technique are that: 5 to 10 days are needed to establish that a P deficiency exists, and the method is difficult to adapt for routine work. Nevertheless, the procedure may be useful in research studies.

ISSN:0010-3624    

DOI:10.1080/00103628809367919

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Three methods for soil potassium extraction (MNH4OAc pH 7, 0.01 M AgTU and 30 % hot H2SO4) were compared for a variety of kaolinitic soils of the tropics. The AgTU‐extractable K was much higher than theMNH4OAc‐extractable K when vermiculite clay was present in the soil. The correlation between both was given by an R value of 0.937. The amounts of K extracted by 0.01MAgTU and by hot H2SO4were approximately the same. The R value for these two methods was 0.843.

ISSN:0010-3624    

DOI:10.1080/00103628809367920

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

In a greenhouse experiment, the relative agronomic effectiveness of Togo and Egypt rock phosphate sources were compared with triple superphosphate on high fixing volcanic ash soil of Ethiopia using(Medicago sativa) lucerne as the indicator crop. The P applied ranged from 0 to 160 kg P/ha. In the first cutting, Togo and Egypt rocks were relatively most effective at 60 and 43 kg P/ha, respectively. At these rates, Egyptian rock phosphate was 92% as effective as triple superphosphate compared with 64% for the Togo rock phosphate. Residual values of TSP were also higher than those of the rocks.

ISSN:0010-3624    

DOI:10.1080/00103628809367921

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Effect of soil sample treatment on potassium (K) release characteristics of Northern Great Plains soils was studied. Samples of agricultural soils were extracted with neutral normal ammonium acetate for K after selected pretreatment. Field‐moist sub‐soil samples with approximately 100 mg/kg extractable K release nearly double this amount after they were air on oven‐dried prior to analysis. The percentage increase in extractable K in dried soils decreased as the K level in the field‐moist soils increased. At 420 and 500 mg/kg, the extractable K content of air‐dried and oven‐dried soils, respectively, equaled the extractable K content of field‐moist samples. Above these concentrations, drying decreased extractable K. Oven‐drying (60 C) affected extractable K more severely than did air‐drying the soils. Drying and grinding the 15‐ to 30‐cm depth samples significantly increased exchangeable K compared to field‐moist samples. Rehydration of oven‐dried soils to 40% water did not affect extractable K. However, results indicated that rehydration of dried soils to 40% water, followed by freezing (‐29 C air temperature) for 15 hours, and redrying the samples to a range of 0.5 to 5% water, returned extractable K to the level which existed in the original field‐moist samples.

ISSN:0010-3624    

DOI:10.1080/00103628809367922

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The routine determiniation of lead and zinc in soil by atomic absorption spectrometry (AAS) of a hotaqua regiaextract and by X‐ray fluorescence (XRFS) spectrometry of the powdered soil is described and the results obtained by the two techniques compared. A strong positive correlation was found between the concentration for both elements obtained by the two methods. Generally, assaying by XRFS gave higher soil lead and zinc concentrations than that determined by AAS assay of an acid extract. However, extraction byaqua regiafollowed by AAS provides a satisfactory method for determining the lead and zinc concentrations in soil as a routine procedure.

ISSN:0010-3624    

DOI:10.1080/00103628809367923

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

An Investigation was initiated to examine the feasibility of using catfish (Ictalurus punctatus) pond sediment, or pond mud, as a growing medium by examining the growth and plant nutrient content of bell pepper (Capsicum annuumL.) grown in pond mud and in a field soil. Analysis of the two media indicated that pond mud contained relatively high levels of calcium (Ca) and magnesium (Mg), and had a high base saturation percentage. Phosphorus (P), potassium (K), copper (Cu), zinc (Zn) and manganese (Mn) levels in pond mud were comparable to those in the field soil. The organic matter level of pond sediments was lower than that of the field soil; however, pepper uptake of nitrogen (N) was greater in the pond mud. Tissue dry weights of peppers in the field soil increased in a linear manner in response to increasing rates of fertilizer N. Fruit dry weights of peppers in pond mud, however, did not increase at N rates in excess of 84 kg/ha. There appear to be no elements at phytotoxic levels in catfish pond sediments, and pond mud was found to be quite satisfactory as a growing medium.

ISSN:0010-3624    

DOI:10.1080/00103628809367924

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor