摘要:

Yields were evaluated three years after applied treatments to determine if responses that were not evident during earlier years eventually occurred. Potassium sulfate was applied to established, non‐irrigated, K deficient trees on fine textured soil by banding, placing in augered holes, adding to the backfilled trenches, and by injecting into the soil. Trenches were dug in the fall beside trees to break roots and ammended during backfilling with K2SO4, dolomite lime or combinations of the two. Additional trees received a heavy compost mulch in the early fall. Trenching treatments were generally detrimental. Trenching alone reduced yield and leaf Ca but increased fruit soluble solids content. Trenching plus K2SO4, trenching and lime, all soil amendments, and mushroom compost elevated leaf K from deficient or below normal to the normal range, but decreased leaf Mg. Most K application techniques eventually increased yield, but simple surface applications of K2SO4in a narrow band were as effective as other more costly procedures. Mulching treatments appear to be as effective as K additions and produce quicker yield responses. Mushroom composts and alfalfa increased leaf N and yield in two years. Mushroom compost doubled yield even three years after a single application.

ISSN:0010-3624    

DOI:10.1080/00103628609367727

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The rapidly growing, woody perennial legume, Leucaena (Leucaena leucocephala(Lam.) de Wit), is adaptable to a wide range of neotropical soil conditions. EffectiveRhizobiuminoculation and endophyte mycorrhizal colonization are essential for high levels of production and symbiotic N2fixation. The objective of this study was to determine growth, nodulation, nitrogenase activity and nodule composition of inoculated Leucaena as affected by mycorrhizal colonization and factorial soil fertility treatments of a Typic Eutrustox. Highly significant increases in top growth, nodule fresh wt. and nitrogenase activity resulted withGlomus fasciculatumcolonization, soil K and linear increases with low‐soluble P fertilization to 300 mg P kg‐1soil. Highly significant interactions for increased nodulation and nitrogenase activity resulted with K × mycorrhiza. Interactions of all three factors P, K and mycorrhiza were highly significant for nodule fresh wt. However, responses comparing inoculation withG.fasciculatumand with combinedG.fasciculatum,G.microcarpusandG.claviumwere not significant. Highly significant increases with applied K levels to 300 mg K kg‐1soil resulted with top and root growth, nodulation and nitrogenase when applied with soluble P at 100 mg kg‐1soil and 500 mg Ca kg‐1soil. Significant and highly significant interactions of P, Ca and K level resulted for all parameters. Plant nutrient element composition of nodules increased with the fertilization treatments for P, Ca and increased K levels. A highly significant inverse relation was apparent with decreased Na resulting with increased K levels. Half or more of total nodule K, P and Mg but less than 20% of Ca and Na were within the nodule cytosol. Sodium, Mg, P, and Ca decreased in the cytosol fraction with increased K content.

ISSN:0010-3624    

DOI:10.1080/00103628609367728

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The aim of this study was to compare 1% citric acid and 1% bicarbonate solutions as extracts for the determination of phosphorus in sandy arid‐zone soils, using 64 samples from the Kalahari dunefield. For 56 of these samples, measured phosphorus concentrations were <8 ppm in both extracts, and for these 56 samples the acid‐extractable and bicarbonate‐extractable phosphorus concentrations were statistically equivalent. For the remaining 8 samples, with phosphorus concentrations >8 ppm in at least one of the extracts, phosphorus concentrations in citric acid extracts were consistently greater than those in bicarbonate extracts.

ISSN:0010-3624    

DOI:10.1080/00103628609367729

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Percent nitrogen (N) in peanut leaves (Arachis hypogaeaL.) is known to decline as the season progresses. If leaf N drops below the critical level for maximum photosynthesis, the yield potential for that crop will decrease. In an attempt to increase leaf N, several studies were conducted during 1979, 1980, and 1981 at two locations in the state of Georgia, USA. Both inoculation and N fertilization of the peanut cv. Florunner failed to increase either ZN in the plant (shoot and fruit composite). Although strains ofBradyrhizobiumshowed a wide range of effectiveness (total N accumulation in the plant) in controlled environment conditions, no significant differences were seen in field studies. Discrepancies between these studies could be due to poor nodule occupancy of the introduced strains ofBradyrhizobiumin the field studies or to differences in strain performance due to environment. Post‐emergence treatments of urea or Ca(NO3)2fertilizers also failed to increase either %N in the plant tissue or pod yield. A slight non‐significant reduction in nodule weight/plant due to N fertilization was measured; urea decreased nodule weight less than Ca(NO3)2.

ISSN:0010-3624    

DOI:10.1080/00103628609367730

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The germination and growth of wheat seedlings were studied at pH 5.5 in liquid growth media with organic acids in concentrations ranging from 800 to 1200 ppm, before and after interaction of the organic acids with montmorillonite and hydroxy‐Al montmorillonite. Germination was not affected by the organic acids, but subsequent growth was dependent on the kind and concentration of organic acid in the growth medium. Acetic acid was more inhibitory than citric acid. Gallic acid polymerized at pH 5.5 and was phytotoxic at 1200 ppm. Interaction of organic acids with montmorillonite and hydroxy‐Al montmorillonite reduced the concentration of organic acids in solution by adsorption. Despite this reduction in concentration the phytotoxicity of the growth media was enhanced after the interaction. This was caused by the dissolution of surface Al and the effect was more pronounced in cases where hydroxy‐Al interlayered montmorillonite was the adsorbent. Additions of P as KH2PO4alleviated the phytotoxicity of organic acids but not the associated Al toxicity. The amount of P lost by adsorption or precipitation was dependent on the form of Al in the growth media.

ISSN:0010-3624    

DOI:10.1080/00103628609367731

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Comparative measurements of the clay fraction of soils were made with a beta‐ray gauge system, a density meter, and a hydrometer. Reliable clay fraction determinations could be made by a beta‐ray gauge, and a density meter in less than 25 minutes of sedimentation. The beta‐ray gauge measured clay fractions were not affected by surface tension which was the possible cause for variable results obtained with the gamma‐ray attenuation technique.

ISSN:0010-3624    

DOI:10.1080/00103628609367732

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A procedure for the simultaneous extraction of phosphorus, potassium, calcium and magnesium from soils, by an ion‐exchange resin procedure applicable to large‐scale advisory soil testing, is described. The important steps are the disaggregation of soil by shaking in water during 15 minutes with a glass marble, the transference of the elements from the soil to a sodium bicarbonate treated mixture of anion and cation exchange resins during a 16‐hour shaking period, the separation of the resin from the soil by sieving and extraction of the elements from the resin.

ISSN:0010-3624    

DOI:10.1080/00103628609367733

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628609367726

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor