摘要:

A greenhouse experiment was conducted with alfalfa (Medicago sativaL. cv. Aragon wide leaf) to test the performance of a zeolite (phillipsite) phosphorus‐potassium (P‐K) fertilizer versus soluble potassium dihydrogen phosphate (KH2PO4) applied to a coarse‐textured substratum consisting of a mixture 1: 4 (in volume) soihbasaltic ash. Plants were sown at four fertilization rates and five harvests were collected after nine months. The nutrient content in plant tissue was higher in the plants treated with zeolitic fertilizer, although the response was primarily due to P. No differences due to the fertilizer source were observed for dry matter yield. When considering nutrient uptake, differences between the two fertilizers were enhanced, although the results for P are more pronounced. The soil nutrient content found after the experiment shows that available P was significantly higher in those pots that received the zeolite fertilizer, but no differences were found for K.

ISSN:0010-3624    

DOI:10.1080/00103629409369185

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Blackgram (Vigna mungoL.) plants were grown in glasshouse earthen pot experiment. Zinc (Zn) was applied to the soil at different concentrtions. Plant leaf samples were analysed at the age of 30, 45, and 65 days after sowing. The accumulation of Zn in the plant increased with the applied Zn concentration to the soil. Also a variation in the uptake of Zn by the plant with age has been observed. The excess accumulation of Zn in the plant induced a reduction in the content of some macro‐ [calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na)] and micro‐elements [iron (Fe), manganese (Mn), and copper (Cu)] in the plant leaves. Furthermore, the Ca: Zn ratio decreased with increasing Zn concentration which clearly indicates a toxic Zn effect on blackgram plants.

ISSN:0010-3624    

DOI:10.1080/00103629409369186

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The most common directin‐situmethod for the measurement of soil denitrification requires many acetylene (C2H2) supply probes and airflow lines to measure nitrous oxide (N2O) flux from the soil under a sealed cover. A modification to this method simplified C2H2supply by placing a single acetylene supply probe 30 cm deep into the soil and measured soil N2O emission flux over a 0.11 m2area. Acetylene concentrations ranging from 0.1–10.0% were readily and predictably established by radial diffusion from the supply probe. Over 94% of the N2O released into the enclosed air space of the soil cover was recovered at an air flow rate of 21 L/h. Recovery decreased rapidly with increased flow rates of 31 and 37 L/h.

ISSN:0010-3624    

DOI:10.1080/00103629409369187

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The effect of swelling ratio of a novel material as Hydrolysed Sulfonated Styrene Acrylonitrile Copolymer (HSSAN) on the emergence and growth of tomato and lettuce seedlings was investigated. Water insoluble polymers having various swelling ratios were incorporated into soil and quartz sand at a constant concentration of 0.15% w/w and growth curves were obtained for each case study. The data show that HSSAN having high swelling ability produced higher seedlings in a short time. High swelling ratio values reflect the amount of crosslinking agent needed for the preparation of the resin. Low cross‐linking agent concentrations are required for satisfactory results of the conditioner on soil substrate.

ISSN:0010-3624    

DOI:10.1080/00103629409369188

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The 23 surface paddy soils (0–20cm) representing varying range of calcium carbonate (CaCO3) were collected to evaluate silicon (Si) supplying power and the factors which affect Si availability. A pot experiment and consecutive four‐year field trials were also carried out in this study to investigate the response of rice (Oryza sativaL. cv Wuyujing No. 3) and wheat (Triticum aestiumL. cv Yangmai No. 5) to Si‐containing materials applied to the calcareous paddy soils. The result indicated that the available Si contents (sodium acetate‐extractable SiO2) of the soils surveyed were much higher than the accepted critical value. Stepwise regression analysis showed that pH value, clay, and CaCO3contents significantly affected the available Si content. The pot experiment indicated that the grain yield, spike number, and filled grain percentage and ratio of grain/shoot of the Si‐treated rice markedly increased as compared to the control, but Si added had little effect on the shoot dry matter yield and 1,000‐grain weight. On the other hand, the available and water soluble‐Si contents in the Si‐treated soils were obviously higher than those of the untreated soil both at tillering and elongation stages. The same was true for the TCA (Trichroloacetic acid)‐soluble Si and total Si contents in rice plants. The Si content in the percolating water also increased in the Si‐treated soils as compared with the control—especially during the first week after rice transplanting. Consecutive four‐year field trials indicated that Si applied increased the rice and wheat yields by 4.6–20.7% and 4.1–9.3%, respectively. The added Si‐containing materials enhanced the resistance of rice and wheat against fungal and bacterial attacks and lodging. The results obtained in this study suggest that calcareous paddy soils which have a high content of sodium acetate extractable‐Si were still Si deficient and the available‐Si extracted by this extractant might overestimate the Si‐supplying power of these calcareous soils. It will either be nessesary to develop a new extractant suitable for evaluating the available‐Si status of calcareous soils or to modify the level of available Si in these soils above which rice responses to Si fertilizer will not be obtained.

ISSN:0010-3624    

DOI:10.1080/00103629409369189

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The one and two Langmuir, the Freundlich, and the Temkin isotherms were fitted to phsophorus (P) sorption data for P sorption by calcium (Ca)‐bentonite at different initial concentration and pH values of 3.8, 4.8, 6.0, 7.0, 8.0, and 9.0. Each was found to describe P sorption by Ca‐bentonite with comparable success. The effect of pH on P adsorption by Ca‐bentonite was studied and Langmuir, Temkin, and Freundlich isotherms were converted to the forms:

ISSN:0010-3624    

DOI:10.1080/00103629409369190

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Agrostis capillaris’Parys’,Beta vulgaris cicla’Fordhook Giant’ (Swiss chard),Brassica oleracea’Lion Heart’ (cabbage),Cineraria’Miranda White’, Festiica rubra litoralis ‘Merlin’, Matthiola incana ‘Austral Apricot’ (stock),Phaseolus vulgaris’Hawksbury Wonder’ (bean), andPolycarpaea spirosrylis(Copper Weed) were grown in pine bark‐based soilless media of pH 4.5, 5.5, and 6.5 amended with copper or zinc sulfate or composts containing high concentrations of either copper (Cu) or zinc (Zn). Growth responses ranged from none, through iron (Fe) deficiency, to symptoms of severe Cu or Zn toxicity. Correlations between growth and shoot Cu or Zn concentration on the one hand and total metal content of the medium and several measures of extractable metal content on the other were obtained. Medium pH had to be included in regressions to obtain high correlation coefficients. Total metal content and DTPA‐ and NH4OAc‐extractable metals were about equally well correlated with growth response in these experiments, but when the results were combined with those from an experiment in which sewage sludge was the source of Cu and Zn, DTPA‐and NH4OAc‐extractable metals gave better correlations than did total content.

ISSN:0010-3624    

DOI:10.1080/00103629409369191

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In many poultry producing areas, the amounts of poultry litter generated exceeds the amounts needed for application to soil, as fertilizer, at environmentally safe rates. To reduce the amounts of litter produced, Ndegwa et al. (1991) proposed fractionating the litter to generate a fine fraction that could be used as fertilizer, and a coarser fraction that could be recycled into poultry houses as bedding material. Because the fine fraction may need to be stored for several months before land application, knowledge of the changes that occur during storage would be important from the point of view of litter utilization. The objective of this study was to monitor water and inorganic nitrogen (N) contents, as well as potential ammonia (NH3) volatilization and carbon dioxide (CO2) emission in samples of whole litter and fine fraction stored in an unheated building for 16 weeks. Potential NH3volatilization and CO2emission were measured at unamended water contents and at a water content of 0.5 kg kg‐1. Water and inorganic N contents of the whole litter and fine fractions showed some fluctuations during the first 4 weeks, but remained relatively stable from weeks 4 to 16. At unamended water contents, potential NH3volatilization and CO2emission were relatively low and similar for the whole litter and the fine fraction. Also, potential NH3volatilization remained stable whereas CO2emission decreased with time. Increasing the water content to 0.5 kg kg‐1significantly increased potential NH3volatilization and CO2emission in the whole litters and fine fractions, with larger increases usually observed in the fine fractions. At 0.5 kg kg‐1, both potential NH3volatilization and CO2emission decreased with time. These results suggest that the fine fraction and the whole litter should be stored at relatively low water contents to prevent N losses through NH3volatilization and possibly denitrification.

ISSN:0010-3624    

DOI:10.1080/00103629409369192

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An investigation was conducted to determine the nature of decomposition products resulting from the interaction between humic acid and apatite and assess their availability to plant growth. Interaction analyses were performed by shaking 200 mg apatite with 0 to 800 mg/L HA or FA solutions at pH 5 or 7 for 0 to 12 hr. Phosphorus concentrations were determined in the supernatants by spectrophotometry. The nature of P‐humic acid complexes was determined by31P NMR analysis. Availability of these dissolution products was studied by growing corn plants in aerated hydroponics to which 200 mg apatite and 0 to 800 mg/L HA were added at pH 5 or 7. The results indicated that the rate of dissolution of apatite was parabolic in regression with time, and increased by increasing the amounts of HA or FA applied from 100 to 800 mg/L The dissolution reaction was influenced by pH, because larger amounts of PO43‐ions were detected at pH 5 than at pH 7.31P NMR spectroscopy indicated the presence of P‐humic acid complexes, previously believed to be humophosphate esters. The PO43‐ion was complexed by HA at pH 7 or above, but PO43‐appeared to be released again as adsorbed and free ions at pH <5.0. Plant performance corresponded with increased PO43‐concentrations at pH 5.0. No significant improvement over the control was observed in the growth of corn plants by apatite + HA treatments at pH 7. However, plant growth was increased significantly over the control by apatite + HA treatments at pH 5.0. Better growth performance of corn plants were noticed by apatite + HA than by KH2PO4treatments at pH 5.0.

ISSN:0010-3624    

DOI:10.1080/00103629409369193

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Spatial variation of soil test phosphorus (P) was studied by measuring soil‐test P for individual soil samples collected from uniform areas in south‐western Australia. The soil samples were collected using standard 10 cm deep by 2.5 cm diameter samplers. The Colwell alkaline bicarbonate soil test, the standard reagent adopted in Western Australia, was used. There were two parts to this study. In Part 1, 36 individual soil samples were collected on 20 m by 20 m grids within a uniform 100 m by 100 m area in paddocks on 16 different lateritic soil types. Superphosphate had been applied each previous year, using normal farmer practices, for either nine years at two sites or >20 years at the other sites. For pastures, fertiliser is usually applied to the surface. For crops, it is drilled with the seed at about 5 cm depth. In Part 2, 10 to 20 individual soil samples were collected at random locations within experimental plots (either 2 or 4.8 m wide by 30 m long) of five long‐term field experiments that were treated once only with different amounts of superphosphate applied from two to eight years previously. The P was applied to the soil surface and either incorporated through the soil with a rotary hoe or when sowing crops at 5 cm depth with tined implements, or the P was placed at 5 cm depth in bands that were 180 mm apart and the soil was not disturbed thereafter. For each site in Part 1, or each plot of each experiment in Part 2, soil‐test P for the individual soil samples varied, often markedly. Coefficient of variation was large. It was up to 56% for Part 1. For Part 2, it was up to 82% when P was incorporated into the topsoil, and up to 210% when P was banded in the soil. Spatial variation of soil‐test P is attributed to natural variation of soil physical, chemical, and mineralogical properties. Some of the variation may also be due to heterogenous mixing through the topsoil of fertiliser P applied in recent years. Soil‐test P is usually larger for recently applied fertiliser P.

ISSN:0010-3624    

DOI:10.1080/00103629409369194

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor