摘要:

Upland pastures on coarse‐textured sulphur (S)‐deficient soils in moderate to high rainfall areas may benefit from S fertilization using elemental S to avoid leaching losses. Two grades of elemental S, 120 and 300 mesh, were assessed as a source of S for grass and clover. In laboratory incubations using an upland soil at 7 and 14°C, oxidation of the 120 mesh S was very slow while 65% of the 300 mesh S was oxidized after 48 days at 14°C. In pot trials of ryegrass in a lowland soil and of ryegrass and clover in the upland soil both elemental S grades gave satisfactory yield increases which were not significantly different from applying potassium sulphate. High ambient temperatures during the pot experiment probably ensured an adequate oxidation rate of both elemental S grades. High application rates of the potassium sulphate gave rise to luxury consumption while very high rates of elemental S (equivalent to 200 kg S ha‐1) showed some toxicity. Application of a previously‐described model of S oxidation confirmed the importance of soil temperature in controlling S oxidation rates.

ISSN:0010-3624    

DOI:10.1080/00103629809370028

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Paper pulp was evaluated, with reference to lime, as a soil amendment to a tropical acid soil (typic Kandiudult). Rye grass(Lolium perenneL.) was grown under greenhouse conditions. Amendments were applied at rates to attain target pH values of 5.5,6.0, and 6.5. Paper pulp and lime were equally effective in increasing dry matter production. Similar to lime, paper pulp provided high calcium (Ca) inputs and alleviated aluminum (Al) and manganese (Mn) toxicity. Paper pulp can be applied to a tropical acid soil as a lime substitute.

ISSN:0010-3624    

DOI:10.1080/00103629809370029

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The growth rate of a root is a useful indicator for the evaluation of nutrition, and for the presence of pollutants, allelochemicals, and herbicides. For its sensitive and real time measurement, we have developed a computer‐aided microscopic image analyzing system which enabled us to determination the growth rate of aRaphanus sativaL. root to a precision of 0.1 μm min‐1at every 15 seconds. A sample harvested at the 3rd day after germination, for instance, showed a 7.3 μm min‐1growth rate. Moreover, a transient increase in the growth rate which occurred just after the release from a cold stress was sensitively detected.

ISSN:0010-3624    

DOI:10.1080/00103629809370030

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Nitrogen (N) fertilizer recommendations for corn(Zea maysL.) are normally developed from field experiments that determine yield response to applied N. The objective of this study was to examine the severity of border row competition with the harvest rows for sidedressed N in field experiments measuring grain yield. This study was conducted in 1993 and 1994 on a Sharpsburg silty clay loam (fine, montmorillonitic, mixed, mesic argiudoll). Ammonium nitrate was broadcast to the center two rows of a four row plot, all four rows of a four row plot and all six rows of a six row plot. Results showed that grain yield from four and six row plots were similar and indicated that while grain yields were much less in 1993 than 1994 (7.36 versus 12.06 Mg ha‐1, respectively), corn yield response to N was similar regardless of the number of rows fertilized. Thus, there is little reason for plots larger than four rows. The results also lend credibility to sidedressing only harvest rows for soil test calibration studies where grain yield response is the primary response variable.

ISSN:0010-3624    

DOI:10.1080/00103629809370031

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Development of a quantitative, preharvest quiektest for NO3levels in cereal forages would improve crop management options to avoid NO3toxicity in livestock. Our objective was to determine if concentrations of NO3in sap expressed from oat(Avenasativa)and barley(Hordeum vulgare)are correlated with those in dry tissue of simultaneously harvested hay, and to test the reliability of the Cardy portable NO3meter for sap analysis in these species. In 1993, whole plant samples were gathered from plots fertilized with variable nitrogen (N) rates at four environments in Montana, and were analyzed for NO3concentration in lower‐internode sap and in whole plant dry matter. In 1994 and 1995, the study was repeated at two environments. The sampling technique included three subsamples from each plot for sap analysis, followed immediately by harvest of the entire plot for hay, and further subsampling for dry matter NO3analysis after drying. Linear correlations between dry matter and sap NO3concentrations were found across species at each environment in 1993 with r values of 0.64 to 0.81. No relationship was established for oat at one environment. Locations differed in the coefficient of correlation, indicating environmental influences on the relationship and/ or variability due to sampling technique. In 1994 and 1995, each species fit a separate linear correlation across site‐years with r values of 0.89 (oat) and 0.87 (barley). The consistency across site‐years (1994–1995) indicates that the variability in preliminary results was overcome with sampling technique. We propose a quantitative quiektest for NO3levels in cereal forages using conditional predictions of dry matter NO3based on observed values of sap NO3. Since sap NO3readings with the Cardy portable nitrate meter were well correlated (r=0.93) with Accumet ISE readings across critical ranges, quiektest procedures are practical.

ISSN:0010-3624    

DOI:10.1080/00103629809370032

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103629809370007

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor