摘要:

Concentrations of cadmium measured in not acidified soil solutions were lower than those measured in acidified solutions. Differences between two measurements were in the range of 3.6 to 18.2 percent. For the determination of total cadmium in soil extracts by atomic absorption, the pH of the solution should be adjusted to 3.5 or less.

ISSN:0010-3624    

DOI:10.1080/00103627709366712

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Snap beans,Phaseolus vulgarisL., were grown on four commercial fields with fertilizer treatments consisting of three rates of N, of P and of K in all combinations.

ISSN:0010-3624    

DOI:10.1080/00103627709366713

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

A new soil test was developed for simultaneous extraction of NO3, P, K, Zn, Fe, Cu and Mn from alkaline soils. The new extraction solution is 1Min ammonium bicarbonate (NH4HCO3), 0.005Min Diethylene Triamine Pentaacetic Acid (DTPA) and has a pH of 7.6. The new extracting solution should be stored under mineral oil. Ten grams of soil are weighed out into 125 ml Erlenmeyer flasks. Two 2.5 ml scoops of Fisher G carbon black (to remove color for colorimetric determination of nitrates) are added to each soil, followed by 20 ml extracting solution. The soil mixture is then shaken on an Eberbach reciprocal shaker for 15 minutes at 180 cycles per minute. The extract is then filtered through a Whatman 42 filter paper or its equivalent for NO3, P, K, Zn, Fe, Cu and Mn determinations. The results obtained with the new procedure are highly correlated with results obtained with Olsen's P test, ammonium acetate K test, and Lindsay and Norvell's DTPA‐Zn, Fe, Cu and Mn test. Regression equations between the levels of nutrients extracted by the new procedure and those extracted by the procedures mentioned above were developed. These equations were used to calculate index values for nutrients extracted by the new extraction procedure based on values used at the Colorado State University Soil Testing Laboratory for the standard extraction procedures. The new procedure extracted about the same amounts of K and Fe as ammonium acetate and DTPA, respectively, from soils having low to marginal levels of these elements. However, it extracted about half as much P as NaHCO3and about 0.5 PPM more Zn, 0.8 PPM more Mn, and 0.3 PPM more Cu from soils having low to marginal levels of these elements.

ISSN:0010-3624    

DOI:10.1080/00103627709366714

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Single point phosphate sorption curves effectively estimated phosphate fertilizer requirements while requiring less work than multiple point curves. Correlation coefficients of 0.961 and 0.981 were obtained when phosphate rates, estimated using single point curves, were compared with those from multiple point curves. Reducing the ionic strength of the supporting electrolyte solution by using 0.001 M CaCl2or water rather than 0.01 M CaCl2during equilibration increased dissolved inorganic phosphate 73% and 141% on the average thus improving analytical precision. The relative effects of salt concentration were sufficiently independent of pH and phosphorus concentration to suggest that a simple conversion factor can be used to convert external P requirements from one set of equilibrium conditions (salt concentration) to another.

ISSN:0010-3624    

DOI:10.1080/00103627709366715

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The effects of nitrogen fertilization and age of regrowth on a number of indices for assessing the sulphur status of the perennial tropical pasture grassPanicum maximumvar. trichoglume (green panic) have been examined in pot experiments. A non‐rectangular hyperbola regression model has been used as an aid in deriving critical sulphur concentrations and evaluating their confidence limits. The merits and limitations of this model together with problems associated with other methods of deriving critical nutrient concentrations are discussed.

ISSN:0010-3624    

DOI:10.1080/00103627709366716

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

While total N: total S ratios varied widely from 4 to 331 depending on plant part, age, N supply and S supply, there was no discernable trend in protein N: protein S ratios attributable to any of these factors.

ISSN:0010-3624    

DOI:10.1080/00103627709366717

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The Diagnosis and Recommendation Integrated System (DRIS) has previously been shown to be a valuable tool in making diagnoses of mineral imbalances in plants which, when corrected, result in yield increases. The basic tenets of this approach are discussed in relation to making diagnoses at high yield levels. Data for corn previously published in the literature are used to test the precision of the DRIS and critical value approaches. The results show that the DRIS approach is superior because it is capable of making valid diagnoses irrespective of crop age. It is also able to rank nutrients in their limiting order on crop yield which emphasizes the importance of nutrient balance in plant nutrition. The reason for the poorer performance of the critical value approach probably stems from the fact that the leaf tissue from which diagnoses is to be made, is not always taken at precisely the same physiological stage as was used in developing the norms.

ISSN:0010-3624    

DOI:10.1080/00103627709366718

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The indices calculated from the Diagnosis and Recommendation Integrated System (DRIS) are used to interpret previously published data on the variation in N, P, K, Ca and Mg content in corn leaves. The results indicate that the DRIS approach is able to make consistent diagnoses of the order of requirement of the above elements by the plant irrespective of position of the leaf on the plant and portion of leaf sampled within certain limits. The diagnoses are completely consistent if any whole leaf from the middle of the plant is sampled.

ISSN:0010-3624    

DOI:10.1080/00103627709366719

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103627709366711

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor