Jump to ContentJump to Main Navigation
Handbook of Soils for Landscape Architects$
Users without a subscription are not able to see the full content.

Robert F. Keefer

Print publication date: 1999

Print ISBN-13: 9780195121025

Published to Oxford Scholarship Online: November 2020

DOI: 10.1093/oso/9780195121025.001.0001

Show Summary Details
Page of

PRINTED FROM OXFORD SCHOLARSHIP ONLINE (oxford.universitypressscholarship.com). (c) Copyright Oxford University Press, 2021. All Rights Reserved. An individual user may print out a PDF of a single chapter of a monograph in OSO for personal use. date: 18 September 2021

Macronutrients—Phosphorus and Potassium

Macronutrients—Phosphorus and Potassium

Chapter:
(p.131) 12 Macronutrients—Phosphorus and Potassium
Source:
Handbook of Soils for Landscape Architects
Author(s):

Robert F. Keefer

Publisher:
Oxford University Press
DOI:10.1093/oso/9780195121025.003.0014

Plants have a P concentration between 0.03 and 0.70%, but the usual amount is between 0.1 and 0.4%. Phosphorus is found in every living cell of a plant and is involved in genetic transfer and energy relationships. The actively growing parts, that is, stem tips, new leaves, and new roots, need much P. Seeds, especially at maturity, also have a rich supply of P acting as reserve food. Phosphorus is used in plants for (a) root development—especially the lateral and fibrous roots; (b) cell division—energy for metabolism; (c) reproduction—flowering, fruiting, seed formation all controlled by nucleic acids; (d) maturation—counteracts the ill effects of excessive N fertilization; arid (e) disease resistance— especially important in root rots of seedlings. Plant P is a major constituent of chromosomes present as DNA (deoxyribonucleic acid) used in reproduction and RNA (ribonucleic acid) used in growth processes. Plant P is also a constituent of adenosine triphosphate (ATP) that stores energy for plant use, along with many other phosphate compounds, such as phytin (inositol hexaphosphate) stored in seeds, phospholipids in the chloroplasts, and complexes of sugars, sugar amines, aldehydes, amides, and acids—all involved in plant metabolism. Deficiency of P is not striking or characteristic and is difficult to diagnose. The older leaves may be dark bluish-green, bronze, or purple. The stalks are thin, leaves small, limited lateral growth, delayed maturity, and defoliate prematurely. Probably the most obvious symptom would be the purple coloration, but this is exhibited by only a limited number of plants. The best way to determine if a plant is deficient in P would be to conduct a plant tissue test. If the P level is lower than 0.2% P, then P probably is deficient and the soil in which the plant is growing would benefit from P fertilization. . . . Phosphorus Toxicity? . . . Phosphorus toxicity has not been observed in the field and has only been evident in greenhouse culture solutions when P was present at extremely high concentrations.

Keywords:   biotite, chlorophyll, feldspars, manures, peat, sawdust

Oxford Scholarship Online requires a subscription or purchase to access the full text of books within the service. Public users can however freely search the site and view the abstracts and keywords for each book and chapter.

Please, subscribe or login to access full text content.

If you think you should have access to this title, please contact your librarian.

To troubleshoot, please check our FAQs , and if you can't find the answer there, please contact us .