Plants & Human Affairs - Introduction
Cherries.wmf (7140 bytes) Plants & Human Affairs (BIOL106)  -  Stephen G. Saupe, Ph.D.; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321;;

Soil/Growth Medium
(also see Powerpoint in Public Folder)

I.  Soil

A.  Composition

II.  Function/Requirements

A. Anchor plant � substrate for root attachment, support (hydroponics � must provide support)

B.  Aeration for roots � for cellular respiration in mitochondria, requires oxygen to produce ATP (cell�s energy).  Soil � pore space; Hydroponics � bubble or aerate solutions, running;

C.  Moisture � function of soil structure and texture

  1. Texture:  properties of particles of different size:  sand > silt > clay

  2. Structure:  soil particles aggregate in clumps or remain individual grains; clumps better cuz allows for greater pore space = more air and water; clumps develop from freeze/thaw cycles or dry/wet cycles or activites of soil organisms

D.  Fine-textured soil � lot of clay

E.  Coarse-textured (sand)

F.  Soil and water.
    In lab we looked a the following: saturated, field capacity, capillary water,  wilting percentage (click here for the growth medium lab)

II.  Plant Food

A. Required Nutrients

 B.  CHO � required in large amounts; C taken up through pores in leaf (stoma) as carbon dioxide and used in photosynthesis to make carbohydrates.   O - uptake with C in carbon dioxide, also taken up as water via roots; H - primary uptake via roots

C.  Macronutrients:  N P K Ca Mg S

D.  Micronutrients � Fe, Cl, Zn, Mo B Cu, Mn

E.  Fertilizers provide the macro & micronutrients, especially macro 

F.  Labeling - fertilizers labels with percent N, P, & K 

G.  Forms

H.  Organic vs. Inorganic fertilizer

I.  Slow release � pellet, release nutrient over time

III.  Fertilizer Cost Comparisons   (not covered, not on exam)
    Nitrogen most important element � because it is required in the greatest amount (1-4%)  Since it is a major consideration, calculate cost.  Click here for details.

IV.  Fertilizer Dilution Rate  (not covered, not on exam)

V.  pH (not covered, not on exam)

VI.  Electrical Conductivity
(not covered, not on exam)

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Last updated:  04/11/2005   � Copyright  by SG Saupe