Plants & Human Affairs (BIOL106) - Stephen G. Saupe, Ph.D.; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321; ssaupe@csbsju.edu; http://www.employees.csbsju.edu/ssaupe |
Soil/Growth Medium
(also see Powerpoint in Public Folder)
I. Soil
A. Composition
organics (derived from organisms; partly decayed plant and animal, fecal material, roots)
inorganics (not derived from organisms; minerals; rocks)
living organisms (bacteria, fungi, nematodes, protozoans, worms, mycorrhizae)
gasses (carbon dioxide, oxygen, ethylene)
water
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
Texture: properties of particles of different size: sand > silt > clay
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
avoid destroying structure causes forms large clumps, dry as large hard clods
slow to warm/cool
holds lots of water, minerals
good for main season crops
E. Coarse-textured (sand)
large pores, good aeration
poor water holding capacity
warm quickly, good root and bulb crops
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
C H O P K N S Ca Fe Cl Zn Mo B Cu Mn Mg
mnemonic device: C Hopkins Caf�, Closing mob coming with machine guns
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
liquid �dilute prior
soluble salts � dissolve in water
H. Organic vs. Inorganic fertilizer
organics � contain carbon, from living source (manure, fish emulsion, gelatin)
inorganic � no carbon, from mineral source
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)
growers typically apply 100 � 200 mg N/liter
click here for details on how to calculate the concentration of nitrogen in a fertilizer.
V. pH (not covered, not on exam)
VI. Electrical Conductivity (not covered, not on exam)
monitors soluble salts
EC readings
millimho�s
refers to amount of CA, Mg,, Na, Cl
fertilizers increase
measure of amount of fertilizer and other in root zone
0 � 1.5 mmho/cm acceptable for irrigation water
| Top | PHA Home | PHA Course Materials| SGS Home | |
Last updated: 04/11/2005 � Copyright by SG Saupe