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Soil Chemistry & Fertility

Unit 2.2 | Part 2 –51
Introduction

Introduction: Soil Chemistry & Fertility

Unit Overview

This unit introduces students to

basic concepts in soil chemistry, with

an emphasis on how soil chemistry

relates to the development and

maintenance of soil fertility.

The unit begins with a review of basic
chemistry concepts and terminology, includ-
ing atoms, compounds, ions, and chemical
reactions. Soil nutrients essential to plant
growth and the processes involved in nutri-
ent uptake are introduced, with particular
attention paid to cation exchange capacity
(CEC) and base saturation as they relate to
soil fertility. Soil pH and its effects on nutri-
ent availability are also covered.

Lecture 2 provides an overview of the
biogeochemical cycles involved in making
essential nutrients available to plants; the
physiological role of essential plant nutri-
ents; the characteristic symptoms of plant
nutrient deficiencies; and the soil amend-
ments used to supply limiting nutrients for
organic farming systems.

MOdes Of instrUctiOn

> LeCtURe (2 LeCtUReS, 1.5–2.0 hoURS eACh)

Lecture 1 covers basic chemistry concepts and definitions

relating to soil chemistry, in particular, nutrient uptake

processes and plant nutrients.

In Lecture 2, the role of individual plant nutrients and

nutrient cycling are discussed.

> DemoNStRAtIoNS

Five suggested demonstrations are designed to be integrated

into the lecture. They provide visual representations and

analogies for the concepts presented in the outline.

> ASSeSSmeNt QUeStIoNS (1.0 hoUR)

Assessment questions reinforce key unit concepts and skills.

Learning Objectives

CoNCePtS

•    Basic chemistry concepts (atomic structure and atomic

bonding) and terminology

•    Principles and processes involved in cation exchange

•    pH and its effects on nutrient availability

•    Soil acidity

•    Soil alkalinity

•    Plant nutrients: What they are, their cycles and how

they move through the soil, their use by plants, and the

problems plants exhibit when deficient in nutrients

SKILLS

This material is primarily conceptual, providing back-

ground for the skill-based sessions in Part 1, Organic

Farming and Gardening Skills