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¹ Professor of Agriculture and Chairman of the division of Agriculture and Home Economics at the College of Guam. Laplante, Albert A. The Soil Units of Guam and their Agricultural Capability Oct 1964 Div. of Agriculture and Home Economics, College of Guam Bulletin 2

00003

The Soil units of Guam and their agricultural capability By

Dr. Albert A. Laplante¹

Introduction

“The soil may be defined as a natural body, built in profile form from a variable mixture of

broken and weathered minerals and decaying organic matter, which covers the earth in a thin layer and

which supplies, when containing proper amount of air and water, mechanical support and, in part, food

for plants.”

The management of this mass of minerals, organic matter, water and air is, therefore, the key to

agricultural development.

Soil Components

A silt loam surface soil in the best condition for plant growth contains:

45 percent mineral matter

5 percent organic matter

25 percent air

25 percent water

Importance of Air and Water

Without the proper proportion of air and water in soil, plant roots cannot find: (1) space to

grow, (2) mineral nutrients, since all mineral nutrients must be dissolved in water before entering the

plant and (3) the oxygen which is essential for growth and development.