Building Soils for Better Crops, p87

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Building Soils for Better Crops, 3rd Edition
Sustainable Agriculture Research and Education (SARE).

The publication can be downloaded from SARE’s web site.
Sustainable Agriculture Research and Education – Publications – Building Soils for Better Crops, 3rd Edition.
To obtain paper copies, contact SARE.

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* Front Cover.
* Contents.
* About the Authors.
* About SARE.
* Preface.
* Introduction.
* 1.Healthy Soils.
* 2.Organic Matter: What It Is and Why It’s So Important.
* 3.Amount of Organic Matter in Soils.
* 4.The Living Soil.
* 5.Soil Particles, Water, and Air.
* 6.Soil Degradation: Erosion, Compaction, and Contamination.
* 7.Nutrient Cycles and Flows..
* 8.Soil Health, Plant Health, and Pests.
* 9.Managing for High-Quality Soils: Organic Matter, Soil Physical Condition, Nutrient Availability.
* 10.Cover Crops.
* 11.Crop Rotations.
* 12.Animal Manures for Increasing Organic Matter and Supplying Nutrients.
* 13.Making and Using Composts.
* 14.Reducing Erosion and Runoff..
* 15.Preventing and Lessening Compaction.
* 16.Reducing Tillage.
* 17.Managing Water: Irrigation and Drainage.
* 18.Nutrient Management: An Introduction.
* 19.Management of Nitrogen and Phosphorus.
* 20.Other Fertility Issues: Nutrients, CEC, Acidity, and Alkalinity.
* 21.Getting the Most from Routine Soil Tests.
* 22.How Good Are Your Soils? Field and Laboratory Evaluation of Soil Health.
* 23.Putting It All Together.
* Glossary.
* Resources.
* Index.
* Back Cover.

Chapter 9
Managing for High-Quality Soils:
Organic Matter, Soil Phys ical Condition, Nutrient Av ailability
Because organic matter is lost from the soil through decay, washing, and leaching,
and because large amounts are required every year for crop production, the necessity of
maintaining the active organic-matter content of the soil, to say nothing of the desirability
of increasing it on many depleted soils, is a difficult problem.
—A.F. Gustafson, 1941

Increasing the quality of a soil—enhancing it as a
habitat for plant roots and beneficial organisms—takes
a lot of thought and action over many years. Of course,
there are things that can be done right off—plant a cover
crop this fall or just make a New Year’s resolution not to
work soils that really aren’t ready in the spring (and then
stick with it). Other changes take more time. You need
to study carefully before drastically changing crop rotations,
for example. How will the new crops be marketed,
and are the necessary labor and machinery available?
All actions taken to improve soil health should
contribute to one or more of the following: (a) growing
healthy plants, (b) stressing pests, and (c) increasing
beneficial organisms. First, various practices to build
up and maintain high levels of soil organic matter are
key. Second, developing and maintaining the best possible
soil physical condition often require other types of
practices, in addition to those that directly impact soil
organic matter. Paying better attention to soil tilth and
compaction is more important than ever, because of the
use of very heavy field machinery. Last, although good
organic matter management goes a long way toward
providing good plant nutrition in an environmentally
sound way, good nutrient management involves additional
practices. In this chapter we’ll focus on issues of
organic matter management.
ORGANIC MATTER MANAGEMENT
As we discussed in chapter 3, there are no generally
accepted guidelines as to how much organic matter
should be in a particular soil. And it is difficult to be
sure exactly why problems develop when organic matter
is depleted in an individual field. However, even in the
early 20th century, agricultural scientists proclaimed,

Photo by Jerry DeWitt

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