continue to farm in the same way. A major effort is under
larger farm equipment after World War II, and the avail-
way by farmers, extension educators, and researchers to
ability of cheap water for irrigation in some parts of the
develop and implement practices that are both more envi-
western United States, many people working with soils
ronmentally sound than conventional practices and, at
forgot or ignored the importance of organic matter in
the same time, more economically rewarding for farmers.
promoting high-quality soils.
As farmers use management skills and better knowledge
to work more closely with the biological world and the
“[Organic matter was] once extolled as the
consumer, they frequently find that there are ways to
essential soil ingredient, the bright particular star
increase profitability by decreasing the use of inputs pur-
in the firmament of the plant grower . . .”
chased off the farm and selling direct to the end-user.
As farmers and scientists were placing less empha-
SOIl HEAlTH INTEgRAl TO SUSTAINAblE AgRIcUlTURE
sis on soil organic matter during the last half of the
With the new emphasis on sustainable agriculture
20th century, farm machinery was getting larger. More
comes a reawakening of interest in soil health. Early
horsepower for tractors allowed more land to be worked
scientists, farmers, and gardeners were well aware of the
by fewer people. Large four-wheel-drive tractors allowed
importance of soil quality and organic matter to the pro-
farmers to do field work when the soil was wet, creat-
ductivity of soil. The significance of soil organic matter,
ing severe compaction and sometimes leaving the soil
including living organisms in the soil, was understood
in a cloddy condition, requiring more harrowing than
by scientists at least as far back as the 17th century. John
otherwise would be needed. The use of the moldboard
Evelyn, writing in England during the 1670s, described
plow, followed by harrowing, broke down soil struc-
the importance of topsoil and explained that the produc-
ture and left no residues on the surface. Soils were left
tivity of soils tended to be lost with time. He noted that
bare and very susceptible to wind and water erosion.
their fertility could be maintained by adding organic
New harvesting machinery was developed, replacing
residues. Charles Darwin, the great natural scientist of
hand harvesting of crops. As dairy herd size increased,
the 19th century who developed the modern theory of
farmers needed bigger spreaders to handle the manure.
evolution, studied and wrote about the importance of
More passes through the field with heavier equipment to
earthworms to the cycling of nutrients and the general
spread fertilizer and manure, prepare a seedbed, plant,
fertility of the soil.
spray pesticides, and harvest created the potential for
Around the turn of the 20th century, there was
significant amounts of soil compaction.
again an appreciation of the importance of soil health.
A new logic developed that most soil-related prob-
Scientists realized that “worn-out” soils, whose produc-
lems could be dealt with by increasing external inputs.
tivity had drastically declined, resulted mainly from the
This is a reactive way of dealing with soil issues—you
depletion of soil organic matter. At the same time, they
react after seeing a “problem” in the field. If a soil is defi-
could see a transformation coming: Although organic
cient in some nutrient, you buy a fertilizer and spread it
matter was “once extolled as the essential soil ingredi-
on the soil. If a soil doesn’t store enough rainfall, all you
ent, the bright particular star in the firmament of the
need is irrigation. If a soil becomes too compacted and
plant grower, it fell like Lucifer” under the weight of
water or roots can’t easily penetrate, you use an imple-
“modern” agricultural ideas (Hills, Jones, and Cutler,
ment, such as a subsoiler, to tear it open. If a plant dis-
1908). With the availability of inexpensive fertilizers and
ease or insect infestation occurs, you apply a pesticide.
xiii
Building SoilS for Better CropS: SuStainaBle Soil ManageMent