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Crop-yield and economic
comparisons of
organic,
low-input, and
conventional
farming systems in
California's Sacramento Valley
Sean Clark, Karen Klonsky, Peter Livingston,
and Steve Temple
Abstract. We compared the crop yields and economic performance of
organic,
low-
input, and conventional farming systems over an eight-year period based on research
from the Sustainable Agriculture Farming Systems (SAFS) Project in California's Sacra-
mento
Valley.
The SAFS Project consisted offour farming-system treatments that differed
in material input use and crop rotation sequence. The treatments included four-year
rotations under conventional (conv-4), low-input, and organic management, and a con-
ventionally-managed, two-year rotation (conv-2). The four-year rotations included
pro-
cessing tomato, safflower, corn, and bean and a winter grain and/or legume double-
cropped with bean. The conv-2 treatment was a tomato and wheat rotation. In the low-
input and organic
systems,
inorganic fertilizer and synthetic pesticide inputs were reduced
or eliminated largely through crop rotation, legume cover crops, composted manure
applications, and mechanical cultivation.
All crops, except safflower, demonstrated significant yield differences across farming
systems in at least some years of the experiment. Yields of tomato and corn, the most
nitrogen (N)-demanding crops in the rotations, responded most years to the farming-
system years treatments, while bean and the winter grain/legume displayed treatment
differences less often and instead tended to vary more with yearly growing conditions.
Nitrogen availability and/or weed competition appeared to account for lower crop yields
in the organic and low-input systems in some years. The economics of all farming
systems depended mainly on the costs and profits associated with tomato production.
The most profitable system was the conv-2 system due to the greater frequency of tomato
in that
system.
Among the four-year
rotations,
the organic system was the most profitable.
However, this system's dependence on price premiums leads to some concern over its
long-term economic
viability.
Among the low-input cropping
systems,
corn demonstrated
clear agronomic and economic advantages over conventional production
methods.
Based
upon
these
findings, we suggest that future research on organic and low-input farming
systems focus on developing cost-effective fertility and weed management options based
upon improved understanding of N dynamics and weed ecology.
Key words: sustainable agriculture, alternative agriculture, economic analysis
Introduction
A fundamental goal of alternative agri-
culture, including organic and low-input
farming systems, is to reduce non-renew-
Volume 14, Number 3, 1999
able resource use and environmental deg-
radation while maintaining productivity
and profitability. Although there is great
interest in pursuing this goal, there is un-
certainty and risk in adopting unconven-
tional production practices. Recent studies
from Maryland (Abdul-Baki et al., 1996),
Kansas (Diebel et
al.,
1993), South Dakota
(Smolik et al., 1993; 1995), California
(Drinkwater et al., 1995), and North Caro-
lina (King and Hoag, 1998) have shown
that alternative systems can perform as
well as conventional systems agronomi-
cally and/or economically throughout the
United States. However, other studies
have demonstrated that reliance solely on
organic methods, particularly for vegeta-
bles and fruits, can lead to substantial re-
ductions in yield and profit (Pimentel,
1993;
Sellen et
al.,
1995;
Nelson and King,
1996).
Although long-term, comprehensive
records are not available, recently reported
statistics indicate substantial growth in the
organic farming industry in California.
According to 1992-1993 records, there
were 1,159 organic growers farming
18,418 ha, with gross sales exceeding $75
million. Industry experts, however, esti-
mate that the number of growers increased
by 25% per year between 1992 and 1995
Sean Clark is former Research Manager, Sustainable
Agriculture Farming Systems Project; Karen Klon-
sky is Extension Specialist, Department of Agricul-
tural Economics; Pete Livingston is Staff Research
Associate, Department of Agricultural Economics;
and Steve Temple is Extension Agronomist, Depart-
ment of Agronomy and Range Science, University
of California, Davis, CA 95616. Corresponding au-
thor is Sean Clark, Department of Agriculture and
Natural Resources, Berea College, Berea, KY 40404
(sean_clark@berea.edu).
109
(Klonsky and Tourte, 1995). Moreover,
gross sales of organic foods nationwide
more than doubled during that same period
(Mergentime and Emerich, 1996; Scott,
1997).
By contrast, the total number of
farms in California declined slightly while
net farm income remained relatively
steady during this period (California De-
partment of Food and Agriculture, 1997).
The degree to which California farmers
are adopting low-input production meth-
ods is difficult to assess. Although there
is clear evidence that increasing numbers
of growers are using or are planning to
use low-input practices in fertility and pest
management (Grieshop and Raj, 1992),
statewide material input expenses are in-
creasing at a much greater rate than is total
gross farm
income.
Total manufactured in-
put expenses of fertilizers, lime, and pesti-
cides increased by 19, 35, and 22%, re-
spectively, from 1992 to 1995 (California
Department of Food and Agriculture,
1997).
Moreover, state records indicate
that total pesticide use in California con-
tinues to increase (California Department
of Pesticide Regulation, 1996). Thus,
while there are numerous examples of
farmers experimenting with or adopting
more environmentally-sound practices in
California (Auburn, 1994), reduced de-
pendence on purchased inputs is not
widely apparent at the state level.
In this paper we report results from the
Sustainable Agriculture Farming Systems
(SAFS) Project at the University of Cali-
fornia at Davis, which is experimentally
evaluating the transition from conven-
tional to low-input and organic farming
practices in California's Sacramento Val-
ley (see Temple et
al.
[1994] for a detailed
description of the SAFS Project). The ma-
jor crops of the region, based on area
planted, are rice (Oryza sativa), wheat
(Triticum aestivum), processing tomato
{Lycopersicon esculentum), corn (Zea
mays),
and safflower (Carthamus tinctor-
ius) (California Department of Food and
Agriculture, 1997). The Sacramento Val-
ley accounts for nearly a quarter of Cali-
fornia's organic hectarage (Klonsky and
Tourte, 1995). Most of this land is in vege-
table, fruit, and/or nut production, while
field crops account for about 18% of the
planted area. Here we compare the agro-
nomic and economic performance of con-
ventional, low-input, and organic farming
systems over the first eight years of the
project.
Materials and Methods
Farming-system descriptions
The Sustainable Agriculture Farming
Systems (SAFS) Project was established
on an 11.3-ha site in 1988 to study agro-
nomic, economic, and biological aspects
of conventional and alternative farming
systems in California's Sacramento Valley
(Fig. 1). The Sacramento Valley has a
Mediterranean climate, with most rainfall
occurring during the winter months and
relatively little during the growing season.
Thus,
irrigation is needed for most crop
production.
The SAFS Project consists of four
farming-system treatments that differ pri-
marily in crop rotation and use of external
inputs (Fig. 2). These include four-year
rotations under conventional (conv-4),
low-input, and organic management, and
a conventionally-managed, two-year rota-
tion (conv-2). All of the four-year rota-
tions include processing tomato, saf-
flower, bean (Phaseolus vulgaris), and
corn. The conv-2 treatment is a tomato
and wheat rotation. During this study
beans were double-cropped with winter
wheat in the conv-4 system, while in the
low-input and organic treatments, beans
followed a winter grain/legume crop
which was either harvested for seed, cut
as hay or green chop, or incorporated as
green manure. In 1989 and 1990 this crop
was lupine (Lupinus alba); however, a bi-
culture of oats (Avena sativa) and
woolypod vetch (Vicia dasycarpa) was
grown from 1991 to 1996. Vetch {Vicia
spp.) cover crops were grown during the
winter preceding all other cash crops in
the low-input and organic systems. There
were four replications of each treatment
and all possible crop rotation entry points
were represented. Thus, there was a total
of 56 plots, each measuring 0.12 ha, ar-
ranged in a randomized block design.
All farming systems used "best-farmer
management practices" determined
through discussion among researchers and
staff,
consultation with growers cooperat-
ing on the project, and market conditions.
The conv-4 and conv-2 treatments were
managed with practices typical of the sur-
rounding area, which included the use of
synthetic fertilizers and pesticides. Thus,
the conventional tomato, corn, and wheat
crops received approximately 175, 225,
and 180 kg/ha of N, respectively, as urea
or ammonium nitrate. Safflower and bean
crops generally did not receive fertilizer.
The organic tomato and corn crops re-
ceived 5-7 t/ha of composted poultry ma-
nure several weeks prior to planting,
which generally supplied 150-200 kg/ha
of N. Organic bean, safflower, and oats/
Figure 1. The Sacramento Valley region of California (dark area) comprised of Butte, Colusa,
Glenn, Sacramento, Solano, Sutter, Tehama, Yolo, and Yuba Counties.
110American Journal of Alternative Agriculture
CONVENTIONAL
SYSTEMS
Conv-4 rotation
Conventional 4-yr inputs
synthetic fertilizers
synthetic pesticides
(both at conventionally-
recommended amounts)
r safflower
V corn
bean
wheat
ALTERNATIVE
SYSTEMSOrganic rotation
1 vear s'"^
Organic inputs
cover crops (c.c.)
composted animal manure
CCOF-approved pesticides
CCOF-approved fertilizers
safflower
,cc
V cornbean
oats/vetcb
Conventional 2-yr inputs
synthetic fertilizers
synthetic pesticides
(both at conventionally-
recommended amounts)
Conv-2 rotation
wheat
wheat
Low-input inputs
cover crops (c.c.)
synthetic fertilizers
(reduced amounts)
synthetic pesticides
(reduced amounts)
Low-input rotation
c.c.
safflower
,c.c
V cornbean
oats/vetc
Figure 2. Graphical description of the four farming system treatments comprising the Sustainable Agriculture Farming Systems (SAFS)
Project based upon differences in inputs and rotations.
vetch crops did not receive composted ma-
nure applications.
Decisions to use pesticides in these
treatments were based upon common prac-
tices in the area as well as University of
California integrated pest management
(IPM) guidelines. In the low-input system,
fertilizer and pesticide inputs were re-
duced primarily by using legume cover
crops to improve soil fertility, and me-
chanical cultivation and cover cropping
for weed management. The organic treat-
ment was managed according to the regu-
lations of California Certified Organic
Farmers (CCOF). Therefore, no synthetic
chemical pesticides or fertilizers were
used. Instead, management included the
use of cover crops, composted animal ma-
nure,
mechanical cultivation, and minimal
use of CCOF-approved products (CCOF,
1995).
Summer cash crops in all systems were
furrow-irrigated in a similar manner,
though differences in the timing of soil
preparation, cultivation, and harvest activ-
ities caused some variation in irrigation
scheduling. Tomatoes in all systems were
typically sprinkler-irrigated immediately
after planting or transplanting, and furrow-
irrigated throughout the remainder of the
growing season. Winter cover crops in the
organic and low-input systems and wheat
in the conventional systems were usually
irrigated after planting in the fall to
achieve establishment, but winter precipi-
tation provided most of the water used by
these crops.
Crop-yield and economic
measurements
Yields of all cash crops from 1989-
1996 were determined each year using
commercial-scale machinery and small-
scale hand harvests. In general, statistical
comparisons were made using data from
machine harvests, which consisted of the
yield from the center one-third of each
plot. Hand-harvest data were usually used
to verify machine-harvest data, but occa-
sionally used for statistical treatment com-
parisons when problems were noted in the
machine harvest due to equipment fail-
ures.
Statistical comparisons for tomato,
corn, safflower, and bean yields were
made using Analysis of Variance (AN-
OVA) followed by the Student-Newman-
Keuls (SNK) test for mean separation
when significant differences were found
(P
<0.05).
Yield comparisons of wheat and
oats/vetch crops, which were represented
in only two of the four farming system
treatments, were made with t-tests. An im-
portant aspect of yield
is
temporal variabil-
ity, which is of particular interest in com-
paring alternative to conventional systems
because of the potential implications for
farm income when adopting non-conven-
tional practices. Yield variability was as-
sessed by calculating the coefficient of
variation (CV) for each cropping system
for the first four years (1989-1992), sec-
ond four years (1993-1996), and the entire
eight-year period (1989-1996). Again, sta-
tistical comparisons of CV across treat-
ments were made with ANOVA and SNK
tests,
or
t-tests.
Published and unpublished
studies conducted at the SAFS site on indi-
vidual crops (corn and tomato) and spe-
cific disciplines (soil fertility, plant nutri-
tion, pest management, etc.) were used in
the interpretation of crop-yield data.
The economic performance of each
cropping system and farming system was
quantified using the Budget Planner com-
puter program (Klonsky and Cary, 1990;
Klonsky and Livingston, 1994). This pro-
gram generates costs, returns, and profits
and simulates the economic performance
of a hypothetical 810-ha farm. The actual
costs of material inputs and labor were
Volume 14, Number 3, 1999111
based upon current prices within
the re-
gion. American Society
of
Agricultural
Engineers (ASAE) formulas were used
to
calculate equipment costs
for
fuel, lubrica-
tion,
and
repair.
The
economics
of
field
operations were derived from costs
for la-
bor, materials,
and
equipment;
and
field
operation time
was
based
on the use of
commercial-sized equipment. This
ap-
proach produced budgets representative
of
real-farm conditions rather than budgets
based
on the
disproportionately large
amount
of
time needed
to
manage small,
experimental plots.
All
crop yields were
based upon experimental treatment means.
The land area of each hypothetical farming
system
was
divided equally among
all
crops
in the
rotation.
For
example, crop-
land
in the
conv-2 farming system
was
split between tomato
and
wheat each year.
Total costs
and
profits were compared
graphically among treatments with
de-
scriptive statistics. Total costs included
operating costs
(all
production practices
including planting, pest management,
har-
vesting, etc.), cash overhead (land rental,
property taxes,
and
other business
ex-
penses),
and
non-cash costs (depreciation
and opportunity costs
for
equipment, irri-
gation systems, tools,
and
buildings).
Gross returns were generated from
the av-
erage plot yields multiplied
by the com-
modity farm-gate price.
The
farm-gate
prices were obtained from local
and re-
gional buyers
at
the time
of
harvest.
Gross
returns
for the
organic system were calcu-
lated
two
ways, with conventional prices
and premium prices
for
organic commodi-
ties,
to
examine
the
economic viability
of
both markets.
Net
returns (profits
or
loss)
were calculated
by
subtracting total costs
from gross returns.
Results
Crop yields
All crops, except safflower, demon-
strated significant yield differences across
farming-system treatments
in
at least some
years
of
the experiment. Yields
of
tomato
and corn,
the
most nitrogen (N)-de-
manding crops
in the
rotations, responded
differentially to the treatments during most
years,
while bean, wheat,
and
oats/vetch
crops displayed treatment differences less
often and instead tended to vary more with
yearly growing conditions than with farm-
ing-system effects
(Fig. 3).
CD
110
100
90
80
^
70
60
50
3500
3000
j$ 2500
5* 2000
1500
1000-
CO
0)
O
3500-
3000-
§
2500
-
2000-
1500-
05
s
8000-
O
ro
7000-
•*
6000
H
5000-
8000-
05 6000-
-* 4000
H
2000-
14000-
=512000-
10000-
8000-
Tomato
• Organic
• Low-input
A Conv-4
• Conv-2
Bean
Safflower
/**
Wheat
Oats/Vetch
Corn
1989
1990 1991 1992 1993 1994 1995 1996
Figure
3.
Yields (kg/ha
or t/ha) of
the SAFS Project cropping systems, 1989-1996. Different
letters indicate significant differences between farming system treatments (ANOVA,
SNK,
P<0.05).
112American Journal
of
Alternative Agriculture
Table 1. Mean coefficient of variation (%) for crop yield (a measure of yield variability)
in the four SAFS Project farming systems for three periods: 1989-1992, 1993-1996, and
1989-1996.
Crop
Tomato
Bean
Safflower
Corn
Wheat
Oats/Vetch
Tomato
Bean
Safflower
Corn
Wheat
Oats/Vetch
Tomato
Bean
Safflower
Corn
Wheat
Oats/Vetch
Organic
26
29
8
21a2
—
NA5
38
40
21
22a
—
61a
19
30
26
21a
—
62a
Low-Input
1989-1992
15
30
10
16ab
—
NA
1993-1996
36
21
21
lib
—
31b
1989-1996
21
26
30
15ab
—
39b
Conv-4
16
36
13
8b
17
—
42
12
16
12b
21
—
17
39
9
10b
20
—
Conv-2
12
—i
—
—
13
—
44
—
—
—
21
—
19
—
—
—
17
—
1 Indicates that crop is not part of the farming system.
2 Means with different letters indicate significant differences (Analysis of variance, Student-
Newman-Keuls test, P <0.05).
3 Crop not grown or harvested for seed.
Tomato yields in the conv-4 system
tended to be the highest among the four
farming systems, averaging 83 t/ha, while
those of the organic system tended to be
the lowest. Organic tomato yields were
significantly lower in five of eight years,
three in the first rotation and two in the
second, and averaged 16.5% less than
those of the conv-4 system over the eight-
year period. In contrast, low-input tomato
yields were significantly lower than conv-
4 yields in only two of the eight years and
averaged 6.3% less over the entire period
(Fig. 3). Similarly, yields in the conv-2
system averaged 6.7% less, but were sig-
nificantly lower in only one year. No sta-
tistically significant difference in yield
variability among treatments was ob-
served (Table 1).
The two most important factors in ex-
plaining tomato yield variability over the
eight years of the SAFS study were differ-
ences in N source and availability among
treatments and the switch from direct seed-
ing (1989-1991) to transplanting (1992-
1996) in the organic and low-input sys-
Volume 14, Number 3, 1999
terns.
The conventional and low-input sys-
tems received about 175 and 100 kg/ha of
N annually as inorganic fertilizer, respec-
tively. About 10% of this was applied at
planting while the rest was side-dressed.
Nitrogen derived from the previous cover
crop was intended to substitute for inor-
ganic fertilizer in the low-input system.
By contrast, the organic system received
less than 2 kg/ha of N as organic fertilizer
(fish meal and kelp) which was applied at
planting or as a foliar spray. A combina-
tion of cover crops and composted manure
was intended to provide most of the re-
quired N to the crop in this system. During
the first two years of the project, tomato
plants in the organic system appeared to
suffer from N deficiency, and to a lesser
extent, weed competition (Scow et al.,
1994).
The decision to use transplanting
was made in consultation with cooperating
farmers to take advantage of the N-gener-
ating and weed-suppressing effects of the
cover crops. By using transplants, legume
cover crops could be allowed to grow
longer in spring, leading to greater N-fixa-
tion and better weed suppression prior to
planting. Moreover, the transplants had an
advantage over early-season weeds.
In the first year of using transplants
(1992,
the last year of the first rotation),
yields in the organic and low-input sys-
tems improved markedly (Fig. 3). Yields
declined, however, in 1993 in all systems
as a result of poor growing conditions
throughout the region, but were still statis-
tically similar across treatments. In 1994
a viral infection in the transplants, origi-
nating in the greenhouse, resulted in poor
vegetative growth and reduced yields in
the low-input and organic systems. Low-
input tomato yields improved in 1995 and
were similar
to
those of the conv-4 system;
however, intensive plant and soil analyses
conducted throughout the growing season
indicated that the organic system was N
deficient despite estimated inputs of 80
kg/ha of N from the previous cover crop
and 125 kg/ha of N from composted poul-
try manure. Slow N mineralization rates
and N immobilization by soil microflora
appeared to account for the problem (Cav-
ero et al., 1997; Clark et al., 1999). In an
effort to compensate for N unavailability
the manure application rate in the organic
system was increased dramatically in
1996.
In addition to 115 kg/ ha of N from
the preceding cover crop, approximately
22.4 t/ha of composted poultry manure
was applied, supplying an additional 308
kg/ha of N. Tomato plants in the organic
system still showed some signs of early-
season N deficiency according to conven-
tional indicators (petiole nitrate at "first
bloom," "one-inch fruit," and "first
color"),
but nevertheless reached their sec-
ond highest yields of the eight-year period.
Tomato yields in 1996 were statistically
similar across the four treatments (Fig. 3).
Corn showed significant treatment ef-
fects in five of
the
eight years of the study,
but yield patterns differed from those of
tomato in that the low-input system, aver-
aging over 12,300 kg/ha of grain, had the
highest average yield among the four-
year-rotation farming systems (Fig. 3).
Low-input corn yields averaged 10.6%
higher than conv-4 yields over the entire
eight years and 18.6% higher over the sec-
ond four-year rotation. Organic corn
yields, by contrast, averaged 5.0% lower
than the conv-4 yields over the eight years.
113
Significant differences in corn yield
variability were also found (Table
1).
Dur-
ing the first four-year rotation, yields in
the organic system were significantly
more variable than those of the conv-4
system. During the second four-year rota-
tion, yield variability in the low-input sys-
tem declined somewhat while that in the
conv-4 system increased slightly. Conse-
quently, there was again no significant dif-
ference in yield variability between these
two systems, but yield variability for the
organic system remained relatively high
and was significantly greater than the other
systems. Comparison of corn yield vari-
ability over the entire eight years showed
all three systems differing statistically
from each other, with the conv-4 system
having the lowest variability and the or-
ganic system, the highest.
Differences in corn yields across the
farming system treatments appeared to be
linked in part to N availability. The most
striking, and perhaps most important, ob-
servation over the eight-year period was
the dramatic increase of low-input corn
yields beginning in 1992 (Fig. 3). Prior to
1992,
composted animal manure had been
used to supplement cover crop-derived N
in both the organic and low-input systems.
In 1992 the manure was replaced in the
low-input system with side-dressed, sup-
plemental inorganic N fertilizer, used at
about one-half the rate of the conv-4 sys-
tem. Thus, while the conv-4 corn system
received 180-230 kg/ha of N annually as
inorganic fertilizer, the low-input system
received 80-140 kg/ha. Detailed tissue and
soil analyses conducted from 1993 to 1995
indicated that N deficiency was a problem
in the organic system due to the unpredict-
ability of N mineralization and immobili-
zation (Friedman et al., 1999). This defi-
ciency was overcome in the low-input
system by the addition of the inorganic N
fertilizer.
Weed competition also was identified
as an important factor contributing to corn
yield differences among the treatments.
Although weed pressure was relatively
similar and stable in the low-input and
conv-4 systems, it was more variable and
difficult to manage in the organic system.
Attempts were made to incorporate the
cover crop and plant the corn while there
was still adequate soil moisture remaining
from the winter
rains.
In some years, how-
ever, irrigation was necessary to establish
a strong corn stand and this sometimes
resulted in a strong weed stand as well.
Weeds were especially problematic in the
organic system in 1993 and 1995 (Lanini
et al., 1994; Clark et al., 1998a), years that
resulted in relatively low corn yields in
that system (Fig. 3). Herbicide use was
the primary means of weed management
in the conv-4 system, while the organic
system depended exclusively upon me-
chanical cultivation. The low-input system
relied on a combination of both tactics and
used 60% less herbicide (based upon the
amount of active ingredient applied) than
the conv-4 system and still achieved
equally effective weed control.
The differences in corn yields between
the conv-4 and low-input systems did not
appear to be linked
to
N availability. Fried-
man et al. (1997, 1999) concluded that the
use of cover crops in the low-input system
provided benefits beyond the N contribu-
tion. They suggested that water availabil-
ity to the low-input corn crop may have
been superior to that of the conv-4 system
because of reduced soil compaction and
greater water infiltration resulting from the
cover crop.
Bean yields were relatively similar
across farming systems throughout the
study (Fig. 3). Yields in the conv-4 system
averaged 1,905 kg/ha, while those of the
organic and low-input systems were
slightly higher, averaging 1,941 and 2,047
kg/ha, respectively. Significant treatment
effects were found in only two of the seven
years,
1990 and
1995,
in which beans were
grown (Fig. 3). In both of those years dif-
ferences in bean varieties and lengths of
growing seasons may also have been re-
sponsible for yield differences. Bean vari-
eties were chosen each year based upon
the length of the growing season following
the harvest of the winter grain/legume crop
and, in the organic system, the premium
price offering. In 1990, "Yolano" beans
were grown in the organic and low-input
systems, while "Sutter" beans were grown
in the conv-4 system. Similarly, in 1995
"Red Kidney" beans were grown in the
organic and low-input systems, while
"Midnight Black" beans were grown in
the conv-4 system. In all other years the
three systems had the same bean variety,
either "Midnight Black" or "Yolano."
Heavy weed pressure in the organic sys-
tem in 1995 and 1996 appeared to contrib-
ute to lower yields in that system as well.
No significant differences in bean yield
variation were found (Table 1).
Safflower yields showed a slight, yet
steady, increase over the course of the
study in all three systems. Although
signif-
icant treatment effects were not detected,
the conv-4 system generally had the high-
est yields (Fig. 3). Over the eight years of
the study, crop yields in all systems ranged
from about 1,500 to 3,000 kg/ha. No sig-
nificant difference in yield variation was
detected among systems; however, the
conv-4 system had the lowest variability
over the tight years (Table 1). In 1992,
the safflower crop in the organic and low-
input systems was tilled in because of a
combination of heavy weed pressure and
a poor crop stand. In order to minimize
economic losses in these farming systems,
beans were planted as a substitute.
Wheat yields in the conv-4 and conv-
2 systems showed significant differences
in three of the eight years of the study
(Fig. 3). However, average yields over the
entire period were nearly identical. The
conv-4 system averaged
5,723
kg/ha,
while the conv-2 system averaged
5,688
kg/ha, a 0.6% difference. In addition, no
difference in yield was found between the
systems. One noteworthy point is the rela-
tively high wheat yields in both systems
in 1994. This was a particularly favorable
year for wheat production throughout the
Sacramento Valley region.
Due to the use of different best-farmer
management alternatives in the organic
and low-input systems, including incorpo-
ration, green chop, and cutting for hay,
seed yields in the oats/vetch crop could
be directly compared in only four of the
eight years of the study. Average yields
in the low-input and organic systems in
those four years were 3,389 kg/ha and
3,179 kg/ha, respectively, a 6.6% differ-
ence.
A significant yield difference was
found in one of the four years compared
(Fig. 3). Yield variability in the organic
system was quite high (Table 1), due pri-
marily to the dramatic yield increase be-
tween 1994 and 1995 (Fig.
3).
Excessively
wet conditions in 1995 provided a favor-
able environment for oat growth, leading
to yields that were more than double those
of any previous year.
114American Journal of Alternative Agriculture
Economics
The economics of each farming system
depended primarily upon the costs and re-
turns associated with tomato production.
The total costs of tomato production
ranged from about $2,000/ha to over
$4,500/ha, while the total costs of other
crops in the rotations ranged from less
than $200 to just under $2,000/ha (Fig.
4).
Moreover, tomato costs clearly showed
the most substantial differences between
farming systems. Total tomato production
costs in the organic and low-input systems
were substantially greater than those of
the conv-4 and conv-2 systems throughout
the study. All other crops incurred rela-
tively similar costs across farming-system
treatments. Several notable exceptions in-
clude the organic and low-input safflower
crops in 1992, which were tilled in due to
a poor stand and heavy weed competition
and replaced by beans, and the organic
corn crop in 1996, which had to be re-
planted due to a poor stand, apparently
caused by seedling pests including seed-
corn maggot (Delia platura) and wire-
worms (Elateridae). Differences in the
costs of winter grain/legume crops among
treatments were due to differences in crop
species (wheat versus oats/vetch or lupine)
rather than to farming-system effects.
Several factors contributed to the rela-
tively high costs of tomato production in
the organic and low-input systems com-
pared to the conv-4 and conv-2 systems.
Clearly, the most important factor was the
use of transplants rather than direct seed-
ing. A comparison of operating costs
among the four tomato cropping systems
from 1993 to 1996 showed that planting
costs in the organic and low-input systems
were nearly three times greater than those
of the conv-4 and conv-2 systems (Table
2).
Others factors contributing to higher
costs in the organic and low-input systems
were cover crop and weed management
practices. It should be noted that cover
crop economics were evaluated only on
N contribution (substitution for fertilizer)
and weed suppression (substitution for
herbicide, cultivation, and/or hoeing).
Long-term benefits, including increased
soil organic matter and nutrient storage,
which have been documented at the SAFS
site (Clark et al., 1998b), as well as re-
duced likelihood of erosion, were not in-
i
c
o
3
T3
O
O
to
O
u
o
4500
4000
3500
3000
2500
1400
1200
1000
800
600
2000
1500 -
1000 -
500 -
1200
900
600
300
2000
1800
1600
1400
1200
1000
-•— Organic
-A-
•
Low-input
-w~- Conv-4
•••••• Conv-2
Tomato
Bean
J I
Safflower
J I
Winter Grain/Legume
J I I I I I
Corn
1989 1990 1991 1992 1993 1994 1995 1996
Figure
4.
Total production costs ($US/ha) associated with each crop of the four SAFS farming-
system treatments, 1989-1996.
Volume 14, Number 3, 1999115
Table 2. Average operating costs, total costs, gross returns, and profits ($US/ha) for to-
mato management practices in the four farming systems of the SAFS Project, 1993-1996.
Managment practiceOrganic7Low-InputConv-4Conv-2
Ground preparation
Planting
Fertility management
Cover crop management
Weed management
Insect pest management
Disease management
Irrigation
Harvest
Residue management
Interest
Total operating costs
Total costs
Gross returns
Profits
94
1005
343
156
571
0
0
188
613
12
100
3082
4331
5267
936
94
1005
106
156
571
0
0
168
613
5
86
2804
4001
4078
77
111
358
106
0
412
12
0
109
610
5
52
1808
2924
4159
1235
119
366
106
0
427
12
0
109
605
12
52
1775
2732
3842
1110
1 Calcuated for the organic system receiving premium prices.
eluded in the accounting. There was
greater dependence upon hand hoeing, a
relatively expensive weed management
practice typically used in processing toma-
toes,
in the organic and low-input systems
compared to the conventional systems.
One additional practice that contributed to
higher costs in the organic system was
the use of purchased composted manure.
Consequently, fertility management costs
in the organic system were about 60%
higher than those of
the
other farming sys-
tems (Table 2).
Tomato also showed the greatest range
in net returns (profits and losses) among
the cropping systems (Fig. 5) and contrib-
uted the most to profits in all farming sys-
tems,
except for the organic system with-
out price premiums. Tomato crops in the
conv-4, conv-2, and organic (with premi-
ums) systems were profitable in all years
of the study, with average net returns of
$l,725/ha, $l,625/ha, and $2,119/ha, re-
spectively. Low-input tomato crops were
profitable in six of the eight years, but
averaged only $605/ha. Without price pre-
miums, the organic system would have
been profitable in only four of the eight
years and averaged a loss of $69/ha be-
cause of the high costs of production.
Following the tomato crop, bean and
corn crops were generally the next most
profitable components of the four-year
rotations. Bean crops were profitable in
the three farming systems in all years,
except in the organic system without
premiums, in which net returns were
positive in five of the seven years. Beans
were most profitable in the organic sys-
tem with premium prices, averaging
$645/ha (Fig. 5). By contrast, average
net returns for the conv-4, low-input, and
organic (without premiums) systems were
$122/ha, $254/ha, and $200/ha, respec-
tively. Clearly, high premium prices for
organic beans contributed significantly to
profits in the organic system. The rela-
tively low profitability of beans in the
conv-4 system was due to higher op-
erating costs (Fig. 4), primarily in fertility
and pest management.
Corn was most profitable for the low-
input system due to relatively moderate
costs and high yields. Net returns in this
system averaged $38O/ha. Average annual
profits for corn in the organic (with premi-
ums) and conv-4 systems were $276/ha
and $249/ha, respectively. Corn in the or-
ganic system without premiums averaged
a loss of $27/ha.
Safflower and the winter grain/legume
were generally the least profitable crops
in the rotations. Safflower was profitable
in the conv-4 and organic (with premiums)
systems in six of eight years and averaged
net returns of $220/ha and $118/ha, re-
spectively. However, due to crop losses in
1992,
safflower crops in the low-input and
organic (without premiums) systems aver-
aged losses of $24/ha and $50/ha, respec-
tively, despite being profitable in five of
the eight years.
Winter grain/legume crops in the conv-
4 and conv-2 systems (wheat) were profit-
able in four and five years of the study,
respectively, and averaged profits of $53-
60/ha. Similarly, the winter grain/legume
crop in the low-input system (lupine or
oats/vetch) was also profitable in five of
eight years and averaged $249/ha. By con-
trast, it produced positive net returns in
the organic systems in only two of eight
years and averaged losses of $113/ha and
$157/ha for the system with and without
premiums, respectively. It should be
noted, however, that this multipurpose
crop was harvested as a cash crop in only
six of eight years in the low-input system
and only five years in the organic system.
Due to the critical importance of tomato
in all of the farming systems, the general
patterns in whole-farm costs were similar
to those observed in tomato; costs were
higher in the organic and low-input sys-
tems compared to the conv-4 and conv-2
systems (Fig. 6). The dramatic increase in
whole-farm costs in the organic and low-
input systems in 1992 was largely due to
the shift from direct seeding to trans-
planting tomatoes and the complete loss
of the safflower crops and subsequent re-
planting to beans in those treatments. The
conv-2 system was more costly than the
conv-4 system throughout the study be-
cause half of its cropland was planted to
tomato each year.
The most profitable farming system
over the eight years was the conv-2 system
due to the greater frequency of tomato in
that rotation. This system averaged $840/
ha over the eight years. Among the four-
year rotations, the organic system with
price premiums was most profitable, aver-
aging $740/ha, while the organic system
without price premiums was unprofitable,
averaging losses of $31/ha. The conv-4
was the second most profitable four-year
rotation, averaging $589/ha, while net re-
turns in the low-input systems were
$358/ha.
Discussion
Research on dynamic agricultural sys-
tems typically creates some difficulties in
clearly identifying the causes of observed
patterns. However, systems research also
provides opportunities, unavailable in
more reductionist or single-discipline
116American Journal of Alternative Agriculture
CO
CO
o
o
2
Q.
5000 -
4000 -
3000 -
2000 -
1000 -
o
-
-1000 -
1500 -
1200 -
900 -
600 -
300 -
0 -
600 -
300 -
o
-
-300 -
-600 -
900 -
600 -
300 -
o
-
-300 -
-600 -
900 -
600 -
300 -
0
-300 -
-600 -
Tomato
Bean
i i
Safflower
i i
^ Winter
\
\\\
•••••••-'^•Ai-i
Corn
~w
1 1
• Organic (+)
-•— Organic (-)
—A-
•
Low-input
-•-• Conv-4
••••••• Conv-2
A
/\
A
/\
J
\
^£*£^%^
^r' jr^'
,¥,,,,
Grain/Legume
* A-
1 1 1 1 1 1
\
1 1 1 1 1 1
1989 1990 1991 1992 1993 1994 1995 1996
Figure 5. Profits or losses ($US/ha) associated with each crop of the four SAFS farming-
system treatments, 1989-1996. Numbers for the organic system are presented with (+) and
without (-) premium prices.
Volume 14, Number 3, 1999
studies, to observe the interactions of mul-
tiple factors in agroecosystems. Through
a combination of long-term, descriptive
and analytical data collection on crop
yields and management practices, and
more in-depth, disciplinary studies at the
SAFS site, major factors affecting the crop
yields of these fanning systems were iden-
tified. In addition, the economic viability
of management practices, cropping sys-
tems,
and farming systems was assessed.
The findings of this study provide a
number of insights into future possibilities
for the adoption of low-input and organic
cropping and/or farming systems in Cali-
fornia's Sacramento Valley. Although
many factors, both within and beyond the
farm, may influence adoption, two key
questions are critically important: 1) What
are the effects on crop yields? and 2) What
are the effects on farm income? Ad-
dressing these questions, especially the
latter, in small-plot experiments has limi-
tations because of variability in farmer ex-
perience and skills, environmental condi-
tions,
and economic markets (Lockeretz,
1989).
However, such experiments also
provide opportunities often not possible
with on-farm studies, such as replication,
precise field measurements, and long-term
comparisons. Thus, cautious extrapolation
can be used, if only qualitatively, to gain
a greater understanding of the potential
positive and negative consequences of al-
ternative agricultural systems.
Among the four crops represented in
both the conventional and alternative
farming systems of the SAFS Project, to-
mato and corn yields displayed substantial
treatment effects, while bean and saf-
flower yields were less affected. Detailed
analyses of the tomato and corn crops
(Cavero et
al.,
1997;
Friedman et
al.,
1997;
Clark et
al.,
1999; Friedman et al., [unpub-
lished manuscript]) have identified N defi-
ciency and weed competition as the most
important factors leading to reduced yields
in the organic and low-input systems at
the SAFS site.
Other studies on conventional and al-
ternative corn production have had similar
findings to those of the SAFS Project.
Lockeretz et al. (1981) reported that corn
yields on organic farms in the Midwest
averaged 8% less than on conventional
farms.
Similarly, Liebhardt et al. (1989)
found that corn yields in systems that de-
117
CO
SI
CO
Z)
2200
2000
1800
1600
1400
3500
3000
2500
2000
1500
H
1200
900
600
300
0
-300
6000
4000
2000
o
-
-•— Organic (+]
-•- Organic (-)
-*•• Low-input
-•-• Conv-4
• • Conv-2
Total Costs
Net Returns
•
Cumulative Net Returns
1989
1990 1991 1992 1993 1994 1995 1996
Figure 6. Whole-farm total costs, gross returns, net returns, and cumulative net returns
($US/ha) associated with the four SAFS farming system treatments, 1989-1996. Numbers
for the organic system are presented with (+) and without (-) premium prices.
pended upon animal manure or legume
cover crops for N were 25% less than in
conventional systems that used inorganic
N fertilizer. In the SAFS Project, the or-
ganic corn system, which depended upon
legume cover crops and composted animal
manure for
N,
performed somewhat better
118
than the alternative systems in the afore-
mentioned studies, averaging yields only
5%
lower than conventional yields, al-
though they were considerably more vari-
able from year to year. However, yields
in the low-input system, which used 50%
less inorganic N fertilizer than the conv-
4 system, were the highest among the three
treatments. Furthermore, the low-input
system produced the highest net returns in
three of the four years during the second
rotation. Based on these results, the low-
input system appears to hold promise for
corn production in the Sacramento Valley.
And, with 40,000 ha grown in the region,
the reduction of inorganic N fertilizer by
50%
and herbicides by 60% could have
substantial positive environmental bene-
fits as well.
Most comparisons of conventional and
organic and/or low-input tomato systems
have focused on fresh-market rather than
processing production. Moreover, the
findings of these studies have been highly
variable. Studies in eastern North America
have reported
45-55%
yield reductions un-
der organic management (Sellen et al.,
1995;
Brumfield et al., 1995). By contrast,
Drinkwater et al. (1995) found no signifi-
cant differences in tomato yields among
commercial organic and conventional
farms in California's Central Valley and
concluded that biological processes on
these organic farms compensated for the
lack of synthetic chemical inputs. We
would expect the findings of the SAFS
Project to have greater similarity to those
of Drinkwater et al. (1995) than to studies
conducted in eastern North America, due
to the extreme differences in climate, pest
pressures, and production practices be-
tween the regions. However, the results of
the SAFS Project do indicate that depen-
dence solely on legume cover crops and
composted animal manure for N needs can
be risky due to the unpredictability of N
mineralization, immobilization, and plant
availability. The use of supplemental inor-
ganic N fertilizer, used at 60% or less of
the rate used in the conv-4 treatment,
brought yields in the low-input system
within 5% of those for the conv-4 system.
Production costs in both the organic
and low-input systems were substantially
greater than those of the conv-4 and conv-
2 systems, largely because of the use of
transplants and greater dependence on
hand weeding. Thus, the importance of
premium prices for the economic viability
of these systems is clear (Table 3). In fact,
high premium prices for the organic toma-
toes throughout this study made this the
most profitable cropping system per hec-
tare despite the high production costs.
American Journal of Alternative Agriculture
Table 3. The average and range for conventional and organic premium prices ($US/t) in
the lower Sacramento Valley, California, 1989-1996.
Crop
Tomato
Corn
Bean
Safflower
Conventional
Average
57
120
526
319
prices
Range
52-61
105-154
485-684
281-353
Organic
Average
90
144
761
490
premium prices
Range
73-105
113-198
529-1323
331-1103
Without the premiums the organic tomato
system would have been unprofitable. The
low-input tomato system, which did not
have the advantage of premium prices,
made 70% less profit than the organic sys-
tem (with premiums) despite averaging
10%
greater yields.
The dependence of organic tomato pro-
duction on price premiums naturally leads
to questions regarding the long-term eco-
nomic viability of the system. As long
as market demand for organic processing
tomato continues to increase, premium
prices should remain high. However,
widespread adoption of organic methods
would eventually lead to lower prices (Ba-
tie and Taylor, 1989). It should be noted
that the price for organic tomatoes de-
clined from $105/t in 1989 to $73/t in
1996.
Because of
this,
we have some con-
cerns regarding the use of high-cost trans-
plants in the organic and low-input sys-
tems and the dependence upon imported,
animal-manure compost in the organic
system. If premium prices continue to de-
cline the use of these production practices
would have to be reconsidered.
Assumptions regarding the source and
cost of manure can also have a dramatic
effect on the outcome of economic com-
parisons. All manure inputs in this study
were assumed to be purchased from off-
farm sources. If, instead, disposal costs
were assumed for the manure source, fer-
tility management costs in the organic corn
and tomato systems obviously would be
less (Karlen et al., 1995). Such a scenario
seems unlikely for the Sacramento Valley.
Bean yields and profits over the eight
years indicate good short-term and long-
term potential for low-input and organic
systems. The economic performance of or-
ganic beans with and without premium
prices makes this a good candidate as a
transition crop. Relatively low production
Volume 14, Number 3, 1999
costs and high premium prices made this
crop highly profitable in the organic sys-
tem. Even without premium prices, the
organic system was more profitable than
the conv-4 system over the eight years.
Based on the SAFS study, safflower
appears to hold only limited potential in
organic and low-input farming systems in
the Sacramento Valley. In 1992, the com-
plete loss of this crop, which typically
yields only marginal economic returns in
good years, resulted in economic losses
that could not be recouped in the low-
input and organic (without premiums) sys-
tem over
the
other seven years of the study.
Even with the addition of premium prices
(Table 3), this crop was only marginally
profitable over the eight years in the or-
ganic system. Thus, safflower may not be
a recommendable crop during the transi-
tion to organic production.
The economic performance of the win-
ter grain/legume crop showed substantial
variability among farming systems largely
because of the differences in crop species
and management options. Wheat, a com-
mon crop in the Sacramento Valley, pro-
vided only marginal profits for the conv-4
and conv-2. The winter grain/legume crop
in the organic system
was
unprofitable as a
cash crop because it
was
harvested and sold
in only five of eight
years.
In the
other three
years it
was
incorporated
as
a green manure
preceding beans and costs were included,
but the value of the benefits
was
not directly
measured. By contrast, the winter grain/le-
gume crop in the low-input system was
profitable largely because it was sold as
seed, hay, or green chop in seven of the
eight years of the
study.
On farms with
live-
stock within
a
short transportation distance,
this cropping system could have an impor-
tant role in producing feed; however, with-
out livestock nearby its value is somewhat
questionable.
Conclusions
The whole-farm profit comparisons
demonstrate the economic incentive for a
two-year rotation with tomato, a common
cropping strategy in the Sacramento Val-
ley for conventional growers. The primary
concerns about this system are the poten-
tial for increased disease pressure and/or
degradation of soil structure. Although
such problems have been apparent, they
have not yet resulted in important crop-
yield or economic
losses.
Among the four-
year rotations in the SAFS study, the or-
ganic system with premium prices was the
most profitable. Thus, it is a potentially
viable farming-system option for the Sac-
ramento Valley, with the current market
demand for organic products. This sys-
tem's dependence on price premiums
leads to some concern over its long-term
economic viability as more growers begin
transition to organic methods, particularly
if demand does not continue to increase
at
its
current
pace.
Yield comparisons indi-
cate that the transition to organic produc-
tion may be somewhat problematic for
crops with high N demands, such as to-
mato and corn. Bean appears to be a reli-
able and profitable crop during and follow-
ing the transition. The conv-4 farming
system generally had the lowest costs but
ranked third in profitability. The low-input
system performed well agronomically but
had relatively high costs. Among crops in
the low-input system, corn demonstrated
clear agronomic and economic advantages
over conventional production methods.
Furthermore, environmental advantages
may accrue from increased adoption of
this cropping system throughout the re-
gion. Based upon the research at the SAFS
site,
we suggest that future research on
organic and low-input farming systems fo-
cus on developing cost-effective fertility
and weed management options based upon
improved understanding of N dynamics
and weed ecology.
Acknowledgements. We gratefully acknowledge
Diana Friedman, Oscar Somasco, and Mary Kirk,
former research managers on the SAFS Project, for
collecting data on agronomic variables, and Don
Stewart and William Cruickshank, former SAFS crop
production managers. We also thank the many stu-
dents from the University of California at Davis who
worked on the project over the years. Support for
the SAFS Project has been provided by USDA/EPA
SARE/ACE, University of California Sustainable
119
Agriculture and Education Program (UC SAREP),
California Department of Food and Agriculture
(CDFA) Fertilizer Research and Education Program
(FREP), University of California Division of Agri-
culture and Natural Resources (UC DANR), and
many local businesses that contributed supplies.
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Canada Introduces National
Organic Standard
The Government of Canada has intro-
duced a new National Standard of Can-
ada for Organic Agriculture that "can be
recognized and applied in markets
around the globe," according to John
Manley, the Minister of Industry who is
responsible for the Standards Council of
Canada. "For Canadian producers of or-
ganic agri-foods produce, this will trans-
late to greater and easier access to inter-
national markets that demand these kinds
of standards."
The standard was developed through
the Canadian General Standards Board's
Standards Committee on Organic Agri-
culture, which includes various technical
experts, and announced through the Stan-
dards Council of Canada, which pro-
motes efficient and effective standard-
ization. The standard "outlines principles
for organic agriculture that endorse
sound production and management prac-
tices to enhance the quality and sus-
tainability of the environment and ensure
the ethical treatment of livestock."
Specifically, it prohibits the use of
ionizing radiation in the preservation of
food, prohibits the use of genetically en-
gineered or modified organisms, encour-
ages maximum use of recycling, and en-
courages maximum rotation of
crops
and
promotion of biodiversity.
The scope of the standard includes
production plans and records; crop and
livestock production; production re-
quirements for maple products, honey,
greenhouse crops, mushrooms, sprouted
plants, and wild and natural products;
the production and processing of organic
products; and the packaging, labeling,
storage, and distribution of organic food
products.
"This new National Standard of Can-
ada will provide consumers with a con-
sistent meaning for 'organic,' helping
them to make more informed choices,"
said Lyle
Vanclief,
Canadian Minister of
Agriculture and Agri-Food.
An abstract of the Standard is avail-
able on the Internet at www.pwgsc.gc.ca/
cgsb;
to order copies of the entire Stan-
dard (listed as CAN/CGSB-32.310),
contact CGSB Sales Centre, Ottawa,
Canada K1A 1G6; (819) 956-0425;
e-mail
ncr.cgsb-ongc@pwgsc.gc.ca.
Consumers Union Calls for
Labeling of Modified Foods
Consumers Union, in Consumer Re-
ports (September 1999), has recom-
mended that "all foods containing geneti-
cally engineered ingredients be labeled
as such, including milk with recombinant
bovine growth hormone," and that the
USDA "set a single, national standard
for certified-organic food that excludes
genetically engineered food from the
definition." The Consumer Reports arti-
cle examined genetically modified foods,
tested "everyday groceries," and re-
vealed that "genetically engineered
foods are already on supermarket
shelves."
Although
"U.S.
consumers are largely
unaware of
the
issue," its effects on them
include the U.S.'s "collision course"
with the European Union over geneti-
cally modified foods, and "environmen-
tal questions over genetically engineered
crops [that] have taken on a new urgen-
cy....What happens if a hybrid 'su-
perweed' emerges that withstands herbi-
cides?"
Genetically engineered foods "should
be subject
to a
mandatory federal human-
safety review before they hit the mar-
ket," according to the story. It also calls
for "thorough, mandatory safety reviews
of genetically engineered plants and ani-
mals before they are released into the
environment," and recommends that
EPA require "more rigorous resistance-
management
plans.
Innovations like 'ter-
minator' technology, which produces
sterile seeds, should not be used until
society has found a way to carefully con-
sider their profound environmental and
societal implications." For
now,
the mag-
azine says, consumers who want to avoid
genetically modified foods "have little
choice but to buy organic."
Bugs May Become Resistant to
Bt Cotton Faster Than Expected
University of Arizona scientists have
written in Nature that some insects
may be able to develop resistance to
genetically modified "bug-proof cotton
plants more quickly than expected, ac-
cording to an article in The Wall Street
Journal (August 5, 1999). "The peer-
reviewed laboratory study, which is be-
ing published in today's issue of the
science magazine Nature, signals that
some genetically modified plants might
become obsolete sooner than their in-
ventors had planned," the article said.
Farmers this year are planting 3.5 mil-
lion acres of bug-resistant cotton, which
contains a gene transplanted from Bacil-
lus thuringiensis, or Bt. "The potential
problem exposed by the University of
Arizona study is that the mating cycle of
its Bt-resistant bugs was out of synch
with that of regular pink bollworms," ac-
cording to the article. "That suggests any
Bt-resistant bugs that develop in the wild
might only be able to mate with each
other, which could trigger a population
explosion of their kind."
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