2002 Annual Report
Dickinson Research Extension Center
1089 State Avenue
Dickinson, ND 58601
Organic and Tillage Study (LOTS)
Results from a Cropping System in Transition from Conventional to
Synthetic-Chemical Free Management
Patrick M. Carr, Woodrow (Chip) W. Poland, Glenn B. Martin, and Burt A. Melchior
Dakota State University
Dickinson Research Extension Center
Many cropping systems are
diversifying because of economic and environmental considerations. The objective
of the Long-Term Organic and Tillage Study (LOTS) is to identify alternative
cropping systems that optimize economic returns and non-renewable energy use.
The study began in 1999 and includes a 6-yr rotation in which no synthetic fertilizers
or pesticides are used (organic). This rotation originally included flax (Linum
usitatissimum L.), but in 2001an intercrop of oats (Avena sativa
L.) and peas (Pisum sativum L. subsp. sativum ) was substituted
for flax in the rotation because of recurring weed infestations when flax was
grown. Other crops in the 6-yr rotation include alfalfa (Medicago sativa
L. subsp. sativa var. sativa), corn (Zea mays L.),
and hard red spring wheat (HRSW) (Triticum aestivum L. emend. Thell.
Yields of HRSW in the organic rotation were similar to yields rotations where
synthetic fertilizers and pesticides were used (conventional) and HRSW was grown
continuously, or HRSW was rotated in alternate years with peas and canola (Brassica
napus L.) in 2002. Corn averaged 62 bu/acre in a conventional rotation
but was disced under in the organic rotation because of a weed infestation along
with a severe deficiency in nitrogen among corn plants. The LOTS is ongoing.
Dryland wheat-fallow monoculture
is declining in much of the Great Plains because of economic and environmental
inefficiencies. Interest in "chemical-free" production systems (i.e., organic
farming) is expanding in the region. In response to these developments and also
directives by two independent agronomy boards, the Long-Term Organic and Tillage
Study (LOTS) was established.
Materials and Methods
Two 4-yr rotations and
one 6-yr rotation were established in 30 ft x 100 ft plots in a replicated and
randomized design at the Dickinson Research Extension Center in 1999. The rotations
were developed jointly by scientists and commercial agriculturists in North
Dakota. The 4-yr rotations include: (i)  HRSW -  pea -  winter wheat
(1) -  canola; and (ii)  HRSW -  pea -  corn -  buckwheat
(Fagopyrum esculentum Moench.) The 6-yr rotation include:  HRSW
+ alfalfa -  alfalfa -  alfalfa plowdown -  HRSW -  corn -  oat
+ pea for hay. Continuous HRS wheat also is included in the study.
The 2, 4-yr rotations and
the continuous HRS wheat monoculture are managed without tillage, while tillage
is used in the 6-yr rotation. Conventional fertilizer and pesticides are used
in the 4-yr rotations and the HRS wheat monoculture, but not in the 6-yr rotation.
Soil nutrient and water
content, crop and weed vegetative growth, grain production, and other data are
being collected. Data will be analyzed using PROC MIXED from SAS once the contrasting
cropping systems have achieved a new steady state, which will not occur for
several more yr. Means of yields for crops from the various rotations and the
continuous HRS wheat monoculture are reported for 2001.
Results and Discussion
No differences occurred
between the yield of HRSW in the organic rotation and in the continuous HRSW
monoculture, or when HRSW was rotated in alternate years with pea and canola
(Table 1). Yield of HRSW averaged 45 bu/acre in the organic
rotation. An additional 11 bu/acre were produced when HRSW was grown conventionally
in the 4-yr rotation with pea, corn, and pea compared with the organic rotation.
The design of the study prevents the impact of management (organic vs. conventional)
and rotation from being evaluated independently for their abilities to explain
differences in yield of HRSW in the organic rotation and the conventional rotations.
Protein concentration of
HRSW grain tended to be lower in the organic rotation than in the conventional
systems (Table 1). Rotation and management system did not
affect grain test weight but did influence kernel weight. Heaviest kernels resulted
when HRSW was grown every forth year in a rotation with pea, corn, and buckwheat.
There was no difference in kernel weight of HRSW grain among the other rotations
and production systems.
The organic rotation failed
to produce higher yields of HRSW than the conventional management systems included
in the study during 2001, and in one instance produced less grain (Table
1). Protein concentration sometimes was less for HRSW grain produced in
the organic rotation than in conventional production systems. However, the premium
paid for HRSW in the organic market resulted the organic production system generating
the greatest gross returns for HRSW.
Grain/seed yields of other
crops in the LOTS study during 2002 were: canola - 1200 lb/acre; corn -62 bu/acre;
and peas - 41 bu/acre average across both rotations that included peas. Average
yield for alfalfa forage was 1.1 tons dry matter (DM)/acre for second and third
year stands in the organic rotation. Average yield for oat + pea forage in the
organic rotation was 1.2 tons DM/acre.
The authors gratefully thank the Northern Plains Sustainable Agriculture Society and the Organic Crop Improvement Association #1 for their financial support of the LOTS.
|Table 1. Performance of hard red spring wheat for selected traits in different crop rotations.|
|Rotation1||Plant Height||Yield||Kernels||Test Weight||Protein||Return|
NS = No statistical difference at the P < 0.05 level.
1 Organic = (1) HRSW + alfalfa - (2) alfalfa - (3) alfalfa plowdown - (4) HRSW - (5) corn - (6) oat + pea (hayed); Continuous = HRSW grown continuously; Cool = (1) HRSW - (2) field pea - (3) HRSW [dormant seeded] or HRWW - (4) canola; Cool/Warm = (1) HRSW - (2) field pea - (3) corn - (4) buckwheat
*Organic returns were calculated based on a $5 per bushel rate.
Returns were calculated
by multiplying the 2001 yield by protein premium or discount paid at the Southwest
Grain Terminal located at Gladstone, ND on September 17. The price paid on this
date was $2.74/bu, assuming that grain protein concentration was 14%. An additional
$.02/bu was paid for each additional 0.25% increase in grain protein up to 15%
protein, where an additional $0.05/bu was paid. An additional $0.01/bu was paid
for each additional 0.25% increase in grain protein up to 17%, above which an
additional premium was not paid. Grain was discounted $0.05/bu for each 0.25%
reduction in grain protein from 14% to 11%, below which no additional discount
was not assigned. Returns factored in discounts for grain with a test weight
<58 lb/bu [-$0.01/bu for 0.5 lb/bu between 58 and 57 lb/bu; -$0.02/bu for
0.5 lb/bu between 57 and 55 lb/bu; -$0.03/bu for 0.5 lb/bu between 55 and 50
lb/bu; and -$0.04/bu for 0.5 lb/bu between 50 and 46 lb/bu].
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