Martin Entz, Jeff Hoeppner, Shauna Humble, Pam Knaggs,

Joanne Thiessen-Martens and Keith Bamford

Department of Plant Science

University of Manitoba

Winnipeg, Canada

m_entz@umanitoba.ca

This paper is written from an agronomic, not an economic, perspective. Agronomists can make specific suggestions about how farmers can reduce input costs, however, there is no guarantee that these steps will actually improve net income or reduce income variability (risk). Also, because each farm is different, it is impossible to develop a "one size fits all" approach.

Our research has focused on crop rotations involving perennial and annual forage herbage and seed crops, and relay and double cropping. We have also considered various low input and organic production systems.

A long-term crop rotation study was established at the Glenlea research station in the spring of 1992. The objectives of this study are: 1) to compare the biological and economic performance of conventional, low input and organic crop production systems, 2) to monitor the impact of crop rotation and input level on pest population dynamics (annual and perennial weeds, insects and crop diseases), 3) to isolate the contribution of commercial fertilizers and herbicides to the profitability of crop production in different rotations, and 4) using a native tallgrass prairie treatment as a benchmark, to determine the long-term effects of different cropping systems on soil and environmental quality. An additional objective is to develop alternative cropping systems for Manitoba farmers. In this connection, farmer-directed conventional and organic rotations are being investigated as part of the study.

The experimental area covers 24 acres. The factorial experiment has crop rotation as mainplots, and fertilizer and herbicide use as subplots. Individual mainplots are 2 acres in size. Crop rotations under investigation include 1) wheat-pea-wheat-flax, 2) wheat (underseeded to sweet clover)-wheat-flax, 3) wheat- alfalfa (two years)-flax, 4) two "flexible" organic rotations (in cooperation with the Organic Producers of Manitoba), 5) two "flexible" conventional rotation (under the direction of the Domain marketing club, Domain, MB), and 6) a restored native prairie grassland (mixture of indigenous cool and warm season grass species; successfully established in summer of 1993). The three main rotations have different levels of crop inputs (full inputs - herbicides and fertilizers; low input - +herbicide/-fertililzer or -herbicide/+fertilizer; organic - no fertilizer or herbicide inputs). All treatments are replicated three times. Results are shown below:

Flax test crop yield as influenced by crop rotation and fertilizer and herbicide inputs. The rotations include a flax test crop every 4 years. The table below shows the yields of these flax test crops after 4 years (1995) and after 8 years (1999). Flax yields are shown in bushels/acre.

The results show:

• With full inputs, rotations containing a sweetclover green manure year produced the highest grain yields in 1999, however no differences among rotations were observed in 1995.
• In both low input systems, flax yields were lowest in the annual crop rotation vs the sweetclover and alfalfa-containing rotations.
• In both low input systems, the alfalfa-containing rotation performed better than the sweetclover-containing rotation in 1995, but few differences were observed between these two rotations in 1999.
• Under organic production conditions, flax in the alfalfa-containing rotation had the highest grain yield, followed by flax in the sweetclover rotation, followed by flax in the annual crop rotation.
• In 1999, the yield of flax after alfalfa in the organic system was identical to the yield of flax in the annual rotation with full inputs!

This information shows that by including soil-building crops such as alfalfa and sweetclover, inputs can be reduced without significant yield reductions in some instances. Clearly, an integrated cattle-grain farm would be in the best position to capture these rotational benefits.

Economic analysis of 8 years of the Glenlea Rotation Study The following table shows the cost of production and net income for the 8 years (1992-1999) of rotations 1 and 3 at Glenlea. Costs are in "1996 Canadian dollars" while returns are in 1996 dollars minus 20%. Values are averaged over the 8 year rotation and are shown in mean annual dollars/acre.

Results indicate:

• With full inputs, input costs were lower and net returns were higher in the alfalfa-containing vs the annual crop rotation.
• In the annual rotation, removing either fertilizers or herbicides did not seriously reduce the net return, but did reduce input costs (equal reduction in input costs).
• In the alfalfa-containing rotation, removing inputs increased net return in a number of cases compared with the full inputs treatment.
• The organic systems had the lowest cost of production and the highest net returns over the 8 year period in both the annual grain and alfalfa-based rotations.

This approach embraces the philosophy that crop production systems should reflect, as much as practically possible, the ecosystem which they replaced. Relay and double-cropping, though a radical concept in dryland cropping, mimics the natural prairie ecosystem better than current crop production systems. For example, while the indigenous prairie in the northern Great Plains was a combination of warm and cool season grasses and forbs which produced dry matter for the entire 4 or 5 month growth period each year, current cropping systems include only one crop, which uses significant resources for less than 75 days during the growing season. Relay/double cropping systems will use temperature, light and water resources more efficiently, resulting in a more productive and environmentally benign system. For example, research by Dean and Clark in Manitoba in the 1970's showed that late-season N fixation by fababean regrowth was as high as 40 lb/acre. Because this system means more plant growth for a longer portion of the season, the potential to use water is also greater.

Field experiments were established to evaluate different relay/double crop options in 1997/1998, 1998/99 and again in 1999/2000. The 1997 trial was seeded to a spring wheat test crop in 1998, while the 1998 trial was seeded to an oat test crop in 1999. The effects of the legume relay/double crops on weeds, soil water at freeze-up, and test crop yield are shown.