A major deterrent to adopting no-till or organic crop production in the Northern Great Plains is concern about weed management problems during the transition from conventional systems and moisture conservation associated with crops as alternatives to fallow. We conducted plot experiments and farm comparisons and found that productivity was reduced in diversified no-till and organic systems, but weed populations were discouraged and costs of inputs reduced in the alternative systems. Net returns were greatest on average for the organic system with organic price premiums, and the no-till reduced-input systems were similar to conventional systems.
- 1. Understand weed dynamics to predict species shifts within organic and no-till production systems.
2. Determine crop performance and water use efficiency within organic and no-till systems.
3. Quantify input levels and costs for organic and no-till systems, including both purchased and operator supplied inputs.
4. Quantify profitability (net return) of organic and no-till systems.
5. Educate producers on potential benefits of organic and no-till systems through dissemination of research results.
The predominant small grain cropping system of the Northern Great Plains has utilized a crop fallow rotation under an assumption that the fallow period is required for moisture conservation. The risk of soil moisture loss by removing fallow periods with crops such as legumes into crop rotations in the Northern Great Plains has been thoroughly investigated (Zentner et al. 2001). More sustainable agriculture systems may include the use of reduced tillage, more diversified, and organic cropping systems that minimize off-farm purchased inputs, but may represent increased threat from weeds (Derksen et al. 2002). The transition to more sustainable systems represents a challenging step for producers and requires prediction of how crops and weeds will perform (Maxwell, 1999). Understanding weed population dynamics in response to more sustainable agricultural systems is critical to implementation of these systems on the Northern Great Plains (Davis and Liebman, 2003; Peairs et al. 2005). There has been limited ability to predict the economic density thresholds or distributions of weed populations that require management. In addition, in order to get farmers to tolerate some level of weeds it is critical to predict the future threat that unmanaged populations represent. Adoption of more sustainable systems that reduce purchased inputs and tillage was lagging due to lack of comparative economics among systems (Robertson and Swinton, 2005).
Over the past decade, numerous studies have been conducted to examine the effects of crop rotations on weed populations (Bàrberi et al. 1997; Ball and Miller 1993; Blackshaw 1994; Kegode et al 1999; Liebman and Dyck 1993). However, few studies have investigated the role of input levels and crop sequences within rotations on weed management specific to the NGP region (Thomas et al. 2001). Even less research has separated the effects of crop diversity and associated weed management practices on weed population dynamics (Doucet et al. 1999). The overall goal of this study was to quantify the temporal population dynamics of key weed species during the transition period from a cropping system with little crop diversity managed with tillage and high levels of off-farm inputs to a diversified no-tillage cropping system with reduced levels of off-farm inputs. The specific objectives were to assess the effects of crop rotation, and crop sequence within rotations, coupled with management intensity (input level) on weed population temporal dynamics by quantifying changes in weed seedling densities over time.
A large-scale experiment was established at Moore, MT (Table 1) to compare reduced input no-till and organic systems to conventional small grain production systems. A similar systems experiment was established at Bozeman, MT (Table 2). The goal was to evaluate farm profitability and sustainability within a system that increases crop diversity and reduces off-farm inputs. Thus we quantified production, profitability, and weed population dynamics among the production systems in the experiments at each site and on farms in north central Montana.
In 1999, a large-plot (96′ X 100′) no-till crop rotation study was initiated near Moore, MT, with the primary goal of studying weed population dynamics and cropping system productivity in response to crop diversity, rotation and a range of input levels. Each rotation was split into two management schemes, conventional and reduced input, to investigate the potential of enhancing cropping system profitability and sustainability. One rotation was additionally split to include an organic system to provide a comparison to conventional and reduced input no-till systems (Table 1). Detailed measurements of cropping system productivity and weed population dynamics were conducted from 2000 to 2003 to monitor the transition period from conventional management to no-till and organic systems. Geo-referenced 1-m2 circular patches of wild oats, Persian darnel, pigweed, and lambsquarters were established to permit the simultaneous study of weed dispersal and weed population dynamics in response to cropping system management. In addition, a background infestation of downy brome, field pennycress, and other mustard species exists on the site and will be monitored.
The Moore site is located at an elevation of 1281 m and the mean annual temperature is 5.5° C. Limiting resources for crop production in the area were soil type and annual precipitation. Average annual precipitation at the location is 350 to 400 mm with approximately 50 % of the total occurring during the months of May to July. Over the duration of this study, precipitation during these three months was well below normal ranging from 10-45 % below 50 yr averages. A more typical precipitation pattern for this location occurred only during the spring and summer of 2001. The soil type at the experimental site was a Judith clay loam with moderate slopes of 4 to 8%. The soil type is a typical Mollisol found in Montana on high elevation benches and terraces and is productive, but tends to be shallow to gravel. The site was well drained and crop growth can be subject to drought stress during the growing season. Conversely, because of the shallow nature of the soil profile, adequate soil moisture recharge can generally be expected over months when crop growth is not present in the field (personal communication, Dave Wichman).
Objectives 2 and 3 were accomplished with research trials on the Bob Quinn farm near Big Sandy, MT, and Merja Bros. Farms near Sun River, MT, respectively. The on farm experiments utilized field scale equipment. The producer participants were essential in the development of the questions surrounding objectives 2 and 3. The treatment structure was developed through collaboration of local conventional and organic small grain producers and Montana State University-Agriculture Experiment Station staff and researchers.
The framework for study of weed population dynamics within the overall design of the experiments described above was established in late September 1999. Within every split plot of the above rotations two sets of weed subplots were established. Both sets consisted of the same four weed species with one set of plots established inside the main body of the plot and the other set positioned in an untreated check strip with dimensions of 3.3 m by 7.3 m. The four weed species established were redroot pigweed, common lambsquarters (Chenopodium album), Persian darnel (Lolium persicum), and wild oat (Avena fatua). The four species were chosen for the study because visual observations and soil seed bank samples taken during the summer of 1999 at the beginning of the study before weed seeds were planted indicated that there were very low background populations of these species present at the site, but they are common in the region. Greenhouse germination methods were used to quantify the number of viable seeds in the soil cores obtained from the site (Ball and Miller 1989; Forcella 1992). Values of less than 1.0 seeds m -2 of wild oat and 5 seeds m-2 of pigweed were quantified for the site. No seeds of common lambsquarters or Persian darnel were found in the 1999 soil core samples taken from the site. On the basis of these results, each species was established in separate 0.84 m2 plots. The weed sub-plots were established by planting each of the four weed species at a density of 600 seeds m-2 by scattering the seed on the soil surface and gently raking. These plots were permanently marked by staking two corners of each plot with fluorescent polypropylene “road markers” attached to a spike and driven into the ground to a depth of approximately 10 cm.
Enterprise budgets were developed for both the organic and no-till rotational systems described previously. The organic and no-till enterprise budgets were compared with one another and also with enterprise budgets for the conventional rotation. In addition to information from the producer-managed field trials and the large plot rotation studies, the comparisons were drawn on USDA statistics (Montana State Department of Agriculture, 1999-1999 and United States Department of Agriculture, 1990-1999) and regional enterprise analysis efforts (e.g., Johnson et al., 1997ab, Baquet et al., 1998). Budget components of particular interest include input costs (e.g.; fertilizer, fuel, seed, and herbicides), crop revenue, and labor and management requirements.
Organic and no-till producers were interviewed to evaluate their cropping systems, costs and returns over a period corresponding to the plot experiments described above. These producers were selected based on the following criteria, in addition to their willingness to participate:
1. the producers have been in either an organic or a no-till rotation for a long period of time, not less than 8 years;
2. the producers were located in an important cropping area in North Central and Central Montana of approximately 100 miles in radius. This area is roughly east of Ft. Benton, South of Havre, West of Malta, and North of Lewistown;
3. the producers were of a scale comparable to most commercial producers in Montana, farming over 1500 acres for the organic producers and over 2500 acres for the no-till producers;
4. the producers had maintained detailed records adequate for survey purposes, allowing returns estimates from crop year 1998/99 to present;
5. the set of organic producers correspond with the set of no-till producers in terms of the management ability.
These five criteria limited the set of potential cooperators considerably. Three organic producers matched these criteria, and three no-till producers were subsequently identified to roughly match these organic producers in terms of their (admittedly subjectively assessed) management ability. Both sets of producers are viewed locally and statewide as progressive and outstanding farmers. These producers are largely the “cream of the crop” in terms of their success in these rotations and are early adopters.
The period of this project spanned a significant drought in Montana with every year averaging 2-3 inches of precipitation below the previous 30-year average. Thus, it was a significant challenge for proposed diversified systems that remove fallow periods to perform well. In general, the high input systems consistently provided greater crop productivity, but this response was much greater when moisture was less limiting. At the driest sites there was little crop productivity advantage of high input systems over low input or organic systems. Weed population growth rates were generally reduced in diversified and organic systems relative to high and medium input systems with little crop diversity. Economic net returns from the organic rotation with premiums were consistently higher than those for the competing rotations, largely due to the reduced herbicide and fertilizer inputs. The importance of the organic premiums is clearly shown by the differences in the net returns for the premiums case vs. the no premiums case in the organic protestations. The spring wheat based and the diverse no-till rotations provide the highest average returns of the remaining rotations.
The objective of the weed component of this study was to achieve a greater understanding of the temporal and spatial dynamics of the newly established (planted) weed populations in response to crop rotation, crop sequence within rotations, and input levels. It was evident that crop rotation and associated weed management practices (input levels) in the herbicide treated weed populations played a role in the significant differences observed in seedling densities for both species between systems and over time (Table 3).
These findings were similar to that of Liebman and Dyck (1993) who concluded that crop rotations made up of crop species of varying types with varying management practices could be effective weed management tools. We found that independent of input level (conventional, reduced, or organic), increased crop diversity in crop rotations and including fallow years, whether managed chemically or through the use of a green manure crop, had the effect of suppressing the density and spatial extent of all the weed species populations that we studied. However, chemical weed management practices within both the conventional and reduced input rotations in this study were the major management factor driving weed population dynamics. The range of weed management options that a diverse crop rotation affords can be tailored to meet the specific needs of land managers to address a specific weed management concern. For example in this study, management of wild oat, which is notoriously difficult to control in continuous small grain/fallow rotations in the NGP, was significantly improved through the addition of the dicot crops to the alternative rotations in this study. This allowed for the use of effective herbicide applications in the dicot phases of the rotations that negatively impacted the wild oat populations. The benefit of crop rotation, from a weed management perspective, is the ability that it gives growers to develop a weed management plan that enables them to use alternative weed management strategies and practices that target a specific weed species or life history stage of a particular weed species (Anderson 2004).
Conversely, crop rotation in the absence of chemical weed management played a much smaller role in the dynamics of the weed populations in the untreated areas of this study. This finding is similar to those of other studies (Davis and Liebman 2003; Doucet et al. 1999; Légère et al. 1997; Thomas et al. 1996), where crop rotation and crop sequence played a relatively small role in influencing weed density when decoupled from corresponding weed management practices. This represents a significant hurdle in encouraging adoption of low input and organic production systems. It is also indicative of the further research needed to develop optimum weed management practices in these systems. The cultural weed management practices utilized in this study, such as delayed crop planting and increased crop seeding rates, in the absence of chemical weed managements practices did not reduce the densities of either wild oat or redroot pigweed in this study. Even if weed densities were held at a low equilibrium with cultural practices, the populations had high enough densities to have a significant potential to increase without the added mortality from herbicide applications. If chemical weed management inputs are to be reduced, even more cultural mechanisms need to be introduced to suppress weed populations to levels acceptable by conventional producers.
Results of this study also suggest that initial starting point or entry point into the rotation can have a profound influence on the dynamics of the weed population over the period of a rotation. For example, when a wild oat population was established in the herbicide-tolerant canola phase of the reduced input alternative crop rotation, this population decreased dramatically after the establishment year and as a result was lower over the duration of the rotation compared to when a population was established in spring wheat phase of that same rotation. This highlights the importance of having an in-depth understanding of the potential effects that a particular crop sequence may have on a given weed population. Crop rotations are critical for breaking up weed life cycles and reducing populations, but starting weed population densities and the first crop encountered may determine the success of any given rotation.
The results of this study underscore the importance and power of long-term cropping system studies, however difficult or costly they are to manage and maintain, to determine the effect of past management history on future weed population temporal dynamics. This study also highlights the need for continued investigation into ecologically based weed management strategies as optimization of reduced-input systems continues across the region. A powerful finding of this study was that weed populations in systems that rely on more integrated methods of weed control coupled with a reduction in off-farm inputs (herbicides) could be successfully managed. In the reduced-input systems, crop diversity in rotations and associated management practices facilitated the management of the wild oat and redroot pigweed in this study when herbicide inputs were reduced compared to inputs in the conventional systems, but even the reduced-input systems remained reliant on chemical weed management practices.
The results suggest that it is possible to mange specific weed problems with an understanding of the interplay between crop rotation, crop sequence, and input level. Undoubtedly, this will require more time and energy on the part of the grower to be put into crop and weed management tasks. However, if the current trend towards the development of low input cropping systems continues, there may well be incentives, both economic and environmental, for the grower to manage according to low input objectives. The risk of adopting a similar cropping system to one of the alternative systems described here and managing it with a given level of inputs is dependent on a wide array of production factors specific to individual growers. We have demonstrated, however, some positive weed management attributes of the cropping systems in this study that may be further fine-tuned as part of an individual’s crop production strategy. This will enable a grower to develop crop rotation strategies with a given level of inputs facilitating the design of a suite of weed management tools that are both effective and profitable.
Accomplishments and Milestones:
The first important accomplishment of this project was to further demonstrate that diversified cropping systems can be successful even under the drought conditions encountered over the course of the study. Water use efficiency was generally increased with the reduced-input diversified systems over the conventional wheat/fallow system.
It is clear from this study that more diversified crop rotations can improve weed management in reduced-tillage small grain production cropping systems. We found, however, that reliable weed mortality offered by herbicides is important to add to the less reliable (higher risk) weed suppression offered by cultural weed management practices. Variability in weed population response to cultural practices emphasizes the requirement to express these results as general principles rather than as prescriptions of specific rotations or weed management practices. Certainly, within the range of weed population variation in response to these systems, it is possible that the weed species that we studied could be managed with reduced or even no herbicide inputs. Thus, there may be sites or years where, under particular crop rotations and sequences, these reduced cost systems could be implemented with minimal risk of future weed management problems. However, site-specific and improved knowledge of weed behavior in response to cultural practices will be crucial for risk reduction. This is an important accomplishment because it emphasizes the risk associated with transitioning to new systems and has made it clear that those who embark on a transition to reduced inputs and/or organic systems must be cognizant of the influence of past cropping sequences and weed populations. In addition, prescriptive approaches to transitioning to new systems are not possible.
This study compared gross return, production costs, and net returns for organic, no-till, and conventional production systems. The comparison was uniquely carried out for both plot studies and for producer case studies, all for multiple years. The study also includes both a period of relatively normal rainfall and a period of drought in a dryland production system. The organic producers changed their rotations and tillage practices considerably in response to drought; the no-till producers changed their activities less. The net returns from the management systems evaluated showed both the no-till and the organic rotations to have superior net revenues to more conventional rotations as measured by county averages. Organic production had higher net returns per acre than the no-till rotations did, but these organic rotations appear to require higher labor and management hours than the no-till rotations do. That is, organic producers seem to trade off higher labor and management time per acre for higher returns per acre.
The predominant small grain cropping system of the Northern Great Plains has utilized a crop fallow rotation under an assumption of moisture conservation. More sustainable systems may include the use of more diversified and organic systems that reduce inputs. The transition to more sustainable systems represents a challenging step for producers and requires prediction of how crops and weeds will perform. Weed population dynamics in response to more sustainable agricultural systems on the Northern Great Plains is critical to implementation of these systems. This study has already begun to show significant differences in weed behavior under different crop management and promises to allow prediction of weed responses to a wide range of management approaches from organic to high- input conventional. To our knowledge, there are no other studies that have simultaneously measured spatial and temporal dynamics of weed populations. Thus, there has been limited ability to predict the economic thresholds or distributions that determine optimum weed management under most conditions.
Evaluation surveys of recent farm conferences in Montana highlight strong producer interest in diversified crop rotations. Pulse crops (pea, lentil, chickpea) are featured prominently in this research project and pulse crop acreage in Montana jumped dramatically to 350,000 acres in 2005, due in part to the contributions of this research project. This has meant an important new source of income for Montana farmers. This research project continues to investigate optimal agronomic practices for alternative crops so inclusion in cropping systems will have a greater chance of being successful. Rotation studies address longer term questions related to water use efficiency and soil quality.
Results of this study reinforce the importance of why crop rotation diversification has long been acknowledged as a crucial practice in any type of integrated weed management plan and also why more diverse crop rotations in the NGP should be promoted, assuming specific other crop production factors can be resolved.
Educational & Outreach Activities
Direct Communication With Farmers:
Bruce Maxwell poster presentation: Using Crop Diversity in No-till and Organic Systems to Reduce Inputs and Increase Profits and Sustainability in the Northern Plains. AERO Organic Training and Conference / Montana Organic Organization Dec 5, 2003, Great Falls, MT
Perry Miller poster presentation: Increasing crop water-use efficiency in advanced no-till systems. AERO Organic Training and Conference / Montana Organic Organization Dec 5, 2003, Great Falls, MT
Alternative Agriculture Farm Tour. Co-sponsored by: NRCS and AERO. Floweree, MT. June, 2003.
Maxwell presentation on weed seed banks in CRP. MABA. Great Falls, MT, Jan. 2004
Results from experiments were presented by Drs. Maxwell and Miller at a Field Tour at the Post Agronomy Farm near Bozeman, MT in 2004 and 2005.
Hulting reported results summary to the AERO Agricultural Task Force meeting in Oct. 2003.
Buschena and Maxwell participated in Transition to Organic Workshops at Malta and Great Falls, MT in February, 2005, sponsored by AERO.
Maxwell and Miller participated in Transition to Organic Workshop at the Montana Organic Growers Association meeting in November, 2005.
Maxwell and Miller have participated in the 2005-2006 NCAT phone conference sessions to educate NRCS farm program people about the use of diversified, low-input and organic systems.
Peer Reviewed Journal Papers, Chapters, Theses:
Hulting, A.G. 2004. Weed population dynamics in diversified cropping systems of the Northern Great Plains. Ph.D. Thesis, Department of Land Resources and Environmental Science, Montana State University. Pp. 144.
Maxwell, B.D. and L.C. Luschei. 2005. Ecological justification for site-specific weed management. Weed Science 53:221-227.
Maxwell, B.D. and E. Luschei. 2004. The ecology of crop-weed interactions: Toward a more complete model of weed communities in agroecosystems. Journal of Crop Improvement 11:137-154.
Maxwell, B.D. and E. Luschei. 2004. The Ecology of Crop-Weed Interactions: Toward a More Complete Model of Weed Communities in Agroecosystems. pp. 137-152. In D.R. Clements and A. Shrestha (eds), New Dimensions in Agroecology. Hawthorn Press.
Wagner, N., B. Maxwell, L. Rew, and D. Goodman. 2002. Development of a yield prediction model for site-specific management of herbicide and fertilizer. Proceedings of the 6th International Conference on Precision Agriculture. Minneapolis, Minnesota. July 14-17.
Miller, P.R., and J.A. Holmes. 2005. Cropping sequence effects of four broadleaf crops on four cereal crops in the northern Great Plains. Agron. J. 97:189-200
Nielsen, D.C., P.W. Unger and P.R. Miller. 2005. Efficient water use in dryland cropping systems in the Great Plains. Agron. J. 97: 364 372.
Clayton, G., P. Miller, Y. Gan, R. Blackshaw, P. Carr, B. Gossen, K.N. Harker, G. Lafond, J. O’Donovan, O. Olfert. 2005. Ecological pulse crop management. In (CD-ROM) Agronomy Abstracts ASA, CSSA, SSSA, Madison, WI.
Hulting, A.G., A.J. Bussan, B.D. Maxwell and P. Miller. 2001. Weed population dynamics in diversified cropping systems of the northern plains. West. Soc. Weed Sci. Proc. 54: Coeur d’Alene, ID, March, 2001.
Hulting, A.G., A.J. Bussan and B.D. Maxwell. 2002. Development of a spatial simulation model for evaluating potential patterns of spread of an invasive grass in a diversified cropping system. Weed Sci. Soc. Am. Abstracts 42:62.
Hulting, A. G., B. D. Maxwell, and A.J. Bussan. 2002. Spatial pattern and rate of spread of Persian darnel and wild oat in a diversified cropping system. West. Soc. Weed Sci. Proc. 55:27. Salt Lake City, Utah
Hulting, A.G., B.D. Maxwell, A.J. Bussan, P.R. Miller. Can the processes that determine weed metapopulation spatial patterns be identified? WSSA Abstracts 43:44, Jacksonville, FL. Feb. 2003.
Jones, C.A. and P.R. Miller. 2005. Soil fertility differences in diversified no till and organic rotations following a 4 yr transition. In W.B. Stevens (ed.) Western Nutrient Management Conference Proceedings. 6:94 99. Potash and Phosphate Institute. Brookings, SD.
Maxwell, B., A. Hulting, C. Repath and L. Rew. Linking spatial and temporal dynamics to estimate invasiveness of non-indigenous plant populations. The Ecological Society of America Conference August 1-6, 2004 Portland, OR. p88.
Maxwell, B.D. and L.C. Luschei. Ecological justification for site-specific weed management. WSSA Abstracts 44:69, Kansas City, MO. Feb. 2005.
Maxwell, B.D. (2005) Assessing the relative role of competition and dispersal in determining the dynamics of plant populations in agroecosystems. Ecol. Soc. of Am. Ann. Meeting, Montreal, Canada, August, 2005. p 110.
Miller, P., J. Holmes, D. Buschena, and C. Jones. 2005. Comparing low and high input strategies in diversified organic and no till cropping systems. Crop Sci. Soc. Am. Summer Mtg., Bozeman, MT, 19-22 June. Abstract on CD-Rom.
Miller, P., K. McKay, C. Jones, S. Blodgett, F. Menalled, J. Riesselman, C. Chen and D. Wichman . 2005. Growing dry pea in Montana. Montana St Univ Ext Serv Montguide MT200502 AG. 8 p.
Miller, P., D. Wichman and R. Engel. 2005. Sequencing annual legume forage before wheat to increase water use efficiency in no till systems in the northern Great Plains. In (CD-ROM) Agronomy Abstracts ASA, CSSA, SSSA, Madison, WI.
Pollnac F, Maxwell BD, Menalled F. (2005) Preliminary observations of the species area curve in organic and conventional spring wheat systems. Western Society of Weed Science, Vancover, Canada, March 2005. p 14.
Walley, F.L. G. Clayton, P. Miller, P.M. Carr, and G. Lafond. Nitrogen economy of pulse crop production in the northern Great Plains. In (CD-ROM) Agronomy Abstracts ASA, CSSA, SSSA, Madison, WI.
There are two parallel efforts to evaluate the economic returns to organic and no-till crop rotations. The first method evaluates controlled plot studies carried out by researchers involved in this project. The second utilizes surveys of no-till and organic producers in central Montana to ascertain their rotational experience concurrently with the plot studies.
Data from experimental plots have been evaluated for the period 2000-2004. Detailed data for input use, tillage practices, yields, and crop quality have been used to assess the relative net returns of three no-till rotations, one organic rotation, and a continuous crop-conventionally tilled wheat rotation. Returns for the organic rotation were evaluated under both representative organic premiums and under no premiums. The no-till rotations included a spring-wheat based rotation, a winter wheat-based rotation, and a diverse rotation.
The average comparative costs per acre for each of the management systems indicated high variability in costs associated with more conventional systems as compared to organic systems( Figure 1). The average per acre net returns (abstracting from returns to labor, land, management, and machinery ownership) from all five rotations are illustrated in Figure 2. Returns from the organic rotation with premiums are consistently higher than those for the competing rotations, largely due to the reduced herbicide and fertilizer inputs. The importance of the organic premiums is clearly shown by the differences in the net returns for the premiums case vs. the no premiums case in the organic rotations. The spring wheat based and the diverse no-till rotations provide the highest average returns of the remaining rotations.
The variability of the average net returns for these rotations over the four years considered was measured by the coefficient of variation (standard deviation/mean) because these rotations had quite different means. These coefficients of variation (CV) measures were:
Organics, price premiums .179
Organics, no price premiums .214
No-till winter based .215
No-till spring based .327
No-till diverse .216
Continuous wheat .203
The average net returns for the organic rotation with price premiums show the lowest CV among the rotations, while the no-till spring wheat based rotation shows considerable variation in these annual average returns. The CV values for the other rotations were very close to one another. Note that the small number of years of this study does not permit statistical tests for the significance of these CV differences.
The plot data provided some very useful comparisons of returns from various rotations in a scientifically controlled setting. With these relatively new rotations, however, come numerous questions regarding how effectively an experimental study matches the practices and experiences of commercial producers. To address these questions, a parallel effort gathered survey data from a number of long-time organic and no-till producers in Central Montana. These producers’ yields and production practices were elicited for years 1999-2003. Of particular interest for these survey interviews were the responses by these producers to the extensive and severe drought conditions experienced during crop years 2001, 2002, and, to some extent, 2003. These interviews were completed in December, 2003, with some follow-ups that were carried out in 2004.
The systems used by the organic producers interviewed can be quite complex, utilizing green manure plow-down annual crops such as peas, perennials such as alfalfa, and small grains. The rotation and crops utilized are tailored to the particulars of the field. The producers have multiple goals of improving the soil, controlling weeds, stabilizing moisture, generating revenues, and other goals. One challenge to comparing revenues from organic systems to those of conventional systems is that organic producers often use non-traditional crops with thin markets. Each one of the three organic rotations assessed included a grain crop (a type of spring or winter wheat) in the rotation, but some producers used grain crops sparingly (1 of 5 years) while others used them extensively (2 or even 3 of 5 years). All of these organic rotations incorporated fallow and green manure plowdown crops, typically for 2 of the 5 years studied. Specific details of these rotations are omitted for confidentiality reasons.
Tillage costs are higher in organic relative to conventional systems used by adjacent farmers because: (1) herbicides were not used and (2) the organic rotations generally include green manure plowdown crops such as field peas. If a crop was planted but not harvested by these organic producers, the cropping costs (tillage, seeds, etc.) were assessed to this rotation. The time period of the study included a number of very dry years that induced some crop failure. Note, however, that organic producers have a lower yield threshold for crop harvesting because of the higher prices their crops bring.
The no-till rotations considered in these case studies were all primarily wheat-based, utilizing either winter wheat, spring wheat, or both. One of these rotations is a continuous crop effort with no fallow, while the two others are somewhat more conservative in this regard by typically incorporating fallow for 2 of the 5 years studied. The continuous crop rotation includes a number of “specialty” crops such as lentils. Another rotation includes other less traditional crops on occasion.
Herbicide and to some extent fertilizer costs under no-till practices are considerably higher than under conventional rotations, as expected. Machinery costs under the no-till approach are typically somewhat lower than under conventional or organic rotations due to reduced tillage. The no-till producers surveyed did not have any non-harvested crop during the time period considered, supporting arguments for the moisture conserving benefits of the no-till approach.
The organic and no-till producers are located in three adjacent counties in Central/North Central Montana, with some, but not complete, overlap for these two cropping systems. Farmers in these counties plant both winter and spring wheat, and typically fallow from between one-third and one-half of their acreage. Two county averages were constructed using three counties (A, B and C). County Average #1 includes the two counties in which the no-till producers were located (two no-till producers were located in County A, one in County B). County Average #2 includes the two counties in which the organic producers were located (two no-till producers were located in County B, one in County C). County average yields and marketing year prices received by Montana farmers (Montana Agricultural Statistics) were used to develop returns for these county averages. Cropping costs were developed using published survey information for producers in the area (Johnson et al. 1997) updated for fuel costs, interviews with producers, and current input cost data.
Producers in these counties reported a considerable number of acres that were planted but not harvested, primarily due to drought. The costs of this cropping (tillage, seeding, other inputs) were included in the net returns calculations even if no crop was harvested to provide consistent treatment of these county averages relative to the organic and the no-till rotations. The county average calculations discussed below also included these planting costs using the proportion of planted to harvested acres based on the reported county acres (Montana Agricultural Statistics, various years).
There are a number of alternative candidate rotations for these county averages. Producer rotations in these counties differ in (1) the use of winter or spring wheat, (2) the amount of fallow, typically between one-third and one-half of crop acres, and (3) the inclusion or exclusion of barley in the rotation. Net returns for four rotations were considered. The final county average used was selected as the rotation with the highest mean net revenue; the variance of these net revenues was also considered in the selection of the rotations. These county averages were thus favorably calculated. These county averages reflected (1) crop production using both tillage and herbicides for cropping and for fallow and (2) under both conventional and reduced-tillage methods. These four rotations are:
Rotation 1: ½ of acres planted to winter wheat and ½ of acres fallowed, wheat follows fallow in every field;
Rotation 2: as for Rotation 1, spring wheat replaces winter wheat;
Rotation 3: 1/3 of total acres planted to spring wheat, 1/3 planted to barley, and 1/3 fallowed, barley follows wheat, fallow follows barley, wheat follows fallow;
Rotation 4: As for Rotation 3, winter wheat replaces spring wheat.
Average net returns in all three counties were highest for Rotation 4 for the five years considered, with Rotation 1 a close second. Note that the time period considered in this study included a number of very dry years, tending to favor winter over spring wheat. Rotation 4 additionally had slightly lower variability as measured by its CV than Rotation 1 did. Rotations 2 and 3 had quite low average returns during the period studied in these counties. Rotation 4 was selected as the relevant one for comparisons for all three counties.
Figures 3-5 illustrate the annual and mean per acre returns and costs for the no-till producers, for the organic producers, and the two county average rotations using the 1/3 winter wheat, 1/3 barley, and 1/3 fallow rotation (Rotation 4). The organic and the no-till costs and returns in every year are averages across producers. Note that County #1 is the relevant county for the no-till producers and that County #2 is the relevant county for the organic producers.
The per acre returns in Figure 3 illustrate the differences in intensity of cropping between the no-till, the organic, and the largely conventional production reflected in the county averages. No-till production yielded on average the highest per acre gross returns in the years evaluated. Gross returns under no-till were highest among the rotations in every year except 1998/99; note that the severe drought conditions during the middle and late years of this period favored no-till production over the more tillage-intensive conventional (measured through the county averages) and organic rotations. These drought effects are clearly evident for all rotations in the annual returns.
The average per acre costs illustrated in Figure 4 show one of the attractive features of the organic system. Note, however, that these costs do not include labor and management. Interviews with organic producers suggest that the labor and management requirements per acre for organic crops in Montana are approximately 30% higher than for conventional farming. Labor and management requirements for fallowing/green manure in the organic system are approximately 38% higher than for conventional fallowing. Producers using organic systems face a tradeoff: fewer purchased fertilizers and pesticides but more labor, fuel, and management.
The per acre net returns illustrated in Figure 5 illustrate the very difficult financial situation the average Montana producer has faced in recent years. Note that these per acre returns do not include any payments from crop insurance, (nor do they include premiums for crop insurance), commodity, or disaster payments. Producers under both the no-till and the organic rotations compare favorably to the county averages in net revenues, with the average organic net returns per acre about $7 per acre higher than the net returns per acre for the no-till producers. Note that: (1) the no-till and the organic producers surveyed are expected to have higher than average management skills, (2) that the organic producers have higher labor and management requirements per acre and also typically farm fewer acres, and (3) that the drought experienced from 1999/2000 to 2003 favored no-till production relative to the more tillage intensive organic or conventional systems. With all these caveats, these results indicate that the organic and no-till producers studied appear to be earning returns commensurate with their expected management and labor capabilities. Producers using these rotations, while facing some financial stresses due to drought, fared considerably better financially than the average producers in their respective counties.
Producers using no-till had the lowest (CV=.59) annual income variability over the five year period considered. Organic producers had somewhat higher income variability (CV=.72), while the variability of returns from the county averages were considerably higher (CV for County #1=1.06; CV for County #2 = 7.05). These differences in variance are likely to be due largely to the drought conditions experienced during the time period of study.
No-till and organic producers were asked a number of questions meant to assess: (1) how they changed their practices because of drought, and (2) the level of erosion they faced as a result of the very dry conditions experienced during the period of study. No-till producers typically reported that they avoided wind erosion, while their neighbors using conventional practices experienced very severe erosion in 2001 and somewhat in 2002. The no-till producers interviewed reduced their cropped acres somewhat (increased fallowed acres) in response to drought, and planted more acres to winter, rather than to spring, wheat. These no-till producers also tended to harvest a greater proportion of their planted acres relative to their conventional neighbors and relative to the organic producers. Organic producers, however, faced numerous challenges due to wind erosion, with damage varying considerably due to terrain and cropping system. The reliance of these producers on tillage, in particular for green manureing, gave rise to some erosion problems. These organic producers responded to the drought by (1) decreasing tillage, (2) increasing fallow, (3) planting fewer acres to green manure crops that require plowdown. Organic producers faced with soil losses due to erosion reevaluated their production decisions.
- Adoption of organic production has increased in Montana and the Transition to Organic Production Workshops conducted with AERO and in conjunction with the Montana Organic Growers Association Conference seem to have contributed to the increased adoption rate. The number of farmers involved in these workshops was approximately 60 in total.
Recommendations to conventional farmers based on the results from our studies would include:
1. There is minimal risk in moisture and weed management when moving to more diversified systems.
2. Producers must strategically plan crop rotations to avoid herbicide crop injury problems in future crops.
Recommendation to farmers transitioning to low input systems:
1. When transitioning to low input diversified systems producers must anticipate weed problems based on past practices and crop sequence.
2. Choose a crop sequence for a particular field based on the prevalent weed species and their abundance paying particular attention to the life cycle of the weed species.
3. Be flexible and use principles of adaptive management
Recommendation to farmers transitioning to organic systems:
Converting native prairie and CRP land to organic production seems to be very popular because it allows immediate organic certification. This behavior is risky and should be avoided.
1. If transitioning to organic, try to convert existing crop land rather than breaking native prairie because it will be easier to anticipate weed and nutrient problems and preserve natural pest control mechanisms that seek refuge in native systems.
2. Avoid converting CRP land to organic, because often it harbors large reserves of weed seed and may provide amenities similar to native prairie.
Recommendations to organic farmers:
1. Choice of cropping sequence is critical for success. Weed management requires a keen eye for which species are increasing and adjusting crop sequence to break weed life cycles.
Areas needing additional study
We are currently communicating with AERO to seek more funding for workshops relating to transitioning to organic or low-input farming practices. The model that we used in 2005 was highly successful with a large proportion of the farmers in attendance doing some kind of adoption in the growing season following the workshops.
We are developing an MSU extension bulletin on transitioning to organic production that we hope will reduce the potential failures due to choice of lands (primarily CRP) that accommodate immediate organic certification, but may be very risky with regard to high weed seed banks and dead soils.
The most critical research needs include development of methods for farmers to locally parameterize weed population dynamic models that will aid them in identifying future weed problems. Clearly, our research has shown that weed population demographics are highly site specific and erratic during the transition years. Therefore, some mechanism that encourages on-farm research or automated data retrieval (e.g. precision agriculture technology) through policy or just ease of use will accomplish a major hurdle in the adoption of more sustainable systems. Research should be directed at creating and testing methods on farms to quantify weed impacts and population dynamics under an adaptive management paradigm.
Extending the time for the economic analysis to span more average and high precipitation years, would likely prove quite valuable. Such a longer-term study would help to address questions regarding the long-term nature of these systems and their profitability.