Planning Your Transition to Organic Production
The key to successful organic crop production is diversity. Enhancing diversity involves a holistic approach with carefully planned crop rotations. Good crop rotations benefit the soil, while also creating an environment that supports interrelated strategies to manage pests and support healthy nutrient cycling and improved soil fertility.
The holistic approach involved requires a broad range of expertise. We recommend that you consult a variety of organic production publications available from Saskatchewan Agriculture to learn more.
Products and practices available to organic producers vary depending on the organic certification organization to which they belong. Always review the standards you are complying with to ensure your practices are acceptable to your certifying organization.
Producers considering making the transition to organic production are recommended to do it incrementally. By converting portions of the farm to organic production while leaving other parts in conventional production, the producer has time to learn new management skills. In addition, the income earned from conventional crops will provide a financial buffer during the three-year transition period when producers experience yield reductions but are not earning organic price premiums.
Crops grown during the transition period are not eligible for organic premiums. The minimum conversion period is 36 months from the last application of a prohibited substance to the first certifiable harvest. An inspection is generally required 12 months before the first certified organic harvest.
The goal of a transition strategy is to use management strategies that make soil as fertile, weed-free and healthy as possible going into the certified period. Soil testing will provide the base from which the strategy will evolve. Soil testing over time will also allow the producer to monitor the benefits of various agronomic practices.
Economic considerations play an important role during transition. Ideally, a high nitrogen-fixing, competitive forage is planted in the early stages of transition. Transition of the entire farm at once provides the producer with the opportunity to improve soil quality quickly, but it will reduce revenue.
The use of legume crops in organic crop rotation is essential.
Unless the harvested grain is returned to the soil through manure cycling, the land will undergo a net export of nutrients. A 40 bu./ac. crop of wheat will require approximately 85 lb./ac. of nitrogen, while returning only 25 lb./ac. to the soil. The remaining 60 lb./ac. are exported in the seed.
Some producers will have as many as three legume crops within a seven-year rotation. When properly inoculated with rhizobia, legumes will fix approximately 50 to 90 percent of the required nitrogen from the air. Legume residue has a higher level of nitrogen than non-legume residue, and is broken down quickly, making more nitrogen available for subsequent crops.
Additional benefits of seeding legumes, other than nitrogen fixation and weed control, include improved soil structure, increased soil aeration and improved water-holding capacity.
Although legumes are critical to successful organic production, producers must adhere to the key of successful organic production - diversity. Not only does this apply within the selection of legume crops, but also in combination with other crop types.
Understanding both the nutrient demands of crops as well as the nutrient-supplying abilities of crops and soils will help the organic producer manage the rotation to maintain a long-term equilibrium.
Understanding the suitability of legume crops grown in the main prairie soil zones (see Table 1) will help the producer prepare the land for successful organic production.
Table 1: Suitability of legume crop to the main Prairie soil zones
|Crop||Brown||Dark Brown||Black||Dark Gray||Gray|
||OK||Best suited||Not recommended
|Red clover||Not recommended
|Sweet clover||OK adopt
||Best suited||Best suited
|Field pea||OK adopt
|Faba bean||Not recommended
|Chickling vetch||Best suited
"Seed bank" is the term for all the viable weed seeds present in the soil. The composition of weed populations in each field is a direct result of selection pressures. Weed seeds that are currently germinating are not necessarily those that are most abundant in the weed seed bank. Rather, the crop type and agronomic practice being used at that time are providing those particular weeds with an advantage relative to other weed types. Understanding the strengths and weaknesses of various weed species will help the producer understand how cropping practices can alter weed-selection pressures. Understanding this relationship is necessary in developing management strategies.
Changing the crop type also allows the producer to change factors such as seeding date (early, late spring, fall), seeding depth, pre-plant tillage and in-crop tillage (pre- and post-emergence tillage). Continually changing these factors reduces the likelihood of a buildup of specific weed species. In all crops, the producer should strive for good crop establishment before weed establishment occurs, thereby allowing the crop to out-compete the weeds.
Table 2 contains information from various studies on weed characteristics that will provide better understanding of the weed/environment/management practice relationship.
Table 2. Characteristics of Problematic Weeds
|Weed||Habit||Seed Dormancy||Germination Conditions||Indicator of||Competitiveness||Comments|
|green foxtail (noxious weed)||Annual reproducing only by seed.||Initially high at maturity but declines rapidly in moist soil near surface. Dormancy increases with deep burial.||Warm soil temp - 20-30oC is optimal. Depth from three inch prefers top inch.||Responsive to N fertility.||Very low - 100 plants/m2 = 5% loss in wheat & canola yield, 3% loss in barley. Generally found in high numbers when present.||Nearly disappears in zero-till systems. Is a greater problem when delaying seeding for wild oat management. Early crop emergence and heavy crop canopy are effective management tools.|
|wild oat (noxious weed)||Annual reproducing only by seed.||Seed viable up to nine years, generally three to five years. Greater persistence in heavier soils.||Moderate soil temp - 10-20oC is optimal. Depth from nine inch preference within 3 inch.||Tolerates higher pH soils.||High - 20plants/m2 = 11% loss in wheat, 6% in barley, 15% in canola and 10 plants/m2 = 19% loss in flax when emerging at the same time. Add 3% loss for each day they emerge before the crop.||Seeds did not survive more than 21 days in well composted manure, liquid manure or silage, but viability did not decline in vegetable compost.|
|persian darnel (noxious weed)||Annual reproducing only by seed.||Seed viable in soil for three years.||Germinates earlier than wild oat.||High - similar to wild oats, but can be worse since higher populations are possible (100 plants/m2 = 20% loss in wheat).||Can be confused with downy and Japanese brome.|
|quack grass (noxious weed)||Perennial reproducing from both seed and vegetative rhizomes.||It must out-cross to produce seed, and does not produce many seeds. Viability of buried seeds is about two to three years.||Alternating temperatures (10-25oC) is preferred. Rhizome buds initiate growth in April and May, then from July onward, with a dormancy period in June.||Tolerates saline soils. Prefers moister areas.||Very competitive. Quack grass stands can reduce the yield of oat and barley by 30 - 70%. Quack grass is a luxury consumer of the major nutrients. Reported to be allelopathic to other plants, but only dead material is implicated.||Careful and repeated tillage from August to freeze-up can give excellent control, but moderate tillage may increase the density of a stand. Tillage should be designed to cut rhizomes to encourage sprouting of rhizome buds, and then to exhaust reserves in those sections.|
|stinkweed (noxious weed)||Winter annual or annual reproducing only by seed.||Seeds are viable in soil up to six years. Will remain dormant in low oxygen conditions (deep burial or saturated)||Light stimulates germination. Alternating temperatures (10-25oC) is preferred.||Early colonizer of open ground. Dry weight content of 16% in wheat stands can reduce yields by 36%.||Tillage will stimulate germination of this plant by providing light stimulus and scarification of the seed.|
|kochia||Annual reproducing only by seed.||Very low - seed does not survive in soil for more than one year.||Germinates very early in the spring. Most seeds germinate before mid-May.||High tolerance for saline soils. Drought tolerant.||More competitive with wheat under warm droughty conditions than cool conditions.||Prevention of seed production will eliminate existing stands, but asa "tumbleweed" can be reintroduced easily from other fields.|
|lamb's-quarters||Annual reproducing only by seed.||Seeds produced under short day length exhibit low dormancy and seeds produced under long day length show high dormancy. Seed can survive for at least 39 years when buried deep.||May be triggered by light since tillage stimulates germination. No information on temperature.||Highly competitive for nutrients - 20-80 plants/m2 reduced canola yield by 20-25%||Does not tolerate clipping or other disturbances early in its lifecycle.|
|wild mustard (noxious weed)||Annual reproducing only by seed.||Seed longevity in the soil up to 60 years. Seed viability after five years of burial was still 78% in one study.||Cultivation stimulates germination. Germinates rapidly with emergence in three to seven days. Germination takes place at about the same time as annual crops.||May have an allelopathic effect on certain plants.||Before the introduction of phenoxy herbicides, it was considered the worst weed of crops on the prairies. Ten plants/m2 can reduce canola yield by 20%, and 20 plants/m2 = 36% loss. Yield loss can be equal to wild oat as a competitor in wheat.||Wild mustard tends to increase in density under intensive tillage regimes.|
|Canada thistle (noxious weed)||Perennial reproducing from both seed and reproductive roots. It must out-cross to produce seed; propagation by seed is relatively unsuccessful.||Seed can remain viable in the soil for up to 20 years. Most seeds germinate the following year. Single root piece will survive for no more than two years. Energy storage goes into new root growth.||New shoots emerge at a minimum of 5oC and optimum 8oC soil temperature. Seed germination is best at high temperatures (25-30oC) and ample soil moisture.||Very competitive on a per plant bases. Wheat yield reductions are: two plants/yd2 = 15%, 12 plants/yd2 = 35%, 25 plants/yd2 = 60%. Some indication that decaying plant material has allelopathic effects on crops.||Canada thistle is very structured in the way it grows, making it relatively easy to control with tillage. During day lengths of 15 hours or more, the plant is driven to produce flowering stems and draws on root reserves to meet energy needs to achieve this. Tillage or clipping at the early bud stage interrupts this process and the plant starts again. When day length is less than 15 hr. the plant stores energy for winter. Intensive tillage from Aug. 1 to freeze-up will minimize the amount of energy that can be stored and many plants will winterkill.|
|perennial sow-thistle||Perennial reproducing from both seed and reproductive roots. More successful than Canada thistle at seed propagation.||80% of seeds germinate within the first year of production, but seedling survival is low. Shoots from roots begin to grow when the soil warms in late April or early May.||Seeds are viable five days after pollination. Soil temp of 25-30oC is optimal for seed germination with ample water. Light may improve germination but is not required. Seedlings emerge from depths of less than one inch.||14 plants/m2 = 15% loss, 27 plants/m2 = 45% loss in wheat.||Although not as structured as Canada thistle, perennial sow-thistle does exhibit some of the same trends in energy use for flowering and storage in the fall. A more intensive fallow regime may be required to keep green material from emerging.|
|redroot pigweed||Annual reproducing only from seed.||Over 96% of freshly collected seeds were viable. Longevity of buried seeds can be as long as 40 years. Survival increased with depth.||Optimum soil temp for germination is 30-40oC. Stimulated by light.||Can be competitive in late seeded crops and wide row spacing.||Easily controlled with competitive crops and early seeding.|
* temperature ranges are considered optimal; seeds will germinate outside this range
Noxious Weed Legislation
The Weed Control Act is provincial legislation that empowers municipalities to enforce the control of noxious weeds within their boundaries. Noxious weeds are those weeds that are considered a detriment to agriculture, health or the environment. They are generally non-native plants that have been imported to North America from places like Europe or Asia. Noxious weeds are also very invasive. In their place of origin, they are kept in check by insects and diseases, but here they can be the dominant species if left unmanaged. Noxious weeds are also very costly – through crop yield losses, livestock or human poisoning, or destruction of native habitat.
The Weed Control Act states that land owners/operators are responsible for controlling noxious weeds on their land and preventing spread to neighbouring land. Weed inspectors are appointed by the municipality to enforce the Act and have the power to enter land to look for noxious weeds, to compel landowners to control noxious weeds and to perform work not completed as they have ordered.
Weed inspectors are encouraged to work within the management systems of landowners to find workable solutions. Those considering a transition to organic production must also realize that control or prevention of noxious weeds will often require more intensive management measures than conventional production. These measures may include the use of higher seeding rates, or fallow and perennial forages grown in rotation.
Five highly invasive and destructive weeds named in The Weed Control Act are difficult to eliminate and can cause the order for the destruction of a crop. These weeds are leafy spurge, hoary cress, Russian knapweed, field bindweed and toadflax. They are all persistent deep-rooted perennial weeds that, once established, will dominate an environment and often have seed that will emerge for many years. Two to three years of intensive tillage may be required to deplete root reserves of established plants. Those considering a transition to organic production should avoid land with these weeds or take measures to reduce their numbers before initiating transition.
Shifts in Weed Populations
Moving from conventional to organic production can have a dramatic effect on weed populations and community composition.
A recent trend in conventional production has been the shift from intensive tillage to direct seeding. As a result, weed communities are increasingly comprised of winter annual and perennial species such as thistles, dandelion, flixweed and narrow-leaved hawk's-beard.
A conversion back to intensive tillage, as is required with an organic production system, will result in more annual weed species such as mustards, pigweeds and lamb's-quarters. Some perennial weeds such as quack grass and thistles will proliferate under tillage due to the spread of reproductive root pieces, but may be controlled with intensive fallow tillage. Some weed species, such as wild buckwheat, smartweed, stinkweed and shepherd's purse, are indifferent to tillage. While stinkweed and shepherd's-purse are winter annuals, they can also exhibit an annual habit.
Reduced tillage can result in lower overall weed populations by increasing the mortality of weed seeds at the soil surface. Conversely, a return to an intensive tillage system will see an increase in the number of weeds emerging from seed.
The use of herbicides is the other obvious influence in conventional systems that will be absent in organic farming systems. Annual weeds, including lamb's-quarters, pigweed, mustard, shepherd's-purse, stinkweed, smartweed, Russian thistle, kochia and wild buckwheat, are controlled easily by several herbicides. In the absence of herbicides, these species will be more prevalent in weed communities in organic fields than in conventionally managed fields.
Successful organic production requires an understanding of plant characteristics in relation to the specific conditions of your field. Producers need to incorporate this knowledge into the art form of organic farming. Understanding these characteristics will provide producers with a starting point from which they will need to fine-tune the rotations best suited for their conditions.