ORGANIC FIELD CROPS OVERVIEW. Farm production 1 (per cent) Cereals 97% 133,000. Forages 64% 81,000. Pulses 63% 19,000.

Transcription

1 ORGANIC FIELD CROPS OVERVIEW FACTSHEET AC RG O P S R I C U LT U R E Introduction This factsheet provides a summary of management practices used by Saskatchewan organic producers and identifies some areas of crop management that require particular attention. Saskatchewan leads the country in organic producer numbers, having approximately 30 per cent of the organic farms in Canada. These,3 individual farms represent 57 per cent of the total Canadian land farmed organically. Saskatchewan is the leading Canadian exporter of organic grain and oilseed products and cerealbased food ingredients. The province is well suited for organic agriculture because of its clean, natural environment, cold winters and abundant farmland. Cereal crops dominate Saskatchewan organic production, followed by forages (Table ). Flax is the only oilseed grown organically on a significant land area. While pulse crops are grown on approximately twothirds of organic farms, they only represent about five per cent of the total land area. Table. Percentage of Saskatchewan organic farms growing a particular crop and total land area used. To convert land area to acres multiply hectares (ha) by.47. Farm production (per cent) Land area (ha) Cereals 97% 33,000 Wheat/Durum Oats Barley 80,000 3,000,000 Forages 64% 8,000 Pulses 63% 9,000 Flax 59%,000 Other crops 9% 68,000 Green manures 58% 33,000 Fallow 8% 44,000 Total 399,000 Percentage of farms with identified land use; From Knight and Shirtliffe, 003. From Macey, 00.

2 Soil Fertility Plant available nutrient levels on Saskatchewan organic farms tend to be low, especially levels of phosphorus and sulphur (Table ). Although nitrogen levels are generally low, there are farms in each of the soil zones that have levels that are approaching optimal. It is recommended that organic producers seed 40 per cent of their land to legumes (pulses, forages, green manures or underseeded crops) to benefit from biological nitrogen fixation. Table. Summary of fertility status of soils in Saskatchewan organic fields. To convert to lb. per acre, multiply by 0.89 Soil Zone Nitrogen (N) Phosphorous (P) Potassium (K) Sulphur (S) (kg per ha) Brown Median Minimum Maximum Dk. Brown Median Minimum Maximum Black Median Minimum Maximum Grey Median Minimum Maximum Generalized Critical Limit (kg per ha) Deficient <67 <34 <79 <9 Marginal Optimal Excessive >45 >34 >0 >90 The median indicates the central value 50 per cent of farms surveyed had levels higher than the median and 50 per cent had levels lower than the median. Adapted from Knight et al., 00. Generalized Critical Limit refers to soil testing lab ranges for categorizing soils as deficient, marginal, optimal or excessive (based on Norwest Labs, Edmonton, AB).

3 Soil nutrients on organic farms are typically managed through crop selection and rotations, encouraging biological diversity and carefully managing organic inputs including animal manures, crop residues and live plant materials (green manures, cover crops, intercrops). Soil Amendments Producers in Saskatchewan are challenged by the fact that most organic farms do not have livestock or have insufficient numbers of livestock to supply the farm landbase with animal manures. The Organic Production Permitted Substances List provides a list of substances that can be used in organic production (Government of Canada 006b). Producers in Saskatchewan typically do not apply a wide range of soil amendments. A 003 survey conducted on five per cent of the organic farms in Saskatchewan showed that only 6 per cent of the surveyed producers applied any soil amendments over the past five years, and that cattle manure was the most commonly applied soil amendment (Table 3). Table 3. Types of soil amendments (percentage) used. Soil Amendment Total producer usage Cattle manure % Rock phosphorus 8% Gypsum 3% Humic carbon 3% Sheep manure % Kelp % Penicillium bilaiae % Based on total number of organic producers surveyed. From Knight and Shirtliffe, 003. Green Manures Green manures or ploughdown crops are crops grown with the intention of ploughing the live material into the soil sometime before seed set. Almost all green manure crops grown in Saskatchewan are legumes grown for their biological nitrogen fixation abilities (Table 4). Organic producers grow green manures for two main reasons:. to add nutrients to the ploughzone of the soil, and. for weed control. Legume green manures add nitrogen to the soil through biological nitrogen fixation. Although other nutrients (e.g. P, K, S, micronutrients) are not added to the soil, green manures can redistribute nutrients extracted from the rooting depth into the ploughdown layer, making them more available to the next crop in rotation. Forage legumes like alfalfa and sweet clover are especially good at redistributing nutrients because of their deep roots. Some nonnitrogen fixing crops like oilseed radish and buckwheat are reported to have excellent phosphorus uptake characteristics making them good green manure choices for improving phosphorus fertility. However, under Saskatchewan conditions legume green manures Table 4. Types of green manure crops (percentage) used. are as good at extracting phosphorus and have the added advantage of fixing nitrogen. Green Manure Crop Sweet clover Total Producer Usage 35% Termination of a green manure is generally recommended around the mid to late flowering stage to minimize soil drying from the growing crop, while still achieving a nutrient benefit. Green manures are commonly used in organic production. A 003 survey conducted on five per cent of the organic farms in Saskatchewan showed that 58 per cent of the surveyed producers used green manures in their crop rotations, and that sweet clover was used most often (Table 4). Alfalfa 5% Peas 9% Indianhead Lentil 5% Red Clover % AC Greenfix 5% Other 3% Based on total number of organic producers surveyed. From Knight and Shirtliffe,

4 Yellow sweet clover (left) and alfalfa (right) green manures after a discing operation in southern Saskatchewan. Photos: Saskatchewan Agriculture Chickling vetch (AC Greenfix; left) and 400 forage pea (right) green manure stand prior to incorporation in southern Saskatchewan. Photos: Saskatchewan Agriculture Cover Crops and Intercrops Cover crops are typically planted to protect soil from wind or water erosion, to minimize soil nutrient loss from leaching, provide organic matter back into the soil and improve weed and pest management. Cover crops are selected from a wide variety of crops including legumes and nonlegumes. Intercropping is not a common practice on the Prairies, but there is growing interest in this practice. Intercropping includes growing multiple crop species on the same land during the growing season, and some growers have had success with cereal/pulse intercrops. If two annual crop species are harvested at the same time, it is important to have equipment available to separate the two crops and to consider potential market impact of crosscontamination (e.g. pea chips in milling oats). 4

5 Weed Control The ideal way to manage weeds in organic crop production systems is to avoid them entirely through the use of clean seed, good crop rotations and other methods that prevent weeds from establishing. In practice, however, this is nearly an impossible goal. Instead, growers use a combination of mechanical and agronomic methods to minimize weed pressure and give the crop a competitive advantage. Growing a diverse array of springplanted cereals, oilseeds and pulses can effectively control weeds. The specific rotation will depend on various factors including soil type, environment, specific weed species and commodity markets. Competitive varieties of many crops exist and can enhance weed control or maintain crop yields in the presence of weeds. Increasing seeding rates, seeding in narrower rowspacings and using large seed can increase a crop s ability to compete with weeds. Mechanical weed control should be used in combination with cultural controls and not as the primary means of control to minimize the negative effects of tillage on soil quality and erosion. Green manures control weeds by competing with weeds for resources. The act of terminating the green manure also provides weed control comparable to fallowing. Except in especially dry regions in the Brown soil zone, green manures are recommended as an alternative to fallow because they protect the soil from erosion. For more information on weed control in organic systems see Organic Crop Production: Weed Management on the Ministry of Agriculture website. Insects and Disease Control Saskatchewan s colder climate and large land base is ideal for organic agriculture as insect and disease outbreaks are typically infrequent and negative effects can be minimized by applying good agronomic practices. Wellplanned crop rotations are the best defense against insects and disease. To minimize disease, rotate crop species and choose cultivars that have been bred with disease resistance whenever possible. Insect problems can be reduced by growing multiple crop species in the rotation, a practice that promotes beneficial insects. To help reduce pest damage in high pressure years, maintain longer rotations between susceptible crop species and plan fields so that similar crops are not in close proximity with each other in the same year. Other cultural controls can be very effective, depending on the pest. Removing crop residue will reduce disease inoculum and prevent certain insects from successfully overwintering. Using diseasefree seed and staggering seeding dates and rates can provide crops with a competitive advantage in the event of an insect or disease outbreak. A healthy crop will better withstand pest pressure with less yield loss, thus proper soil fertility is also very important. For more information on insect and disease control in organic systems see the following documents on the Ministry of Agriculture website: Organic Crop Production: Disease Management; and Organic Crop Management: Insect Management. References Knight, J.D. and S. Shirtliffe Saskatchewan Organic OnFarm Research: Part I: Farm Survey and Establishment of Onfarm Research Infrastructure. Final report #00006 submitted to Saskatchewan Ministry of Agriculture, Agriculture Development Fund. Knight, J.D., R. Buhler, J.Y. Leeson and S.Shirtliffe. 00. Classification and fertility status of organically managed fields across Saskatchewan, Canada. Canadian Journal of Plant Science 90: Macey, A. Certified Organic Production in Canada 009, Canadian Organic Growers. 5