Modern Practices Agronomy is a science which combines crop production and soil management techniques. Examples of crop production skills include determination of planting times, seed depth, rotation of crops and the types of chemicals to use. Soil management involves methods of working the soil, erosion-prevention techniques and soil testing. Sustainable agricultural practices involve the combination of these techniques. A cropping system, then, consists of the integration of various components (environment, economics, production and human resources) and varies from farmer to farmer depending on their management choices. Cropping systems in place in Saskatchewan include the following components: cropping practice - the frequency of crop production (every year, every second year, two to three years) tillage operations - the frequency and intensity of tillage practices crop rotation - the type and sequence of various crops being grown on the same field moisture conservation - the type of technique used to help save and keep moisture in a field Cropping Practice Two types of cropping practices are in operation in the province. Continuous Cropping - This type of cropping is commonly practiced in the dark, black soils of the central plains and parklands. An annual crop is planted every growing season, even though the plant growth may not necessarily be intended for seed production. For instance, a cereal or legume crop could be removed as forage or plowed down as green manure. Rotation of crops helps control pests, diseases, weeds and can actually build and replace soil nutrients. Intercropping - This is a variation of the previous system, where more than one crop is grown in the same time in the same field. For example, if a producer raises animals, oat­barley mixtures could be seeded together to yield feed grains and cereals (wheat, barley...) may be sown just before grasses or legumes, as companion crops which provide the forages with some protection from weeds. Sweet clover­canola could be another combination, where canola is harvested in the first year and sweet clover can be used for forage, green manure or seed production in the second year. Intercropping is may lead to yields that are less than those of a one crop field. Some of the plants of different species may compete, rather than complement each other. Tillage Operations Traditional tillage operations involve the extensive cultivation of the land. Summerfallowing is used in the traditional tillage system. While the technique has various benefits for cropping, as few as two decades ago, farmers realized the problem of soil erosion and began to adopt practices of soil conservation. To prevent erosion, farmers are using crop production techniques such as minimum tillage, where there is only lightly tilling the soil and this is done fewer times a year. Minimum tillage is used under a continuous or extended cropping system and has been more common in the northeast of the province. Since moisture is less of a concern, a field may produce a crop for two or three successive years before fallowing takes place. Weeds and diseases, soil conditions, the amount of crop residue and the type of crop being planted influence the number of tillage operations required. zero-tillage, where crops are seeded directly into stubble without tilling the soil first. This system conserves moisture, control soil erosion, uses less fuel, and reduces labour costs. The decision to zero-till may depend upon the availability and cost of new seeding equipment and herbicides. Zero Tillage Growing crops involves all aspects of a farm system -- soil, location, climate, crop type, weeds and pests, tillage, equipment -- and the cropping system used takes into account all of these. A total management system (integrated approach) of crop production is important in zero tillage. Zero tillage benefits the soil and helps to restore then maintain soil conditions leading to profitable farming. organic matter - Organic matter increases, especially if summerfallow has been eliminated. Organic matter consists of living and dead plant material, microorganisms, insects and earthworms. The amount of this matter generally increases in a zero-till operation which then leads to improved soil structure. Conventional tillage destroys soil aggregates (pieces of soil). One of the advantages of the aggregates formed in no-till soil is the large network of pores which form and act as a channel system for the movement of nutrients, air and water to crop roots. Like aggregates, these pores are destroyed by tillage. trash layer - This is a layer of plant material on the surface. No-tilling allows this layer to build up to useful levels. The layer suppresses weeds and reduces evaporation of water from the soil. This layer must be managed, however, since a too thick layer can result in difficulty in seeding and it can harbor diseases. The proper crop rotation help to ensure a proper amount of trash cover. root zone - Under the trash cover, the root zone is an area where the important decomposition of matter occurs. Soil aggregates that form from no-till help to slow this decomposition and build the amount of organic matter. Rapid decomposition leads to nutrients loss. Crop rotations of legumes (the roots of which fix nitrogen) also help to increase soil nutrients. soil moisture - Conventional fields do not trap as much moisture as fields that are no-till. The extra stubble left on the surface traps snow, and the trash layers prevents evaporation. The system of pores created by no-till supply water to plant roots. surface soil temperatures - Soil temperatures of no-till soils are regulated by the trash cover. The surface may remain insulated in the winter because of the trapped snow in the stubble. This insulation is important for the survival of winter wheat. Spring temperatures may be cooler than conventional tilled soils, but fall temperatures may be warmer. The temperatures affect the type of seed the may be planted in an area. increase in soil life - Less tillage means more biodiversity. Organisms that recycle matter are present in greater quantities thus improving soil quality. Crop Rotation Crop rotations have been used for years by farmers in establishing a crop management plan. Every farm differs in the type of rotation that can be used; saline soils are improved by planting perennial forage crops and legume crops can improve soil nitrogen levels. With the adoption of minimum and zero tillage as part of the crop management system, farmers use a number of different operating techniques, one of the most important being the use of proper crop rotation. Good rotations are the key to creating and managing a viable zero till program and rotations influence every aspect of a zero till system. Since zero till catches and stores more soil moisture, this enables farmers to diversify into more profitable rotations. These rotations can be optimized by discovering which crop sequence best suits the many factors that exist for the farmer. Crop Rotation - Factors to Consider crop water use patterns historic rainfall patterns snow catch ability disease organisms insect cycles weed control problems effects of toxins in trash cover herbicide rotation profit potential equipment needs optimum row widths seeding and harvesting dates workload spread individual attitudes access to markets Crop characteristics are important when planning balanced rotations. Tables outlining characteristics are available for the farmer to assist in planning. Coupled with rotations is the need, in some cases, to apply herbicides. The factors as listed in the previous table, are considered before and during a rotation. For example, the southwest area of the province has moisture and soil fertility limitations which reduce the variety and lengths of rotations which are possible. Wheat, or other cereal grains, and summerfallow is the popular rotation. Direct seeding of winter wheat into pea, canola or mustard stubble can extend rotations in which certain fields produce two crops every three years. Areas from the southwest to the northeast, where soil moisture is less of a limiting factor, exhibit weed, disease and insect problems. Planned rotations must deal with these problems. Types of Rotations There are four types of plants available as crops that can be grown in rotation: cool season grasses (winter wheat, spring wheat, barley, oats) warm season grasses (corn, millet, sorghum) cool season broadleafs (flax, safflower, canola, peas, sunflower) warm season broadleafs (soybean) Different plants have different growth and maturity habits. These traits affect seeding and harvest periods, pest susceptibility and water use capacities. So, plants of the same type will be affected in similar ways. Planned rotations take this into account. An example of a rotation system is that of the two crop-type rotation. In cooler areas of the province, a cool season grass is alternated with a cool season broadleaf crop (like wheat-peas; barley-winter wheat-sunflower). In warmer areas, a warm season grass is followed by a warm season broadleaf (corn-soybean). These simple rotations work for a while but lack diversity and overtime, problems with weeds, insects and diseases can develop. Crop protection strategies have been developed to deal with these problems. Additional plants may be substituted in a rotation to help deal with potential problems - for example, flax can be substituted for a cool season broadleaf and effectively break disease and pest cycles. Cool season legumes such as peas and lentils may be substituted for field beans one year. Another way to increase diversity is the use of three crop-type rotations. These rotations combine a cool season grass, a warm season grass and a cool or warm season broadleaf. Including a warm season crop limits the use of this system to the southern areas of Saskatchewan. Some examples of the three crop-type rotation system include wheat-canola-fallow; wheat-barley-canola; wheat-winter wheat-canola-millet. Moisture Conservation Saskatchewan is a province of diverse moisture levels. The southwest area is typically dry to extremely dry while the northeast maintains a higher level of moisture. Farmers use a variety of techniques to conserve moisture levels on their farms. Some of these techniques are part of the regular cropping practice such as strip cropping, alternate height crop cutting, the use of shelterbelts to trap snow and leaving stubble to catch snow. Other methods used to specifically address moisture conservation include chem-fallowing (the use of chemicals to control unwanted growth rather than tillage which disturbs the land), barrier strip seeding and snow ridging.