MSU Extension Service Resource For Crops,Grain,Fertilize,Grain Varieties,Stubble and Related Links

MSU Extension agriculture and natural resources programs apply university research and resources to help Montana agricultural producers and land owners increase profits, reduce loss, protect our food supply and sustain future resources. Here are some Extension Service Resource For Crop Weeds, Crop Pests, Soil Survey, Crop Varieties, Fertilizing, Tillage, Crop Storage, Crop Diversity, Chemical, Irrigation, Value Added Crops:

  • Crop Weeds

    • Getting the most from fall perennial weed management
    • Integrated strategies for managing agricultural weeds
    • Cultural management practices can improve jointed goatgrass control
    • Managing jointed goatgrass in Clearfield winter wheat
    • Persian Darnel: Identification, Biology and Ecology
    • Kochia Management: Reducing the Risk of Carryover and Crop Injury
    • Seed size matters
    • Jointed Goatgrass Introduction
    • Key points to remember in controlling Kochia

      Kochia has been a real problem for small grain producers the last few years as the drought has intensified. Poor control of kochia from in-crop treatments or no in-crop treatment has resulted in increased kochia pressure during the cropping year. The end result is a tremendous problem in fallow fields the following year. Doug Ryerson, Monsanto representative at the Crop Protection and Improvement Clinic, offered these key points to remember: 1) Good weed control in the crop is essential! 2) Manage weeds post-harvest if a problem exists after combining. This is key and help reduce the seed bank in the soil. 3) Spray before weeds get large. 4) Spray during periods of least stress; early in the day or after a rain event, for example. (Some of us wonder what those rain events are really like!) 5) Good coverage is essential; slow down/raise the water volumes.

    • Preplant Weed Control - The First Key to Successful Management
      By Alvin J. Bussan, MSU Extension Cropland Weed Specialist

      Grass in yards, along roadsides or in pastures may or may not be greening up with the warm temperatures South Central Montana has received over the last few weeks. However, one thing is for sure: weed seed buried in the soil will soon germinate and emerge and winter annuals will break dormancy. In fact, weeds like wild oat, mustards and kochia begin germinating at soil temperatures less than 40 degrees Fahrenheit.

      As field work begins, think about how to ensure these early emerging weeds are managed before planting.

      Early emerging weeds cause the greatest yield loss and produce the most seed if they are not managed before planting. For example, research at Montana State University suggests wild oat infesting a barley field at 10 plants/ft2 would cause 5-10 percent more yield loss if they emerged prior to the crop than if the wild oat emerged at the same time as the crop.

      Likewise, the early emerging weeds produce much more seed than weeds emerging with the crop. In addition, early emerging weeds will be large when post-emergence herbicides are applied making them harder to control.

      Therefore, the key to successful weed management and profitable crop production is to control early emerging weeds as they are the most detrimental to yield and produce the most seed.

      Time of wild oat emergence Yield loss (%)  Wild oat seed (seed/ft2)
      Before the crop



      With the crop



      Managing weeds before planting can be achieved by tillage or with a "burndown" herbicide treatment. To be effective, weeds should be tilled when less than 2 inches tall, or they may re-root and continue to grow (this is especially true for dense patches). In addition, crops should be planted within a day or two of the final tillage. Increasing the time between the final tillage and planting increases the head start weeds can get over the crop.

      Burndown herbicides such as Roundup at 12 oz/A or Gramoxone Extra at 2 pt/A can be applied before planting to control emerged weeds. Crops should be planted three to five days after burndown herbicides are applied for best results. Roundup and Gramoxone Extra applications also can be made after planting, but before the crop emerges to manage existing weeds. However, if rain occurs shortly after planting but before the herbicide is applied, the window for post-plant treatment may be narrow for preventing crop injury.

      Many growers use a combination of tillage and applying burndown herbicides to control early emerging weeds. Tillage after applying a burndown herbicide, a common practice, can cause deeply buried or dormant seed to germinate. This can lead to increased weed pressure and decrease the effectiveness of the burndown herbicide. However, tilling fields in the fall or early spring can stimulate a large flush of weeds. This technique followed by a burndown herbicide treatment can be very effective at reducing the weed pressure in problematic fields.

      Managing early emerging weeds is extremely important to preventing crop yield loss and weed seed production. However, effective tools exist to help prepare a seedbed free of weeds. Growers should pay special attention to use these tools properly within their own system.

    • Dry weather could affect weed management
  • Fertilizing

    • Ammonia Volatilization
    • Farm Business Economics: Some info on expected fertilizer and fuel prices
    • Small Farms for Small Landowners
    • Study says phosphorus fertilization more important in drought
    • Fertilizer Guidelines for Montana Crops
    • When is Organic Matter Built Up or Used Up?
      By Jim Bauder, MSU Extension Soil and Water Quality Specialist

      Plant and animal residues, sewage sludge, wastes and manures in various stages of decomposition are the sources of organic matter in soil. The degree of decomposition depends partially on micro and macro organisms, burrowing animals and insects, earthworms, centipedes and ants. These are important in decomposition and translocation of plant residues in soil.

      The amount of organic matter in soil and the rate of its accumulation or decomposition is a result of the balance of organic matter production, climate, environment and land use practices.

      The threshold soil temperature for organic matter accumulation is 77 degrees Fahrenheit (25 degrees Centigrade). Below this temperature, organic matter accumulates, and above it organic matter decomposes. Organic matter and nitrogen in soils increase about two-to-three times for each 10-degree C decrease in mean annual temperature.

      Wet soils tend to accumulate organic matter more than comparable dry soils; organic matter generally accumulates under cold, anaerobic conditions (oxygen devoid), such as wetlands, bogs, swamps and frequently wet soils.

      Dry/desert soils generally have low organic matter content, because decomposition is faster than accumulation. Organic matter content of two percent or less is common (based on dry soil mass). Volcanic soils usually have high organic matter content, as much as 10-12 percent. Organic matter levels tend to be higher under grassland or prairie than under forests, because grassland roots contribute more to organic matter than leaves and stems of woody species.

      Surface soil organic content is almost always greater than that of associated subsoils. The bulk density of surface soils with 1-2 percent organic matter are usually 1.3-1.5 g/cc.

      The following list shows examples of the affect of organic matter on bulk density (from "Soils in Our Environment," Miller and Donahue, 1995) decomposed peat (low particle density): 0.66 g/cc clay soil 3 years in pasture: 1.13 clay soil 3 years in barley crop: 1.3 sandy loam under bush 15-20 years: 1.15 sandy loam 5 years conventional corn: 1.51

      Soils with more than 30 percent organic material are considered 'organic' soils and are generally referred to as peat or muck. These soils have bulk densities as low as 0.4 to 0.6 g/cc.

      Generally, as one moves from a warmer to a cooler area, whether by a change in latitude, elevation, slope or direction of the slope, the organic matter and associated nitrogen content of comparable soils tend to increase.

      The greater the organic matter in a soil and the coarser it is, the faster water will enter. Organic surface mulches are especially helpful in keeping infiltration high, because they protect soil aggregates from breakdown by reducing the impact of raindrops and by continuing to supply cementing agents for aggregates as the mulch decomposes.

      One percent soil organic matter is considered "low." Soil organic carbon content in mineral soils usually ranges from 0 to 4 percent by weight and may be as high as 20-30 percent.

      Organic matter usually is lowest in locations with high temperatures and low rainfall. Organic carbon increases with precipitation and clay content, and decreases with temperature. Carbon losses due to cultivation increase with precipitation.

      Generally, finer-textured soils have higher organic matter content than sandy soils, because of greater nutrient and water-holding capacities and plant production and slower decomposition. Relative organic carbon losses are lowest in clay soils.

      Generally, cropped soil has much less nitrogen and organic matter than comparable virgin areas, and a tenth to two-thirds of the above ground part of a crop is incorporated into the soil.

      If you are a cereal grain producer, you've probably been told that you need to 'add a little extra nitrogen' when you have a lot of straw being worked into the soil during tillage. And, if you are a gardener, you may have even noticed that there are times when composting seems to be counter-productive.

      In both cases, there is a reason, and, yes, it is a good idea to add a little extra nitrogen when you have a lot of straw and stubble to incorporate. The reason relates to the carbon/nitrogen ratio of the plant material you incorporate.

      Forty-five to 58 percent of stable soil organic matter is carbon, while nitrogen makes up 5-6 percent. A mineral soil with 4 percent organic matter contains as much as 80,000 pounds per acre of organic matter in the 0-6-inch depth; 31,800 - 41,000 pounds of carbon, and 4,200 pounds of nitrogen per acre. Needless to say, carbon is a significant component of organic matter.

      Organic matter has a cation exchange capacity 2-30 times that of clay minerals and can account for 20-90 percent of the soil cation exchange capacity.

      About 75 percent of plant material is water. Ninety percent of the remaining dry material is made up of carbon, oxygen, hydrogen and nitrogen. Sulfur, phosphorus, potassium and calcium are the other important components.

      The breakdown that organic matter undergoes leaves a dark-colored organic residue that resists decomposition and is responsible for much of the property of organic matter called 'humus.' In fact, some of the very stable materials in the organic matter complex can remain in the soil for hundreds or thousands of years.

      The carbon/nitrogen ratio of organic matter is important in soil quality. The ratio of organic matter in cultivated surface soil ranges from 8/1 to 15/1, with the median about 12/1 (58 percent/5 percent). The carbon/nitrogen ratio is relatively uniform among different soils within a climatic region.

      Heavily leached soils are likely to have much higher C/N ratios, i.e., 30/1 or more. Organic matter with a high carbon to nitrogen ratio, i.e., C/N ratio 15, frequently have unstable soil organic matter and intense competition among micro organisms for available soil nitrogen.

      Residues which contain the lowest amount of carbon in relation to nitrogen, (C/N ratio <12), come from green manure/cover crops like legumes and mustards. These decompose rapidly and provide nutrients in excess of microbial needs. Residue from grain, grass and cotton are low in nitrogen but high in carbon and thus take longer to decompose.

      Typical Carbon and Nitrogen Contents and C/N Ratios
      Material % C % N C/N
      Spruce sawdust
      Wheat straw
      Com stover
      Rye cover crop, anthesis
      Bluegrass - lawn
      Rye cover crop, vegetative
      Mature alfalfa hay
      Rotted barnyard manure
      Young alfalfa hay
      Hairy vetch cover crop
      Digested sludge
      Soil organic matter
      Forest soils

      Most soil microbes obtain the energy necessary to grow from carbon in the soil organic matter. Most organic matter undergoes essentially a "burning" or oxidation process. Since nitrogen is an essential for cellular components, micro organisms must obtain nitrogen from organic matter, other microbes or from the air. When organic materials with high carbon concentrations relative to nitrogen concentrations are added to the soil, soil microbes use most of the available nitrogen in the soil, thus creating deficiency conditions for higher plants. Organic residues with C/N ratios greater than 25/1 often will result in nitrogen deficiencies. This is called nitrate depression, sometimes referred to as the 'priming effect,' which will persist until activity of the soil micro organisms decreases due to a lack of carbon.

      Generally, nitrogen will not be released from the soil organic matter complex through mineralization until the C/N ratio has dropped below 20/1. Hence, it is often necessary to add supplemental nitrogen fertilizer when carbon-rich organic materials are added to the soil.

    • Tolerance of Various Crops and Plants to Salinity
      By Jim Bauder, MSU Extension Soil and Water Quality Specialist

      There are two sources of salts that appear in the soil: either from the soil itself or from irrigation or drainage water. In either case, the presence of saline conditions in the soil indicates inadequate drainage, either due to slow percolation rates, high water table, not enough water to cause leaching, or upward water movement. There are three essential requirements for mediating a salinity problem:

      1) improve the drainage to allow the removal of the excess salts;
      2) remove or reduce the source of the salinity by either shutting off the water or reducing the amount of water being applied,
      3) add sufficient good quality water to leach the existing salts.

      So, what crops can you grow in salt-affected soil? The logical answer is salt-tolerant crops. Among crops grown in the Montana, barley has the highest degree of salt tolerance, followed closely by sugar beets. The degree of salt tolerance is expressed by milli-mhos per centimeter (mmhos/cm), which relates to the conductivity of electricity when two electrical prongs are stuck in the soil. The following list of crops ranges from most tolerant to least tolerant, with respect to salinity.


      You might consult the Western Fertilizer Handbook which contains a complete listing of salt tolerant crops. This is an excellent reference book for farmers. Another question that comes up is something like this: "I have a saline seep which I have been trying to reclaim. What forage crops can I grow in the salt-affected area?" The answer depends on the soil conditions.

      However, the list of tolerant forages is pretty well defined. It includes the following, from most tolerant to least tolerant:

      • Forage Crops: Mmhos/cm
      • tall wheat grass: 7.5
      • wheat grass (fairway): .5
      • Bermudagrass: 6.9
      • hay barley: 6.0
      • perennial ryegrass: 5.6
      • birdsfoot trefoil: 5.0
      • harding grass: 4.6
      • tall fescue: 3.9
      • crested wheat grass: 3.5
      • vetch: 3.0
      • Sudan grass: 2.8
      • big trefoil: 2.3
      • alfalfa: 2.0
      • berseem clover: 1.5
      • orchardgrass: 1.5
      • meadow foxtail: 1.5
      • clover: alsike, ladino, red, strawberry: 1.5

      Keep in mind that seedlings are generally much more sensitive to salinity than established plants. You can assume that the yield of each of these forages and the previous crops will be reduced by 10-15 percent if the conductivity is increased 25 percent, 25-35 percent if the conductivity is increased 50 percent and 50 percent or more if the conductivity is doubled. If you suspect you have a salinity problem, collect a soil sample, send it to a lab and ask for the EC (electrical conductivity or conductance), the pH (an index of salinity), and the SAR - the sodium adsorption ratio. With that information and the list provided here, you should be able to decide what is the best cropping strategy for your situation.

    • Organic Matter: The Rest of the Story
      By Jim Bauder, MSU Extension Soil and Water Quality Specialist

      On your land, have you noticed pockets of erosion, drainage problems or soils that crust easily or are highly compacted? Or perhaps you've noticed droughty areas, slow water absorption in the soil, or recurrent deficiencies of micro nutrients, nitrogen or sulfur. These are signs pointing to a possible lack of organic matter.

      In balanced soil systems, the level of organic matter remains relatively stable over time, being controlled by climate and affected by vegetation, disturbance and vegetation patterns. But this balance can be upset by such disturbances as tillage, burning, residue additions, flooding, erosion, drainage or deforestation.

      So, why should you be concerned about your soil's organic matter? Well, a key reason is to build soil humus levels to improve soil conditions. Organic matter can reduce the effects of clay and poor soil structure. Organic materials such as crop residue or other waste can also provide a protective mulch on the soil surface.

      Organic matter levels can be affected by the type and frequency of tillage practices, the crops grown, rotations, and the use of fertilizers, animal manures and soil amendments.

      Rotations: Research shows that a rotation of corn, oats and clovers resulted in a higher soil organic matter level than continuous corn. The addition of animal manure and phosphorus increased organic matter levels. A rotation of continuous cereal grains resulted in a decrease in soil organic matter levels. Soils kept highly productive by supplemental applications of fertilizers, lime and manure and by high-yielding crop varieties are likely to have more organic matter than comparable, less productive soils.

      The following information illustrates the amount of fresh organic residue left following certain crops. Each harvested crop leaves different amounts of residues.

      Estimated addition of organic matter to soils by crops grown and residues left on the field.
      Crop Root portion Plant Tops  Total   Yield
      corn 2200 4100 6300 grain harvested (100 bu/a)
      soybeans 1000  2200  3200 grain harvested (32 bu/a)
      wheat  1700  3100 4800 grain harvested (45 bu/a)
      field beans 500  1400  1900  seed harvested (1500 lb/a)
      alfalfa 3400 800 4200 hay removed (3 t/a)

      The carbon/nitrogen ratio can have a significant effect on the rate of decomposition; organic residue with a low C/N ratio tends to decompose more rapidly than material with a high C/N ratio. In one study approximately 90 percent of a hairy vetch residue with a C/N ratio of 10/1 decomposed over a 4 month period, while only 60 percent of a cereal rye residue with a C/N ratio of 38/1 decomposed during the same period.

      Tillage: Some cropping systems tend to cause greater soil organic matter changes than others. Tillage affects organic matter concentrations. The greater the amount of tillage, the less the amount of humus that accumulates. Uncultivated soils are higher in soil organic matter than they are after cultivation. Tillage reduces organic matter levels by accelerating the oxidation process. This happens when the organic matter is broken into finer pieces and mixed with air in moist soil. Some studies have reported decomposition rates of as much as 50 percent per week for fresh plant material; the typical rate for humus is approximately 3 percent per year.

      Cultivation of grassland soils leads to depletion of soil organic matter. Soil organic carbon losses of as much as 50 percent have been documented in the U.S. Central Plains grasslands. The amount of the losses depended on the management regime and regional location.

      Management practices that decrease tillage and residue incorporation can reduce soil organic matter losses and increase soil organic carbon to a limited extent.

      Organic matter content of the soil is usually estimated from other measurements. The usual procedure is to measure organic carbon content of the soil and then adjust this figure by multiplying by 1.72 to give an approximate amount of organic matter present. The organic nitrogen can then be estimated by dividing the organic carbon content by 12, assuming the typical carbon/nitrogen ratio of 12/1.

      More information on soil organic matter is included in the Certified Crop Advisors Competency Training Manual in Soil and Water Management.

    • Adding Manure: What are the benefits?

      Organic matter can play a valuable role in your farm management program. The recent series of Agronomy Notes dealing with organic matter pointed out some of the benefits of a good organic matter management program. One issue that doesn't get enough attention is the nutrient value or potential of organic matter. Occasionally a producer will ask me about the amount of nitrogen in a ton of composted or stockpiled cattle manure.

      The following information came from the Western Fertilizer Handbook.

      Composition of Manures and Waste Materials









      Beef feedlot
















      Liquid dairy
















      Liquid swine
























      Poultry (no litter)








      Liquid poultry








      * Adapted from L. S. Murphy in Fertilizer Solutions magazine, March-April 1972. See Table B-16 in Appendix B for a more extensive list.

      In some parts of Montana, particularly east of the Continental Divide, phosphorus deficiency in soils seems to be a recurring topic of discussion. Many research projects, including my own, have documented the consistent response of crops to phosphorus, even when soil test show that phosphorus levels are relatively high. Well, organic matter can help. Humus adsorbs phosphate ions. This is good. Consequently, the effect of soil organic matter on providing available phosphorus is significant. When the carbon:phosphorus ratio is wide, available phosphorus is immobilized. When the ratio is narrow, available inorganic phosphorus is increased. Phosphorus adsorbed to organic matter is more available to growing plants than phosphorus precipitated as insoluble compounds such as apatite. Thus, soils high in humus usually contain greater quantities of available phosphorus than soils low in humus.

      Stubble residues from grain, grasses or forages are generally low in nitrogen but high in carbon and thus take longer to decompose than do green manures. Adding nitrogen fertilizer - or livestock manures - to these residues speeds up decomposition and helps satisfy the microbial demand for the nutrients.

      It takes a fairly good "dose" of animal waste to supply the nitrogen needs of a grain crop which is going to be harvested. We are talking tons per acre. However, for a grass or forage crop that does not fix its own nitrogen or enhance the performance of a soil, the addition of animal wastes has much to offer.

    • Top Dressing Nitrogen for Winter Wheat Yield
      By Jim Bauder, MSU Extension Soil and Water Quality Specialist

      In spring, many farmers consider top-dressing their winter wheat with nitrogen. Whether your yield would increase if you top-dress nitrogen depends on the weather, the soil, the growth stage of the wheat and the nitrogen source.

      The most important factor is available water. Without enough water stored in the soil and from rainfall during the growing season, top-dressed nitrogen will not be used by the crop. So the rate at which nitrogen is top-dressed on winter wheat and the time when it is applied should be closely matched to the potential yield established by the available water.

      If the amount of water you expect can support only a 40 bushel per acre winter wheat yield, there is nothing to be gained by top-dressing more nitrogen than a 40 bushel yield can use. So, the actual amount of nitrogen top-dressed will depend on how much nitrogen was applied last fall and what level of yield the field is capable of producing.

      Another factor influencing effectiveness of spring top-dressed nitrogen on winter wheat is the inherent fertility and potential of the soil. Winter wheat grown on high organic matter soils will respond less to spring top-dressed nitrogen than less fertile soils. Organic matter mineralization makes more nitrogen available to the crop in the spring.

      In general, it takes two to three pounds of nitrogen to produce a bushel of winter wheat. The total amount of nitrogen that should be applied, preplant plus top-dressed, should be matched to a realistic yield goal for the field. If a realistic yield goal is 40 bushels per acre, based on available water, then the total nitrogen requirement by the crop will be about 80 to 120 pounds of nitrogen per acre from all the available nitrogen sources.

      Fine textured soils in areas of low winter precipitation have the ability to hold most of the nitrogen that may have been applied at planting. That means there is little potential for loss due to leaching. In such cases, there may be no advantage to top dressing nitrogen, especially if adequate nitrogen was applied preplant. Urea, which converts to ammonium shortly after being applied to the soil, and anhydrous ammonia are tightly held by fine soil particles and organic matter. If nitrogen was applied as nitrate at planting time, then there is a possibility that a positive response can be seen from top-dressing nitrogen in the spring.

      If the soil is sandy and over winter and spring precipitation are heavy there is also good possibility that winter wheat will respond to spring top dressing nitrogen.

      Late winter and early spring top-dress has the advantage that fertilizer rates can be adjusted to soil moisture and general conditions of the wheat at the time of top-dressing. If winter precipitation was much greater this year than average, and the soil is holding more moisture now than it usually does in the spring, then top-dressing may add bushels.

      Another key to successful top-dressing in the spring is early application. Most crop needs for nitrogen are met early in the growing period. The earlier nitrogen is top-dressed, the greater the likelihood of a beneficial yield response. The following guidelines may be of some help in making the decision about whether to top-dress winter wheat with nitrogen this spring:

      Winter wheat requires about two to three pounds of nitrogen per bushel of grain.

      Grain protein may be increased slightly by applying 20 to 30 pounds of nitrogen per acre above the level of nitrogen required for the anticipated yield potential.

      Nitrogen top-dressed on winter wheat after jointing will generally have no effect on yield or will reduce yields. If you decide to top-dress winter wheat, the earlier the better.

      One final note: Replicated studies have shown no advantage from top-dressing versus nitrogen applied at planting when sufficient nitrogen is applied preplant to achieve yield potential and preplant nitrogen has not been leached out of the soil.

      Top-dressing nitrogen is likely to produce more response on sandy soils, where over-winter precipitation has been high, than on fine textured soils in low rainfall areas.