Introduction

1. Long cold winters.
2. Cool or cold soils.
3. Short growing season.
4. High daytime summer temperatures.
5. Potential evapotranspiration rates exceed precipitation much of growing season
6. Low humidity, cool nights
7. Soil relatively unweathered.
8. PH - 7+.
9. Soils contain significant soluble salts.
10. Low in organic matter.
11. Without irrigation, severe water stress occurs on almost a yearly basis. Drought common.
12. Damaging late spring and early fall freezes.
13. Crops damaged by soil particles carried by wind.
14. Subject to significant wind erosion.


Management Under Dryland Conditions

1. Much more done 1910-1935.
2. Tillage and seeding machines largely based on farmer innovations.
3. Major increase in production after 1945.

1. Large tractors
2. Chemical herbicides
3. Fertilizers

1. Dryland technology new.

1. Goseen and Bieroff received Lenin prize in USSR in 1972 for production system in central Siberian Plains
2. Work nearly identical to that used in North American Plains

1. Crops and crop growth.

1. Climate limits crop species
2. Short growing season
3. Continuous water shortage
4. Dominant crops:

1. Small grains
2. Oil seed crops (safflower, rape, flax, sunflower, mustard)

1. Need about 10 cm of available water to produce seed crops

1. Need 25 cm to produce satisfactory yields

1. Stress at critical period (bloom) will always cut yields even if 25 cm water available in season
2. In U.S. - efficiency of stored water and precipitation equal north of 45⁰, precipitation more efficient south of 45^o (South Dakota)
3. One of direct effects of proper fertilization is increased root growth and density - better water absorption

6. Water conservation

1. PET exceeds precipitation
2. Avg. Daily PET at peak far exceeds precipitation at this time
3. Critical stages of plant growth coincides with period of peak daily PET
4. 20-30% of annual precipitation in zone is snow
5. Snow accompanied with high winds

1. Snow swept from fields
2. Unprotected fields lose over 90% of winter precipitation

1. Stubble effective means of conserving snow

1. Soil storage efficiency of winter precipitation can approach 99% at 40 degrees N, only 37% at 50 degrees N
2. Stubble height controls the depth of snow retained

1. A deep layer of snow is insulator and cuts down on soil freezing - better water penetration
2. Intermittently spaced barriers effective means of conserving water in snow

1. Short, stiff stemmed plants like wheatgrass, sunflower, mustard
2. Wheatgrass 1.2 m in single or double rows perpendicular to wind spaced 10-15 m - 60% efficiency
3. Temporary barriers, 2 to 3 rows of mustard 10-12 m apart used in USSR

1. Mechanically formed snow ridges used in USSR

1. Soviets snow depth reaches 30-40 cm between ridges
2. Yield increases in both USSR and Canada from ridges

1. Tree and shrub shelter belts not efficient

1. Uneven snow accumulation
1. Take up excessive amount of land

1. Level bench terraces significantly increase the soil water in North America

1. Especially when used with barriers
2. Allow retention of melted snow after and greater infiltration

1. Conservation of summer precipitation in fallowed land largely dependent on condition of soil surface, intensity of storms and weed control
2. Stubble protects the soil surface from mechanical forces

1. Falling and running water
2. Water moved deeper into profile/retained against evaporation

1. Normal fallow periods

1. 14 mo. if winter grain
2. 21 mo. if spring crop planted

1. Total water retained by soil

1. 75% stored first fall and winter
2. 16% following spring and summer
3. 9% second fall and winter

1. Summer fallow has been significant factor in stabilizing yields in this zone
2. Accumulation of nitrates in soil another benefit of summer fallow

1. Also gives better weed control
2. Spreads out labor on large farms

1. Alternate year fallow system in North America, 2 to 3 crop, 1 fallow in USSR
2. Summer fallow can have detrimental effect

1. Saline seeps caused by downward movement of water
2. Common in North and South Dakota, Montana, and Canadian Provinces
3. Lower profiles over shale contain high soluble salts (sodium and mg sulfates)

1. Prior to farming area, broad spectrum of plants with variable rooting depths

1. Water entering profile all used
2. Without plants, water buildup in soil often moves below root zone
3. Water moves over shale, comes to surface and evaporates leaving thick deposit of salt

1. A modification of standard crop-fallow system will have to be developed

1. It will involve more intensive cropping and more diverse rotations
2. Will need greater efficiency in winter precipitation storage, weed control system (grass weeds) and equipment design
7. Erosion

1. Soil and management factors that influence erosion are:

1. Slope
2. Surface texture
3. Surface roughness
4. Soil protection

1. Most serious wind erosion occurs with strong winds in fall and early spring on tilled lands
2. Two most successful methods of wind erosion control are:

1. Stubble mulch
2. Strip cropping with alternate fallow-cropped strips

1. Erosion more difficult to control in sandy loam or loamy sand soils

1. Don=t hld clods
2. Lower water holding capacity

1. Soil that moves on the erodible strip is trapped in stubble
2. Strips may vary from 50 to 150 m in width

1. Loamy sands may require strips as narrow as 8 to 9 m


h. Intermittent barriers can also efficiently control wind erosion

1. Permanent barriers, grass, shrubs
2. Temporary barriers, mustard, sorghum

1. Tree barriers not used because:

1. Occupy too much land
2. Utilize soil water
3. Cause excessively large snow banks
4. Provide harbor for weeds

1. Permanent grass barriers appear to have real promise

1. About 7% of field provides permanent wind erosion protection and good snow trapping

1. During drought periods might need to resort to emergency tillage

1. Formation of clods on surface

1. Sheet erosion problems with water from storms or melting snow

1. Farming across slope helps prevent this
8. Fertilization

1. Soils of this zone generally unleached and have pH range of 7-10
2. 7-8.7 most productive soils
3. Have many unique fertilizer problems

1. Palouse area in E. Washington, molybdenum essential for legume production
2. P often deficient in this zone

1. Phosphorus utilized by grain more efficiently banded - it takes 2-3 times as much broadcast
2. Grain needs .05 kg N/ha to produce 1 kg/ha of seed
3. Soil tests are used to determine N in root zone
4. In MT, from 30-40 kg/ha of NO₃-N becomes available during growing season where most straw returned to land
5. Some estimate of expected yield based on available water is essential

1. Emphasize importance of stored soil water in determining N fertilization

1. Significant quantities of N can be added to soils by including legumes in rotation
2. Deep root systems beneficial in saline seep control
3. But, deep roots dry soil deeply - fallow 1 season after removing legume
1. Significant economical response from K 50% of time with wheat, 40% of time with barley, and 25% of time with spring wheat on soils that test high in K

9. Weeds

1. Major factor determining both the production costs and productivity of dryland agriculture of the zone
2. Important weeds

1. Pigweed
2. Russian thistle
3. Canada thistle
4. Field bindweed
5. Perennial sowthistle
6. Wild buckwheat
7. Wild oats
8. Pigeon grass
9. Downy brome
10. Volunteer small grains

1. Summer fallow one of most effective means of weed control
2. Many weeds (especially broadleaves) controlled by chemicals
3. Others, especially perennials are only set back or top killed
4. Timing of chemical application is important

1. Buckwheat can be easily killed with 2,4-D but spraying at that stage can damage small grain

1. Weeds can be best controlled when crops diversified
2. Inclusion of a broadleaf crop in systems will further improve weed control because grass chemicals can be used in broadleaves

10. Saline-sodic soils

1. Under nonirrigated conditions, reclamation of saline and sodic soils difficult and slow
2. Deep plowing can be effective in reclaming sodic soils if sodium is concentrated at or near surface
3. Addition of gypsum will help

10. Machinery

1. Power to speed up operation on larger scale, seedbeds can be prepared quickly
2. Large acreage can be planted on time to take advantage of rainfall
3. Seedbed preparation material has had dramatic evolution

1. Moldboard plow/replaced by rolling disc plow
2. Stronger steel beams, tool bar cultivator or chisel plow came into use - mixes stubble with only surface soil
3. Deep furrow press drill

1. Deep furrow press drill

1. Moves surface dry soil away so seed falls in moist soil
1. 4-8 cm deep furrow creates more favorable microclimatic, reduces frost damage or winter killing
2. Moved winter wheat belt about 300 km north

1. Except for some oil-seed crops, most herbicides applied post-emergence
2. Greater percentage of cereal grains harvested standing at maturity with combine
3. In areas with short growing season, grain is swathed and left to dry until mature - can be done 10-12 days earlier, reduces chances of storm damage

12. Cropping systems

1. A fixed sequence of cropping, either crop-fallow or 3-year rotation including 1 year fallow general pattern throughout zone
2. Cereal grains do well in harsh environment of the zone
3. Near monoculture of spring wheat-fallow-spring wheat has caused disease, insect and weed problems
4. Excessive fallow has led to seep problems
5. Wider adoption of flexible cropping systems is in order with root zone water storage as the decision-controlling factor.
6. Probability of success of proposed flexible system would be improved by doing a better job of snow conservation and by including broadleaf crops in the system for improved weed and disease control

1. Yields of all crops mentioned can be increased with irrigation.
2. Less drought tolerant crops such as sugar beets, potatoes, silage corn, beans, etc. could be grown.
3. Greater crop diversity would facilitate disease, insect and weed control.
4. Capital cost of crop diversity can be tremendous.

1. A typical irrigated farm might grow potatoes, sugar beets, small grain, silage corn, and alfalfa
2. Each has its own specialized equipment
3. In recent years, high equipment costs has forced many farmers to revert to almost monoculture farming

 

       This page was produced and is maintained by Annie Hassall.
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