Fertilizers and TillageFertilizers and Tillage PLS 386PLS 386 09/23/0509/23/05

Outline of topics:

I. Land preparationII. Tillage systemsIII. Tillage implements

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Land preparation

Virgin land must be cleared by removing vegetation.

Terrain modification can be undertaken on new land:

1. Leveling- for surface drainage, irrigation installation2. Terracing- for steep slopes3. To correct drainage problems

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Purpose of tillage practices:

1. Land leveling2. Seed bed preparation

tilth- physical condition of a soil as related to itsease of tillage, fitness as a seedbed, and suitability to support crop growth.

3. Incorporating organic matter and other amendments4. Weed control

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Purpose of tillage practices, continued

5. Improve soil physical conditions6. Erosion control7. Shaping soil (raised beds, furrows, etc.)

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Tillage systems Two types, depending on degree of soil stirring:Conventional versus Conservation Tillage

Conventional tillage used primary and secondary tillage operations.

Primary tillage- topsoil is stirred to a depth of 6-14”a slice of soil is cut and inverted, burying theplant debris from the surface.

This produces a rough surface, and takes lots of fuel.

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Tillage systems Secondary tillage- follows primary tillage to produce a

finer tilth for seeding.Plowing is a primary tillage operation, while disking,

harrowing, and listing are secondary tillage practices

Soil moisture and texture are very important in the determination of tillage timing and equipmentthat is used.

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Advantages of conventional tillage

1. Even though tillage causes compaction, it is the best way to manage soil compaction when it occurs.

2. Clean soil is easier to apply fertilizers and seed.3. Lack of crop residue reduces pest populations.

(less overwintering or oversummering)

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Diasdvantages of conventional tillage

1. Erosion2. Compaction3. Cost (fuel, machines, time)4. Loss of soil organic matter

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Conservation tillagecrop residue management systems

No-tillage, zero tillage, direct drilling, direct seedingMulch tillageStrip tillageMinimum tillageRidge tillage

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Advantages of conservation tillage

1. Reduced erosion from wind and water.2. Reduced compaction.3. Applicable to steep slopes.4. Better infiltration and water conservation.5. Reduced costs of production.6. Soil temperature modification.7. Increased soil organic matter content.

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Disadvantages of conservation tillage

1. Dependence on chemicals (mainly herbicides)2. Costs (new equipment)3. Higher risks of pests during establishment.4. Higher soil moisture increases risks of nitrate leaching.5. Crop residue impedes fertilizer applications.6. High herbicide use increases risk of weeds becoming

resistant to the herbicide. 7. New weed species become a problem.

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Tillage implements

Primary tillage Moldboard plowDisk plowChisel plowPowered rotary tillerSweep plow = stubble mulch plowLister/bedder

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Tillage implements, con’t.

Secondary tillage Disk harrowHarrowField cultivator

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Tillage implements, con’t.

Special tillage operationsDeep tillage- can be used to bury topsoil with a problem (like salinity).

Subsoiling- is used to break up compaction and plow pans or hard pans in soil.

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Tillage practices use considerable energy

Fuel, equipment, etc.

Shift from gasoline to diesel tractors (more efficient).

1978-1993 saw a 25% reduction in energy use by the agricultural sector in the USA.

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1965 1993

Gasoline 42% 11% (% of on farm energy use)

Diesel use 13% 29%

Agricultural output increased by 47% during this period.