# Presentation: 180497

## Conservation Tillage and Crop Residue ManagementIntegrated IWM Field HandbookSQ-8b

**Conservation Tillage**** and Crop Residue Management****Integrated IWM Field Handbook****SQ-8b**

##  What is Residue Management/Conservation Tillage 

** *****What is Residue Management/Conservation Tillage***** **

**Any tillage or planting system that maintains at least 30% crop residue cover on soil surface (leaves about a third of soil covered after planting). **

## Residue Management, Mulch-Till

**This full-width tillage system usually only includes one or two tillage passes.  **
**Yet after planting, at least a third of the surface remains covered with residue.**

## Residue Management, No-Till & Strip-Till

**No-till: Leaving the residue from last year’s crop undisturbed until planting**
**Strip-till: No more than a third of the row width is disturbed with a coulter or specialized shank that creates a strip.  If shanks used, nutrients injected at same time.**

## Why Use a Conservation Tillage System? Environment:

**1. **Reduce sheet and rill erosion.
- 2. Reduce wind erosion.

## Why Use a Conservation Tillage System? Environment:

- 3. Maintain or improve soil organic matter content and tilth.
- Each tillage trip oxidizes some organic matter
- Continuous no-till can increase organic matter in top 2 inches of soil about 0.1% each year.

## Why Use a Conservation Tillage System? Environment:

- 3. Maintain or improve soil organic matter content and tilth.
- Each tillage trip oxidizes some organic matter
- Continuous no-till can increase organic matter in top 2 inches of soil about 0.1% each year.

## Why Use a Conservation Tillage System? Environment:

- 4. Conserve soil moisture. (Improved infiltration and increased organic matter; tillage reduces available moisture by about 1/2” per trip)
- Residue reduces evaporation:
- Surface Cover %  	       Relative Potential Evaporation
- 		          0			1.00
- 	            10			0.90
- 	            20		           0.78
- 	            30			0.70
- 	            40			0.67
- 	            80			0.58

## Why Use a Conservation Tillage System? Environment:

- 5. Manage snow to increase plant available moisture.
- 6. Improves water quality
- 7. Provide food and escape cover for wildlife.

## Why Use a Conservation Tillage System? Economic:

**Yields - are as good, if not better**
**Saves time and labor**
**	****On a 1000-acre farm, an additional 100 hours needed for every pass (example based on 18’ disk, 160 Hp FWD)**

## Why Use a Conservation Tillage System? Economic:

**Reduces fuel consumption****	**
**	****No-till can reduce fuel use by 3.5 gal/ac**
**Reduces machinery wear**
**	****Less machinery means fewer pieces need to be replaced. Up to a $10/acre cost reduction**

## Differences in residue cover between Conservation Tillage practices

**Differences in residue cover between Conservation Tillage practices**

- No-till leaves the most surface residue
- With high residue crops, e.g. corn, wheat , sorghum, 75 % +
- With low  residue crops, e.g. soybeans, cotton, residue cover is   significantly less
- a cover crop may be needed to meet residue  goals
- In some climates, some residue cover may carry over from year to year
- Winter annuals also add to surface residue

## Differences in residue cover between practices, continued: 

**Differences in residue cover between practices, ****continued:**** **

- Mulch-till residue levels can be significantly less than no-till
- With high residue crops, 30-50 % possible
- With low residue crops, difficult to retain 30 percent
- May need cover crop to achieve residue goals

## Management of Residue

**Management of Residue**

- Surface residue must be evenly distributed
- Residue decomposes with time
- If target is 40 percent cover after planting, will need more over winter
- May need to control winter weeds in dryland areas

**Notes:**
Important to point out to the trainees that in RUSLE, residue cover is assumed to be evenly distributed over the field.  If residue is not evenly distributed, the user may want to estimate erosion on separate areas of the field.  (high residue areas from low residue areas and then take a weighted average.  Surface residue must be evenly distributed to obtain full erosion reduction benefits.

Important to note that surface residue decomposes.  Therefore, if you estimate 60 percent in the fall, you will not have 60 percent in the spring.  Residue decomposition must be taken into account when planning residue management practices.   Decomposition of crop residue has been accounted for in RUSLE.    

In dryland agr. areas, may need to control winter weed growth to help conserve soil moisture in the spring.

## Management of Crop Residue, continued:

**Management of Crop Residue, ****continued:**

- Crop residue and moisture level impacts soil temperature - less variation
- Under no-till, soil temperatures will be cooler
- May be critical in cool, wet springs
- May be justification for strip-till
- Less extremes in soil temperature under no-till may result in increased root growth and improved soil biological activity

**Notes:**
Cooler temperatures may be an advantage later in the growing season

## Residue Management - Irrigation

**Residue Management - Irrigation**

- Surface residue
- slows flow - especially with furrow
- increases opportunity time, water holding capacity, random roughness (structure)
- decreases surface evaporation
- cools seedbed temperature

**Notes:**
Under irrigation, no-till and other high residue management systems can reduce the amount and frequency of irrigation because runoff is slowed and infiltration is increased, surface evaporation is reduced and over time, the water holding capacity of the soil can increase.

## Residue Management - Irrigation

**Residue Management - Irrigation**

- More difficult - small seeded vegetables
- More requirements for incorporation of pesticides
- Management techniques may need modification
- especially with furrow irrigation.

**Notes:**
1.  Repeated tillage trips to obtain a fine seedbed and incorporation of pesticides for vegetable crops is often not compatible with residue management systems.  Where transplants are used this is generally not a concern.

2.  With furrow irrigation, flow rates may be significantly reduced, influencing the amount of water applied at the upper end of the filed compared to the lower end of the field.  It will take longer for the water to flow to the end of the field when residue is present in the furrow.  

## Potential Problems from Residue

**Potential Problems from Residue**

- Residue may float off of field
- Accumulate in fence rows and road ditches
- If not evenly distributed can cause planting/weed problems
- May have cool, wet soils at planting

## Low Residue Crops (i.e., Vegetables)

**Low Residue Crops (i.e., Vegetables)**

- Residue orientation and row orientation become more important
- Leave as much residue standing as possible
- Orient rows perpendicular to prevailing wind direction

**Notes:**
Where ridge-till is used, every effort should be made to orient ridges perpendicular to the prevailing wind direction in those areas that are very prone to wind erosion.

## Benefits of Increasing Organic Matter

**Benefits of Increasing Organic Matter**

- Soil aggregate stability increases
- Plant available water increases
- Cation exchange capacity of soil increases

**Notes:**
Increasing soil aggregate stability helps to reduce soil erosion from both wind and water erosion.

Research in the Northern Great Plains showed that high residue management systems can save from 2-4 inches of soil moisture annually.  Each inch of moisture saved increased wheat yields by about 5 bushels per acre and increased barley yields by nearly 9 bushels per acre.
Low CEC soils can not hold as many plant nutrients as high CEC soils. CEC is directly related to the type of clay and the O. M. content of the soil.  The type of clay can not be changed, but the O.M. content of the soil can be changed with proper management.  

## Crop Residue and Microorganisms

**Crop Residue and Microorganisms**

- Provides an energy source for microorganisms
- As surface residue increases, microorganisms increase
- Through their life processes, they return humus to the soil
- When residue is plowed under, residue is rapidly consumed and microorganism processes end

**Notes:**
#4 .  When residues are plowed under it leaves little or no energy source for top-feeding organisms and with out this energy source, the processes carried out by them end.

## Crop Residue and Microorganisms, continued:

**Crop Residue and Microorganisms, ****continued:**

- Microorganisms utilize surface residue slowly, remain active for longer periods, and significantly improve soil humus
- When soils are tilled, it is similar to stirring a fire.
- C02 is one of the greenhouse gases

**Notes:**
1.  Once the fire (soil) is stirred, the fire is quick to ignite (microorganism activity increases), and C02 is oxidized to the atmosphere.

## Microorganisms can tie-up Nitrogen, continued:

**Microorganisms can tie-up Nitrogen,**** ****continued:**

- Microorganisms utilize N during decomposition process
- N is temporally tied-up, but released during growing season
- Under no-till systems, N release is more evenly distributed during growing season compared to conventional systems.
- No-till systems do not have typical flush of N released as in conventional systems

**Notes:**
Adequate nitrogen may not be available during the early growing season for some crops.  In such cases starter nitrogen may need to be applied to help the crop get off to a good start.  Under long-term no-till scenarios, nitrogen will be released more evenly throughout the growing season compared to conventional systems. 

Although N is temporally tied-up, it will be released as the organisms complete their life cycle.

Since no-till does not have the rapid flush of N as in conventional till, plants sometimes show N deficiency early in the growing season. l 

## Soil Properties - Soil Structure

**Soil Properties - Soil Structure**

- Surface soil becomes more granular and friable with continuous residue management systems
- Extent of change is dependent on the residue management practice used, climate, and soil

**Notes:**

1.  No-till/strip-till and ridge-till will result in more rapid changes than 
          mulch-till.
2.  Differences primarily related to amount of soil disturbance and
          amount of residue left

## Soil Properties - Soil Structure, continued:

**Soil Properties - Soil Structure, ****continued:**

- Changes apparent in about 3-5 years with no-till/strip-till and ridge-till
- Type of soil and climate strongly influence the rate of this change

**Notes:**
1.  Changes more rapid in humid and slower in sub-humid or arid
         climates
2.  Sandy soils and soils high in clay respond more slowly

## Expected Changes in Soil Structure with Residue Mgt.  Systems 

**Expected Changes in Soil Structure with Residue Mgt.  Systems**** **

- Improved soil aggregate stability
- Improved water holding capacity
- Increased granular structure at the surface
- Less surface ponding of rainfall

## Soil Properties - Infiltration

**Soil Properties - Infiltration**

- Major benefit from Residue Mgt.
- No-till/Strip-till and Ridge-Till
- improved soil structure
- slowed runoff
- leaves old root and macropore structure undisturbed
- fastest way to improve soil quality

**Notes:**
These benefits from crop residue management practices favorably impact infiltration.

## Soil Properties - Infiltration, continued:

**Soil Properties - Infiltration****, ****continued:**

- Mulch-Till
- full width tillage disturbs macropores
- slows runoff due to increased surface roughness
- chisel can break-up shallow compaction layers

**Notes:**
Although mulch-till can increase surface roughness which is beneficial in slowing runoff, this is only temporary.  When the field is smoothed by secondary tillage surface roughness will be lost.  

## Role of Macropores

**Role of Macropores**

- Develop from decayed root channels and earthworms
- If open to the surface infiltration may be significantly increased
- May be direct conduit for contaminants

**Notes:**
There is some concern that macropores may act as a direct conduit for potential contaminants, especially when the water table is close to the surface.  This may be a valid concern, however, macropores developed by earthworms are generally enriched with organic matter that absorbs potential contaminants.  Except for the large night crawlers that can burrow vertically up to 4 feet, most earthworms live and maneuver horizontally in the upper 2 feet of the soil.  

## Role of Macropores, continued:

**Role of Macropores, ****continued:**

- Full-width tillage disturbs macropores to depth of tillage
- In Argentina, years of tillage are referred to as “aggression” and years of no tillage are “recuperation”

**Notes:**
After full-width tillage, macropores are no longer open to the surface.

## Compaction created by tillage and vehicle traffic can be corrected

- Other compacted layers occur naturally and may or may not be correctable

**Soil Properties - Compaction**

**Notes:**
Other types of compacted layers occur naturally, such as hard pans or fragipans, and depending on their depth and thickness, may or may not be correctable. 

## May be extremely limiting factor in crop production

- Limits root penetration
- Reduces water and nutrient uptake
- Problem may not be evident if adequate moisture

**Soil Properties - Compaction,**** ****continued:**

## Soil Properties - Compaction, continued:

- Correct compaction prior to no-till/strip-till or ridge-till
- Once corrected, stay off field when soils are wet
- Keep grain carts/trucks to certain areas
- Controlled wheel traffic with ridge-till is important benefit

**Soil Properties - Compaction,**** ****continued:**

**Notes:**
Once compaction occurs, it is difficult to repair without deep tillage.  Deep tillage will destroy benefits previously gained under no-till.  If deep tillage is necessary to repair compacted areas in a no-till field, it should be done only in those areas needing treatment.

Since chisel plows are often used in mulch-till, they can help eliminate shallow, compacted layers that may have occurred during tillage the previous year.  Once these layers are broken, they can return quickly if heavy equipment is used again, especially if operated on wet soils.  

##  Soil Properties - Compaction, continued:

* ***Soil Properties - Compaction,**** ****continued:**

- Soil surface bulk density may increase with no-till/strip-till
- May require adjustments at planting

**Notes:**
In some cases this increase in bulk density of the surface may require adjustments at planting, such as adjusting down pressure springs or adding weight to the planter.  

Concern over higher bulk density at the surface with no-till will lessen as organic matter and soil structure improves over time.  Generally with ridge-till and mulch-till, an increase in surface bulk density is less of a concern since row cultivation is used with ridge-till, and full width tillage is used with mulch-till.

## Soil Properties - Crusting

- Serious concern in soils low in organic matter, like NM
- More prevalent on soils excessively tilled
- Can interfere with crop emergence
- May require operation to break crust

**Soil Properties - Crusting**

**Notes:**
As falling rain hits the soil surface directly, it can cause the soil to puddle, and when it dries, a crust is formed.

## Residue mgt. Practices can reduce crusting - especially no-till

- Surface residue absorbs impact of falling raindrops
- Organic matter is increased
- Improved aggregate stability

**Soil Properties - Crusting, ****continued:**

**Notes:**
Generally speaking, no-till/strip-till and ridge-till practices will have less problems with surface crusting compared to mulch-till since more surface residue is left, and soil organic matter and soil aggregate stability are generally higher.  Soils with low organic matter levels may experience crusting problems for several years even in a continuous no-till system.

Even though one can expect less crusting under no-till/strip-till and ridge-till, crusting can occur in the row area, if row cleaning devices are used too aggressively or if the field is in the first year or two of no-till. 

## Sediment is number 1 pollutant 

- Sediment is number 1 pollutant
- Creates physical problems
- Potential hazard to fish and wildlife

**Water Quality - Sediment**

##  Water Quality - Sediment, continued:

* ***Water Quality - Sediment, ****continued:**

- Residue mgt. practices can result in a major benefit through:
- reduced soil erosion, improved aggregate stability, and increased organic matter

**Notes:**
When these benefits occur together on a field, sediment delivery is reduced, resulting in improved water quality.

## Water Quality - Sediment, continued:

- Greater amount of surface residue, the greater the reduction in soil erosion
- As erosion is reduced, sediment delivery is generally reduced

**Water Quality - Sediment, ****continued:**

**Notes:**
If reducing sediment is a primary concern, choosing no-till, would likely be the best choice if it is properly suited to the soils and climate of the area.

There is no “silver bullet” for eliminating sediment in continuous row crop systems.  However, the application of proper management practices, can significantly reduce the amount of sediment that leaves a farm.  Occasionally, high intensity heavy rainfall storms occur that simply overwhelm land treatment measures and cause soil erosion and resulting sediment loads.

## Water Quality - Nutrients

- Phosphorus attached to soil is slow to move in the soil profile
- But soil attached phosphorus can move with surface runoff
- Residue mgt. practices reduce soil erosion, improve infiltration, and reduce runoff

**Water Quality - Nutrients**

**Notes:**
Therefore, residue management practices play a key role reducing the transport of phosphorus across the surface and potential contamination of surface water. 

## Water Quality - Nutrients, continued:

- Nutrients that are dissolved but not infiltrated the soil can move freely in surface runoff
- Nitrate-nitrogen can move freely as water percolates through the soil

**Water Quality - Nutrients, ****continued:**

**Notes:**
These fine soil particles may not settle out and can be transported with water flowing across the surface.

Crop residue left on the soil surface will slow surface runoff and increase the opportunity time for surface water to infiltrate.

## Water Quality - Nutrients, continued:

- Residue mgt. practices often increase water infiltration - care must be taken when applying nitrogen
- If nitrogen is fall applied, consider nitrification inhibitor
- Apply nitrogen as close as possible when crop needs are greatest

**Water Quality - Nutrients, ****continued:**

##  Water Quality - Nutrients, continued: 

* ***Water Quality - Nutrients, ****continued:*** *

- Use caution when manure is surface applied
- Avoid applying on frozen ground
- Injecting manure reduces risk of surface runoff, but there are tradeoffs
- With mulch-till, manure may be incorporated using one of the planned tillage trips

**Notes:**
Tradeoff: Soil is disturbed and residue cover is reduced.  This may conflict with other resource management objectives.  In the case of no-till/strip-till and ridge-till, injecting manure will disturb some macropores.  In the case of mulch-till, injecting manure without reducing other tillage operations may reduce surface residue cover below  what is needed to meet other resource objectives.

## Water Quality - Pesticides

- Pesticides can be soluble or attach quickly to soil particles
- If soluble, can move with surface runoff
- If attached to soil particles, can move offsite via erosion

**Water Quality - Pesticides**

## Water Quality - Pesticides, continued:

- Residue mgt. practices reduce erosion, surface runoff, and sediment delivery
- Increase infiltration which may be detrimental where shallow groundwater exists
- Extensive macropores, open to the surface raise some concern

**Water Quality - Pesticides, ****continued:**

**Notes:**
1.  Therefore res. Mgt. Practices reduce potential water quality problems with pesticides.  If the pesticide is quick to tie-up with soil particles, then residue management practices that leave the greatest amount of surface residue cover, will have the greatest benefit in reducing surface water contamination of the pesticide.  If the pesticide is highly soluble, practices that reduce surface runoff and increase infiltration will help keep the pesticide from moving off-site via surface flow. If the pesticide is quick to tie-up with soil particles, then residue management practices that leave the greatest amount of surface residue cover, will have the greatest benefit in reducing surface water contamination of the pesticide.  If the pesticide is highly soluble, practices that reduce surface runoff and increase infiltration will help keep the pesticide from moving off-site via surface flow. 

2.  The potential for ground water contamination, especially where the depth to the water table is shallow, may increase. 

## Water Quality - Pesticides, Macropores and Solute Movement

**Water Quality - Pesticides, Macropores and Solute Movement**

**Notes:**
Extensive macropores, especially if open to the surface, have raised some concern about providing a direct conduit to ground water.  As pesticides mix with water flowing over the surface, they may enter these large macropores that are open to the surface and move quickly into the soil profile. 

In this slide discuss the difference between movement into an open macropore compared to those macropores that are closed to the surface.

## Water Quality - Pesticides, Macropores, continued:

- Earthworm channels contain large   amounts of O.M.
- This O.M. material can help absorb pesticides
- Earthworm channels have increased microorganism activity

**Water Quality - Pesticides, Macropores, ****continued:**

**Notes:**
Increased microorganism activity in earthworm channels assists in increasing pesticide degradation.  As a result, degradation of pesticides often occurs deeper in the profile with macropores than in fields where macropores do not exist.

## Water Quality - Pesticides, Macropores, continued:

**Water Quality - Pesticides, Macropores, continued:**

- Timing and amount of precipitation important
- With small rain pesticide moves into soil profile
- If large storm occurs before pesticide enters soil, direct entry into macropore is possible

**Notes:**
A one-half inch rain after application of a soil applied pre-emerge pesticide is ideal to activate the pesticide and move it into the soil surface where it is needed to stop weed emergence.  If a large storm occurs following a smaller rainfall event, saturated flow across the surface may enter the macropores and move quickly down toward the ground water.  In this case, this water is not carrying the pesticide because it has already been moved into the soil profile.  Consequently, the flow in the macropore is much cleaner than if the pesticide had not been moved into the upper soil surface.
The opposite of the above situation can also occur.  If a large storm occurs before the pesticide moves into the soil, there is a greater chance that the chemical may go into solution and move off-site with surface runoff.  If surface flow is occurring as a result of saturated soil conditions, the pesticide may directly enter macropores.  It is important to avoid the surface application of a pesticide with a high solubility value just prior to an imminent storm if it is not immediately incorporated.  

## Avoid surface application of a pesticide, especially if highly soluble, just prior to an imminent storm if not immediately incorporated 

- Avoid surface application of a pesticide, especially if highly soluble, just prior to an imminent storm if not immediately incorporated

## Water Quality - Pesticides, continued:

**Water Quality - Pesticides, ****continued:**

- Mulch-till provides opportunity to make a tillage pass to incorporate a pesticide

**Notes:**
Purpose of this tillage pass is to incorporate a pesticide immediately after application which will lower the risk of pesticide moving offsite by surface flow.

## Air Quality - Particulate Matter

**Air Quality - Particulate Matter**

- Particulate matter of 2.5 or 10 microns (PM-2.5 or PM-10) is potential health hazard
- Can occur from wind erosion events, smoke, and tillage operations

## Air Quality - Particulate matter continued:

- Surface residue reduces soil erosion caused by the forces of wind
- No-till/strip-till, ridge-till, and mulch-till should provide sufficient cover to reduce air quality hazards
- Exception, low residue-producing crops

**Air Quality - Particulate matter ****continued:**

**Notes:**
Under low residue producing crops, erosion by wind can occur and could present serious problems in all three residue management practices.  Cover crops, where practical, can be utilized to increase surface residue cover.  Other supporting practices such as Cross Wind Trap Strips, Herbaceous Wind Barriers, and Field Windbreaks can be used to reduce the wind erosion hazard.  

## Surface roughness created with 

- Surface roughness created with
- mulch-till may add additional
- temporary protection

**Air Quality - Particulate matter ****continued:**

**Notes:**
Supporting practices, such as Cross Wind Trap strips, Herbaceous Wind Barriers, and Field Windbreaks may be necessary when developing a plan to reduce air quality hazards where the mulch-till system is used since less residue is retained on the soil surface.  

## Air Quality - Animal Manure Application - Odors

- With no-till/strip-till and ridge-till, surface application can present odor concerns
- Consider wind direction at time of application
- Consider nearness of neighbors*** ***

**Air Quality - Animal Manure Application - Odors**

## Air Quality - Animal Manure Application - Odors, Continued:

- Odors can be significantly reduced by injection
- Choose injection equipment that does not excessively disturb soil and surface residue
- A large application without secondary tillage may burn the new crop

**Air Quality - Animal Manure Application - Odors, ****Continued:**

**Notes:**
Injecting manure in a no-till/strip-till or ridge-till system should be viewed no differently than knifing-in anhydrous ammonia or other forms of nutrients.

In the case of mulch-till, chisels or disks can be used to incorporate the manure and reduce odor and runoff concerns.  Again, care should be taken when incorporating the manure to ensure that sufficient residue will be left on the soil surface to meet the erosion reduction goal.  For example, a normal tillage trip might be omitted to accommodate the manure incorporation.

## Conservation Tillage – 

***Helps keep topsoil, nutrients (P), and crop protection products on your fields and out of creeks, streams and lakes***
***If you properly manage crop rotation, soil conditions, irrigation, equipment selection and adjustments, plant nutrients, and weed control, it helps  improve yields and soil productivity***

**Conservation Tillage – **
**Bottom Line**

**Notes:**
Injecting manure in a no-till/strip-till or ridge-till system should be viewed no differently than knifing-in anhydrous ammonia or other forms of nutrients.

In the case of mulch-till, chisels or disks can be used to incorporate the manure and reduce odor and runoff concerns.  Again, care should be taken when incorporating the manure to ensure that sufficient residue will be left on the soil surface to meet the erosion reduction goal.  For example, a normal tillage trip might be omitted to accommodate the manure incorporation.