soil health and drought

8/9/2019 Soil Health and Drought

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Soil Health and Drought

Slide 1

Barbara Bellows, NCAT Soils Specialist

SOIL HEALTH and DROUGHTSOIL HEALTH and DROUGHT

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Slide 2

Soil Health:

Nature and Management

Natur e and soil char acteristics

Local geology and climate determines soil type

Soil type determines natural water- and nutrient-

holding capabilities

Land m anagem ent practices

Can decrease or enhance soil nutrient- and water-

holding capabilities

These management changes may not be apparent forseveral years


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Slide 3

Natural Soil Characteristics

Soil texture Soil m ineralogy: sand, loam, clay,

muck

Particle size

Soil profile

Soil depth Subsoil characteristics

Soil slope


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Slide 4

Soil Texture and Water

PoorExcessiveExcessiveMuck soil

GoodGoodGoodLoam soil

PoorGoodPoorClay soilGoodPoorGoodSandy soil

Drainswater

Holdswater

Absorbswater

WaterSoil


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Slide 5

Soil Profile and Water

Char acteristics of deep topsoils

Absorb and hold water and nutrients

Promote thick root growth able to reach water

Subsoil char acteristics

Clay, hard rock, or compacted subsoils restrict waterentry and movement !!!! low water absorption

Gravelly or cracked rock subsoils allow excessivewater to flow through the soil profile !!!! low waterholding


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Slide 6

Soil Slope and Water

W ater absor ption

Limited by water flow on steep slopes

Limited by thin topsoils on steep slopes

W ater r etention

Conservation practices slow water

flow downslope Conservation practices protect

topsoil, enhancing soils water-holding capacity


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Slide 7

Soil Water Conservation

Cropping practices

Rotations w ith perennial grasses

Adds organic matter to soil

Minimum til lage

Cover cropping

Grazing practices Managed rotational grazing

Riparian area protection


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Slide 8

Cropping Practices

for Healthy Soils

Add m anur e and crop residues to soil

Promotes growth of soil organisms

Builds soil organic matter

Enhances soil aggregation and tilth

Use cover crops, m inimumtillage, and m ulches

Protects against erosion and runoff

Minimizes water loss through

evaporation


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Slide 9

Soil Organic Matter

and Soil Organisms

Soil or ganisms build soil tilth

Insect and earthworm burrows make soil porous

Fungi and bacteria build soil aggregates

Mycorrhizae enhance plant uptake of water andnutrients and create soil aggregates

Mycorrhizae

Soil organism s decom pose organic m atter and

build soil hum us

Increase nutrient availabill ity

Increase water-holding capacity


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Slide 10

Aggregated Soils

Enhance plant water uptake Facilitates soil water and nutrient movement

Facilitate root growth through soil profile

Enhan ce w ater availability

Decreased soil crust formation,resulting in better water absorption

Increased water storage throughout thesoil profile

Decreased leaching and evaporat ion


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Slide 11

Practices to Protect Soil Life Use m inim um tillage

Soil cover moderates temperature and protectsagainst water loss by evaporation

Does not disrupt the habitat of soil organisms

Add m anur e and cr op residues to land toprovide soil organism s with food an dfavorable grow ing conditions

Minimize or eliminate use of syntheticchem icals to pr otect soil biological healthEarthworm

burrow


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Slide 12

Soil Health Indicators

Moder ate to high or ganic m atter Even distr ibution of nutrients

Good w ater infiltration

Minim al soil erosion

Deep crop ro ot grow th

Active populations of soil insects, earthw or m s,and m icrobes


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Slide 13

Residues for

Water Conservation Surface residues conserve soil organic matter

Feed soil organisms that buildaggregates

Cool soil and slow organic matter

decomposition

Soil cover facilitates waterinfiltration

Cushions against raindrop impact and crust format ion

Protects soil against runoff and erosion

Soil cover decreases water evaporation


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Slide 14

Windbreaks to Reduce

Evaporation Hot w inds blow ing across soils and plants

increases evapo-transpiration

Tree shelter belts reduce w inds andevapor ation potential

Choose windbreak treesthat

Use water efficiently

Create minimum shade

Provide habitat for beneficialorganisms


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Slide 16

Plant According to

Water Needs Plants have cr itical per iods of water need

Leafy vegetables need water throughout the growingperiod

Root, tuber, and bulb crops need water when roots

are enlarging

Fruit and seed crops need water at flowering and atfruit or seed set

W hen possible, plant crops so their criticalperiods of w ater need coincide with tim es ofnorm ally wet weather


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Slide 17

Plant to Enhance

Water Availability Tim e planting to avoid know n dr y periods

Use fall-seeded crops that overw inter and takeadvantage of spring moisture

Tim e planting to corr espond w ith know w et

periods, such as spring or m id-sum m er rains

Time planting to harvestbefore dry periods

Plant short-season crops thatproduce yields before onset ofdry periods


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Slide 18

Conserve Moisture

During Planting To conserve m oistur e during planting

Till shallow ly to min imizemoisture loss

Plant seeds deeper, wheresoil is moist

Pack seed follow ingdrilling to close soil


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Slide 19

Use Drought Resistant

Crops

Early-m atur ing, low w ater-use crops

- Barley - Peas

- Oats - Lentils

W hen m oistur e is favorable,har vest crops for sale

If drought reduces crop yieldsor quality, graze these cr ops torecover som e of their value


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Slide 20

Rotate to Build Soil Quality Rotate betw een ann ual and peren nial crops

Deep rooted perennials can get water and nutrientsthat have moved out reach of annual plant roots

Fine roots of perennial grassesbuild soil aggregation and tilth

Rotate cr opping and grazingland

Aids soil recovery from compaction

May decrease weed competition


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Slide 21

Avoid Water Competition

Between Rotated Crops Choose appropriate cover crops

and crop rotations

Know each crops water needs

Match with soil moisture availability

Determ ine best time to cut or kill cover crops

Limiting cover crop grow th reduces water depletion Extending cover crop growth produces more residues

while decreasing the potential for soil erosion and waterloss through evaporation


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Slide 22

Control Weeds to Conserve

Moisture Availability W eeds com pete w ith crops for soil m oistur e

W ide spacing between plants provides rootsw ith m or e area to obtain m oistur e from soil,

but wide spacing Reduces moisture-

conserving canopy

Can increase weedcompetition


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Slide 23

Weed Control Practices Organic w eed contro l

Crop rotations and cover crops decrease weed pressureover time

Flaming, acetic acid, corn gluten meal

Herbicides for w eed contro l

Often used in minimum ti llage chem ti ll

Preplant herbicides dry out soil

Soil-applied herbicides need moist soil to be effective

Harm to soil organism s and soil tilth is usuallyless from herbicides than from tillage


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Slide 24

Tillage and Compaction Tillage and heavy equipm ent use com pacts soils

Tillage degrades soil aggregates Disrupts soil organisms that form aggregates

Allows heat to breaks down organic gels and glues

Tilling or driving equipment onwet soils compresses them andforms clods

Repeated plowing at the samedepth forms plow pans


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Slide 25

Tillage and Moisture Loss Tillage increases m oistur e loss by evapor ation

Exposes moist soil to drying forces of sun andwind

Reduces residues that protect against evaporation

Soil moistur e loss increases w ith tillagepasses and tillage depth

Most moisture is lost on the first pass, w ith approximately1/ 3 to inch additional loss w ith each til lage pass

Deeper tillage increases moisture loss

Till E i t


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Slide 26

Tillage Equipment

and EvaporationAs tillage decreases r esidue cover , it increases

w ater evaporation from soil

Moldboard

Disc

Cultivator w ith har row

Chisel w ith sw eeps

Rodweeder

Undercutter (v-blade)

Minim um till Most residue cover/ least evaporation

Least residue cover/ most evaporation


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Slide 28

Minimum Till Trade-Offs Killed m ulch

Cover crop needs sufficientmoisture and time for growth

Suitable for organic production

Chem-till

Soil applied herbicides are lesseffective when soil is dry

Not suitab le for organic production

All m inimum tillage practices retain m oistur e,slow ing soil w arm -up in spring


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Slide 29

Killed-Mulch Tillage Tools Stalk pullers pull stalks, leaves residues

Uprooter-shredder-m ulchers uproot andshred stalks, then inject them into the soil

Undercutters sever plants below crow n, thenflatten residues

Roll-chopper s flatten plantsand cut stem s perpen dicularly

Flail choppers shred stalksbehind picker


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Slide 30

Minimum Tillage Alternatives Minimum till practices are not suitable for

areas with cold and wet w inters Surface mulches prevent w et soil

from drying and warming in spring

Cool, wet soils cause seed rot andpoor root growth

Zone or ridge tillage

Seeding zone tilled and raised

Allows the seed zone to warm upand dry out


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Slide 31

Frost Tillage Soil tilled in winter w hen frost is less than 4

deep (But these w eather conditions may notoccur every year .)

Produces a rou gh soil surface

Encourages moisture infiltration

Reduces potential for soil

compaction

Early tillage a llow s for ear lierspring planting


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Slide 32

Rangeland Health Indicators

Biological soil crusts

Composed of bacteria, algae,and fungi

Enhance water infiltration andwater-holding capacity of soils

Even distribution of vegetation, residues,and organic m atter across the landscape

Minim al soil sur face loss or degradation

Grazing Practices for


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Slide 33

Graze short-term on sm all paddocks

Forces even grazing across paddocks

Results in an even distribution of plantresidues and manure

Reduces bare spots and compaction fromlounging

Grazing Practices for

Healthy Soils

Rest paddocks betw een grazing periods Permits forage regrow th and enhances forage diversity

Allow s soils to recover from compaction

R t ti f F


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Slide 34

Rotating for Forage

Persistence

Minimum impact

on young forage,slow grow ingforage, or wet soils

Long term

Force use of

unwantedforages

Effective use of

rapidly grow ingforages

Shor t term

LongtermShor t termGrazing

Rest


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Slide 35

Riparian Protection Exclude or lim it anim al access

Designate w ater crossings

Provide alternative water systems

Place minerals, shade, and water

away from streams

Protect vegetation on ripar iansoils

Plant grass and trees

When upland vegetation is sparse, exclude animalsfrom riparian areas to prevent overgrazing


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Slide 36

Riparian Protection Benefits Enhances water r echarge

Reduces flooding by absor bingrainfall, then slowly releasing

w ater into stream s

Protects w ater quality by lim itingnutrient and pathogen m ovementinto stream s

Protects plant and w ildlifehabitat


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Slide 37

Summary Manage your soils to r educe im pacts of

drought

Return organic matter to the soil

Minimize soil compaction Protect soil organisms

Protect against runoff and erosion

Reduce w ater loss from evaporation,runoff, and w eed growth


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Slide 38

Illustration Credits

Tom Bruns, Department of Plant andMicrobial Biology, University ofCalifornia-Berkeley

Soil Organic Matter and SoilOrganisms

USDA Natural Resources Conservation

Service

Cropping Practices for Healthy Soils

USDA Natural Resources ConservationService

Soil Water Conservation


Soil Slope and Water

USDA Agriculture Research Service ImageGallery

Natural Soil Characteristics

USDA Natural Resources ConservationServiceCover

Photo cour tesy of:Slide Title


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Slide 39

Illustration Credits (Cont.)

USDA Photography CenterConserve Moisture During Planting

Marilyn Bria, Department of Geography,Michigan State University

Plant to Enhance Water Availability


Stubble to Increase SnowInfiltration


Windbreaks to Reduce Evaporation

Joe Lauer, University of Wisconsin ShortCourse

Residues for Water Conservation

Illinois Natural History SurveyPractices to Protect Soil Life

USDA NRCS Soil Quality Information Sheets.Aggregated Soils


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Slide 40



Minimum Till Practices


Tillage Equipment and Evaporation

Carter and Gruenewald Co., Inc.Tillage and Compaction

USDA Agriculture Research Service ImageGallery

Control Weeds to ConserveMoisture Availability


Avoid Water Competition AmongRotated Crops


Rotate to Build Soil Quality


Use Drought Resistant Crops


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Slide 42


USDA NRCS Soil Quality Information SheetsSummary


Riparian Protection Benefits


Riparian Protection Methods

soil health and drought

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