Conservation Farming New Mexico

7/29/2019 Conservation Farming New Mexico

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Conservation Farmingin New Mexico

NEWM

EXICO

STAE

UN

IVERSIT

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T Cooperative Extension Service Circular 555

College of Agriculture and Home Economics


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The nation was alerted to the urgent need for betterfarming methods on May 11, 1934, when dust cloudsdarkened eastern skies over the nations Capitol. It wasnot the first time soil erosion was observed, but it was byfar the most dramatic. Its importance had an impressiveimpact on events that followed. Many new soil conser-

vation practices were initiated, followed by decades ofresearch to preserve the soil and to restore and extendthe agricultural economy. A new agriculture evolved.

Consequently, New Mexico agricultural producershave practiced conservation farming methods for manyyears. However, soil conservation also is mandated bythe 1985 Food Security Act. The swampbuster andsodbuster portions of this act required growers whofarm highly erodible cropland to initiate an approvedconservation plan by 1990 if they were to remain eli-gible for USDA program benefits (such as price sup-ports and disaster payments). The 1990 Food SecurityAct further strengthened the conservation requirements

for all highly erodible cropland. These plans and com-pliance with conservation measures were to be fullyimplemented by 1995.

WHAT IS CONSERVATION TILLAGE?

Bare soils, associated with conventional tillage, leadto severe soil erosion from both wind and water. Incontrast, conservation tillage is any tillage or plantingpractice that maintains at least 30% crop residue coveron the soil surface at planting time to reduce soil erosionby water, or, where soil erosion by wind is the primaryconcern, maintains at least 1000 lb/ac of flat, small grainresidue equivalent on the surface during the criticalerosion period (fig. 1).

The most important single contributor to erosion ofNew Mexico soils is wind. While not as significant orwidespread as wind, flash floods can cause isolated, butsignificant, soil erosion. Wind and water erosion dam-age is rarely uniform on a farm or even within individualfields.

COSTS OF CONVENTIONAL TILLAGE

Conventional tillage can cost growers soil productiv-ity, poor water use, and wind and water erosion. Long-term increases in production costs occur when erosionalters the soils productive capacity. Erosion reduces

the rooting zone depth and soil quality, the most perva-sive long-term causes of soil productivity losses.

Frequent tillage causes low precipitation use effi-ciency, which results in reduced water availability in theroot zone and increased susceptibility to drought. Forexample, data collected in the central Great Plainsduring the last 40 years show that normally less than25% of the precipitation received during a 14-monthfallow period is stored in the soil when growers use thedust mulch system with conventional tillage.

A third adverse consequence of conventional tillageis wind and water erosion. Additionally, cultivationincreases oxidation of soil organic matter. Together,

these factors can alter the physical properties of soils.Organic carbon and nitrogen in the surface soil can beselectively eroded by wind and water. In addition,excess oxidation of organic matter can contribute tofurther organic matter loss.

Conservation Farming in New Mexico

R. D. Baker and B. RouppetNew Mexico State University

Agricultural Science Center at Clovis

Fig. 1


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Reducing Production Costs

Conservation tillage provides cost savings in threeprincipal areas: energy, time and labor, and machinerycosts.

Tractor fuel is the single largest use of energy inagriculture. Conservation tillage systems help to reducefuel use up to 60% with no-till compared to conven-

tional tillage systems (table 1).Conservation tillage eliminates field trips, whichreduces time and labor. Labor reductions of 5060% arecommon, while time saved in actual tillage is alsogreater. However, this savings is often offset by greatermanagement responsibilities, slower operation of plant-ing equipment, and extra herbicide application require-ments.

Reductions in machinery costs vary depending uponthe conservation tillage system. A straight no-till farm-ing system requires the least equipment of all the con-servation tillage systemsonly three basic pieces: atractor, a planter, and an herbicide sprayer. When com-

To reduce the potential for soil erosion and complywith provisions of the 1985 and 1990 food security acts,agricultural producers are faced with changing produc-tion practices. To comply with these laws, growers mustleave and maintain crop residues on the soil surfaceduring periods of high erodibility. For many producers,compliance has meant a change in production practicesto implement conservation tillage systems.

IMPLEMENTING CONSERVATION TILLAGE

Conservation tillage has two basic advantages for theagricultural producer: conservation of soil, water, andsoil organic matter resources; and reduction of costlyinputs while maintaining or improving crop yields andprofits.

Conserving Soil, Water,and Soil Organic Matter Resources

Improved soil and water conservation through con-servation tillage results in preservation of topsoil andsoil organic matter. The primary causes of soil erosionare excessive or poor tillage practices that leave baresoil exposed to the eroding forces of water and wind.The basic principle of conservation tillage is to keep asoil- and water-holding cover on the soil surface, whetherby residue or vegetative cover.

Under conditions of limited soil water and precipita-tion, crop yields under conservation tillage systems areequal and often significantly higher than under conven-tional tillage. The higher yields under conservationtillage systems generally are attributed to increased soil

water content resulting from increased infiltration, de-creased runoff, and decreased evaporation. In manyareas of New Mexico, evaporation accounts for themajor water loss from agricultural soils. Even with thebest conventional tillage practices, soils in the GreatPlains lose about 60% of the 20" of average annualprecipitation directly by evaporation.

Because increased infiltration, decreased runoff, anddecreased evaporation often result from converting toconservation tillage systems, growers can change tomore intensive crop rotations with fewer summer fallowperiods or increase crop yields with traditional croppingsystems. When converting to more intensive croppingsystems, precipitation use efficiency greatly increases,resulting in less water loss below the root zone and lesspotential for nitrate leaching. More intensive croppingsystems also have higher potentials for reducing soilorganic matter losses than do traditional monoculturesystems because of more residue production over multi-year cycles.

Table 1. Comparison of fuel requirements for field op-

eration in conventional, chisel, and no-till sys-

tems for corn on loam soils.

Fuel requirementTillage system and field operation (gal/ac)

Conventional system

Disking corn stalks 0.45

Moldboard plowing 1.85

Disking 0.55

Field cultivation 0.60

Fertilizer injection (NH3) 0.70Planting 0.50

Cultivation 0.35

TOTAL 5.00

Chisel plow system

Chisel plowing 1.25

Disking 0.55

Field cultivation 0.60

Fertilizer injection (NH3) 0.70

Planting 0.50

Cultivation 0.35

TOTAL 3.95

No-tillage system

Shred corn stalks 0.75

Liquid fertilizer application 0.20

No-till planting 0.50

TOTAL 1.45

Source: Purdue University


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pared to a conventional tillage systemwhich requiresa moldboard plow, chisel plow, disk, rotary tiller, springor spike tooth harrow, field cultivator, row crop cultiva-tor, planter, tractor, and sprayerit is easy to evaluatedifferences in equipment costs. Harvest equipment forconventional and conservation tillage systems are thesame.

In a sprinkler-irrigated wheat study in the Clovis,

New Mexico area, irrigated cost and return estimatesshowed large differences between conventional andconservation tillage systems. While yields and pur-chased inputs were similar, the conservation tillagesystem saved $27.71/ac in irrigation fuel and oil sav-ings. The difference was caused by less water loss fromevapotranspiration, which allowed growers to reducethe number of irrigations from seven to five. Also,conservation tillage operating expenses for the wheatwere $35.24/ac less than the conventional tillage sys-tem. Together, the conservation tillage system offered atotal savings of $62.95/ac compared to the conventionaltillage system. In a similar study at the NMSU Agricul-

tural Science at Clovis in 1990, no significant yielddifferences between no-till and conventionally tilledirrigated sorghum were found (Jones et al., 1994). Thisillustrates that not only can yield be maintained withconservation tillage systems, but operating costs andwater inputs can be reduced.

Producers may discover additional benefits with con-servation tillage or reduced tillage systems, includingutilization of marginal land, reduced soil compaction,some harvesting advantages, and conservationcompliance.

As a result of changing from conventional tillage toconservation tillage systems, producers also may expe-

rience some short-term disadvantages while they adaptto the selected conservation tillage system. Growersmay experience increased management inputs; yieldreductions until crop rotations, residue management,and fertility use patterns and techniques are establishedfor their individual farm situations; changes in weed,insect, and disease pressures; delayed planting times forcooler soils; and purchase of specialty equipment.

TYPES OF CONSERVATION TILLAGESYSTEMS

Successful substitution of conservation tillage forconventional tillage requires that planting equipmentplace seed in a rough-surfaced soil partially or com-pletely covered with residues; that weeds and pests becontrolled by chemical means; and that fertilizer andother agricultural chemicals be effective with reducedor no tillage incorporation. Five conservation tillage

systems are defined here to identify the kind, amount,and sequence of soil disturbance during seed bed prepa-ration.

No-Till (or Slot Planting). A procedure by which acrop is planted directly into a seedbed that has been leftuntouched since harvest of the previous crop. Gener-ally, planting is completed in narrow (13") seedbeds. A

device on the planter (a rolling coulter or disk) cutsthrough the sod and crop residue, and a seed slot openerprepares a slot for the seed. Weed control is accom-plished primarily by herbicides to kill all live vegetationon or near the soil surface (fig. 2).

Ridge-Till. The soil is left undisturbed before plant-ing. Approximately one-third of the soil surface is tilledat planting with V sweeps or row cleaners. Planting is

completed on a ridge (or bed) usually 46" higher thanthe row middles. Weed control is generally accom-plished with a combination of herbicides and cultiva-tion. Cultivation is used to rebuild ridges or beds (fig. 3).

Fig. 2

Fig. 3


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Strip-Till. The soil is left undisturbed before plant-ing. Approximately one-third of the soil surface is tilledat planting time. Tillage in the row may be accom-plished by using a rototiller, in-row chisel, or rowcleaners. Weed control is accomplished with a combi-nation of herbicides and cultivation (fig. 4).

Fig. 4

Stubble Mulch (or Mulch-Till). Stubble much tillageis performed with implements such as V sweeps androd weeders that undercut residue, loosen soil, and killweeds but leave much of the previous crop residue onthe soil surface. Tillage tools such as chisels, fieldcultivators, disks, or blades, often with a combination ofherbicides, also are used to control weeds. Because thesoil is tilled as often as necessary to control weedsduring the period between crops, the stubble mulchsystem is a tillage-intensive system that requires fre-

quent operations to control weeds. This system wasdeveloped primarily for wheat and other small graincrops (fig. 5).

Fig. 5

Reduced-Till. Reduced-till systems are any othertillage and/or planting systems not covered by previousdefinitions that meet the 30% residue requirement(fig. 6).

Fig. 6

REFERENCE

Jones, J.M., J.D. Libbin, N.B. Christensen, and J.Schroeder. 1994. Economic Comparison of Conven-tional and Conservation Tillage in Eastern NewMexico. Research Report 687. New Mexico StateUniv. Agric. Exp. Sta., Las Cruces, NM.


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New Mexico State University is an affirmative action/equal opportunity employer and educator. NMSU and the U.S. Department of Agriculturecooperating.

March 1996 Las Cruces, NM2M

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Conservation Farming New Mexico