Unit 5: Soil Surveys & Land Use Planning Chapter 17

Objectives  Knowledge of purposes & uses for soil surveys  Identify tasks for soil survey & the reports involved  Methods of soil evaluation & interpretation  Use of electronic databases

Introduction  Soil survey – fact-finding mission, following by a report on the findings  Description of the characteristics of the soils in a given area Classification of the soils Delineate boundaries of soils on a map Predictions of behaviors of the soils

Introduction  Contain Data for many users  Farmers, forecasters agronomists: evaluate potential production of the soil, management needs to maximize that potential  Planners, community officials, engineers, developers, home buyers: evaluate the site for building construction purposes, strengths, limitations

Conducting a Soil Survey  Before any surveying begins, a plan is made & information is collected Conferences Collect aerial photographs Satellite images Initial field reviews

Conducting a Soil Survey  Preparation of a legend Initial field reviews conducted in soil pits in the most extensive landforms  Soil-mapping unit: area of soil that is delineated from adjacent areas on a map Differences may be:  Slope  Erosion  Soil profile

Soil Survey Reports  Normally surveyed on a county basis  Contents of a Soil Survey Temp & precipitation Spring/fall freeze dates Growing season Acreage & proportional extent of the soils Prime farmland Land capability & yields/ac of crops

Soil Survey Reports Rangeland productivity Recreational development potential Wildlife habitat Building site development Sanitary facility needs Construction materials Water management Engineering index

Soil Survey Reports Physical & chemical properties of the soils Soil & water features Chemical analysis Clay mineralogy Engineering index data Soil classification

Soil Survey Reports  Mapping Legends for Soils Typically named for the most extensive soil series w/in each unit  Each unit often a natural mixture of 2-5 soil-mapping units Called soil associations Delineations on the maps called phases of series

Soil Survey Reports  Value of Detailed Soil Survey Reports Most soil properties recorded in a soil survey change very slowly Typically semiperminent properties:  Land relief (topography)  Soil texture  Organic matter content  Soil lime content  Geologic origin

Soil Survey Reports  Natural fertility  Soil depth  Tendency to accumulate soluble salts  Soil structure  Soil engineering properties  Climate  Natural vegetation  Adapted crops & their expected productivity

Soil Survey Reports Reasons why a resurvey may be done:  Some information was not gathered in a previous survey  New management practices  Changes in crops grown  Yield prediction changes 

Special Soil Designations  Benchmark Soils Considered to be of great importance in an area Occupy a key position in the system of taxonomy ~1000 soils in the U.S. designated as benchmark soils Soil scientists hope that data from these soils can be extrapolated for soils for which less information is provided

Special Soil Designations  Prime & Unique Farmland Lacking in many states due to many reasons  Climate extremes  Short growing seasons  Mountainous terrain Some states contain lots of prime farmland  Ex. Jewell Co., KS – 67% prime farmland, Wayne Co., IN – 74% prime farmland  Some counties in IA - >90% farmland

Special Soil Designations Prime farmland soils  Best suited to producing food, feed, forage, fiber, & oilseed crops  Soil properties that lend themselves to sustained high yields  Need to be treated & managed using acceptable farming practices  Adequate moisture  Growing season must be sufficiently long  High yields w/ minimal inputs  Least environmental damage

Land Evaluation  Land-use planning done for: urban areas, rural areas  Major issues: Quality of environment Environmental sustainability of ag production systems  Pollution of nitrate, phosphate, pesticides  Erosion of land  Declining soil fertility

Land Evaluation  Low-input farming  Exploitation of timber & range resources  Engineering use info Problems caused by these issues may have various/multiple facets  Agronomic  Economic  Political  Social

Land Evaluation  LESA system – Land Evaluation and Site Assessment Guide the conversion of farmland to urban uses Attempts to preserve the best farmland Three procedures:  Land capability classification  Current category of land is documented  Soil rated according to capability

Land Evaluation  Land Capability Classification Classification & sub classification for all soil- mapping units in the U.S. Class I Soils  Can be used continuously for intensive crop production w/ good farming practices  No restrictions Class II Soils  More limitations than Class I land for crop production  2-5% slope is main difference

Land Evaluation Class III Soils  Severe limitations  Requires more special conservation practices than Class II to keep it continually productive  Can have shallow soil  Slopes 6-10%  Shallow water tables

Land Evaluation Class IV  Severe limitations for cropping use  Greater intensity of conservation practices for cultivated crops that Class III  Recommend permanent crops (e.g. pastures)  Slope 12-18% Class V  Boulders, wetness, problems impractical to correct  Not necessarily erosion risk  Can’t be cultivated  Use for pasture, range, woodland, wildlife habitat

Land Evaluation Class VI  Slope 18-30%  Same limitations as Class V soils, except more need for sustainable management practices Class VII  Severe limitations  Extreme care to protect the soil Even using grazing, wildlife, timber  Slope >30%

Land Evaluation Class VIII  Very severe limitations Steep slopes, rock lands, swamps, etc.  Can only be used for wildlife, recreation, watersheds, aesthetic appreciation Land capability subclasses – soil groups w/in the 8 classes that explain the reasons for limitations of intensive crop production  e – erosion hazard  w - wetness

Land Evaluation  s – shallow, droughty, stony, permafrost  c – climate too cold or dry

Land Evaluation  Ratings for Soil Potential Indicates the relative quality of a soil for a particular use compared with other soils in a given area Developed for planning purposes Supplement land capability classes, woodland suitability groups, range sites, soil limitation ratings

Land Evaluation Soil Potential Index (SPI) – value assigned from  Yield/performance - sum of costs of corrective measures + costs for continuing limitations

Data Interpretation for Soil Uses  Can be rated to have slight, moderate, severe limitations  Severe Soil will require major soil reclamation, special design, high costs, or intensive soil maintenance to use for the item listed  Very Severe Great difficulty in the soil’s use, high costs, or both

Data Interpretation for Soil Uses  Slight & Moderate May indicate problems w/:  Shallow  Low permeability  Strong acidity  High salt concentration  Various other problems

Data Interpretation for Soil Uses  Any soil may be good for one use, but poor for another Permeable, well-drained soil – good for crops, poor for landfills, lagoons, etc. Clayey soil w/ good, deep drainage – good for lagoons, ponds; difficult for cropping, unstable for roads, etc.

Controlling Land Use  Much disagreement at all levels of government regarding how much control to impose on land use, and whether to develop or preserve natural resources  Land-Use Laws & Customs Very difficult/controversial to control private property People generally agree that some controls are necessary, just don’t agree on what they should be

Controlling Land Use <1% of U.S. population are farmers  More prisoners than farmers in U.S. Land-use regulation began w/ 1926 Standard State Zoning Enabling Act  Gave gov’t right to zone areas for limited uses as protection to general public  Zoning Laws – local, regional, national gov’t ability to guide land development

Controlling Land Use  Easements & Contracts – used by gov’t bodies to implement land-use planning by mandatory action May demand easement or contract to purchase to specified reason (e.g. park) Easement/contract may be broken by gov’t at any time w/ no penalty, but not by landowner  Public Purpose – nat’l or state gov’t have authority to purchase land for nat’l/state forests, parks, hunting areas, flood control dams

Controlling Land Use  Private Sales or Bequests – land trusts & holding companies promising to protect the land  Eminent Domain – forced legal sale due to promotion of the general welfare of the public over private good Can force you to sell your land

Controlling Land Use  Recent Trends in Land-Use Controls 1 million ac of prime ag land converted to non-ag uses each year in the U.S.  This trend has prompted some states to pass laws to protect prime ag farmland Limited effectiveness No way for enforcement  Preferential Tax Assessment – made to fit current use of land instead of other uses that might be assessed at higher rates

Controlling Land Use  Buying Development Rights – owner sells development rights to gov’t, but retains ownership to use at its current use  Enforced Planning – state requiring local gov’ts to establish & enforce land-use planning, identify most productive farmland & housing growth areas

Controlling Land Use  Threatened Farms & Farmers Priority for U.S. to have stable, wholesome, inexpensive food supply All 50 states have laws against urban sprawl, lawsuits that urban dwellers may bring against farmers for nuisances (odor, noise, dust)  Called right-to-farm laws  IA Supreme Court struck down this law in 1999  What is your reaction?  What should we do to rectify the situation?

Assignment