What Does an Appraiser Not Learn From Looking at a Satellite Image

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1 Agriculture has become more of a science even in the practical application of farming practices. Tractors are now equipped with GPS and specified fertilizer application. When an agricultural appraiser picks up an air photo to look at it, they do so with an in depth body of knowledge. Critical thinking is required, which includes the characteristics of Saskatchewan Soils and their productivity, knowledge about glacial geology and how the soils formed. Detailed knowledge about how to rate each soil s productivity is required. Farming practices play a big role in maintaining soil productivity and the SAMA appraiser needs to be aware of these as well. A degree in Agriculture teaches a person to articulate logical thinking processes and determine the "science" behind the basic principles of plant and soil function. This critical thinking process that is developed during the 4-5 years of taking specialized courses in University is the underlining structure to becoming a Professional Agrologist. All appraisers appraising farmland in Saskatchewan require this designation. The study of range management is closely webbed with the knowledge of geography the study of elevation, climatology, plant ecology, soil science, and range animal nutrition. A person must have specialized knowledge in these sciences to develop the skills in determining the productivity of farmland. Determining the productivity of range plants requires a person to have an in depth knowledge of the above specialized fields as well the "art" to articulate the surrounding micro-environment occurring on the landscape to determine what the current range condition is. I think H.D. Harrington sums it up with his poem on the identification grasses. It takes a certain specialized knowledge base secondly, the ability to formulate reason from your findings and lastly years of experience to do the work a rural appraiser does. What Does an Appraiser Not Learn From Looking at a Satellite Image If one were looking at a satellite image one cannot simply get from the image the following information to Assess land to determine the productivity rating of the soil: 1. Climate What area of the province was the photo taken? Climate has a profound effect on productivity. The province gets more humid and less arid moving from the Southwest to northeast. However, moving too far north and east the heat units drop off and the number of degree growing days is limited. Tied to climate is elevation. Lower elevations are warmer and result in less moisture for plant growth. There is more evapo-transpiration at lower elevations. There is less evapo-transpiration at high elevations. So in a rural municipality where part of the RM is at higher elevation and an area is a lesser elevation, the area at higher elevation will have more moisture available for crop growth and a better climate. The climate gets cooler in Saskatchewan as one moves from west to east and from south to north In southwest Saskatchewan on the Cypress bench the climate is cooler and the rainfall amounts are higher. There are black, dark brown and Grey soils on the Cypress bench. 1

2 Climate does not change suddenly in Saskatchewan, it changes gradually as one moves north and for each 50 foot rise in elevation the soil temperature is much cooler. That is why there are forests and forested soils in the Last Mountain Upland only a short drive out of Regina to Stasbourg Saskatchewan Climate makes up 32 percent of a soil s rating in the province, but the lowest ratings are given to soils in southwest Saskatchewan where the rate is as low as 5 points. The highest ratings occur in northeast Saskatchewan 32 points Each appraiser has a Munsell colour chart and uses the chart to determine the soil zone. On cannot tell the soil colour from looking on a satellite image or air photo but has to know something about the climate of Saskatchewan and how soil zonal color has developed. 2 Geologic Deposits One does not get from the imagery what the glacial geology is. In order to understand the soil, one needs to know was the soil deposited by ice, by flowing water, or in a glacial lake. Was it deposited from an end moraine? Was it deposited in a ground moraine? If an end moraine the landscape will be hummocky, the soil stony If a ground moraine the landscape with be gently undulating the soil medium textured If the soil was deposited in flowing water-was it fast water? Gravel soils result in Fluvial Outwash deposits. Was the soil deposited in slower moving water? If deposited in a very slow moving flood plain, a sandy lacustrine soil results Did the water rush in to an area, slow down, and was a lake formed? If so it is possible to have silt deposits underlain by fine sand and then gravel. Such a deposit will have a profound effect on the productivity of a soil Was there a glacial lake on top of the ice? Then the geologic deposit could be a clay deposit overlying glacial till. The profile will be smooth and the landscape gently undulating and the texture loamy Was the soil formed in a glacial lake? If so it will be heavy textured silty loam, silty clay loam clay or heavy clay. It will not be stony and will be very productive due to fine textured soils that have high cation exchange capacity. The appraiser can look at soil survey maps, but as an appraiser must know the glacial geology in order to identify what the geologic deposit to properly classify the soil. The Sask. Centre for Soil Research has provided SAMA with their 700-page soil map unit book and an accompanying 5-page soil classification flow chart. If one can understand the geologic deposit one is classifying and the soil zone one is located in, one can classify the soil, but as well a complete knowledge of the Canadian System of Soil Classification is required. A complete knowledge about Saskatchewan Soil Associations and their map units is required. Soils are classified at the Order level then the Great Group then the Sub Group, then the Soil Series and then, finally the soil association. An assessment appraiser working is Saskatchewan needs time and practice to build a complete working knowledge of these 700 soil survey map units. Not many appraisers come out of University and are readily able to classify soil. It takes years of exposure and practice to be able to become confident and proficient in classifying soil. 2

3 One needs a basic level of knowledge about soils to interpret existing maps but a lot more knowledge about the soils themselves to be able to map and classify them. An unknowledgeable appraiser could do serious harm to the accuracy of soil classification by changing work he/she has no knowledge about. At one time there was close affiliation between the Soils Department of the U of S and Assessors. The SAMA research office at the U of S closed in In 1985 soil survey ramped up a complete new soil survey of the province. We have completed very few reinspections of municipalities since then in Saskatchewan. Appraisers need an in depth knowledge of the new soils mapped and classified. Why is Soil Classification So Important in Assessment? It is the classification criteria that are used in rating the soils. The very morphology of the soils that makes them unique that has been given ratings in the Saskatchewan Assessment Manual that lead to a productivity rating for each soil. In many parts of Saskatchewan it is possible to find three soil zones and three geologic deposits within a section of land. SAMA agrologists map and classify the soil at a scale of 1:15,840, while the soil survey map is at 1:50:000 scale. Often there are differences in soils mapped on quarter between a soil survey map and a SAMA Mylar map and often there are different soil lines because SAMA work is more detailed and to a different scale than soil survey. The determination of accurate productivity ratings for a parcel of land requires it. Over all on the whole there is strong correlation between soil survey and SAMA data. At a time when Crop Insurance provided SAMA with crops yields by quarter section, there was a strong correlation between crop yields and SAMA s productivity ratings. The SAMA appraiser requires the same critical thinking in classifying the soil as a soil survey mapper. To understand why some tracts of land are productive and why some are not requires the knowledge of soil classification and a rating system. It requires knowledge of glacial geology, and lastly it requires a great deal of knowledge about the soil associations and their characteristics themselves. For example south of Melfort one can go from a Thick Black variable clay lacustrine deposit to a Tiger Hills silty lacustrine deposit over till to a Northern Light Orthic Grey Luvisolic silt deposit over glacial till all within a mile. The Melfort would be the best producing soil in the province. The Tiger Hills would be the middle of the road producing soil and the Northern lights would be a very poor producing soil. The progression from Black to Dark Get to Grey soils is due to elevation. A slight rise in elevation favours trees over grasses and leads to different soils with far differing productivity. Before the soil classification concept came along and was introduced into the assessment process, none of the differences in the soils described above would have been recognized by any appraiser and all three soils with completely different productivity levels would have paid the same taxes. But the classification and rating criteria developed now allows us to find different productivity ratings for each soil. 3

4 The soil productivity classification concept that is very hard for municipal and public politicians to understand as much of the soil classification and rating terminology involves latin and Russian names, yet it the basis of the fairness in the assessment system. Canadian soil science adopted much Russian soil descriptions and some of the terminology used on SAMA profiles is the same terminology used in the Canadian System of Soil classification to describe soils. Determining the texture of the parent material will allow one to properly classify the soil. The parent material is the unaltered geologic deposit, usually at a depth of 8 to 10 or 12 inches in southern Saskatchewan and as much as five foot deep in north eastern and northern Saskatchewan. Appraisers must dig to the parent material using a Dutch auger and texture the parent material. While digging to the parent material the appraiser must check the top four feet of the soil surface. If there are lighter textured soils at depth, then the appraiser must apply a sub surface texture adjustment to reduce the surface texture for coarser deposits at depth. Once the appraiser has determined the texture of the parent material and looked at the morphology of the soil profile the appraiser can review the soil survey classification flow chart and from determining the geologic deposit from the texture and reviewing the soil profile morphology one can determine the Soil Order and then the Soil Association. 3. Organic Matter Ratings Organic matter ratings for Saskatchewan Soils were obtained for the Centre for soil research based on 8000 samples they took across Saskatchewan. Sand deposits have low ratings while the highest ratings are applied to the heavier textured soils in the black soil zone. Organic matter has a profound effect on the soil fertility. Thirteen percent of a soil s rating in our productivity model is based on the amount of organic matter that is present. The rating system we employ is to give the soils with the most organic matter the highest rating, for example Black variable clay lacustrine Melfort soils get the full 13-point rating. Organic matter can also hold many of the nutrients required for crop growth 4. Soil Texture Determination Soil texture is the single most important data that is collected in determining soil productivity ratings. It accounts for 35 percent of the soils rating. The texture-rating table is based on the scientific finding that clay soils can hold 11.5 times more moisture for crop growth than sands. Texture would make up about 50 percent of a soil s rating. So if the east side of a quarter is Elstow silty clay loam and the west side of a quarter is Bradwell sandy loam in the Dark Brown soil zone. The silty clay loam texture will have a rating of 30 points while the sandy loam soil will have a rating of 12 points. If the soil profile is an Orthic 12 profile for both soils, the silty clay loam soil will have a profile rating of 20 points and the sandy loam soil will have a profile rating of 11.4 points. There will be 27 points difference in productivity x $6.60 per rating point or about $180. In 2013 this will be $ 260 per acre assessed value difference between the sandyloam textured soil and the silty clay loam textured soil. It is therefore critical that the SAMA appraiser ensures that soil lines are accurate and are the best fit to the data collected. This is determined by hand texturing. Texture is a major component of the productivity rating system. Textures are sent to the lab for sand fractionation and particle size distribution to ensure accuracy. 4

5 The SAMA appraiser can t determine texture from a satellite image. An appraiser must have a good knowledge of how to determine textures. Like classifying soils, this requires regular practice. One has to regularly texture soils. One cannot sit inside a vehicle or an office and look at a map. Soil survey maps are on too large of a scale to reflect textures on the quarter section level. It is not unusual for a SAMA appraiser to find lighter or heavier textured portions of quarter sections. Texture is critical. The mere fact of being off by one or two or three texture classes can mean an error of $3,000 to $15,000 in assessed value. If an appraiser does not know how to properly texture, assessed values can be out considerably or they can change previously accurate assessments and cause large errors. 5. Soil Profile Identification and Rating Soil profiles account for 20 points or twenty percent of a soils rating. Since profile ratings are based on the depth of soil development for a Chernozemic soil, and the profile morphology for the Solonetzic, Luvisolic, Gelysolic, Vertisolic, Brunisolic and Regosolic soils, one needs to have a basic knowledge of the Canadian System of Soil Classification to classify and the soils and determine a soil profile rating. For classifying a Chernozemic soil an appraiser needs to know what a "Chernozemic A-horizon" is and what the Chernozemic soils are and where they are found in the landscape. The catenerary sequence is taught to appraisers. The orthic profiles are the most productive, followed by the eluviated, calcareous and the rego profile. One needs to know the surface colour that relates to each of soil zones. The Swift Current Soil Report discusses the relative amounts of productivity that may be found in the landscape of a typical Saskatchewan parcel of land. Research showed that most of the production in the soil landscape comes of the mid slope position where the orthic slopes are. It is therefore critical that when a quarter has mostly rego or calcareous profiles that the profile be rated accurately because such a quarter is less productive. For Solonetzic soils appraisers must understand that the Solod is the most productive Solonetzic soil followed by the Solonetz and then the Solodized Solonetz. Appraisers require enough knowledge to be able to readily identify these profiles in a landscape and determine where they are most frequently found in a landscape. In areas of heavy clay such as at Roleau, in alluvial flats, in areas northeast of Tisdale and in the Carrot River and Hudson Bay area, appraisers need to be able to dig in the soil and determine if the soil has massive structure as this affects the rating of the profile. These soils are so heavy they often flood and remain wet for most of the growing season. Associated with these soils is poor drainage that can severely hamper productivity. Forested soils have strongly leached profiles and the Orthic Grey Luvisol soils have very poor productivity. Appraisers need to be able to determine the depth of the Ae horizon and the depth to the B horizon, as these are important rating and classification features in the Saskatchewan Assessment Manual. Appraisers use colour charts in the aid of classification. 5

6 Dark Grey Luivisolic soils are more productive and have darker surface colours and not as tough profiles as the Orthic Grey Luvisols. 6. Topsoil depth One can estimate the percentage of the area of a quarter section that is eroded from an aerial photo, but one can not determine if the soil is a Thin Black or Thick black soil or what the depth of topsoil is without being in the field to dig. Also what is on photos has to be taken with a grain of salt. Appraisers have seen hummocky landscapes where tillage erosion has pulled the C-horizon from upper slopes over top of A- horizons at lower slopes making erosion appear worse than it really is. We are finding that on slopes of 10 to 15% typically 24 to 49 percent of the landscape of many quarters in Saskatchewan is eroded. Research indicates that tilled soils can lose as much as seven tons per acre per year of topsoil. 7. Miscellaneous Physical Factors One can see where crop growth is not as good from an aerial photo but one cannot determine a photo if the sparse crop grown the due to Luvic Gleysols, salinity, sand pockets, burnouts, poor drainage, peat deposits, loose top or acidity. An appraiser usually has to put a spade in the ground and it usually is a good practice to find out from a farmer what the percentage of the field is affected and what the reduction in crop yield normally is. This must be done by field inspection and detection of where in the field areas that are not growing healthy crops are. Appraisers must be able to know and identify these factors and be capable of estimating loss un productivity due to these factors. One must have an under standing of all of these factors and how they effect crop yields in order to be able to recognize these factors in the field and apply them. On cannot tell the miscellaneous physical factors by simply looking at an air photo image or a satellite image. Economic Factors The Soil Survey department built these into the rating model to address costs of production that farmers face in farming the land. Topography and Stones: One needs to be out in the field to determine the average percent slope in a field. One has to be in the field to discover how much stones there are on the surface. Percentage deductions are applied to the productivity rating to reduce the rating. Quarters with sloping land cost more in farming operations. Land that is stony causes wear and tear on farm equipment and there is a specific cost of removal of the stones. The ratings were designed to take into consideration these costs. Natural and Man Made Hazards: This can be determined from a photo or satellite image Les Henry has commented that quarters that are badly cut up with numerous wetlands, creeks, ravines, highways and ditches are very costly to farm and with the new technology that uses 6

7 GPS some of these quarters are losing there utility because of all the turning to go around potholes and all the over application of fertilizer and chemical. Percentage deductions are applied based on how badly a quarter is cut up into tiny parcels that required more time and fuel to farm. Pasture and Land seeded to grass. Just looking at an air photo will not suffice for pasture. One needs to be out on the land to perform an inspection. It is interesting that the Saskatchewan Assessment Manual requires the appraiser to evaluate the productivity of land seeded to grass and determine its suitability. Land with excessive detrimental features that make the land unsuitable for crop production are best suited as pasture. One cannot determine what the detrimental features of the land are from an air photo or satellite image. Rather, an appraiser must inspect the land to determine what the excessive detrimental features of a land parcel are. Perhaps land is excessively saline, perhaps the land is too stony to cultivate or has excessive slopes or perhaps it floods nine years out ten years. Perhaps it is Solonetzic and has round tops within an inch of the land surface. One cannot simply sit in an office and look at a satellite image without doing some ground inspection of the land. One also requires knowledge on what factors severely limit land productivity to be able to make decisions. There has been very little study in Saskatchewan on the productivity of lands that have been seeded to tame grass species. Often when land is seeded to grass it is because the land has suffered from degradation, is eroded, has very little organic matter left and has low productive capability. SAMA and the Saskatchewan Ministry of Agriculture, Lands Branch, adopted the technical report: An Assessment Procedure for Saskatchewan Rangeland, Technical Report 228, 1990, by Z. Abouguendia, J. Thorpe, and R. Godwin of the Saskatchewan Research Council. The adoption of the report allowed for the rating of native pasture rangeland based on sound scientific research. The rangeland-rating model in the SAMA manual determines the carrying capacity of pasture using the formula: Carrying Capacity = Range Site x Vegetation x Tree Cover x Water Carrying capacity is in animal unit months per quarter - Range Site is the carrying capacity range site - Vegetation is an adjustment for the grass stand type: native or improved grass - Tree Cover is an adjustment for the type of tree cover: Shrub Aspen 7

8 Coniferous or Coniferous aspen - Water is an adjustment for high water table Carrying Capacity rates are obtained for pasture range sites from the Carrying Capacity table in Chapter 3, Document 3.2.2, page 7 of the Saskatchewan Assessment Manual The vegetation type adjustment factor is: 1 for native grass stands 1.3 for improved grass stands 1.3 for improved reverting grass stands, and 1.0 for reverted grass stands Tree Cover adjustments are found in Chapter 3, Document 3.2.2, page 9 to 11 of the Saskatchewan Assessment Manual The water table adjustment table is found in Chapter 3, Document 3.2.2, page 12 of the Saskatchewan Assessment Manual Carrying Capacity: This is the potential productivity of the range and can be defined as the average number of animals that can graze the range for a specific number of days without inducing degradation to the range. The concept of grazing capacity assumes proper management of a nondegraded range. Carrying capacity depends on the range site quality, type of vegetation, and climatic characteristics Range Condition: the parameter or tool that relates the present productivity of the range to its natural potential productivity. Stocking Rate: - is the actual number of animals on a specific period of time, usually a grazing season. Actual Stocking rate depends on range condition, current season s precipitation, topography, grazing management and the availability of range facilities. Animal Unit Month: a term used to describe the carrying capacity of pastures. Carrying capacity is based on the forage requirements of a 1000-pound cow, with or without calf, for one-month. Forage requirement 780 pounds of dry forage per month. Range Site: - different kinds of rangeland are called range sites. Range sites are ecological subdivisions and are, in effect, different rangeland capability classes. Range sites are ecological subdivisions into which rangeland is divided for the purpose of study, evaluation, and management. Range Site Determination There are about 13 major range sites and a number of inter-grade range sites. In total there are about 43 different range sites and agrologist can identify in the assessment manual. In 5 soil zones this results in about 200 range sites in Sakatchewan for the 15.9 million acres of pasture. 8

9 Major range site factors that influence forage production and management are: Soil Moisture: Available soil moisture depends on such things as: o Depth of soil profile development o Texture o Organic matter o Topography o Amount of precipitation characteristic of the ecoregion and o Amount of evaporation characteristic of the eco-region Soil Nutrients: Available soil nutrients depend largely on the following: o Organic matter content o Soil texture, and o The type of parent material Salinity: Soil Salinity is influenced by: o The type of parent material o Internal drainage, and o Soil texture Each range site has its own characteristics that result in a specific plant community or level of productivity, which make it different from other range sites. Range sites for a particular region are commonly determined on the basis of the following criteria: Differences in the dominant plant species in the climax or original plant community - If one is inspecting pasture that has been closely grazed, one will not see the original plant community as it might have been invaded by other plant species Differences in the proportion of the most important species in the climax plant community Differences in the total annual yield of the climax plant community Steps in Identifying Range Ecosites: Read the Soil Survey map for the area and review SAMA soil maps Look at the land surface Dig a soil pit and look at the soil profile Determine the texture of the soil Determine the soil association by identifying the parent material and soil profile Identify the topography rating (estimate the average slopes) Identify the range site by reading descriptions of the possible ecosites Determine the kind of the vegetation native or improved Determine if part of the pasture is covered with aspen, shrubs, or coniferous trees and if a tree over deduction is required Determine if there is a high water table present Find the grazing capacity using the appropriate guide Calculate the total number of animal unit months (AUMs) for the site 9

10 Convert AUMs per acre to animal unit months per quarter by multiplying by 160 Determine Soil Zone and Soil Type: The first step in identifying range sites is to read the soil map for the area. The Land Resource Unit of Agriculture and Agri-Food Canada has mapped the soils of Saskatchewan. Soil maps and reports can be ordered from: The Saskatchewan Land Resource Centre 5C26 Agriculture Building University of Saskatchewan Campus 51 Campus Drive SASKATOON SK S7N 5A8 (306) The link to the maps online is The areas shown on a soil map are called map units. Each map unit has a different distribution of soil series within it. For example, the soil map for the Saskatoon map sheet shows that Biggar soils (Dark Brown soils formed on gravely parent materials) occur in three map units: Biggar 1, Biggar 2, and Biggar 3. In all three, the dominant soil series (the one occupying the largest area in the map unit) is Biggar Orthic Dark Brown. However, in the Biggar 2 map unit there is also a significant area of Biggar Orthic Regosols, while in Biggar 3 map unit there is a significant area of Biggar Carbonated and/or Saline Chernozemic Dark Brown soils. Usually, we will base the range site on the dominant soil series in the map unit. The soil map also shows the surface soil texture and the slope class in each mapped area. The Map Unit Table shows how to determine the most likely range site based on the soil map unit. The Soil Series Table shows how to determine the range site if you know the soil series. For example, if the map unit is Biggar 3, the Map Unit Table shows that the most likely range site is Gravely. However, you could also use the soil series. The dominant Biggar Orthic Dark Brown series corresponds to the gravely range site, but there is also a significant area of the Biggar Carbonated and/or Saline Chernozemic series, which corresponds to the Saline Upland range site. The Map Unit Table also shows that the surface texture and slope class on the soil map may be used in some cases. For example a soil, which would normally be placed in the Sandy Loam range site, may have a surface texture of gravely sandy loam. In this case, the site would change to Gravelly. Similarly, a soil that normally would be placed in the loam range site classification may have very steep slopes in a given mapped area (slope class 7), which would change the range site to Thin to TX. Areas of wind-blown sand are usually mapped as Antelope, Vera, or Edam soils. However, the range site depends on the topography. Areas of gentle relief (slope classes 1, 2, or 3) are placed in the Sand range site, areas of moderate relief (slope classes 4 or 5) are placed in the Sand to Dune Sand classification, and areas of steep slopes (slope classes 6 or 7) are classified as Dune Sand range site. 10

11 Determining the range site from information on the soil map will often give the right answer. However, because maps are somewhat generalized, the information on the soil map may not be detailed enough to identify the range site you are interested in. You need to look at the land surface and soil profile in the field to be sure you have identified the range site correctly. Keep in mind that if soil survey has used slope class 6 or 7 you will need to make a judgement on what range sites provide the best fit. Slope class 6 is slopes of 15 to 30 percent and this could be loamy, loamy to thin, or Thin range site. Slope class 7 has slopes over 30 percent. This corresponds to Thin to TX range site. 11