Precision Soil Map for Future Vineyards. Maple Grove Road Farm Acre Tract Maple Grove Road, Monmouth, Oregon.

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1 Precision Soil Map for Future Vineyards Maple Grove Road Farm Acre Tract Maple Grove Road, Monmouth, Oregon. July 30, 2008 By Andy Gallagher Soil Scientist

2 INTRODUCTION AND BACKGROUND Soil diversity and soil quality within the vineyard can profoundly affect winegrape management and quality. Winegrowers use soil information to guide vineyard development and management. Winemakers are emphasizing the soil and site characteristics in their wines and are providing this information to wine drinkers who are increasingly discriminating. Site selection is a critical first step in the production of fine wine, and site specific soil and terrain information are major drivers of site selection. This soil investigation was done to evaluate the soils for vineyards on a acre tract consisting of two parcels, TL with acres and TL with acres located on Maple Grove Road in Polk County, Oregon. Soils here are more diverse than they are shown at the 1:20,000 scale of the county soil survey. This report provides more detailed site-specific soil information, identifies potential viticultural soil management issues and provide an estimate of plantable acres. The report is not intended to give a precise acreage suitable for vineyards, since that figure is influenced by many management decisions, practices and levels of acceptable risk. Current Land Use At the time of this survey this site was partly in Christmas trees and partly in grass fields. The noble fir Christmas trees appeared to be in excellent condition. Small areas are in pole sized Douglas fir. The Lukiamute River flows along and near the southern boundary of the parcels, where there are bottomland soils with high potential for irrigated cropland and orchards. There is an old rock quarry on the site that is no longer used and has become a small farm pond; western pond turtles, newts and many bullfrog tadpoles were observed in the pond. The Lukiamute banks have thick growth of reed canary grass and giant smartweed. Geology and Topography The parcel is situated on gently sloping benches to very steep side slopes of the foothills of the Oregon Coast Range on the west side of the Willamette Valley. Much of the survey area is south, southeast and southwest facing with smaller areas that are steep and north facing. Underlying rocks on the main slopes are marine sedimentary rocks with small areas of basalt. The abandoned rock pit has vertical basalt walls that rim the pond. Basalt outcrops in places on the west parcel. Alluvium of the Willamette Silt influences soils at elevations of feet m.s.l. and lower in the Willamette Valley which includes all of the foothill soils on this site. Elevation of the parcel ranges from about 240 feet on the lowest part along the creek on the south side up to about feet above sea level on the ridge in the northwest corner near Maple Grove Road. Small intermittent streams and springs flow in the winter and spring in narrow drainage ways.

3 Previous Soil Mapping The Soil Survey of Polk County Area delineated primarily well drained moderately deep Soils, very deep soils, and shallow Chehulpum soils on the foothills. Well drained, deep Cloquato and Chehalis soils were mapped on the floodplain, and poorly drained Waldo soils were mapped in the drainage swale in the middle of the tract. and Chehulpum soils formed from colluvium and residuum of sedimentary rocks on the foothills of the Coast Range. soils formed in colluvium of sedimentary rocks and basalt (GIS soil data layer NRCS). Cloquato soils and Chehalis soils formed in loamy alluvium. The previous soil map is shown in an attached map of soil types. The soils in this foothill setting are usually moist but are dry for 45 to 60 consecutive days during the summer between depths of 4 and 12 inches. METHODS This investigation was conducted July 10, Fifteen soil borings were made to classify soils and terrain and to record soil properties including soil drainage, depth to bedrock and rock type, surface thickness, soil texture of the surface and the subsoil. For each boring, a soil core was observed to a depth of 60 inches (or shallower where bedrock is restrictive or where wetness prevented a deeper sample). Average sampling intensity was approximately one boring per four acres of suitable terrain. Soils were described from 3-inch diameter soil cores to a depth of five feet. Boring locations were recorded using a GPS receiver to 1 m accuracy. Revised map and acreage calculations were made in AUTOCAD based on GPS locations. An orthophotograph and maps of elevation and slope aspect were used to help delineate areas suitable for viticulture based on slope configuration. The contour map was generated from a 10-m digital elevation model and shows elevation contour interval of five feet. Slope gradients were measured at each soil boring. The attached slope aspect map is useful in showing the overlay of contour lines and color shaded slope aspect (direction that the slope faces), showing both the direction the slope faces and the steepness of the slope, which are two factors that impact the amount of solar energy available at any point. RESULTS Soil boring data are shown in Table 1. There are an estimated 61 acres that have soils and slopes suitable for vineyards on this tract. Areas considered suitable to winegrowing on this parcel are grouped into map units based on parent material, soil association or some other property such as depth and drainage (Areas A, B, C, D and E on the revised soil map). There are from 10 to 20 acres of the vineyard acreage where artificial drainage is recommended. Areas that are either too steep (labeled Steep) or have a strong north aspect (labeled North) are shown on the soil map and are not considered in vineyard acres. Some of the lower lying acres are in drainage ways and on the flood plain of the Lukiamute River, these are not included in the vineyard acreage. The floodplain soils were not sampled since they are low lying with high frost risk and are very fertile and are not considered suitable to high quality winegrowing in the present in today s market. Red Hill Soils 2

4 Estimates of acreage suitable for vineyards are subjective and may in practice include more or less acreage for a number of reasons including viticultural practices, easements, block layouts, other site features and inclusions of small unsuitable areas. The area considered suitable for vineyards is based on soil borings, aerial photographs, topographic maps and other information sources interpreted within the framework of prevailing winegrowing practices used in the Willamette Valley. Soil Evaluations Summary soil data and best-match classification are provided for each of the soil borings (Table 1). Soils that are named for each sample plot are the closest match of established NRCS soil series, and are managed similarly to those sampled. Where properties are outside of the range of properties for the named series they are noted and discussed. Soils summaries are provided that describe the properties of the established soil series. Additional information about these soils is available from the Soil Survey of the Polk County Area and on the internet ( Table 1. Summary Soil Properties from Soil Boring Data. Depth to Seasonal Depth to Crhorizon Available Water Boring Soil Name(s)* Slope (percent) High Water Table (IN) (IN) Holding Capacity (IN) 1 Windy Gap 3 >60 > Witzel 15 well drained R-Horizon at Windy Gap 10 > Dupee-Wellsdale Dupee Windy Gap Hazelair Sitton 4 41 > Windy Gap-Dupee Wellsdale-Sitton Chehulpum 5 well drained Wellsdale 3 33 > > > Soil Map Unit Summaries Soil map units are mapped as complexes of soils with suitable soil groups A, B, C, D and E and non-suitable areas are also delineated and labeled as steep areas, north slope and bottomland. Red Hill Soils 3

5 Map Unit A This map unit is a complex of winesoils that are well drained and formed in colluvium of sedimentary soils. These soils are on ridges and side slopes with less than 30 percent gradient. Soil depth ranges from moderately deep to deep to weathered siltstone, but also include small areas of shallow soils. Soil series include the well drained moderately deep and deep Windygap soils. These soils have AWHC of 6 to 10 inches. These soils are suited to dry land viticulture; however the vines will need to be watered during the first few years growth until they are well established, and in spots where soils are moderately shallow with (4 to 6 inches AWHC) vines may show moisture stress during drought and these can benefit from irrigation. The Windygap series consists of deep soil with reddish clay subsoil and the series was established from soils previously mapped as, except Windygap soils have sedimentary rocks at 40 to 60 inches. So much of the soil that was previously mapped in Polk County is correlated to Windygap. Map Unit B This map unit is a complex of winesoils that are moderately well drained to well drained and formed in colluvium of sedimentary soils. The soils included are the moderately well drained Wellsdale and Dupee and the well drained Windygap and Sitton soils. In places the soils are intermediate between these series. Growing conditions can be improved if these soils are artificially drained. The extent and configuration of drainage will vary with depth to seasonal water table and soil hydraulic conductivity. More detailed soil mapping should be done prior to drainage system design to better delineate soils needing drainage from the better drained soils. Map Unit C This is a broad swale of gently sloping Hazelair soils that are somewhat poorly drained. These soils have seasonally high water tables from 12 to 20 inches and have very clayey subsoil so they need extensive artificial drainage and irrigation to be used as winesoils. They are prone to winter and spring wetness, strong early season canopy growth and then droughtiness in the late growing season. These soils often have superficial rooting profiles that can be deepened with artificial drainage. Irrigation provides relief from the natural droughty character of these soils. Map Unit D This unit includes winesoils that are shallow to siltstone. These soils are Chehulpum soils and have siltstone from 12 to 20 inches depth. The Chehulpum soil was previously mapped more extensively in the soil survey on the steep slopes. These steep slopes were not sampled because they are considered too steep. These soils are typically on the more convex parts of side slopes and on slope breaks. It is suspected that this unit is a minor inclusion in the other map units, and would need higher resolution mapping to identify them. Where identified these are areas where it Red Hill Soils 4

6 may be practical to deep subsoil the siltstone to increase rooting volume and AWHC of the soils. Available water holding capacity of these soils is low to very low (1 to 3 inches). These soils need irrigation in most years because they are droughty, and show low vine vigor. Map Unit E This unit includes soils that are shallow to hard basalt. These soils are Witzel and probably include moderately deep stony Ritner soils. Witzel soils and have basalt at 12 to 20 inches depth. These soils were not previously mapped on this site, and represent a small area. Available water holding capacity of these soils is low to very low (1 to 3 inches). These soils need irrigation in most years because they are droughty, and show low vine vigor. More detailed mapping will be needed to identify other areas of Witzel soils. Steep These are areas where slopes are greater than 30 percent gradient based on either direct slope measurements or on topographic maps derived from 10 m digital elevation models. Field measurements generally agree with contour map on slope gradient. A better estimate of the area of this unit can be made after trees are harvested and land is cleared. North This area is north facing and steeper than 12 percent gradient. North aspect slopes are generally not considered suited for winegrapes when steeper than 12 percent because the vines do not get sufficient heat to consistently ripen fruit. Bottomland These areas are located in areas where there are fertile floodplain soils that are periodically flooded by the Lukiamute River, and also includes drainage swales where the soils are wet or where runoff is concentrated into channels. Flood records are not included in this determination. These areas are either too wet for winegrowing or have erosion and runoff hazards that make planting impractical. Additionally the low-lying site position carries with it an increased risk of frost. SOIL SERIES SUMMARIES CHEHULPUM Chehulpum soils are weakly developed and are shallow (12 to 20 inches) to weathered siltstone. Available water holding capacity is low and vine vigor is low on these soils. Winegrapes grown on these soils need vigorous rootstocks and irrigation during establishment and during summer drought. Siltstone is typically highly fractured and Red Hill Soils 5

7 rooting is deep. There are inclusions of soils that are very shallow (<12 inches) associated with the Chehulpum soils. DUPEE SERIES The Dupee series consists of deep, moderately well drained soils that formed in moderately fine and fine textured colluvium overlying weathered sedimentary bedrock. These soils are on side slopes and ridge crests. The subsoil has moderately slow permeability. Available water holding capacity is medium low to medium. On this site the Dupee soils are moderately deep to deep to weathered siltstone. These soils occur on side slopes, ridges and foot slopes. Rooting is generally deep. WILLAKENZIE SERIES soils are on foothills adjacent to the Willamette Valley. They occur on ridges and side slopes. These soils have loamy subsoil. These soils formed in colluvium and residuum mainly from sedimentary materials. soils are moderately deep, well drained with moderate permeability in the upper part and moderately slow permeability in the clayey subsoil. They grade into Chehulpum soils where shallower to siltstone and they grade to Windygap where deeper than 40 inches. Much of the basic cations have been weathered from these clayey foothill soils, which can be very strongly acid. Clay minerals and organic matter are the part of soil where cation exchange with the soil solution and plant roots occurs. These soils have moderate available water holding capacity and yield moderate vine vigor. The subsoil is yellowish brown to brown silty clay loam. They have moderate to strong soil structure and good internal drainage. These soils do not typically need artificial drainage and are suitable to dry land farming though they are typically irrigated where a source of water is available. HAZELAIR SERIES These soils are moderately deep and moderately well drained. They have a very clayey substratum that has predominantly smectitic clay mineralogy. These soils need artificial drainage, that uses intercept drainage lines, which capture lateral flow and divert water away from these soils. These soils tend to be wet in the winter and droughty in the summer, but if drained and irrigated they can produce high quality wines. SITTON SERIES Sitton soils consist of deep to very deep, well drained soils that formed in colluvium weathered from siltstone and sandstone. Sitton soils are on side slopes of hills and foot slopes. These soils have moderately slow permeability. Sitton is recently established soil series name for soils similar to but deeper. Because these soils are deep they have moderately high available water holding capacity and produce more vine vigor than the moderately deep soils. On this site the Sitton soils are a minor component of the foot slope and lower bench. Red Hill Soils 6

8 WELLSDALE The Wellsdale series consists of deep, moderately well drained soils that formed in loamy colluvium overlying weathered sedimentary bedrock. These soils are on side slopes and ridge crests. The subsoil has moderately slow permeability. Available water holding capacity is medium to medium high. On this site the Wellsdale soils are deep to weathered siltstone. These soils occur on side slopes, ridges and foot slopes. Wellsdale soils have less clay than Dupee. Rooting is deep. WINDYGAP SERIES Windygap soils consist of deep, well drained soils that formed in colluvium and residuum weathered from sedimentary rock on ridges and side slopes of foothills. It is believed these soils are influenced by basaltic colluvial sediments, on these foot hills where the bedrock is mixed basalt intrusions and siltstone. These soils have moderately rapid runoff and moderately slow permeability. Available water holding capacity is medium high to high. They have reddish clayey subsoil and compared to other soil series Windygap soils are a transition between and Bellpine soils. Depth to Weathered Bedrock (Cr-horizon) The Cr-horizon retains rock structure and appearance but is soft enough to be dug into with hand tools. The depth to weathered bedrock on this site is typically the depth to the top of the Cr-horizon, which on this site is weathered siltstone and sandstone. The observed depth to siltstone is as shallow as 12 inches to more than 60 inches. The Witzel soil has a hard basalt bedrock at 12 to 20 inches. Depth to bedrock affects the total rooting volume of the soil and hence also affects the available water holding capacity. Root presence was determined by observed roots in soil samples or by presence of soil morphology that is indicative of the roots presence, such as illuvial clay films and organic coatings in the rock fissures. Typically there is evidence of deep rooting in these soils. Soil depth to bedrock can be used as a factor in designing vineyard blocks and in identifying areas that are likely to be droughty. These soils have good subsoil structure, deep rooting and fractured soft siltstone substrata that are conducive to deep rooting. In Map Unit D where soils are shallow to moderately shallow there may be a benefit from deep subsoiling on the AWHC and vine survival. This area is relatively small part of the whole site and deep subsoiling below two feet on the rest of the site is probably not cost effective. The Witzel soil has hard bedrock that can cause problems if deep ripped because the site will become very stony on the surface as the hard rock is brought up. Available Water Holding Capacity (AWHC) Reported AWHC is the amount of the water that can be stored in the soil profile that is available for plant uptake; it represents the amount of water held between field moisture capacity and the permanent wilting point (reported in inches of water). The value reported is calculated from a model based on the sum of the weighted average AWHC Red Hill Soils 7

9 for each soil horizon, using values reported in the literature and measured soil profile data at each numbered point. The AWHC is a function of soil depth, texture, organic matter, bulk density, porosity, and soil osmotic potential. Root restricting layers decrease the depth of the soil profile and the AWHC. Clay soils hold more total water, but have less available water than loamier soils. Clay soils have extremely fine micropores that can retain water at highly negative matric potentials. As soil moisture potentials become more negative (as soils dry), sandy soils hold less total water than finer textured soils, because a larger percentage of the pores are large and are freely drained. Since the majority of grape roots are in the upper soil profile, the AWHC values for the upper root zone provides a useful relative scale of the variability in water supply available to the vine for the classes used here. Potentially droughty areas of the vineyard are moderately shallow soils that have moderately low to low AWHC (1 to 4 inches). Moderately deep soils here have moderate amounts of available water (4 to 7 inches) and these soils can be droughty after prolonged dry spells. Soils with moderately high to high AWHC (8 to 10 inches) will show less moisture stress; these soils tend toward high vine vigor. Where soils have moderately low AWHC and tend towards droughty, this condition can be addressed with management options of micro-irrigation, vine spacing, use of the more drought tolerant rootstocks, and by using managed competition from cover crops and selected native vegetation. Soils with higher AWHC can be managed under dry land conditions and rootstocks that reduce vigor are usually favored on such soils. Varying the cover crop mixture, customizing the mowing and tillage treatments and adjusting vine spacing to match the vine vigor potential of the soil can provide managed competition towards achieving balanced vine growth. For example: more vigorous grass cover crops can be used to compete with the vines for water in deeper soils. In droughty soils, less competitive cover crops may be more appropriate. Alternate row tillage can be used to further reduce competition in low vigor potential soils. Mulching in the vine row will help conserve soil moisture. Seasonally High Water Table (Soil Drainage Interpretation) Soils with wet subsoil include the moderately well drained Dupee, Wellsdale and the somewhat poorly drained Hazelair soils. The poorly drained Waldo soils were not sampled in this survey but were previously mapped in the swale. Saturated soils associated with perched water tables correlate with subsoil redoximorphic features of soil mottling from iron accumulations and depletions. Research in Western Oregon has shown that these Cr-horizons have very low hydraulic conductivity and often result in perched water zones. The soil water moves subsurface laterally down slope. Where water tables intersect the ground surface, seeps occur, and several such areas experience overland flow in the winter rainy season. Red Hill Soils 8

10 Installing drainage lines into the soils with seasonally high water tables can reduce the duration of wetness, the amount of subsurface flow and runoff in the winter and reduce water erosion, an important management issue on this site. A combination of intercept drainage, which diverts water from upslope areas, should be used with pattern tile drainage to increase the depth and reduce the duration of seasonal water tables. The Waldo soils in the swale are too wet for winegrowing. Recommended Soil Mapping Needs: This soil investigation was done to identify soil types at a finer resolution than the soil survey and to make general interpretations for vineyards in preparation for the sale of the land for development into a vineyard. It is recommended that prior to actual development and following land clearing, important soil properties be precision mapped in finer detail with an emphasis on accurate mapping of parent material types, soil depth classes, available water holding capacity and drainage classes. This allows more opportunity to strategically design blocks in the vineyard and can serve as a foundation to a more nuanced approach to viticultural soil management. An average recommended intensity in precision mapping is one soil observation per acre. In precision mapping soil borings are located with using a global positioning system (GPS). Soil properties can then be mapped using geographic information system (GIS) to produce color thematic maps of depth, drainage, and available water holding capacity to guide drainage design, site specific rootstock and clonal selections and irrigation cells. Surface and subsoil fertility mapping is an available option and can be used to guide site specific soil nutrient management and to further refine vineyard blocks. Red Hill Soils 9

11 Map 1. Revised soil mapping, soil borings and slope measurements (1-15), suitable areas A-E, and unsuitable areas including extremely steep slopes, steep north-facing slopes, bottomland and wet soils. Maple Grove Road North D B C B A Steep A E Steep River Bottomland Lukiamute Red Hill Soils 10

12 Maple Grove Road Property NAIP Imagery Maple Grove 8A! Tarter Study Site Elevation Contour 50' 5' Feet Approximate Property Line Map by Red Hills Soil, Corvallis, Oregon GIS services provided by Northwest Vineyard Service, Inc. Aerial Photo by NAIP Elevation data derived from USGS 10M DEM. Taxlot data by Polk Co GIS. Actual field conditions may vary.

13 Maple Grove Road Property USGS Quad ! A! ! A! A! Study Site Approximate Property Line 0 1,000 2,000 Feet Map by Red Hills Soil, Corvallis, Oregon GIS services provided by Northwest Vineyard Service, Inc. Aerial Photo by NAIP Elevation data derived from USGS 10M DEM. Taxlot data by Polk Co GIS. Actual field conditions may vary.

14 Maple Grove Road Property NRCS Soils McBee Waldo Waldo McAlpin Chehalis Cloquato Wapato Newberg 6 Chehulpum Newberg Newberg Study Site Elevation Contour 50' 5' Feet Approximate Property Line Chehulpum Xerofluvents Waldo Rickreall Cloquato 12 Rickreall 13 7 Water Bellpine Maple Grove 8 9 Cloquato Chehalis Chehulpum Cloquato Bellpine Suver Cloquato Suver Bellpine Malabon Coburg Tarter Map by Red Hills Soil, Corvallis, Oregon GIS services provided by Northwest Vineyard Service, Inc. Aerial Photo by NAIP Elevation data derived from USGS 10M DEM. Taxlot data by Polk Co GIS. Actual field conditions may vary.

15 Maple Grove Road Property Elevation Maple Grove Tarter Study Site Elevation Contour 50' 5' Feet Approximate Property Line Elevation (Ft) Map by Red Hills Soil, Corvallis, Oregon GIS services provided by Northwest Vineyard Service, Inc. Aerial Photo by NAIP Elevation data derived from USGS 10M DEM. Taxlot data by Polk Co GIS. Actual field conditions may vary.

16 Maple Grove Road Property Aspect Maple Grove Tarter Feet Study Site Elevation Contour 50' 5' Approximate Property Line NORTH WEST EAST SOUTH Map by Red Hills Soil, Corvallis, Oregon GIS services provided by Northwest Vineyard Service, Inc. Aerial Photo by NAIP Elevation data derived from USGS 10M DEM. Taxlot data by Polk Co GIS. Actual field conditions may vary.

17 Maple Grove Road Property Slope Maple Grove Tarter Feet Study Site Elevation Contour 50' 5' Approximate Property Line Slope (percent) > 30 Map by Red Hills Soil, Corvallis, Oregon GIS services provided by Northwest Vineyard Service, Inc. Aerial Photo by NAIP Elevation data derived from USGS 10M DEM. Taxlot data by Polk Co GIS. Actual field conditions may vary.