Soil Testing

FAQ

Soil

Testing

The objective of soil testing is to create a soil environment that will allow plants to grow their best.

Proper soil nutrition ultimately leads to more beautiful and productive plants and a reduced need for fertilizers and pesticides. A soil test will allow you to eliminate guessing when applying fertilizers, select more appropriate plants, and identify potential problem areas.

Over-fertilization (even with organic fertilizers) can allow nutrients, such as nitrogen and phosphorus, to pollute our rivers, lakes, and ocean. 

Under fertilization will cause plants to grow more slowly and be more prone to diseases and pests.

Testing

Situations

New Landscapes

Soil testing is especially important at new home sites. Areas that have been graded to the subsoil are often deficient in all nutrients, especially the micro nutrients.

Renovated Landscapes

Established plantings can be revitalized by the addition of proper amendments. Existing gardens may have sufficient fertility levels and only require individual nutrients.

Problem planting areas

Testing can reveal nutrient deficiencies or toxicities that may be affecting plant growth in certain areas.

Vegetable Gardens

Identifying key nutrients that your soil may be lacking can increase productivity. Some plants, such as tomatoes, need extra nutrients to produce the best crop possible.

Imported “top soil”

Locally available products may contain excessively high levels of salts from some compost sources. Some may also require additional amendments to correct low or high fertility levels.

Frequently Asked

Questions

A.  The Horticultural Soil Appraisal Package (H1R) is ideal for new or rehabilitative landscaping projects. Accordingly, California revised the Water Efficient Landscape Ordinance (WELO) in 2020 requiring all landscape projects to obtain a laboratory test with recommendations based on soil physical properties. The H-1-R test is WELO compliant. The H1R test package is ideal for new landscaping projects and new homeowners looking to change an existing landscape. For mineral soils, it is our most complete preplant amendment analysis. This test package sets itself apart from our other packages by including percentages of Sand Silt and Clay to provide the texture (SSCT) analysis and Calcium Carbonate (Lime) content. SSCT analysis is important to know how and when the soil should be fertilized and irrigated. For example, a high clay soil holds water and nutrients much better than a sandy soil thus affecting feeding and watering schedules. Most landscape plants prefer slightly acidic conditions. Knowing the lime content of a soil can dictate the amendment schedule. So, if you are at a starting point in a new landscape or large planting project, choose the H1R package.

(Side note: we need at least one quart of soil for this analyses)

A. Are you managing a nursery or a large-scale potted plant operation? Did you recently get a shipment of substrate media? Are you curious how your plants will grow in said media? If the answer to any of those questions is yes, then choose this package. The Substrate Growing Media Appraisal package (OM-1) is a great starting out point for any container plant producer, from landscape plants, cannabis and substrate berry operations. The package includes moisture holding capacity and air-filled porosity analyses. These measurements can tell a grower a lot about their mix. Most notably, how long they should wait between waterings and how much oxygen a plants’ roots have access to.  The OM-1 package is also helpful for someone making their own substrate mixes.

A.  The pre-plant package is incredibly useful if you are growing a crop in the ground on a large scale. Organic Matter content is a great indicator of both physical and chemical health in mineral soil. It aids in both soil structure and microbial activity. Many growers think that simply cover cropping will add enough organic matter to a field, but this is not always true. This package can tell a grower more about water holding capacity of their soil and is ideal for repeat customers. For example, a berry grower can start the season by testing their soil with this package then monitoring that plot with the General Soil Health Package (S-1-2).

A.  The short answer to this question is yes, you should. The S-1-2R package provides vital nutrient information and covers all the “chemical deficiency” problems in soils. This is our most common test package and is great for the home gardener or a grower looking to monitor the nutrient availability of a soil. That said, this package does not include any physical properties. For that, look to the H1R, OM-1R or APP-1R test packages.

A.  Yes. Yes, you should. Simply choosing a test package with no recommendations will yield useful data but not the amounts or types of amendments that should be applied. We can also provide information on where to buy fertilizers/ amendments.

A.  Negative, but we can point you to who does.

A.  Negative, but we can point you to who does.

A. Depending on the package you choose, your soil report will include the chemical and/or physical analyses and general guidelines for the crop or plants you are growing, an interpretation of the results and, most importantly, a list of recommended amendments. The report is straight forward and easy to understand. You can take the list of amendments to your local nursery or garden center.

A. You will need a random composite sample, consisting of sub-samples, of the area in which you will be planting and managing in the same way. Obtain the sub-samples from 4 to 6 different locations. An easy way to obtain these is with a clean shovel. Dig an 8 to 12 inch deep hole and place the contents to the side then take a two inch slice out of the side of the hole. Discard the upper 2 inches of surface soil. Place this sub-sample in a clean bag or bucket and mix well with the other sub-samples that are representative of where you will be planting. Place 4 cups of your mixed soil into a zip-lock type bag and label it with an indelible marker. Include your name and address and where your sample is from i.e.: front yard, veggie garden, etc. For vineyard and orchards, obtain sub-samples from the 18 to 24 inch deep range. Specific problem areas should be sampled separately.

 

A. Sample as early in the growing season as possible. For vegetable gardens and annual flowerbeds, sample in late winter or early spring. For fall plantings of perennials and cool season vegetables, sample in late summer. Send in samples 4 to 6 weeks before installing your garden or landscaping to allow for proper plant selection and acquisition of planting amendments.

A. Of course. Please specify that you would like organic instead of conventional fertilizer recommendations when you send in or drop off your sample. One thing to remember with organic fertilizers is that they have a lower nutrient analysis than their chemical counterparts so you will need a larger amount to achieve the same results. For example, if your soil is deficient in phosphorous and you need to add 25 lbs of phosphorous per 1000 square feet of planting area, you will need about 55 lbs of Superphosphate (46% P2O5). You will need about 225 lbs of bone meal (11% P2O5) to provide your plants with an equal amount of phosphorous.

A. Manures can add salts, which can build up over time and actually stress out your plants. At moderate levels, salts add fertility to the soil but at high levels they can become unbalanced and toxic. Plant roots have a more difficult time extracting water from the soil water when the Electrical Conductivity, a measure of total salt content, is above 4.0 dS/m or mmhos/cm. Mushroom compost, in particular, can have excessive potassium, sodium and chloride levels and should be regarded more as a fertilizer than a traditional compost. Unlike compost, it is a poor choice for the addition of organic matter because it will reduce its volume by about half within a year because it is still in a state of decomposition. If you choose to use mushroom compost, use no more than a one inch layer and make sure that it is well mixed into the soil. Also, do not use it as a potting soil. Many gardening books recommend the use of wood ashes to supply potassium. Too much ash can elevate soil alkalinity and potassium levels and actually stress out the plants.

Well-aged compost is a wonderful amendment that will buffer the soil pH, improve structure, water penetration, moisture holding capacity, and microbial activity but doesn’t have high fertility. As with most things, moderation is the key. A soil test may reveal that after years of adding compost and manure to your garden, you may only need to add one or two individual nutrients.

A. Yes. If you are planting a large area it may be more realistic to choose plants that will be competitive in your native soil than to add large amounts of amendments. For example, it would be easier to plant drought resistant plants in sandy soils, acid-loving plants in the more acidic soils of the mountains, or salt tolerant plants in saltier soils. The primary toxic salts are sodium chloride, and boron.

A. Generally, city water is suitable for irrigation. Some untreated well waters, however, can have high levels of salts and bicarbonates. Over time, the accumulation of salts from irrigation water can impact the plant’s ability to uptake water and nutrients from the soil. Plants vary in their ability to tolerate salt buildup. Roses and bamboo are intolerant to high salt levels while rosemary and oleander are more tolerant. Irrigating with alkaline water containing high levels of bicarbonates can increase soil pH to ranges undesirable to some plants. Water with high levels of calcium and magnesium, commonly known as hard water, will leave unsightly white spots on plant leaves when used for overhead irrigation. Most soils can be managed to accommodate poor quality irrigation water. Local well water may also contain toxic levels of boron and sodium chloride from seawater intrusion near the coast. Areas in the Santa Cruz Mountains also have pockets of salty ground water. It is essential to know the chemical makeup of water that is used in fertigation (liquid fertilizer) programs. Collect irrigation water samples in a clean one-liter bottle and fill to the top.

A. If you are planting a new landscape or garden, work the amendments evenly into the soil as deep as realistically possible. If you are amending an already established landscape, add the amendments to the soil around the base or drip line of the plant. You can mix it into the top few inches of soil in the root zone underneath the foliage or place it on top of the soil and cover with mulch. This method of top dressing will take a little longer to get the nutrients to the plant roots. Spreading out the amendment well will allow more roots near the surface to benefit from the fertilizer. If you are planting an orchard or vineyard, the amendments are to be added to the backfill soil mixture. Always water thoroughly after fertilizing to allow water to dissolve and transport nutrients down into the soil. Soil microorganisms need moisture to break down organic amendments and make the nutrients available to the plants’ roots. It may take several years for lime to increase the pH of acid soils. So it is better to begin the process sooner than later.

A. pH is known as the master variable of the soil because it controls the availability of plant nutrients. It is a measure of the soil acidity or alkalinity. A pH of 7 is neutral and less than seven is acid and above 7 is basic or alkaline. Most plants prefer to grow in a slightly acidic to slightly alkaline soil of pH 6.5 to 7.2. As pH increases, becomes more alkaline, phosphorous, iron, manganese, boron, copper and zinc become less available or more “tied-up”. As pH decreases, or becomes more acid, phosphorous, potassium, sulfur, calcium, magnesium, and molybdenum become less available. At very low pH levels aluminum and iron can become available in toxic quantities. Soils become more acid when ammonium nitrogen fertilizers are applied and when the cations calcium, magnesium, and potassium are leached from the topsoil into the subsoil. This explains why many soils in the Santa Cruz Mountains are acidic.

A soil’s pH can be increased by the addition of lime. It can be decreased by the addition of acidifying materials such as sulfur, iron sulfate, ammonium sulfate, or peat moss. All amendments need to be well mixed and watered into the soil. Soil texture will determine the appropriate rate of liming or acidifying material.

A. Texture is the measure of the relative proportions of soil particle sizes, which are divided into three categories; sand, silt and clay. The ideal garden soil is a loam, which contains nearly equal amounts of sand, silt, and clay particles. Both sandy and fine textured clay soils have advantages and drawbacks and require different management practices. Clay soils, also called heavy or fine-textured soils, are more susceptible to compaction and require higher levels of amendments, yet have a higher capacity to retain both water and nutrients. Sandy soils hold less water and fewer nutrients and are more susceptible to leaching, yet are not as prone to compaction and water-logging. Be careful not to over fertilize on sandy soils especially if you live near a creek or drainage course.

You cannot realistically change your soil’s texture. The volume of sand needed to change a clay soil to a loam would be prohibitive and likely turn your soil into adobe brick during the summer. The addition of large amounts of organic matter will improve heavier soils rather than the addition or sand to change the soil’s texture. Sandy soils like those in Ben Lomond, Scotts Valley and some coastal areas may benefit from the addition of loam soil to small garden beds but would probably benefit more from the addition of organic matter especially considering the poor composition and quality of locally available “top soil”.

Texture is commonly confused with structure. Structure refers to the way that soil particles are grouped or aggregated together to create a system of large and small pores that allow the passage of air and water. A soil with good structure will maintain its shape when dry and crumble easily when moistened and handled. Structure can be improved by adding organic matter such as aged manure, compost, nitrified sawdust, rice hulls, peat moss, green manures, or straw. Organic amendments that have a high carbon to nitrogen ratio such as brown and dry materials like straw and sawdust will provide a greater benefit once they have decomposed. The addition of a nitrogen source such as ammonium sulfate at the rate of 2.5 lbs per cubic yard will speed up the decomposition of organic matter to a point where your plants can utilize it. Fresh manures should also have a chance to decompose in the soil before planting. Good structure can be maintained by avoiding compaction when the soil is wet. Soils that contain high levels of sodium (sodic soils) often are characterized by poor structure which leads to poor drainage characteristics and can be remedied by the addition of gypsum (calcium sulfate). Although sodic soils are unlikely to be found in our area because of the high rainfall, sodium can build up in soils when irrigated with water that is high in sodium.

Soil development is influenced by parent material, climate, vegetation, aspect (southern vs. northern exposure), topography, and time. Due to variable topography with our mountains, foothill, river beds, ancient sand dunes, soils can vary considerably within a region or even a neighborhood.

The USDA’s Soil Survey catalogs and describes the local soils and their uses and limitations. To view the Santa Cruz County Soil Survey online go to The Natural Resources Conservation Service.

A. The use of cheap nitrogen fertilizers like ammonium sulfate to green up lawns can reduce pH levels and cause deficiencies of calcium and phosphorous. These deficiencies and imbalances will manifest in less vigorous growth and less resistance to disease and wear.

General Soil Health Package

S-15-R
Our most commonly ordered test package. Provides information on soil health and fertility + recommendations
$ 166
  • Fertility Analysis pH, electrical conductivity, nitrate nitrogen, ammonium nitrogen, phosphorous, potassium, calcium and magnesium
  • Sodium, Chloride, Sulfate and Boron from saturated paste extract
  • DTPA extracted Zinc, Copper, Manganese, and Iron
Popular

Horticultural Appraisal Package

(WELO Compliant) H-1-R
Complete soil chemical and physical analyses + recommendations
$ 256
  • Fertility Analysis pH, electrical conductivity, nitrate nitrogen, ammonium nitrogen, phosphorous, potassium, calcium and magnesium
  • Saturation percentage, calcium plus magnesium, sodium, chloride, boron, SAR, ESP
  • Sodium, Chloride, Sulfate and Boron from saturated paste extract, DTPA extracted zinc, copper, manganese, and iron
  • Organic Matter
  • Cation Exchange Capacity
  • Lime content
  • Soil Texture Analysis

Substrate Growing Media Appraisal Package OM-1-R

Complete chemical and physical analyses for potted plant media/ substrate + recommendations
$ 287
  • pH, electrical conductivity, nitrate nitrogen, ammonium nitrogen, phosphorous, potassium, calcium and magnesium
  • Sodium, Chloride, Sulfate and Boron from saturated paste extract
  • DTPA extracted Zinc, Copper, Manganese, and Iron
  • Porosity and Moisture Holding Capacity of Media
  • Cation Exchange Capacity

Agricultural/ Berry Pre-plant Package

APP-1-R
Complete chemical analyses for mineral soils. Beneficial for pre-planting in agricultural settings + recommendations
$ 216
  • pH, electrical conductivity, nitrate nitrogen, ammonium nitrogen, phosphorous, potassium, calcium and magnesium
  • Sodium, Chloride, Sulfate and Boron from saturated paste extract
  • DTPA extracted Zinc, Copper, Manganese, and Iron
  • Saturation Percentage
  • Organic Matter
  • SAR ESP

Other

Services

  • Petiole analysis for vineyards (please call to request a brochure)
  • Fertigation (liquid fertilizer) water analysis
  • Plant tissue analysis.
  • Potting soil analysis

We are here to help you!

Schedule Routine Testing for Your Nursery

Please include the following information with your sample(s):

  1. Name
  2. Address and phone number
  3. Email Address
  4. Planting Situation i.e.- established/new garden, new home site
  5. Sample ID
  6. Conventional or organic fertilizer recommendations
  7. Additional information about sample