To evaluate soils for one or more uses, an inventory must be made to determine the locations and extent of different soils. Such an inventory is called a soil survey. However, many soil surveys have been financed with no clear idea of just what question/s the map and/or report was to answer. The following paragraphs can be useful when considering a soil survey and land evaluation.
- What is a soil survey?
- Who uses a soil survey?
- What kind of soil survey to use?
- Who is responsible for a soil survey?
- What does a soil survey contain?
- Who benefits from a soil survey?
- What are the benefits of a soil survey?
- What is the usable life of a soil survey?
- How much does a soil survey cost?
A soil survey is the process of studying, classifying, evaluating and mapping soils so that predictions can be made about their behavior for one or more uses.
A quality soil survey must predict soil properties influencing their uses and management as, for example, slaking and dispersion causing surface sealing, waterlogging and erosion on this land.
For many years, soil surveys have been used almost exclusively by agriculturalists and irrigators to select and manage the land according to their needs. In recent years, however, the value of soil survey information has been widely recognised by engineers, community planners, hydrologists, educators, miners, realtors, environmentalists, foresters, builders, managers of military land, and others.
There are many kinds of soil surveys in use, none of which apply universally as they are designed to suit different purposes. They operate at different levels of intensity, scaling, accuracy and cost.
We understands that a set of different soil properties are of critical importance for different uses, and our soil surveys are tailor-made to suit the specific needs of a particular project or a land user; corporates, private enterprises or government agencies. We use almost exclusively ground truthing and soil profiling, which is the only internationally-recognized system that has stood the test of time.
In most countries, only accredited soil scientists with adequate training in soil surveying and amelioration are licensed to engage in this kind of work. However, there are exceptions.
A quality soil survey is done only once, and it is vitally important to use only the most experienced personnel and the finest available technology to get the best possible outcome for your money the first time round.
John Rasic Consulting does not engage inadequately-trained staff to do field work, even though their low hourly rates may have some appeal. Instead, we roll up our sleeves, jump into the soil pits and do the “dirty” work ourselves, as we understand that soil maps and reports based on incorrect data can be extremely damaging for land users.
Every soil survey is different and their contents depend on the purpose, kind, scale, accuracy, intensity of sampling and soil complexity.
For some projects, thousands of sampling sites may not be enough to evaluate the land. For other projects, no or only a few sites could be enough to guide decision making.
Our surveys may, therefore, range from only a verbal report to a full comprehensive report with highly detailed maps, recommendations, modeling, satellite images, video clips and other forms of popular media.
We all do! When we better understand the soil under our feet, we have a better chance of not destroying one of the world’s most valuable and non-renewable resources that is basic to all life processes. Soils are always difficult and very expensive to improve once they are physically degraded or chemically depleted.
The main benefit of a soil survey is to provide the right information regarding the right use of the right soils for the right purposes. For example, poorly drained soils are unsuitable for most agricultural crops but suitable for rice. Well-drained soils are favorable for most crops but unsuitable for rice.
As you want to know if a particular crop, irrigation system, remedial work or management practice will work for you, a soil survey provides information that can save you costly experiments.
Some soils will respond readily to certain treatments, others will not; some benefits will be immediate, some will occur over time, and some may not be realized for many years. A soil survey can predict whether the suggested treatments are likely to succeed and help you to minimise guesswork that may lead to poor choices, expensive remediation, irreversible damage, failure, bankruptcy, litigation and unwanted publicity.
Unlike infrastructure, soil survey information is not subjected to wearing and tearing or changes in the climate, economy, water supply, invasion of pests, diseases, and the like. It is a once in a lifetime investment that will outlive your project and pay for itself many times over.
A soil survey can assist you in the making of informed decisions before the pre-designing stage, thus minimising the risk of potentially greater expenses associated with resurveying, redesigning, reamelioration, reinstallation, replanting and refinancing in later stages.
The usable life of a soil survey, based on soil profiling, is in order of 80 or 100 years and more. Some data will be usable for centuries (e.g. morphology, texture, stratification, cracking, parent material, etc.), while others will benefit from frequent revision (e.g. fertility, compaction, permeability, salinity, etc.).
As a rule, the more intensive the survey, the greater the effort required in compilation and, consequently, the greater the accuracy and cost. World-wide experience has demonstrated cost:benefit ratios in the order of 1:40, 1:100, 1:200 and more.
In some countries like Australia, for example, soil survey for irrigation developments are compulsory and, must be based on soil profiling and a 75m or 100m rectangular grid sampling (i.e. sampling density of 1pit/0.6 Ha and/or 1pit/1Ha). Such a high intensity soil survey generally costs between 1.5% and 5% of the total set-up cost of a project.
This cost may seem high when taken out of context, but it is very low in relation to the cost of the land, the farm’s equipment and establishment costs. A soil survey has the same meaning to an irrigation development as a foundation to a skyscraper. The cost, however, is only a small fraction in comparison to major engineering work such as land preparation, levelling, ripping, dams, canals, drainage, irrigation systems, storage facilities, pump stations, power lines, etc., all of which can and must benefit from soil survey information.