Modern soil survey tools and techniques are now widely available to farmers and consultants due to precision agriculture’s data requirements. The cost and speed of data collection are frequently more important than the precision and reliability of the information. Recently, a number of methods have been used to give soil data for site-specific nutrient management. Proximal sensing and remote sensing are some of the most widely used technologies that allow soil scientists to acquire data, both with known benefits and drawbacks.
Proximal Sensing
Due to the use of field-based sensors that are in direct touch with or close to the soil, proximal sensing has proved effective in gathering both quantitative and qualitative information about soil. These sensors are getting smaller, more time- and cost-effective, more precise, more energy-efficient, wireless, and more intelligent as technology advances.
- EC Scanners
The soil’s electro conductivity is an indirect indicator that correlates well with various physical and chemical properties, including salinity, temperature, cation exchange capacity, organic matter content, water content, depth above the clay or stone layer, and particle size and texture. The method’s excellent level of quality, low production cost, and low environmental footprint are highlighted by experts.
- EM Scanners
A quick, non-invasive way to learn about soil ECa (apparent soil electrical conductivity), particularly about soil moisture content and soil texture, is by electromagnetic induction (EMI) scanning. However, the primary soil units of the intensive soil map and the geographical position of ECa borders may not always agree to a precise 100%, since soil ECa depends on soil bulk density, organic matter content, soil texture, and soil water content. It is a fact that this would only be affordable for commercial farming if they were spread out over several years nonetheless. In fields with obvious differences in soil texture, EMI surveying techniques can offer a practical, affordable option to support traditional practices.
Remote Sensing
Remote sensing systems are currently providing data on the characterisation of the land surface and subsurface at ever-higher spectral and spatial resolutions. The purpose of the study, the specific characteristics of the items at the earth’s surface, and the weather conditions are all equally significant factors for choosing the best remote sensing methods (either space-borne or air-borne).
- Satellite Images
The development of a wide variety of medium resolution space-borne sensors on stable and fixed orbits has largely been the driving force behind the use of satellite images in soil research. Cost and availability are still major concerns since high-resolution imaging is more expensive and less likely to cover the region of interest. Scientists may assess soil characteristics quantitatively with a variety of space-borne platforms at a significantly lower cost per unit of coverage. Therefore, satellite images are particularly helpful for studying vast areas. Higher resolution data also need a lot of storage and processing capacity. Some important resources that were released before 2000 feature a low access barrier, a large scene size, and appropriate repeat coverage. It is also noteworthy that images from Landsat 8 and Sentinel-2 are free to use.
- Digital Elevation Model
The Digital Elevation Model (DEM) is a 3D representation of the bare soil surface, without depicting any objects that may exist on it. As a quantitative data source, it has consistency and homogeneity, not to mention that edge-matching issues and data generalization issues are much diminished. Elevation, slope, aspect, curvature, potential drainage density, and other parameters are all DEM-derivatives and can exhibit a strong link with the soil classes. This technique is used to map enormous regions quickly and cost-effectively. The method’s effectiveness, meanwhile, depends on the quality of the picture used as input and the meticulousness of the pre-processing.
So, in order to identify the circumstances under which these tools can be used effectively and provide the necessary precision and reliability, a validation of these tools should be performed. Precision agriculture is a rapidly growing industry and is intended to be one of the main tools for sustainable agriculture.