Some considerations about soil sampling
Dear readers, in agricultural ecosystems, although all the components that make them up are important, there is one in particular “the soil" that significantly influences the production of crops because in addition to serving as a means of support for plants, it supplies the nutrients necessary for their growth and development. In this sense, to know the characteristics of this important component, a series of agronomic practices have been developed, among which is soil sampling, which is carried out to take a portion of this element to be analyzed in laboratories to determine the fertility of the same, through physical, chemical and microbiological analysis.
For the aforementioned, the previous step for the soil analysis is logically to perform a soil sampling in the field which must be representative of the entire cultivated area or where it is intended to establish a crop, all this because the soil is not a homogeneous mass, since it may have variations from place to place due to natural factors such as, for example, the topography of the area, vegetation or any management that has been implemented by the producer or field technician.
The methodology to be able to have a representative sample, is the taking of subsamples at different points of the agricultural surface, which are then mixed to obtain a composite sample, logically that the more subsamples the greater the representative in sampling; which is of great interest because after the analysis the recommendations will be for the entire area. The amount of subsample will be determined by the size of the surface and the variability that the soil may have, for this, it is recommended to walk the entire area before starting the sampling and zoning some areas where there is variation to take samples in those places.
On the other hand, some producers locate information about the soils of the geographical area where their farm is located in government or private institutes that are dedicated to geographical characterization, but this information is very generalized and as we mentioned above this may vary due to some management factors that occur in the production unit.
Below are some steps that can be followed when performing a soil sampling:
- First of all, as mentioned in a previous section it is important to make a tour of the entire surface that is planned to be sampled, then to work in an organized way you can draw a sketch delimiting the areas that we consider heterogeneous in terms of soil color, topography among other characteristics and specify the number of subsamples to be taken.
- Use appropriate tools for sampling such as boreholes or boreholes that allow approximately the same volume of soil to be removed in each subsample.
The composite samples some technicians point out that it should not be of areas greater than 10 hectares, however, we consider that they are not greater than 5 hectares with the possibility that the sampling is more representative.
What is recommended regarding the depth of the soil at the time of taking the sample is that it be taken at 20 or 40 cm deep in soils cultivated with fruit trees or other crops with deep radical systems and 10 cm in soils planted with grasslands, there influences the depth of the radical system that the planted crop has, in the case of grasslands it has its superficial radical system therefore it does not go much deeper in sampling.
- In the case of the periodicity that soil samples can be taken, this can be done every year or every three years, and it should also be considered to take the samples about 4 months before planting, in order to have data of interest to establish an adequate fertilization plan.
| Final considerations |
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Dear readers, the materials to be used for a soil sampling, are shovels, boreholes or boreholes depending on the availability that the producer has, it is also used plastic buckets where all the subsamples begin to be stored to then mix them and take a composite sample. Then bags are used to place approximately 1 kg of soil and this must be identified with some data such as name of the farm, name of the farmer, region, specify the place where the sample was taken, depth of the sample, sampled area, crop to be sown among other information of interest.
| Bibliographic references |
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- Castillo, N. (2005). Introduction to the study of soil and fertilizers. Spasande. Caracas: Venezuela.
- Casanova, E.(1996). Introduction to soil science. Central University of Venezuela.
- FitzPatrick, E. (1996). Introduction to soil science. Trillas: Mexico.
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