hi

In general, sampling is done at the rate of one sample for every 1 - 2 hectare area. However, at-least one sample should be collected for a maximum area from 3 - 5 hectares. For soil survey/sampling work, samples are collected from a soil profile representative to the soil of the surrounding area.

Various studies have shown that proper sampling requires at least 10 cores per sample, and sometimes 15 or more cores, depending on the nature of the soil and size of the area being sampled. A smaller number can introduce variability into the results from different sampling years. There is no rule for the number of acres to include in a single sample. This must depend on the local situation. However, the University of Illinois has long recommended that a single sample should represent no more than 5 acres.

Of course, the budget will have the final say for the final decision.

please have a look:

https://www.cropnutrition.com/nutrient-management/soil-sampling/

The answer depends on how uniform the site is and the purpose of the sampling. Were you planning an experiment with (say) 20 plots you would need a representative sample from each plot so that you could design and allocate the treatments

Larger zones require more samples than smaller zones (One soil sample per 0.5 hectare (5000 square meter). As a rule of thumb, collect two subsamples per acre in a zone. Regardless of zone size, a minimum of five subsamples per zone should be collected. Subsamples should be located randomly within a zone. Zig-zag method of soil sampling (shown in picture attached). A sample normally consists of 0.25 – 0.5 kg of soil and this is taken to represent the entire sampling area or field. Avoid any unusual spots such as old fences, ditches, drinking troughs, dung or urine patches or where fertilizer / manures or lime has been heaped or spilled in the past. Standard soil tests typically evaluate pH, buffer pH, organic matter, cation exchange capacity, phosphorus, potassium, calcium, magnesium and base saturation. Micronutrient soil testing alone is generally not a reliable tool for estimating potential micronutrient deficiencies.

The number of soil samples to take from 10 hectares during soil testing depends on a number of factors, including the homogeneity of the soil, the type of soil test being conducted, and the desired level of accuracy.

In general, a good rule of thumb is to take one sample for every 2 hectares of land. This will ensure that the soil test results are representative of the overall field. However, if the soil is very homogeneous, you may be able to get away with taking fewer samples. Conversely, if the soil is very heterogeneous, you may need to take more samples.

The type of soil test being conducted can also affect the number of samples needed. For example, if you are conducting a nutrient analysis, you will need to take more samples than if you are conducting a pH test. This is because nutrient levels can vary more widely across a field than pH levels.

Finally, the desired level of accuracy will also affect the number of samples needed. If you need very accurate results, you will need to take more samples than if you are only looking for a general idea of the soil conditions.

In the case of a 10-hectare field, a good starting point would be to take 5 samples. This will give you a good overview of the soil conditions and should be sufficient for most soil tests. If you need more accurate results, you can take more samples.

Here are some additional tips for taking soil samples:

• Take samples from different parts of the field, including the edges, the middle, and the areas under trees and shrubs.
• Take samples from different depths, including the topsoil, the subsoil, and the substratum.
• Collect the samples in clean containers and store them in a cool, dry place.
• Label the samples clearly with the location and depth from which they were taken.

Once you have taken the soil samples, you can send them to a laboratory for analysis. The laboratory will be able to tell you the nutrient levels, pH, and other properties of the soil. This information can be used to improve the fertility of the soil and to grow healthier crops.

Syafina Fasya Saiful Anuar ...Can you please add to your question--is this for agricultural use of tilled soils, or grasslands/desert Ecological Restoration? My work is desert/grasslands and is very different than any typical agriculture sampling. Depending on the wild lands species I want to restore, I could take up to 100 samples from one hectare for the first year, and then 30-40 per hectare per year as I monitor my test plot treatments--each treatment minimum size about 3 x 3 meters and the largest about 8 x 8 meters.

I try to do less, but 100 per hectare really give you a good look when you are doing wild lands restoration.

This week I am monitoring 35 different 8 x 8 meter plots that are right next to each other, and different amounts of nutrients added have produced radically different results of what grows in each treatment plot.

I have very clear black-and-white results and then all sorts of shades of gray in between--when adding fertilizers to get rid of a persistent weed that covers 5 million hectares of California's grasslands, the Yellow Star thistle. In some plots, 99.5% of that weed is gone in only 90 days--pictures attached.

For wild lands, the sampling is always tied to an individual species of plants, and the sampling is always from the top 5 cm only, no deeper. I always add the testing of the percentage organic matter, because a minimum level is needed by each plant, to be able to access the nutrients in the soil and for their seedling's survival in wild lands situations on the natural rainfall.