To collect a sample it is recommended to use the zigzag method, in which the area is divided empirically into homogeneous lots of up to 10 hectares each. Plots are selected that have the same topographic position, soil color, texture, previous crop or vegetation, fertilization and previous liming, for example.
How to collect soil:
After mapping the lots, go through the zigzag areas by removing with a auger (or shovel) between 8 and 12 soil samples from each lot at a depth of 0 to 20 cm and from 0 to 40 cm deep. Always avoid collecting samples near sheds, fertilizer storage areas, roads, anthills or termite mounds or that contain many animal feces.
Each sample must be stored in a clean and separated container according to the depth of the sample collected.
After all samples are collected, mix each one in its respective container. Take a final sample of this mixture with about 500 grams of soil and insert it in a plastic bag with a label containing the information about the sample and send it to a specialized laboratory.
Attention should also be paid to the period in which such a sample will be collected. It is recommended that the analysis be done between 90 to 120 days before planting and preferably at the end of the rainy season. This interval is indicated to make it possible to apply acidity correction (liming or plastering) and fertility (fertilization), avoiding the burning of seedlings or seeds.