Soil Mapping in Brazil Reveals Nutrient Deficiencies and Acidity

In order to plan appropriate and efficient future fertilizer use it’s important to have an overview of nutrient levels in soil. For this reason, farmers are encouraged to regularly sample soil from their fields to see if there are any nutrient deficiencies that might be limiting crop growth.

Data from individual samples are then pieced together to get a picture of the state of soil fertility for a region. Until recently a lack of such data in Brazil has made it impossible to create valuable soil fertility surveys.

To solve this problem the IPNI Brazil program partnered with the Agronomic Institute of Campinas and São Paulo State University to collect and produce a soil fertility survey, starting with the state of São Paulo. Soil analysis from 26 laboratories and 501 cities were collected and summarized.

Potassium and Phosphorus Deficiencies

The survey shows that 88% of analyzed soil samples from the state of São Paulo were either “very low”, “low” or “medium” for phosphorus, with 81% of samples in the same categories for Potassium. This shows the huge potential to improve crop yields by supplying sufficient nutrients to the soil to overcome the shortfall.

The frequency of soils falling into various categories of nutrient concentration for phosphorus and potassium. The categories indicate the probability of a crop response to applied nutrients.

Data also revealed that 30% of soils samples were extremely acidic, with yields increasing in those fields if lime was applied as high acidity limits plants’ ability to recover nutrients.

Mapping the Results

Nutrient deficiency and acidity maps created from the results have helped local farmers and agronomists to identify areas that would benefit the most from the addition of fertilizer and lime.

The project highlights the importance of soil mapping for to get a full picture of plant nutrition needs and to improve yields.

The occurrence of potassium soil concentrations (left) and soil acidity (right) in very low, low, or medium categories where crops would benefit from potash fertilization and lime, respectivity, in the state of São Paulo, Brazil.