Brazilian Soil Fertility Survey

Brazil lacks data for soil fertility surveys which can help the government, industry and crop consultants in their efforts to improve soil chemical properties for adequate plant nutrition. Such surveys can be instrumental in guiding, among others, the government to establish proper actions to ameliorate soil fertility, the industry in planning strategies to better serve with products and alternatives those regions most in need of soil fertility improvement, and researchers to plan their experiments. IPNI Brazil has been involved in guiding the process for obtaining such surveys.

The survey was completed based on samples gathered from soil testing results obtained from twenty-six different laboratories (94,904 samples from 501 different cities) in the state, which were analyzed in the year of 2015. Results showed a median of 12 mg P/dm³ and 1.6 mmolc K/dm³, which are considered low and medium concentrations respectively. For P, 20%, 40%, 28%, 8%, and 4% of the samples were in the range of very low (< 6.0 mg/dm³), low (6.0 to 15 mg/dm³), medium (15 to 40 mg/dm³), high (40 to 80 mg/dm³) and very high (> 80 mg/dm³), respectively. For K, these numbers were of respectively 13%, 33%, 35%, 16%, and 3% for sufficiency levels of very low (< 0.80 mmol_c/dm³), low (0.8 to 1.50 mmol_c/dm³), medium (1.51 to 3.0 mmol_c/dm³), high (3.01 to 6.0 mmol_c/dm³) and very high (> 6.01 mmol_c/dm³).

An interesting outcome is that 88% and 81% of the soil samples from the survey have potential for plant response to P and K, respectively. In other words, based on this survey, for the state of São Paulo in Brazil only 12% and 19% of the samples indicate concentrations of P and K, respectively, sufficient to sustain maximum potential crop yields. For soil pH, the survey showed that 30% of the soil samples are in the range of high response to the application of lime. An improvement from last year was the publication of maps of soil fertility for pH, P, K, and base saturation. These maps, showing the situation by municipality, add very useful information that can be used locally by those interested in better programs to manage the soil fertility. IPNI Brazil intends to repeat the survey every five years and also to extend the work to the whole country.