Brazilian Soil Fertility Survey

Brazil lacks the data from soil fertility surveys which could help the government, industry, and crop consultants in their efforts to improve soil chemical properties for adequate plant nutrition. IPNI Brazil has been involved in guiding the process for obtaining such surveys. The project was delineated in three phases. Phase 1 was a simple soil fertility survey from soil test results at IPNI Brazil database. Phase 2 is under development and will consist of a survey with laboratories running the ion exchange resin methodology and will concentrate in the State of Sao Paulo. Phase 3 will include laboratories throughout the country. For phase 2, under development, IPNI Brazil gathered the results from soil testing from twenty-six different laboratories (91,769 samples from 501 different cities) in the state, which were analyzed in the year of 2015.

Results showed a median concentration of 12 mg/dm³ and 1.6 mmol_c/dm³, respectively for phosphorus (P) and potassium (K), which are considered low and medium levels. 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 respectively 13%, 33%, 35%, 16%, and 3% for sufficiency levels of very low (< 0.80 mmol_c/dm³), low (0.81 to 1.5 mmol_c/dm³), medium (1.5 to 3 mmol_c/dm³), high (3 to 6 mmol_c/dm³), and very high (>6.0 mmol_c/dm³). An interesting form to look at these numbers is that 88% and 81% of the samples considered in the soil fertility 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 fertility respectively that would be 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.

IPNI Brazil intends to extend the survey to the whole country, which should be useful for all stakeholders involved with plant nutrition.