The experiment was conducted in the Irrigated Perimeter Senator Nilo Coelho, in an area of 200 ha corresponding to the Extensão Maria Tereza, Petrolina, PE. It had as its objective the evaluation of the phosphorus, potassium and organic matter values of the soil of the referred area and their spatial variabilities. 71 points were sampled with irregular spacing, in two depths, of 0 - 0.3 and of 0.3 - 0.6 m. The chemical properties analyzed were the organic matter, phosphorus and potassium. The data were analyzed through the descriptive statistics and geoestatistics. For the descriptive analysis it was verified that the pH data showed the smallest variation (CV = 10.81 and 9.84% for the depths of 0 - 0.3 and of 0.3 - 0.6 m, respectively) and the data corresponding to phosphorus presented the largest variations (CV = 108.1 and 175.96%, in the two depths, respectively). The analysis of the frequency distribution showed that potassium has a normal distribution in the two depths and the other chemical properties did not present normal distribution. The soil of the Extensão Maria Tereza presents low fertility and should be fertilized when used for agricultural purposes. The geoestatistical analyses revealed that the best model for potassium and organic matter is the spherical and for the phosphorus is the exponential. In the two depths all the studied parameters presented a strong spatial dependence.
fertility; spatial variability; geostatistics
