The study of soil phosphorous status and availability in soils of Urmia Plain, Iran
By: Nikou Hamzehpour, Sara Mola Ali Abasiyan, Aziz Majidi
Key Words: Soil phosphorus, nutrient availability, spatial prediction, ordinary kriging.
J. Bio. Env. Sci. 8(5), 249-256, May 2016.
Soil nutrients mapping and monitoring are of great importance to reach the goals of sustainable agriculture. In developing countries, neglecting soil test results in unbalanced fertilization of soils. The aim of this research was to investigate soil phosphorous (P) availability and mapping in soils of Urmia Plain, northwest Iran. 277 soil samples from an area of 900 km2 of agricultural lands were taken. Soil samples were gathered from the depth 0-30 cm on a grid of 0.7-1 km. Samples were sieved and analyzed for macro and micro nutrients, organic carbon, calcium carbonate equivalent and clay. In order to map the soil Pav, logarithmic transferred values were used to develop variogram. Then spatial prediction of soil salinity was done on a grid of 500 m using ordinary kriging. Results showed that soil samples commonly had P deficiency based on Olsen critical level of 15 ppm. However, small area at the center of the study area had high values of Pav. Correlation analysis revealed that there were significant correlations (1% probability level) between Pav with organic matter, potassium and copper. The application of the organic fertilizers from sewage slug sources could result in local increase of soil P up to 100 mg/kg or more, while in other parts of the area soil available P is normally below 30 mg/kg. According to the findings of this research, neither organic fertilizers nor chemical fertilizers are not being used based on soil test which can be a problem for both sustainable production and environmental health.