The effect of Long-Term Pistachio Cultivation on Phosphorus Fractions and Some Soil Characteristics

This research examined the impact of long-term pistachio cultivation on soil inorganic phosphorus (P) fractions. Soil properties and phosphorus fractions, particularly residual-P, were compared at different depths in pistachio cultivated and the adjacent uncultivated lands in Kerman Province. Soil samples were collected from four different depths (0-10, 10-20, 20-30, and 30-50 cm) in triplicates from both pistachio-cultivated and the adjacent uncultivated lands, using a randomized systematic method. The physical and chemical properties of soil samples were measured, along with soil P fractions, and the data were analyzed using the one-way ANOVA. The findings indicated that, with the exception of bulk density, other soil properties exhibited significant differences between the two land uses. The electrical conductivity (EC) of soil in pistachio-cultivated land was lower than that in uncultivated land, whereas the amounts of calcium carbonate and soil organic matter were greater in the pistachio-cultivated land. The highest content of calcium carbonate (26.2%) and organic matter (0.9%) was found at 10-20 cm depth. There was a significant difference between the two lands regarding inorganic phosphorus fractions. The results showed that soil total and available P concentration were higher in pistachio land compared to uncultivated land by 3% and 37%, respectively. Pistachio land had a higher amount of soil residual-P (146.2 mg/kg) as compared to the uncultivated land (129.8 mg/kg). Additionally, it was observed that the concentration of residual-P fluctuated at different depths. The amount of residual-P was lowest at a depth of 0-10 cm (117 mg/kg) and highest at a depth of 10-20 cm (154 mg/kg). Based on the results obtained, it was found that HCl-P was the most prevalent fraction of inorganic phosphorus in both lands. The findings indicated that understanding phosphorus fractions is crucial for effective phosphorus management in pistachio-cultivated land.