A pot culture experiment was conducted to determine the critical limits of available phosphorus
for durum wheat (cv.WH-896), a pot culture experiment was conducted in which fifteen levels of P
i.e. 0, 2, 5, 10, 15, 20, 30, 40, 50, 75, 100, 150, 200, 300 and 400 mg P kg-1 soil were super imposed
in normal, nickel and chromium polluted soils. The normal soil refers to the processed P deficit soil
collected from the cultivated field whereas nickel and chromium polluted soils were prepared by
applying 75 mg Ni kg-1 soil through NiCl2.6H2O and 15 mg Cr kg-1 soil through K2Cr2O7, respectively
to the normal soil and incubated in pots for 28 days at field capacity. After incubation of 28 days, a
200g representative sample of soil was drawn from each treatment to assess the status of available
phosphorus by Olsen soil test method. Durum wheat (cv.WH-896) was raised as a test crop and
harvested after 10 weeks of germination. Dry matter yield of durum wheat significantly and markedly
increased with the application P upto 50, 75 and 150 mg P kg-1 soil in normal, Ni and Cr polluted
soils, respectively. The uptake of P significantly and subsequently increased upto 50, 75 and 150 mg
P kg-1 soil in normal, Ni and Cr polluted soils, respectively. The critical limits of available P for
durum wheat in normal, Ni and Cr polluted soils were established as 17.38, 22.65 and 35.94 kg
P ha-1, respectively by Olsen's soil test method indicating that there is no single critical P level
for all soils.
