Critical level of DTPA extractable Zn for wheat in alkaline soils of semiarid region of Punjab,India

Field experiments were conducted at 32 locations, chosen for their wide range in DTPA extractable Zn, to determine the critical deficiency level of Zn for predicting response of wheat to Zn application. Soil application of 5.6 kg Zn ha^–1 significantly increased the grain yield in deficient soils. Soil extractable Zn was significantly related with per cent grain response and absolute grain yield. Both the graphical and statistical methods of Cate and Nelson indicated the critical level to be 0.75 mg kg^–1 soil of DTPA extractable Zn. This level gave a predictability value of 82 per cent.