A Study on the Effect of Deep and Differential Depths Placement of Fertilizers on Potato Crop Response

A ‘Field Pot Experiment’ was conducted at Pantnagar during 2012-13 to develop the basic concept for applying organic manures (vermicompost) and inorganic fertilizers either alone or in combination at appropriate depths and rates in the root zone of potato crop (Var : ’Kufri Khyati’). Nine treatments selected for the study were; T1 : (100% inorganic + Mixing 150 mm depth)-control, T2 : (50% N inorganic + 50% N organic + Mixing 150 mm depth), T3 : (100% inorganic placed at 150 mm depth below full width of ridge), T4 : (100% inorganic placed at 250 mm depth below full width of ridge), T5 : (80% inorganic placed at 250 mm and 20% inorganic placed at 350 mm depth), T6 : (50% N inorganic placed at 250 mm + 50% N organic placed at 350 mm depth), T7 : (100% inorganic + Mixing 150 mm and hard pan formed manually at 250 mm depth), T8 : (50% N inorganic + 50% N organic placed at 150 mm & tillage up to 250 mm depth) and T9 : (100% inorganic placed at both sides of ridge i.e. in furrows at 150 mm depth). The experiment was laid in clay loam soil in RBD with three replications. The ‘Field Pots’ of 2.5 × 2.5 m size were dug manually and after placing the fertilizer as per above treatments, all the pots were filled with soil and potato tubers were planted on the ridges at 600 × 200 mm spacing. All the agronomical package of practices recommended for potato crop was followed. Different crop growth parameters were noted at 45, 60 and 75 DAP, and the yield attributes as well as root dry mass and length were noted as per standard protocols for field experiments. The maximum yield in treatment T5 (51.16 t/ha) was found significantly (p < 0.05) higher than treatments T1 (39.12 t/ha), T4 (35.61 t/ha) and T2 (34.08 t/ha) but was at par with treatments T6 (48.10 t/ha), T8 (47.91 t/ha) T9 (46.69 t/ha), T3 (45.84 t/ha) and T7 (44.31 t/ha). In treatments T5, T6 and T8, the average yield was found to be higher by 23.5, 18.67 and 18.35%, respectively than that of conventional method (T1). The maximum tuber yield under grade A ( > 75 g) was found significantly higher in treatment T5 (30.91 t/ha) followed by treatments T1 (24.06 t/ha), T4 (21.42 t/ha) and T2 (18.83 t/ha) which was at par with treatments T3 (26.37 t/ha), T6 (28.20 t/ha), T7 (25.74 t/ha), T8 (27.82 t/ha) and T9 (24.86 t/ha). It was postulated that the placement of fertilizers deeply into the soil and at different depths and rates in the root zone would increase the fertilizer use efficiency leading to substantial saving of fertilizers and increase in the yield. Recommendations were made to develop / adopt deep and differential rate fertilizer application machinery to meet the above requirements.