Direct and residual effects of phosphorus and zinc fertilization on productivity of wheat (Triticum aestivum) - pearl millet (Pennisetum glaucum) cropping system

A field experiment, carried out from winter 2001–02 to rainy season 2003 at Navgaon (Alwar) on sandy loam soil revealed that application of 60 kg P₂O₅/ha significantly improved the growth and yield attributes as well as grain (43.95 q/ha) and straw yield (68.61 q/ha), harvest index (39.13%), protein content (10.72%) and P uptake (40.92 kg/ha) by wheat [Triticum aestivum (L.) emend. Fiori & Paol.] over no-use of P (control), while Zn uptake increased only up to 30 kg P₂O₅/ha and thereafter decreased significantly. Agronomic efficiency decreased up to 90 kg P₂O₅/ha. Recovery of P was higher at 60 kg P₂O₅/ha (21.63%) and thereafter decreased sharply. Similarly, application of 6 kg Zn/ha significantly increased all the growth and yield attributes (except test weight), protein content and Zn uptake by wheat over no-use of Zn (control). Application of graded levels of zinc up to 9 kg Zn/ha, remained at par with12 kg Zn/ha, significantly increased Zn uptake by wheat crop over other levels. Application of 6 kg Zn/ha increased the grain and straw yields by 19.4 and 16.8% over the no-use of Zn (control). Agronomic efficiency (115.3 kg/kg) and apparent Zn recovery (1.87%) were also higher at 6 kg Zn/ha. Available P status of soil increased and Zn status decreased significantly with the increase in phosphorus level up to 90 kg P₂O₅/ha. However, P status decreased and Zn status increased significantly with the increase in zinc level up to 12 kg Zn/ha. Application of 60 kg P₂O₅/ha and 6–9 kg Zn/ha to wheat significantly improved the growth and yield attributes, yield, protein content and P uptake in succeeding pearl millet [Pennisetum glaucum (L.) R. Br. emend. Stuntz] over control, while application of P @ 90 kg P₂O₅/ha decreased Zn and zinc @ 12 kg Zn/ha improved Zn uptake by pearl millet significantly over lower levels.