Phosphorus and zinc requirements of wheat under wheat (Triticum aestivum)-pearl millet (Pennisetum glaucum) cropping system

Phosphorous (P) fertilization up to 60Âkg ha^–1 significantly increased grain and straw yields of wheat and P uptake while Zn removal improved up to 30Âkg ha^–1. Agronomic efficiency decreased up to 90Âkg ha^–1. P recovery was higher at 60Âkg ha^–1 (21.63%) while physiological efficiency (91.14Âkg kg^–1 P₂O₅) and value: cost ratio (VCR), i.e. 8.87 were higher at 30Âkg P₂O₅ ha^–1. Zinc fertilization up to 6Âkg ha^–1 also significantly enhanced grain and straw yields and P removal while Zn removal increased significantly up to 12Âkg ha^–1. Agronomic efficiency (115.3Âkg kg^–1 nutrient) and apparent Zn recovery (1.87%) were also higher at 6Âkg Zn ha^–1 while maximum physiological efficiency (6.84Âkg g^–1 Zn uptake) and VCR (3.21) were recorded at 3Âkg ha^–1. Productivity of wheat-pearl millet system and apparent P recovery were higher at 60Âkg P₂O₅ ha^–1 and 6Âkg Zn ha^–1. Increasing P and Zn levels resulted in decline in VCR of system. Availability of P in soil after harvest increased and Zn decreased significantly up to 90Âkg P₂O₅ ha^–1 while available P decreased and Zn increased significantly up to 12Âkg Zn ha^–1.