Site specific nutrient management for yield maximization in rice (Oryza sativa)-wheat (Triticum aestivum) cropping system in north-western Himalayas

A field experiment was conducted in a permanent layout for 7 consecutive years (rainy season 2007 to winter season (2010) at Palampur for yield maximization of rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system through site-specific nutrient management. Twelve combinations of primary, secondary and micronutrients [T₁, N₁₀₀P₂₅K₁₂₀S₄₀B₅Zn₂₀, (figure as subscript indicate dose in kg/ha of N, P₂O₅, K₂O, S, Borax and ZnSO₄, respectively) T₂, N₁₀₀P₅₀K₁₂₀S₄₀B₅Zn₂₀; T₃, N₁₀₀P₀K₁₂₀S₄₀B₅Zn₂₀; T₄, N₁₀₀P₂₅K₈₀S₄₀B₅Zn₂₀; T₅, N₁₀₀ P₂₅K₄₀S₄₀B₅Zn₂₀; T₆, N₁₀₀P₂₅ K₀S₄₀B₅Zn₂₀; T₇, N₁₀₀P₂₅K₁₂₀S₄₀B₅Zn₀; T₈, N₁₀₀P₂₅K₁₂₀S₄₀B₀Zn₂₀; T₉, N₁₀₀P₂₅K₁₂₀S₀B₅ Zn₂₀; T₁₀, N₁₀₀P₂₅K₁₂₀S₀B₀Zn₀; T₁₁, RDF, (recommended dose of fertilizers, N₉₀P₄₀K₄₀ for rice and N₁₂₀P₆₀K₃₀ for wheat) and T₁₂, INM (integrated nutrient management, N₃₆P₁₆K₁₆ + 5 t FYM/ha for rice and N₄₈P₂₄K₁₂ + 5 t FYM/ha for wheat]-based upon the available nutrient status of the site were evaluated. N, P and K were applied to both the crops. S, B and Zn were applied to rice only. State recommended application of nutrients (T₁₁) maintained its superiority for rice grain yield initially, however, N₁₀₀P₂₅K₁₂₀S₀B₀Zn₀ (T₁₀) excelled over it at last. INM practice (T₁₂) was lowest yielder in the early years but at last next only after N₁₀₀P₂₅K₁₂₀S₀B₀Zn₀ and RDF. The complete deletion of K application from N₁₀₀P₂₅K₁₂₀S₄₀ B₅Zn₂₀ under T₆, resulted in significantly the lowest rice yield. In increasing wheat yield, N₁₀₀P₅₀K₁₂₀ S₄₀B₅Zn₂₀ maintained its superiority throughout and therefore, had the highest sustainable yield index. This was followed by N₁₀₀P₂₅K₁₂₀S₀B₀Zn₀, RDF and N₁₀₀P₂₅K₁₂₀S₄₀ B₅Zn₀ both in terms of yield and sustainability. The system productivity (rice + wheat grain) ranged between 5.0 (N₁₀₀P₂₅K₁₂₀S₀B₀Zn₀) to 12.7 t/ha (N₁₀₀P₅₀K₁₂₀S₄₀B₅ Zn₂₀) under different treatments. The system productivity and sustainability index was higher under N₁₀₀P₅₀K₁₂₀S₄₀ B₅Zn₂₀, RDF and N₁₀₀P₂₅K₁₂₀S₀B₀Zn₀ over other treatments. Among the soil properties, pH decreased significantly over the initial test value of 5.3 in all the treatments except INM (T₁₂). A definite build up of organic carbon over its initial value of 0.7% was observed in N₁₀₀P₂₅K₈₀S₄₀B₅Zn₂₀, N₁₀₀P₂₅K₄₀S₄₀B₅Zn₂₀, N₁₀₀P₂₅K₁₂₀ S₀B₀Zn₀, RDF and INM treatment. There was depletion of available P in all the treatments over its initial test value of 50 kg/ha. There was significant build up of available K in N₁₀₀P₂₅K₁₂₀S₄₀B₅Zn₂₀, N₁₀₀P₀K₁₂₀S₄₀B₅Zn₂₀, N₁₀₀P₂₅K₁₂₀ S₄₀B₅Zn₀, N₁₀₀P₂₅K₁₂₀S₄₀ B₀Zn₂₀ and INM treatment over the initial status of 86 kg/ha. Available K was significantly low where no K or low K was applied. N₁₀₀P₂₅K₁₂₀S₀B₀Zn₀ gave the highest benefit: cost ratio of 3.07 and was comparable to RDF in influencing total net returns. N₁₀₀P₅₀K₁₂₀S₄₀B₅Zn₂₀ resulted in the highest total apparent nutrient recovery, apparent N recovery and N physiological productivity. P physiological productivity was the highest under RDF and K physiological productivity was the highest under N₁₀₀P₂₅K₀S₄₀B₅Zn₂₀.