Impact of graded levels of fertilizer application on soil fertility, nutrient uptake, growth and yield of fodder maize (Zea mays L.)

Field experiment was conducted at Main Agricultural Research Station (MARS), UAS, Dharwad during summer of 2020-21 to study the impact of graded levels of fertilizer application on soil fertility status, nutrient uptake and green fodder yield of fodder maize (variety ‘South African tall’). The experiment field was divided in to three equal strips and three graded levels of fertilizer N, P₂O₅ and K₂O were applied. The low fertility strip received no fertilizer (N₀P₀K₀), the medium and high fertility strips received recommended dose of fertilizer (N₁₅₀P₁₀₀K₅₀) and twice the recommended dose of fertilizer (N₃₀₀P₂₀₀K₁₀₀), respectively. The graded doses of NPK fertilizers were applied in different strips of the experimental field to ensure high heterogeneity between the fertility gradients and homogeneity within each fertility gradient. The main objective of the study was to achieve the operational range of soil fertility by purposefully creating wide differences in soil fertility on the same experimental field. The results indicated that high fertility strip recorded significantly higher post-harvest soil available nutrients (293, 38.4 and 406 kg N, P₂O₅ and K₂O ha⁻¹), nutrient uptake (223, 46.9 and 250 kg NPK ha⁻¹), fodder yield (42325 kg ha⁻¹) and growth parameters viz., plant height (257.3 cm), number of leaves (13.9), leaf area (65.2 dm² plant⁻¹) and total dry matter production (117.7 g plant⁻¹) as compared to medium and low fertility strips. Thus the findings on growth parameters of fodder maize, green fodder yield, post-harvest soil fertility status and nutrient uptake clearly demonstrated the fact that the three fertility strips differed significantly from each other and reinforced the creation of operational range of soil fertility among three strips in the experimental field.