Establishment of Soil Fertility Gradient and Nutrient Dynamics in Lateritic Soil under Successive Crops of Fodder Maize (Zea mays L.) in Kerala, India

Aims: To establish distinct soil fertility levels in the lateritic soil of Kerala using three successive crops of fodder maize under graded nitrogen, phosphorus and potassium (NPK) fertilisation.Study Design: Fertility-gradient experiment with three fertility strips and three replications.Place and Duration of Study: Instructional Farm, College of Agriculture, Vellayani, Kerala Agricultural University, Thiruvananthapuram, Kerala; three fodder-maize crop seasons (first crop: October–December 2023; second crop: March–May 2024; third crop: August–October 2024). Methodology: Fodder maize (Zea mays L., var. African Tall) was grown in S₀ (unfertilized control), S₁ (100:100:100 kg ha⁻¹ N:P₂O₅:K₂O) and S₂ (200:200:200 kg ha⁻¹ N:P₂O₅:K₂O). Post-harvest soil samples were analysed for pH, organic carbon (OC), cation-exchange capacity (CEC), available N, P, K, Ca, S, Fe and Mn. Plant N, P and K concentrations and fresh fodder yield were recorded, and treatment means were compared using analysis of variance.Results: Soil pH did not differ significantly among the strips. Organic carbon and CEC differed significantly, with S₂ recording 0.79% OC and 7.95 cmol (p⁺) kg⁻¹ CEC after the third crop. Available N, P and K after the third crop were 189.82, 9.10 and 105.44 kg ha⁻¹ in S₀; 417.60, 18.06 and 247.95 kg ha⁻¹ in S₁; and 597.15, 25.62 and 288.77 kg ha⁻¹ in S₂, respectively. Fresh fodder yield ranged from 12.65 to 57.90 t ha⁻¹ across strips and crop cycles.Conclusion: Graded NPK application combined with successive fodder-maize cropping established contrasting soil fertility conditions suitable for subsequent soil test crop response (STCR) experimentation.