Influence of tillage depth and organic amendments on root growth of pigeon pea in alfisols

Abstract:

Alfisols present a hidden challenge for pigeon pea: a compacted subsurface layer that roots struggle to penetrate. This research evaluated whether deeper tillage combined with organic amendments could break through that barrier and improve root development, nodulation, and grain yield. Four tillage depths (15, 20, 25, and 30 cm) were crossed with four organic amendment treatments (control, FYM at 5 t ha⁻¹, vermicompost at 3 t ha⁻¹, and a 50:50 FYM-vermicompost blend) in a factorial randomised block design at Udaipur, Rajasthan, during the kharif 2023 season. Root length per plant increased from 19.6 cm at 15 cm tillage depth (control) to 41.8 cm at 30 cm depth with the FYM-VC blend, a 113% improvement. However, grain yield peaked at 25 cm depth (1.94 t ha⁻¹ with the blend), declining slightly at 30 cm (1.87 t ha⁻¹) due to excessive soil disturbance causing moisture loss. Organic amendments raised nodule counts by 34-58% over the unfertilised control. These findings point to 25 cm tillage depth plus a blended organic input as the best option for pigeon pea on compact Alfisols in semi-arid Rajasthan.