Assessing zero-till direct seeding at variable water stress levels compared to traditional puddled transplanting of rice under groundwater-fed irrigation systems in north-west India

Irrigation of rice using groundwater is considered one of the main contributors to north-west India's declining water level. The present study hypothesizes that zero-till direct seeding of rice (ZTDSR) with the optimum irrigation schedule may reduce irrigation compared to puddled transplanted rice (PTR). Crop growth stage-dependent predefined soil matric potential (SMP), that is, −15, −30 and −45 kPa based irrigation schedules either during the entire growing period or their combinations during the vegetative phase in ZTDSR, were compared with PTR for two consecutive seasons. The results showed that irrigation in ZTDSR at lower SMP at any growth stage caused adverse effects on yield. Irrigation at −15 kPa during the entire crop season with straw mulch was found to be the best schedule for ZTDSR. ZTDSR with −15 kPa irrigation, however, saved 36.2 cm of water and recorded higher water productivity but produced 20% less grain yield over the prevailing PTR. A higher groundwater system loss (GWSL) was found in the PTR (29.2 cm) than in the best ZTDSR (23.6 cm) schedule, which indicates better groundwater management in the ZTDSR than in the PTR. Hence, the ZTDSR has the potential to save irrigation, achieve higher water productivity and manage the depletion of groundwater resources in rice–wheat dominant north-west India.