Nitrogen Effects on Productivity and Soil Properties in Conventional and Zero Tilled Wheat with Different Residue Management

Abstract

Changes in tillage regime from conventional tillage to zero tillage (ZT) call for efficient weed and N management. Nitrogen is subject to immobilization/mineralization under residue-laden ZT system and increasing N-use efficiency through scheduling/rationalization of N is a researchable issue. The authors investigated the N and weed management options for wheat under ZT with or without residue. Results showed that ZT + residue retention (R) + 75% N + GreenSeeker™ (GS)-aided N management (ZT + R+75N + GS) recorded significantly higher wheat yield (5.11 t ha−1) over CT − R + 100N (4.48 t ha−1). The ZT + R+75N + GS improved macro-aggregates by 25.3% and decreased micro-aggregates by 6.8% in surface soil than CT − R + 100N. Treatment ZT + R+75N + GS had highest labile C (~ 3.63 g C kg−1 soil), which was 24.7% higher than CT − R + 100N (2.91 g C kg−1 soil). This treatment resulted in highest microbial biomass C (148.6 µg g−1 soil). It showed a significant increment in fluorescein diacetate (by 30.9%), total phosphatase (by 63.2%) and urease (by 31.6%) activities in surface soil over CT − R + 100N. Optical sensor-based N management saved N to the tune of 15–20 kg ha−1 over CT − R + 100 N. The ZT with residue retention and GS-aided N management has greater potential to secure sustainable yield, better soil aggregation, labile C and soil micro-flora than CT without/with residue incorporation.