Improving nitrogen management for zero-tillage rice in China

Abstract

Zero-tillage has become increasingly attractive in rice production in China. This study was conducted to determine the feasibility of two possible improved N management practices with fewer N applications in zero-tillage rice: (1) two split applications of urea at 75kgNha−1 at mid-tillering and 45kgNha−1 at panicle initiation (U120–2), and (2) a single application of cross-linked polyacrylamide-coated urea (a slow-release fertilizer) at mid-tillering at a rate of 150kgNha−1 (PCU150–1). Three field experiments were conducted to compare grain yield and N-use efficiency among several N treatments: a zero-N control (CK), U120–2, PCU150–1, a single application of urea at mid-tillering at a rate of 150kgNha−1 (U150–1), and a commonly recommended N management practice for conventional tillage rice (three split applications of urea with 75kgNha−1 as basal, 30kgNha−1 at mid-tillering, and 45kgNha−1 at panicle initiation) (U150–3). Treatments with N application (U120–2, PCU150–1, U150–1, and U150–3) produced 1.08–3.16tha−1 higher grain yields than CK. Grain yields under both U120–2 and PCU150–1 were comparable to that in U150–3. Recovery efficiency of N (REN), agronomic N-use efficiency (AEN) and partial factor productivity of applied N (PFPN) were increased under U120–2 and were similar under PCU150–1 to those under U150–3. U150–1 showed lower grain yield, REN, AEN, and PFPN than U150–3. These results suggest that U150–3 can be replaced with U120–2 to achieve both an increase in N-use efficiency and a reduction in number of N applications and or by PCU150–1 to achieve a maximum reduction in number of N applications in zero-tillage rice production in China.