PRESIDEDRESS SOIL NITROGEN TEST FOR NO TILLAGE MAIZE AT DIFFERENT ROW SPACING

PABLO A. BARBIERI, HERNÁN E. ECHEVERRÍA AND HERNÁN R. SAÍNZ ROZAS

AGRONOMY JOURNAL

ASA

Lugar: Madison,WI; Año: 2008 vol. 100 p. 1101 - 1105

0002-1962

ABSTRACT A presidedress soil nitrate test (PSNT) can be used to evaluate preplant N applications as a complementary method to N budget in maize (Zea mays L.) under diff erent management practices. Narrow rows have shown increased N accumulation and recovery effi ciency by maize, and therefore soil NO3 −–N critical concentration (CC) for maximum yield could be lower than in conventional row spacing. An experiment was performed at Balcarce (Argentina) in 1996–1997, 1999–2000, and 2000–2001 to evaluate the PSNT for irrigated no-till (NT) maize with diff erent row spacings (70, 52, and 35 cm) and N rates (0, 90, 140, and 180kg N ha− 1). Soil samples were collected to a 30-cm and 30- to 60-cm depth when maize was at the six-leaf stage (V6). Grain yield was signifi cantly increased by narrow rows mainly at low N availability. Relative yield was highly associated (r2 = 0.73 and 0.68) with soil NO3−–N concentration (0–30 cm) at V6 for conventional and narrow rows, respectively. Soil NO3−–N concentration for maximum yield (95%) was greater for conventional row spacing (22 mg kg−1) compared with narrow rows (17 mg kg−1). The reliability of the PSNT (r2) did not improve when sampling was done up to a 60-cm depth. Th ese results confi rm the hypothesis that the NO3−–N CC determined for the PSNT is lower for maize crops growing in narrow rows than conventional row spacing. Narrow rows maize is a simple management practice that could contribute to enhancing system sustainability.