Since June 2007, we had conducted a three-year-round consecutive
field-scale observation to measure total N input and N output of
rice-wheat rotation agroecosystem with improved metering methods
for water flow, including irrigation, runoff and leaching. The
entire N balance and its contributing input/output factors in this
high-N-input agricultural system were discussed separately (Zhao
et al., 2012). The emphasis of this paper therefore was on variation
patterns in N runoff and leaching and their key factors. We aim to
examine how much the potential contribution of direct N export
is from intensive rice-wheat rotation system to water N pollution,
and illustrate how the conventional water management affects N
export via water flow in rice and wheat seasons. The information
could reveal insights for reducing non-point pollution of water from
paddy field in TLR.