Kaiming
Liang^a,b, Xuhua Zhong^a,*,
Junfeng Pan^a, Nongrong Huang^a, Yanzhuo Liu^a,  Bilin Peng^a, Youqiang Fu^a,
Xiangyu Hu^a

Agriculture,
Ecosystems and Environment

Abstract

Optimized
agronomic management improves nitrogen (N) use efficiency in crop production.
However, limited information exists about the effect of improved agronomic
practices on the N surplus in double rice cropping system. In this study, we
conducted field experiments to evaluate the N surplus for the prevailing
farmers’ practices (FP), optimized N management (OPTN) and optimized N and
water management (OPTNW) during 2016–2017 in Guangdong province, South China.
Grain yield, recovery efficiency (REN), partial factor pro[1]ductivity
(PFPN) and agronomic efficiency (AE) of applied N in OPTN and OPTNW were
substantially higher than FP. The yearly N surplus and environmental N loss in
OPTN were 29.4% and 26.2% lower than FP, respectively. The N surplus in OPTNW
was 32.1% lower than FP. Annual N losses resulting from runoff and leaching in
OPTNW were reduced by 45.0% and 17.4%, respectively, compared with OPTN. Pooled
data of 22 on-farm field trials from six sites in 2014–2017 showed that N input
in OPTN and OPTNW was 16.2%–33.8% lower than FP. The tradable N output in OPTN
and OPTNW was 9.9% and 9.0% greater than FP, respectively. The N efficiency of cropping
systems (NUEc) in OPTN and OPTNW was increased by 39.8% and 42.0%,
respectively, compared with FP. N surplus notably increased with the increasing
fertilizer N input, and decreased with the increasing tradable N output and
NUEc. These results suggest that through optimized N and irrigation management,
N surplus and environmental risk can be practically reduced in a double rice
cropping system without yield penalty.

Keywords: Nitrogen
use efficiency  N management  Water management  N surplus  Environmental N losses

附件：Reducing nitrogen surplus and environmental losses by optimized nitrogen and water management in double rice cropping system of South China