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(Advances in agronomy 116) donald l sparks (eds ) advances in agronomy 116 academic press, elsevier (2012)

ADVANCES IN AGRONOMY
Advisory Board

PAUL M. BERTSCH

RONALD L. PHILLIPS

University of Kentucky

University of Minnesota

KATE M. SCOW

LARRY P. WILDING

University of California,
Davis

Texas A&M University

Emeritus Advisory Board Members


JOHN S. BOYER

KENNETH J. FREY

University of Delaware

Iowa State University

EUGENE J. KAMPRATH

MARTIN ALEXANDER

North Carolina State
University

Cornell University

Prepared in cooperation with the
American Society of Agronomy, Crop Science Society of America, and Soil
Science Society of America Book and Multimedia Publishing Committee
DAVID D. BALTENSPERGER, CHAIR
LISA K. AL-AMOODI

CRAIG A. ROBERTS

WARREN A. DICK

MARY C. SAVIN

HARI B. KRISHNAN

APRIL L. ULERY

SALLY D. LOGSDON


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CONTRIBUTORS

Numbers in Parentheses indicate the pages on which the authors’ contributions begin.

K. J. Boote (41)
Agronomy Department, University of Florida, Gainesville, Florida, USA
Jean-Pierre Caliman (71)
PT SMART Research Institute (SMARTRI), Pekanbaru, Riau, Indonesia
Qing Chen (1)
Department of Plant Nutrition, China Agricultural University, Beijing, PR China
Xinping Chen (1)
Department of Plant Nutrition, China Agricultural University, Beijing, PR China
Franc¸ois Colin (71)
Montpellier-SupAgro, UMR-LISAH (Laboratory on Interactions between Soil,
Agrosystem and Hydrosystem), Montpellier cedex, France
Irina Comte (71)
Department of Natural Resource Sciences, Macdonald Campus of McGill University, Ste-Anne-de-Bellevue, Quebec, Canada, and CIRAD (International Cooperation Centre in Agronomic Research for Development), Montpellier cedex, France
Zhenling Cui (1)
Department of Plant Nutrition, China Agricultural University, Beijing, PR China
Mingsheng Fan (1)
Department of Plant Nutrition, China Agricultural University, Beijing, PR China
Steven J. Fonte (123)
International Center for Tropical Agriculture (CIAT), Cali, Colombia
¨nberger (71)
Olivier Gru
IRD (Institut de Recherche pour le De´veloppement), UMR-LISAH, Montpellier
cedex, France
Rongfeng Jiang (1)
Department of Plant Nutrition, China Agricultural University, Beijing, PR China
Xiaotang Ju (1)
Department of Plant Nutrition, China Agricultural University, Beijing, PR China

ix


x

Contributors

Uttam Kumar (41)
International Crops Research Institute for the Semi-Arid Tropics (ICRISAT),
Patancheru, Andhra Pradesh, India
Patrick Lavelle (125)
International Center for Tropical Agriculture (CIAT), Cali, Colombia, and Institut
de Recherche sur le De´veloppement (IRD)/Universite´ Pierre et Marie Curie
(UPMC), Paris, France
Xin Li (219)
Department of Agronomy, Kansas State University, Manhattan, Kansas, USA
Xuejun Liu (1)
Department of Plant Nutrition, China Agricultural University, Beijing, PR China
Guohua Mi (1)
Department of Plant Nutrition, China Agricultural University, Beijing, PR China
Pedro Oyarzun (125)
EkoRural, Quito, Ecuador
Soroush Parsa (125)
International Center for Tropical Agriculture (CIAT), Cali, Colombia
D. Carolina Quintero (125)
International Center for Tropical Agriculture (CIAT), Cali, Colombia
Idupulapati M. Rao (125)
International Center for Tropical Agriculture (CIAT), Cali, Colombia
Terry J. Rose (185)
Southern Cross Plant Science, Southern Cross University, Lismore, NSW,
Australia
Jianbo Shen (1)
Department of Plant Nutrition, China Agricultural University, Beijing, PR China
Piara Singh (41)
International Crops Research Institute for the Semi-Arid Tropics (ICRISAT),
Patancheru, Andhra Pradesh, India
Steven J. Vanek (125)
Department of Crop and Soil Science, Cornell University, Ithaca, New York,
USA
Jiankang Wang (219)
Institute of Crop Science and CIMMYT China, Chinese Academy of Agricultural
Sciences, Beijing, China


Contributors

xi

Joann K. Whalen (71)
Department of Natural Resource Sciences, Macdonald Campus of McGill University, Ste-Anne-de-Bellevue, Quebec, Canada
Matthias Wissuwa (185)
Japan International Research Center for Agricultural Sciences (JIRCAS), Crop
Production and Environment Division, Ohwashi, Tsukuba, Ibaraki, Japan
Jianming Yu (219)
Department of Agronomy, Kansas State University, Manhattan, Kansas, USA
Fusuo Zhang (1)
Department of Plant Nutrition, China Agricultural University, Beijing, PR China
Weifeng Zhang (1)
Department of Plant Nutrition, China Agricultural University, Beijing, PR China
Chengsong Zhu (217)
Department of Agronomy, Kansas State University, Manhattan, Kansas, USA


PREFACE

Volume 116 contains six excellent reviews dealing with environmental
sustainability and food security. Chapter 1 is an enlightening review on an
integrated nutrient management (INM) approach, developed on more than
20 years of research, to address serious environmental quality challenges,
related to excess use of nutrients, in China. The INM approach has led to
increased nutrient use efficiency and decreased inputs of fertilizers. Chapter
2 deals with the effect of climate change factors on crop growth, development, and yield of groundnut. Chapter 3 is a comprehensive review on
practices used in oil palm plantations and impacts on hydrological changes,
nutrient fluxes, and water quality in Indonesia. Chapter 4 is an enlightening
overview of soil fertility decline in the high Andes of Bolivia, Ecuador, and
Peru. Approaches are presented to enhance nutrient cycling, crop nutrient
uptake, and overall increased productivity. Chapter 5 addresses an important global factor affecting future food security, phosphorus utilization
efficiency (PUE) by plants. The review focuses on grain crops and covers
past attempts to improve PUE via plant breeding, and new approaches for
improving PUE. Chapter 6 is a stimulating review on the importance of
computer simulation in plant breeding.
I am grateful to the authors for their outstanding reviews.
DONALD L. SPARKS
Newark, Delaware, USA

xiii


C H A P T E R

O N E

Integrated Nutrient Management for
Food Security and Environmental
Quality in China
Fusuo Zhang, Zhenling Cui, Xinping Chen, Xiaotang Ju,
Jianbo Shen, Qing Chen, Xuejun Liu, Weifeng Zhang,
Guohua Mi, Mingsheng Fan, and Rongfeng Jiang
Contents
1. Introduction
2. Principles of INM
2.1. Optimizing nutrient inputs and taking all possible sources of
nutrients into consideration
2.2. Dynamically matching soil nutrient supply with crop
requirement spatially and temporally
2.3. Effectively reducing N losses in intensive managed Chinese
cropping systems
2.4. Taking all possible yield increase measures into consideration
3. Technology and Demonstration of INM in Different Cropping
Systems
3.1. INM for intensive wheat and maize system
3.2. INM for paddy rice
3.3. INM for vegetable systems
3.4. INM for orchards
4. Large-Scale Dissemination of INM
5. Summary and Conclusions
Acknowledgments
References

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Abstract
While the concept of sustainability as a goal has become widely accepted, the
dominant agricultural paradigm still considers high yield and reduced environmental impact being in conflict with one another. During the past 49years
(1961–2009), the 3.4-fold increase in Chinese agricultural food production can
Department of Plant Nutrition, China Agricultural University, Beijing, PR China
Advances in Agronomy, Volume 116
ISSN 0065-2113, DOI: 10.1016/B978-0-12-394277-7.00001-4

#

2012 Elsevier Inc.
All rights reserved.

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Fusuo Zhang et al.

be partly attributed to a 37-fold increase in N fertilization and a 91-fold increase
in P fertilization, but the environment costs have been very high. New advances
for sustainability of agriculture and ecosystem services will be needed during
the coming 50years to improve nutrient use efficiency (NUE) while increasing
crop productivity and reducing environmental risk. Here, we advocate and
develop integrated nutrient management (INM) based on more than 20years
of studies. In this INM approach, the key components comprise (1) optimizing
nutrient inputs by taking all possible nutrient sources into consideration, (2)
matching nutrient supply in root zone with crop requirements spatially and
temporally, (3) reducing N losses in intensively managed cropping systems, and
(4) taking all possible yield-increasing measures into consideration. Recent
large-scale application of INM for cereal, vegetable, and fruit cropping systems
has shed light on how INM can lead to significantly improved NUE, while
increasing crop yields and reducing environmental risk. The INM has already
influenced Chinese agricultural policy and national actions, and resulted in
increasing food production with decreased climb of chemical fertilizer consumption at a national scale over recent years. The INM can thus be considered an
effective agricultural paradigm to ensure food security and improve environmental quality worldwide, especially in countries with rapidly developing economies.

Abbreviations
AEN
FNP
INM
NCP
NUE
ONR
PFPN
REN

agronomy N efficiency
farming practice
integrated nutrient management
North China Plain
nutrient use efficiency
optimum N fertilizer rate
nitrogen partial factor productivity
recovery N efficiency

1. Introduction
The Green Revolution helped to create the world’s “Miracle in China,”
with 9% of the world’s arable land feeding 22% of the world population. In the
past 49years (1961–2009), cereal grain yields have increased 3.5-fold from 1.2
to 5.4thaÀ1, while total grain production has increased 3.4-fold from 110 to
483 million ton (MT) (FAO, 2011). In 1998, grain, meat, and egg production
per capita in China exceeded the world average. The increased demand in
Chinese grain production has affected the global food supply and the natural


3

Nutrient Management in China

resource bases required for nutrient production (fossil fuels, mineral sources of
P and K) and has attained world recognition.
However, this 3.4-fold increase in Chinese agricultural food production
during the past 49years can be partly attributed to a 48-fold increase in
chemical fertilizers from 1 to 49MT, including a 37-fold increase in N
fertilizer application and a 91-fold increase in P fertilizer use, and a 442-fold
increase in the area of irrigated croplands (Fig. 1). Total consumption of
chemical fertilizers worldwide increased by 3.9-fold from 32 to 164MT,
indicating that 36% of the global increase ($132MT) came from China
during the past 49years. In the past 10years (2000–2009), 54% of the global
increase in chemical fertilizer consumption ($27MT) was contributed
by China, including 11MT fertilizer N (54% of the global increase), 2.5
MT fertilizer P (52% of the global increase), and 1.1MT fertilizer K (58% of
the global increase) (Figs. 1 and 2A,B).
Cereal yields in the past 10years have continued to increase with no
proportional increases in fertilizer use in many developed countries or
regions such as Western Europe (rainfed cereal systems), North America
(rainfed and irrigated corn), and Japan and South Korea (irrigated rice)
(Dobermann and Cassman, 2005). For example, in the past 10years, chemical fertilizer consumption in the United States increased by only 0.04MT
with 0.23% of total fertilizer consumption in 2009 and decreased by 0.32
MT in Western Europe (Fig. 2A). By contrast, the application rate of

600

400

60

300

40

200
20
100
0
1960

1970

1980

1990

2000

Fertilizer consumption (MT)

Grain production (MT)

500

80
Grain production
Total fertilizer
N fertilizer
P fertilizer
K fertilizer

0
2010

Year

Figure 1 The trend of grain production and chemical fertilizer inputs (N, P, and K
fertilizers) in China from 1961 to 2009. The P and K fertilizers are calculated by P2O5
and K2O, respectively. Fertilizer consumption is defined as the difference between
fertilizer production and exports. Source: FAO (2011) and IFA (2011).


4

Fusuo Zhang et al.

200

80

Global fertilizer (MT)

160
60
120
40
80
20

40

0
1960

1970

1980
1990
Year

1970

1980
1990
Year

2000

Regional fertilizer (MT)

A

0
2010

600

B
-1

Fertilizer rate (kg ha )

500
400
300
200
100
0
1960

2000

2010

Global fertilizer

China

United States

Western Europe

Figure 2 Trend of total chemical fertilizer consumption (A) and fertilizer rate per
hectare (B) for global scale, China, United States, and Western European. Source: IFA
(2011).

chemical fertilizers in China was continually increasing and reached 448kg
haÀ1 in 2009, which is 2.8, 2.9, and 1.4 times the world average and rates in
the United States and Western Europe, respectively (Fig. 2B).
On the other hand, Chinese cereal crop production has stagnated at
approximately 450MT since 1998. From 1998 to 2009, grain yields increased


Nutrient Management in China

5

by only 10%, while the consumption of chemical fertilizers increased by
nearly 49%, 19%, and 33% for N, P, and K, respectively (Fig. 1). That
means that the large increase in fertilizer nutrient inputs did not result in a
corresponding yield increase in the past decade in China. For example, the
REN (the percentage of N fertilizer recovered in the aboveground plant parts
at maturity) in Chinese cereal grain production decreased from about 35% in
the 1980s (Zhu, 1998) to 28% in the 2000s (Zhang et al., 2008a), lower than
the world average of 33% (Raun and Johnson, 1999). Often twice as much
fertilizer N or P is applied compared with the removed nutrients by crops,
and this nutrient imbalance in turn drives severe environmental problems,
such as eutrophication of surface waters (Le et al., 2010), soil acidification
(Guo et al., 2010), greenhouse gas emissions (Zheng et al., 2004), and other
forms of air pollution (Liu et al., 2011). For example, about 60% of inland
lakes in China show eutrophication, and 57% of N inputs and 67% of P inputs
are derived from agriculture (Chinese Ministry of Environmental Protection,
2010). Soil pH declined significantly (P<0.001) from the 1980s to the 2000s
in the major Chinese crop lands due to overuse of N fertilizer (Guo et al.,
2010). On the North China Plain (NCP), total wet and dry deposition of N
averaged 80–90kgNhaÀ1 yrÀ1 in the 2000s (Liu et al., 2006b; Shen et al., 2009;
Zhang et al., 2008b), a value nearly 10 times that at Rothamsted, Harpenden,
UK (Goulding et al., 1998) or in central New York in the USA (Fahey et al.,
1999). These problems are meaningful on a global scale.
To meet the demand for grain and to feed a growing population on the
remaining arable land by 2030, crop production must reach 5.8MT (an
increase of >40%) and yields have to increase by 2% annually (Zhang et al.,
2011). Due to environmental and economic (e.g., rising cost of fossil fuels)
constraints, further increases in food supplies projected for the coming 50
years must be attained through improved resource use efficiency rather than
more agricultural inputs, especially N and P fertilizer applications (Cassman,
1999; Matson et al., 1997; Tilman et al., 2002). Toward this end, sound
agronomic and environmentally acceptable integrated nutrient management
(INM) is an essential approach for the achievement of a reduction in fertilizerderived environmental risk while also increasing crop productivity and NUE.
In most intensive agricultural areas, however, current nutrient management strategies are focused on delivering soluble inorganic N and P from
fertilizers directly to crops and have uncoupled soil and environmental N
and P cycles spatially and temporally. As a result, agricultural ecosystems are
maintained in a state of N saturation and are inherently leaky because chronic
surplus additions of N and P are required to meet the goal of maximum yields
(Drinkwater and Snapp, 2007). For example, the N and P surpluses in
intensive wheat–maize systems on the NCP were recently estimated to be as
high as 227 and 53kghaÀ1 yrÀ1 (Vitousek et al., 2009). Therefore, all these
approaches have been successful in terms of maintaining grain yields; however,
attempts to reduce nutrient losses and improve NUE have met with limited


6

Fusuo Zhang et al.

success in intensive agricultural areas (Cassman et al., 2002; Drinkwater and
Snapp, 2007).
In INM, crop yields can be increased while minimizing nutrient losses to
the environment by managing nutrient supply in the root zone within a
reasonable range, which realizes the biological potential of crops, matches
high-yielding crop N requirement, and controls minimal nutrient losses.
Nutrient supply and nutrient requirements in high-yielding cropping systems must be matched in quantity and synchronized in time and space
(Chen et al., 2010; Cui et al., 2010a). To realize this goal, some improvements must be made: using a variety of N sources from fertilizers, the
environment, and the soil to meet crop demand; calculating the nutrient
balance between the inputs and outputs to manage a variety of intrinsic
ecosystem processes at multiple scales to recouple elemental cycles; and
considering the biological potential of the root system and matching crop
requirements by supplying sufficient N only when plant demand exists (Cui
et al., 2010a; Fig. 3). In this chapter, we discuss the principles of INM and
the development of INM technology on a large scale with dissemination of
INM in different cropping systems up to national scale.

2. Principles of INM
The overall principle of INM is to maximize biological potential for
improving crop productivity and resources use efficiency through root
zone/rhizosphere management. Plant roots take up nutrients from soils
Nutrient supplies in root-zone
Nutrient from
environment

Bioavailable
nutrient

Characteristics
of NPK

Nutrient demand for high-yield crop
Total and
periodic demand

Root
response

Nutrient management strategy
Quantify rootzone nutrient
supplies

In-season
management
for N

High-yielding crop
management

Building-up and
maintenance for
P and K

Correction when
deficient for
trace elements

Optimal water
management

Integrated Nutrient Management

Figure 3 Conceptual model illustrating the principles of Integrated Nutrient Management (INM).


Nutrient Management in China

7

via the rhizosphere, a narrow zone of the soil that is directly influenced by
root growth, root secretions, and associated soil microorganisms. In cropping systems, a rhizosphere continuum in the root zone can be formed due
to root/rhizosphere interactions among individual plants. The rhizosphere
is the important interface where interactions among plants, soils, and microorganisms occur and is a “bottleneck” controlling nutrient transformations,
availability, and flow from soils to plants. Therefore, the chemical and
biological processes occurring in the rhizosphere determine the mobilization and acquisition of soil nutrients together with microbial dynamics, and
also control NUE by crops, and thus profoundly influence cropping system
productivity and sustainability (Zhang et al., 2004, 2010).
As plant growth proceeds, the roots can respond to and/or sense changes
in soil nutrient availability including nutrient supply intensity and composition. These responses involve a series of adaptive alterations in root morphology and root physiology. P-deficient plants can commonly increase
their root/shoot ratio, root branching, root elongation, root topsoil foraging, and formation of cluster roots and root hairs (Lynch and Brown, 2008;
Shen et al., 2011b; Vance, 2008). Mycorrhizal associations can also enhance
the spatial availability of P, extending the nutrient absorptive surface by
formation of mycorrhizal hyphae (Marschner, 1995). On the other hand,
root-induced chemical and biological changes in the rhizosphere affect the
bioavailability of soil P, mainly involving rhizosphere acidification, carboxylate exudation, secretion of phosphatases or phytases, and Pi transporter
expression (Neumann and Ro¨mheld, 2002; Zhang et al., 2010). It has been
reported that P deficiency increases the formation of cluster roots by white
lupin (Lupinus albus L.; Shen et al., 2005; Wang et al., 2007), axial root length
and total root length, and larger amounts of lateral roots and more root hair
formation in maize (Zea mays L.) or Arabidopsis (Bates and Lynch, 1996;
Linkohr et al., 2002; Liu et al., 2004b; Schachtman et al., 1998; Schenk and
Barber, 1979). In crop species, Liu et al. (2004b) found that efficient use of
P in calcareous soil by maize is related to its large root system, with a greater
ability to acidify the rhizosphere, and a positive response of acid phosphatase
production and excretion in low P conditions. High P acquisition efficiency
by modifying root morphology and root physiology in terms of rhizosphere
biological and chemical processes is important for achieving high crop
yields with savings in nutrient inputs. The nutrient supply intensity or
concentrations in the rhizosphere/root zone in cropping systems can be
optimized to a critical level through nutrient management to maximize the
biological potential for efficient use of soil P by plants.
Nitrogen fertilization is the most common practice for the regulation of
root growth in field conditions. Maize roots respond to N supply in two
ways. First, in uniform N supply systems, N deficiency increases maize root
length, resulting in longer axial roots (primary, seminal, and nodal roots;
Tian et al., 2006; Wang et al., 2003). This helps the roots to explore a larger


8

Fusuo Zhang et al.

soil volume and thus increases spatial N availability. However, root elongation can be inhibited if the N supply is too high. In maize, for example, the
optimum nitrate level for root length seems to be around 5mmolLÀ1 (Tian
et al., 2008). Second, root growth can be stimulated when plant roots
experience nutrient-rich patches, particularly when the patches are rich in
N and P (Drew, 1975; Hodge, 2004). When a maize plant is suffering from
N deficiency and part of the root mass is supplied with nitrate locally, the
growth of lateral roots in the supplied area is enhanced (Granato and Raper,
1989; Guo et al., 2005; Sattelmacher and Thoms, 1995). This helps plants to
compete with other plant species and/or microbes for limited N resources
(Hodge, 2004). It is suggested that NOÀ
3 plays a key role as a nutrient signal
in regulating root proliferation (Zhang and Forde, 1998). Localized P
application effectively enhances crop growth and P use efficiency. Moreover, manipulating and managing nutrient supply intensity and composition
in the local fertilization zone can greatly strengthen root growth and
nutrient uptake through modifying rhizosphere processes and enlarging
the root absorbing surface. A field experiment showed that localized application of P with addition of ammonium significantly enhanced P uptake
and crop growth through stimulating root proliferation and rhizosphere
acidification ( Jing et al., 2010). The leaf expansion rate was 20–50% higher,
the total root length 23–30% greater, and the plant growth rate 18–77%
greater with a localized supply of P plus ammonium compared with broadcasting of these nutrients. Localized application of P combined with addition of ammonium significantly decreased rhizosphere pH in the fertilized
zone compared with the bulk soil ( Jing et al., 2010). The results suggest that
modifying rhizosphere processes in the field may be an effective management strategy for increasing NUE and plant growth.
Rhizosphere management emphasizes maximizing the efficiency of
root/rhizosphere processes in nutrient acquisition and use by crops rather
than simply depending on excessive fertilizer inputs, which involves regulating the root system, rhizosphere acidification, carboxylate exudation,
microbial associations with plants, rhizosphere interactions in terms of
intercropping and rotation (Li et al., 2007), localized application of nutrients, use of efficient crop genotypes and synchronizing rhizosphere nutrient supply with crop demand. Rhizosphere management has been shown
to be an effective approach for increasing NUE and crop productivity
through “small causes with big effects” for sustainable agricultural production (Zhang et al., 2010). Based on a better understanding of rhizosphere
processes, the key steps of INM are (1) optimizing nutrient inputs and
taking all possible sources of nutrients into consideration, (2) dynamically
matching soil nutrient supply with crop requirement spatially and temporally, (3) effectively reducing N losses in intensively managed Chinese
cropping systems, and (4) taking all possible yield increase measures into
consideration (Fig. 4).


Nutrient Management in China

9

Figure 4 Rhizosphere/root-zone nutrient management is a key component of INM
for achieving high grain yield and high NUE at the same time.

2.1. Optimizing nutrient inputs and taking all possible
sources of nutrients into consideration
Since the 1990s, excessive chemical N fertilization has often been considered
as the main practical strategy to pursue high yields in China. The average N
fertilizer application rate has far exceeded crop requirements for maximum
grain yield, up to double the crop N demand in some areas (Cui et al., 2010a).
Clearly, applying large amounts of N fertilizer does affect grain yield and N
uptake but also increases the potential for N losses to the environment. For
example, N fertilizer could be cut from 588 to 286kgNhaÀ1 yrÀ1 without
a loss in yield or grain quality and, in the process, reduce N losses by <50%
( Ju et al., 2009). Therefore, we believe that “Controlling the total fertilizer N
application rate” should be a top priority policy and practice to reduce
overuse of N in China under current conditions.
Increasing N fertilizer application rates and associated increases in environmental pollution have led to N derived from the soil and the environment
becoming an important N source for crop plants in China. Across numerous
on-farm experiments (n¼269), indigenous N supply (average N uptake in
control) typically provides around 274kgNhaÀ1 yrÀ1 and accounts for 76% of
crop N uptake in intensive wheat–maize systems (Cui et al., 2010a). As a


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Fusuo Zhang et al.

result, high crop yields can be readily obtained in arable soils without
application of N fertilizers (Tong et al., 2004). This large indigenous N supply
aggravates N surpluses and increases the potential for N losses from agroecosystems unless it is considered to be a component part of the plantavailable N when constructing an integrated N management plan.
The large indigenous N supply is attributed to high soil nitrate-N accumulation and environmental N supply. Soil nitrate-N (NOÀ
3 -N) accumulation in the top 90 or 100cm of the soil was above 200kgNhaÀ1 under
conventional N practice in intensive wheat–maize systems (Cui et al.,
2008a,d; Liu et al., 2003); this residual NOÀ
3 -N supply can reach 1173 and
613kgNhaÀ1, respectively, in greenhouse vegetable and orchard systems in
North China ( Ju et al., 2004, 2006). Ju et al. (2006) observed that residual soil
nitrate-N after winter wheat harvest was 275kgNha–1 in the top 90cm of the
soil profile and 213kgNha–1 in the 90–180cm soil depth increment. Liu et al.
(2004a) reported an average residual soil nitrate-N content of 314kgNha–1 in
the top 2m of the soil profile and 145kgNha–1 at 2–4m soil depth based on
on-farm soil tests in annual winter wheat production systems in Beijing
suburbs on the surroundings of NCP (n¼93). Wheat grain yields on the
NCP showed no response to applied N when initial nitrate-N before
sowing in the top 90cm soil layer exceeded 200kgNha–1, but residual
nitrate-N content after harvest and N losses significantly increased (Cui
et al., 2008a). High nitrate-N accumulation in the soil profile is like a “time
bomb” that could explode at any moment and will finally be lost to the
environment through either denitrification or leaching under high N application rates ( Ju et al., 2009; Zhao et al., 2006). Ju et al. (2002) observed
residual nitrate-N from the first growing season (wheat) to leach from the
0 to 1m soil profile during the second growing season (maize) on the NCP
due to high rainfall in summer.
The total amount of N available from the environment in China in the
2000s has more than doubled compared with the 1980s because of the rapid
continuing increases in both oxidized and reduced N emissions (Liu and
Zhang, 2009; Liu et al., 2010, 2011). According to Fig. 5, N inputs from
atmospheric N deposition and irrigation water in China were up to 33 and
12kgNhaÀ1 yrÀ1 in the 2000s but only 14 and 4kgNhaÀ1 yrÀ1 in the 1980s.
Similar rapid increases in environmental sources of N from atmospheric
deposition and irrigation water were reported on the NCP and in the Taihu
Lake region ( Ju et al., 2009). Nitrogen input from deposition plus irrigation
was only 30kgNhaÀ1 yrÀ1 on the NCP and in Taihu Lake region in the
1980s, and this value has increased to 99 and 89kgNhaÀ1 yrÀ1, respectively,
in these two intensive agricultural regions in the 2000s ( Ju et al., 2009).
Evidence from the NCP indicates that dry N deposition (50–60kgNhaÀ1
yrÀ1) (Shen et al., 2009, 2011a) is likely to be a major contributor to the
environmental N in this semihumid/semiarid region compared with wet
N deposition (%30kgNhaÀ1 yrÀ1) (Liu et al., 2006b; Zhang et al., 2008b).


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Nutrient Management in China

35
1980s

N input (kg N ha-1 yr -1)

30

2000s
25
20
15
10
5
0
N deposition

N from irrigation

Figure 5 Changes of N input from atmospheric deposition and irrigation in Chinese
croplands during 1980s and 2000s. Modified from Liu et al. (2011).

Further studies confirm that about 50% of this air-borne N input (52kg
NhaÀ1 yrÀ1) can be utilized by current crops, according to the ITNI-system
which is based on a 15N dilution approach (He et al., 2007a, 2010).

2.2. Dynamically matching soil nutrient supply with crop
requirement spatially and temporally
Nutrient applications that meet, but do not exceed, crop nutrient requirements are essential for achieving maximum yields and minimizing environmental risk. Recent research on improving NUE in crop production systems
has emphasized the need for greater synchrony between crop nutrient
demand and nutrient supply from all sources throughout the growing season
(Cassman et al., 2002; Cui et al., 2010a; Fan et al., 2008). Nitrogen fertilizers
applied during periods of the greatest crop demand, at or near the plant roots,
and in small quantities and frequent applications, can potentially reduce losses
while maintaining or increasing crop yield and quality (Matson et al., 1998;
Tilman et al., 2002).
In INM, we attempt to manage soil nutrient supply in the root zone
within a reasonable range that matches the quantity required by the crop, is
synchronized in terms of time and crop growth, and is coupled in space to
nutrient supply and crop nutrient requirements, especially in N management (Chen et al., 2010, 2011; Cui et al., 2010b). Dry matter production
and thus N requirement is relatively low before the rapid growth stages of
crops, that is, stem elongation of wheat and the expanded leaf stage of maize.
In most cases, a small amount of N fertilizer and indigenous N supply can


12

Fusuo Zhang et al.

meet the crop N requirement, establish growth, and promote the development of healthy roots during the early periods of crop growth (Cui et al.,
2008a,d). Nitrogen application in excess of crop N demand during this
period increases the potential for nitrate-N leaching and results in excessive
crop growth that is more susceptible to disease and lodging. Therefore,
more N fertilizer (around 60–70% of the total N fertilizer input) should be
applied during the most rapid growth stages of the crop to achieve synchronization between the N supply and crop demand (Cui et al., 2008b,c).
Restricted by old knowledge and habits, farmers often apply large
amounts of N fertilizers before planting or at the early growth stages as a
conventional management practice in crop production. For example, the N
supply before planting is usually about 50% of the total amount given (Chen,
2003; Cui et al., 2008c,d). Many rice farmers in China apply 50–90% of the N
as a basal dressing and an early top-dressing within the first 10 days after
transplanting to reduced transplanting shock and stimulate early tillering
(Zhang et al., 2011). Clearly, this large amount of N fertilizer at the early
growth stages has resulted in poor synchronization between soil N supply and
crop demand, leading to high soil inorganic N concentrations before the
occurrence of rapid crop N uptake (Chen et al., 2006; Tilman et al., 2002).
Although the average N application rate in China is excessive for the
maximum crop N requirement, some low-income farmers or those in
remote areas apply N inadequately. If we simply use 150–200kgNha–1 as
a reasonable amount of N fertilizer for the main wheat and maize growing
regions of China (n¼10,000), only one-third of farmers would be in this
range, one-third would be applying too much (N rate>200kgNhaÀ1), and
one-third would be applying too little (N rate<150kgNhaÀ1) (Wang,
2007). On a regional scale, higher crop yields are likely to be achieved
through a combination of increased N application in regions with a low N
input and improved NUE in regions where N fertilizer use is already high.

2.3. Effectively reducing N losses in intensive managed
Chinese cropping systems
The fate of fertilizer N in cropping systems is an integrated result of crop N
uptake, immobilization, and residues in the soil, and losses to the environment, including ammonia volatilization, denitrification, N leaching and
runoff. There are close relationships among these three major fates of applied
fertilizer N, which are influenced by many factors such as crop characteristics,
soil properties, climatic conditions, and management practices. According
to an integrated study, Ju et al. (2009) found that the mechanisms of N loss
were very different in two major intensively managed crop rotation systems,
that is, wheat–maize and rice–wheat systems. Understanding N processes will
help us control the N losses and their harmful environmental effects while
maintaining high crop productivity.


13

Nutrient Management in China

Under current farming practice (about 550kgNhaÀ1 yrÀ1 in both cropping systems and usually without deep placement of urea or ammonium
bicarbonate), ammonia volatilization in the wheat–maize is about 20–25%
of applied N and this is the main N loss pathway due to high pH (around
8.0) in calcareous soils together with surface broadcasting of urea before
irrigation or rainfall under most farmers’ practices (Fig. 6). In paddy soils,
ammonia volatilization is about 12% of applied fertilizer N in the rice
growing phase and is very low and about 2% in the wheat phase (Fig. 6).
Another important N loss pathway in paddy soils is denitrification, which
was found to be 36–44% of applied N (Fig. 6). Because of low levels of
groundwater in these soils and copious rainfall in the wheat season, drying
and wetting cycles frequently occur and these are favorable for denitrification (Zhao and Xing, 2009), with N2 and N2O representing the main
products of denitrification. Within wheat/maize systems under conventional agricultural N management practices, nitrate-N leaching below the
root zone was found to be the important N loss pathway (Liu et al., 2003)
due to concentrated rainfall in summer and flooding irrigation, which
contradicts the conventional wisdom that leaching losses are not an important N loss pathway in semihumid upland agricultural systems on the NCP
( Ju et al., 2004).
50
45

NH3 volatilization

40

Leaching
Denitrification

N losses (%)

35
30
25
20
15
10
5
0
Rice Wheat-South
Taihu region

Wheat-North Maize
North China Plain

Crops and regions

Figure 6 N loss pathways expressed as a percentage of N application rates in farmers’ N
practices for the Taihu region and North China Plain. N fertilizer rates for rice and wheat
are 300 and 250kgNhaÀ1 in the Taihu region and are 325 and 263kgNhaÀ1 for wheat
and maize in North China Plain, respectively. Modified from Ju et al. (2009).


14

Fusuo Zhang et al.

Total fertilizer N losses in wheat–maize rotation averaged 31%, lower
than the 48% in rice–wheat rotation (Fig. 6); correspondingly, the residual
N in the soil is higher than that in the latter system, so that the capacity to
retain synthetic N is higher than that in rice–wheat. However, released
reactive N in wheat–maize rotation systems is higher than in rice–wheat
rotations. Upland–upland crop rotations on calcareous soils lead to substantial ammonia volatilization and nitrate-N accumulation or leaching, which
are the main loss pathways of fertilizer N in North China, and the frequent
flooding and drying cycles lead to N losses via denitrification and ammonia
volatilization in paddy-upland crop rotation systems ( Ju et al., 2009).
In practice, the amount of NH3 volatilization is largely influenced by
fertilization method and N fertilizer type. Deep placement of urea or ammonium bicarbonate increases N use efficiency. For example, N loss through
NH3 volatilization during the maize growing season can be reduced by
11–48% of applied urea-N fertilizer with deep placement compared with
surface broadcasting (Li et al., 2002; Zhang et al., 1992). In China, N is
generally recommended to be applied to wheat before irrigation because of a
very low recovery of broadcast urea when precipitation is low and the fertilizer
cannot reach the rooting zone. In contrast, when urea is applied before
irrigation or plowing, NH3 volatilization is significantly reduced, indicating
the necessity for irrigation or rainfall to leach N fertilizer into the rooting zone.
The strategy to reduce nitrate leaching can be achieved simply by
decreasing the nitrate-N content in the soil profile. For environmentally
sound crop production, the residual nitrate-N content in soil should be
minimized, especially at the end of the growing season, because nitrate-N
leaching is directly related to the mineral N content in the root zone
(Dinnes, et al., 2002; Roth and Fox, 1990; Sogbedji, et al., 2000). However,
achieving high maize yields is impossible if nitrate-N in the root zone is too
low. It then becomes important to consider “the suitable soil nitrate-N level
at which the lower limit does not restrict grain yield and the upper limit
does not lead to unacceptable N losses to the environment.” According to
European experience and our own results (Cui et al., 2008b,c; Hofman,
1999; Schleef and Kleihanss, 1994), residual nitrate-N content after harvest
in the top 90cm soil layer should be maintained around 90kgNhaÀ1. When
inorganic N exceeds 190kg nitrate-N haÀ1 in the top 90cm of soil profiles
before planting, an increase in grain yield in response to added N is unlikely
in Chinese intensive wheat–maize systems (Cui et al., 2008b,d).
Application of nitrification inhibitors such as DCD, DMPP, and nitrapyrin together with NHþ
4 -based fertilizer can reduce N2O emission by 77%
on the North China because N2O emissions occur mostly during the
nitrification processes after fertilizer N application and irrigation ( Ju et al.,
2011). Recently, we estimated that N2O emission was 33.1GgNyrÀ1 from
paddy fields and 255.3GgNyrÀ1 from upland soils in 2007 (Gao et al.,
2011). If 50% of the total area is taken into account and 77% reduction by


Nutrient Management in China

15

using nitrification inhibitors in upland crops, the total emission in upland
soil will be 169.7GgNyrÀ1. The total N2O emission from Chinese croplands would be reduced by 30% from the current amount with careful use of
nitrification inhibitors.

2.4. Taking all possible yield increase measures into
consideration
Many recently developed approaches and tools for fine-tuning N management
have increased the NUE by decreasing the N fertilizer rate, but substantial
and consistent yield increases have been demonstrated in only a few studies
(Dobermann and Cassman, 2005). The major challenge of current nutrient
management in China is how to increase crop yields to meet food demand
while also increasing NUE to protect the environment. Large numbers of
experiments indicate that the grain yield potential of currently grown cereal
varieties in China far exceeds actual yields obtained. For example, the average
maize yields in farmers’ fields are 5.3MghaÀ1 in northeast China, 5.1thaÀ1
on the NCP, and 4.0thaÀ1 in hilly areas in south China (ECCAY, 2006).
However, maize yields in new variety trials in these regions typically average
8.5, 7.3, and 6.7thaÀ1, 60%, 45%, and 68% above the average farming yields
(Fan et al., 2010b). The highest attainable maize yields recorded, achieved with
high inputs of nutrients, water, and labor, were 16.8thaÀ1 in northeast China,
18.0thaÀ1 in the NCP, and 14.7thaÀ1 in south China (Fan et al., 2010a,b).
Similar results have been obtained for wheat and rice over the whole country.
This implies that, when an integrated management approach to crop production is used, there is great potential to increase cereal grain yields above current
farming yields with significant enhancement of the ability of Chinese agriculture to meet food demands in the coming decades.
Increased yields can be attributed to greater NUE from both indigenous
and applied nutrient sources, especially N sources, because rapidly growing
plants have larger root systems that more effectively exploit available soil
resources (Cassman et al., 2002). Crop health, insect and weed management,
moisture and temperature regimes, supplies of nutrients, and use of the best
adapted cultivars or hybrids all contribute to efficient uptake of available
nutrients and conversion of plant nutrients to grain yields. Key contributory
factors include (a) increased yields and more vigorous crop growth associated with greater stress tolerance of modern hybrids, (b) improved management of production factors other than N (conservation tillage, seed
quality, and higher plant densities), and (c) improved N fertilizer management. For example, the nitrogen partial factor productivity (PFPN) in North
China increased to 50 and 47kgkgÀ1 using integrated N management for
wheat and maize production compared with 15 and 25kgkaÀ1 over those
with farmers’ N management practice. The PFPN could further to 60 and
59kgkgÀ1 when N-efficient varieties were used (Cui et al., 2009, 2011).


16

Fusuo Zhang et al.

Additional improvements in soil quality can occur when the benefits of C
sequestration are coupled with increases in crop yields from adoption of
cultivation practices that reduce yield losses from abiotic and biotic stresses,
such as returning straw back to the soil, increasing applications of organic
manures, and using reduced tillage. Over the past two decades, the soil organic
matter content of soils in north China has significantly increased because of
increasing incorporation of crop residues and organic manure and the development of no-tillage and reduced-tillage practices (Huang and Sun, 2006).
Crop yields increased in this region at the same time (ECCAY, 2006).

3. Technology and Demonstration of INM in
Different Cropping Systems
Nitrogen is unique among the major nutrients since it is synthesized
from the atmosphere using the Haber–Bosch process and its transformation
and transport in the pedosphere and hydrosphere are mediated almost
entirely by biological processes (Galloway and Cowling, 2002). As a result,
N is mobile, hard to contain, and even N that is efficiently conserved and
taken away in crop harvest eventually makes its way back into the environment (Robertson and Vitousek, 2009). Hence, efficient use of N in crop
production is essential for increasing crop yields, environmental safety, and
the consequent economic considerations (Campbell et al., 1995).
Recent literature on improving N use efficiency in crop production has
emphasized the need for greater synchronization between crop N demand
and N supply from all sources throughout the growing season (Cassman et al.,
2002; Chen et al., 2010; Cui et al., 2009). Considering site-specific soil N
supply and crop demand, current research has demonstrated that in-season
applied N results in a high grain yield and high N use efficiency (Table 1; Cui
et al., 2009; Chen et al., 2010). As a net result of soil N transformation,
transport, and previous fertilizer applications, soil N supply can significantly
influence crop N uptake. It is very important to quantify the total N balance
þ
including initial soil Nmin (NOÀ
3 þNH4 ), N mineralization, environmental
N supply, crop N uptake, N losses, and N immobilization during the growing
season. However, it is very difficult to measure accurately N balance with all
components, especially under field conditions (Blankenau et al., 2000; Engels
and Kuhlmann, 1993). The amount of soil Nmin at rooting depth may be a
good index to estimate the N balance situation. Substantial attempts should be
made to manage the N supply in the root zone in order to match the total
quantity of N required by the crop in both space and time.
Unlike N, management of fertilizer P and K focuses on maintenance of
adequate soil available P or K levels to ensure that neither P nor K supply
limits crop growth or becomes excessive due to overfertilization (Table 1).


17

Nutrient Management in China

Table 1 Resource characteristics of nutrient and the technologies of INM for different
nutrients
Nutrients

Resource characteristics

N

In-season root-zone
Diverse sources
management
Multidirectional losses
Serious environmental harm
Crop sensitivity
Building-up and
Limited resources
maintenance approach
Large soil pools but low
effectiveness
Long-term effects
Crop sensitivity
Yield failure with deficiency Correction when
Too much causing toxicity
deficiency
Just meeting crop demand

P and K

Micronutrients or
trace elementsa
a

Management strategy

Trace elements include boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn), respectively.

In China, maintenance of fertilizer P or K rates is recommended on the basis
of constant monitoring of soil nutrient supplies and nutrient holding capacities (Li et al., 2011; Wang et al., 1995). In soils with low P status and/or
high fixation capacity, capital investment is required to build up soil nutrients until the system becomes profitable and sustainable. On soils with
moderate P and K levels and little fixation, management must focus on
balancing inputs and outputs at field and farm scales to maximize profit,
avoid excessive accumulation, and minimize risk of P losses (Dobermann,
2007). Therefore, managing nutrients to achieve synchrony between nutrient supply and crop demand is crucial to increase NUE while maintaining
agricultural productivity and improving technical operability.
The management strategy of trace elements such as boron (B), chlorine
(Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel
(Ni), and zinc (Zn) is based on their plant availability in both soil and plant.
Their available contents in soil and (or) critical concentrations in plants are
determined and then the corresponding micronutrient fertilizers are applied
so that trace elements do not become a yield limiting factor (Table 1). This
strategy follows the law of the minimum and uses dose–response curves.
This type of curves for all the essential micronutrients show that the yields
can be affected by deficiencies and can also be reduced by toxicity due to
excessive concentrations. Not all micronutrients should therefore be applied
in the field. It is therefore important to monitor soils and/or crops to ensure
that the available micronutrient concentrations in soils are within the
optimum range and neither too low nor too high (Alloway, 2008).


18

Fusuo Zhang et al.

3.1. INM for intensive wheat and maize system
From 1961 to 2009, wheat production in China increased sevenfold from
14 to 115MT and maize production also increased sevenfold from 18 to 164
MT. In 2009, wheat production represented 24% of the Chinese cereal
output and 17% of global wheat output (FAO, 2011). Similarly, maize
production represented 34% of Chinese cereal output and 20% of global
corn output (FAO, 2011). The rapid development of wheat and maize
production has been attributed to increasing grain yield. During the same
period (1961–2009), wheat grain yield increased seven times from 0.56 to
4.74thaÀ1 and maize grain yield increased three times from 1.18 to 5.26thaÀ1
(FAO, 2011).
With simultaneous increases in fertilizer application rates and grain yields
before the mid 1990s, especially N and P fertilizers, most extension staff and
farmers still believed that the more fertilizer they use and the higher the
grain yields that would be obtained. Based on extensive on-farm investigations from 1997 to 2007 (Cui et al., 2010a; Ma et al., 1999), the typical
annual N rate for farmers was >500kgNha–1 for the intensive wheat–maize
rotation system in the NCP and approached 600kgNha–1 in some regions.
Average grain yields were around 11.5tha–1 yr–1 (around 5.5 and 6.0tha–1
for wheat and maize, respectively), and the estimated N uptake was only
300kgNha–1 yr–1 (around 160 and 140kgNha–1 for wheat and maize,
respectively). Results from region-wide experiments have demonstrated
that the economically optimal N rate is 130–160kgNha–1 crop–1 for the
intensive wheat–maize system (Cui et al., 2008b,c). Similar results showing
excess fertilizer application also observed for P. As a result, nutrient surpluses in the main cropping systems, and hence environmental losses, are
very high (Vitousek et al., 2009). In addition, wheat and maize production
in China has stagnated since 1996. From 1996 to 2009, wheat and maize
grain yields increased by only 1% and 27%, with annual growth rates of
<0.1% and <2% (FAO, 2011).
Soil N tests (NO3-NþNH4-N) for upland soils are an important tool for
assessing soil N supply capacity (Wehrmann and Scharpf, 1979). However,
the original soil Nmin method that is based on a single soil N test before
planting and that disregards variations in the soil N cycle (N mineralization,
N immobilization, and losses) may result in underuse or overuse of N
fertilizer. Several versions of the presidedress soil nitrate-N test only establish the critical threshold above which there is a low probability of a yield
response to sidedress N application, but do not provide an accurate estimate
of the optimal N rate below a critical value (Magdoff et al., 1984; Meisinger
et al., 1992; Schmitt and Randall, 1994). Uncertainties in the prediction of
the seasonal crop N demand and soil N movement require the use of N
status indicators for fine-tuning of N rate and timing of N applications. This
requires monitoring soil N concentrations in the root zone at different


19

Nutrient Management in China

growth stages of crops to achieve the synchronization of crop N nutrient
uptake and N supply from wastes, indigenous soil resources, and environmental sources. For optimum management of soil N supply in the root
zone, we have developed an in-season root-zone N management strategy
for intensive wheat–maize systems on the NCP (Chen et al., 2006; Cui et al.,
2008b,c; Zhao et al., 2006). According to this strategy, the total amount of
N fertilizer is divided into two or three applications over the course of the
growing season, with the optimum N fertilizer rate (ONR) for each application being determined from soil nitrate-N tests in the root zone and a target
N value for the corresponding growth period of the crop (Fig. 7).
To confirm whether ONR using in-season root-zone N management
was the economically optimum N rate, we conducted on-farm experiments
(wheat, n¼121; maize, n¼148) with three N levels during 2003–2007 to
evaluate this N management in terms of agronomic performance and
environmental impact. Compared with farming practice (FNP), the inseason root-zone N management strategy reduced N fertilizer by 60% and
40% for wheat and maize, and simultaneously increased grain yield by 4%

Soil nitrate-N testing in root-zone

3-leaf stage

Planting

10-leaf stage

N demand

N target value

N supply

Fertilizer+ N
from
environment,
etc.

Nutrient bioavailability

Planting
Nutrient spatial
availability

Nutrient temporal and spatial variability
Nitrogen target value for different grain yield for Chinese maize production
Target yield (t ha-1)

8.0–8.5
-1

9.5–10.0

7.0–7.5

5.5–6.0

6.5–7.0
25

Before sowing (kg N ha )

20

30

20

20

Three leaf stage (kg N ha-1)

95

160

85

60

75

Ten leaf stage (kg N ha-1)

190

220

175

140

160

Figure 7 Model of in-season root-zone N management and N target value for different grain yields for Chinese maize production. Date source: Cui et al., 2008b.


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