The document summarizes research on soil organic carbon sequestration and crop production in China based on long-term experiments. It discusses (1) key long-term experiment sites across China that have studied the effects of fertilization on soil and crops over decades, (2) relationships between soil organic carbon levels and crop yields showing that higher SOC contributes to higher and more stable yields, and (3) analysis of optimal SOC levels for different crop producing regions in China.

1. Soil Organic Carbon Sequestration
and Crop Production in China
based on Long-term Experiments
Minggang XU
Xubo Zhang, Wenju Zhang, Changai Lu
(Institute of Agricultural Resources and
Regional Planning, CAAS, China)
International Conference on Black Soil, Harbin, 2018.9

2. Black Soil is Very, Very Important For
Crop production and Food Safety!
3% Black Soil in Arable land
40% Total Crop Production in the
World

3. Soil
productivity
Contribution from
Basic Soil Fertility
Effects of Management:
Fertilization,
irrigation, …...

4. 基础地力
Increasing efficiency of
water and fertilizers
水
肥
效
应
地
力
效
应
Crop Productivity:
Soil fertility interaction with efficiency of Water
and fertilizers
Increasing Soil fertility
Crop
yield

5. <20
20~30
30~40
40~50
50~60
60~70
70~80
80~90
>90
Soil Fertility Contribution to Grain Yield in China: 52%
For rice, wheat and maize in average
Tang and Huang, 2009
单季稻 早稻 晚稻
小麦 玉米

6. <20
20~30
30~40
40~50
50~60
60~70
70~80
80~90
>90
Soil Fertility Contribution to Grain Yield in China: 52%
Lower 20% than that of USA Why???
Tang and Huang, 2009
单季稻 早稻 晚稻
小麦 玉米
SoilFertility
Fertility
Soil
W-F
W-F
Same Varity
Yield
USA
China

7. Low SOM
In China, SOM in 26% of arable soil is less than 1% ,
which is only 30-50% of European Soils.
Requirement:
Techniques to increase soil fertility, SOC
Lower Soil Fertility in China
Region Brown earths
Cinnamon
soils
Chernozems
China 1％－1.5％ ≈1% ≈3%
Europe >3% >2% ≈8%

8. Outline
 Long-term experiments in cropland of China
 Relationship SOC and crop production
 Critical SOC level for high crop production
 Future Research

9. Part One
Long-Term Experiments (LTEs)
in Cropland of China

10. LTEs In the World
Longer than 100 years: around 25 sites
The Longest One:
Rothamsted, established in 1843,
175-year history

11. The classical experiments at Rothamsted
N, P, K,
Manure Broadbalk
Continuous
Wheat
Experiment
First sown 1843

12. LTEs In the World
The 2nd Longest One: Morrow
Plots, located in University of
Illinois at Chamigan-Urbana,
established in 1876
142-year history, Foundation of
USA Agri.

13. 2018年9月10日
Effects of Rotation and Fertilization on Crop Productivity
and Soil Quality, National Historical Landmark

14. LTEs In China
1.Chemical fertilizer experiment net: began
during “the 6th five-year plan” and conducted
about in 1980
2.The Chinese National Soil and Fertilizer Long-
Term Monitoring Net: set up during “the 7th five-
year plan” and conducted in 1990

15. National long-term fertilizer experiment net
From 1980, about 80 long-term fertilizer experiments through 22
provinces and 10 soil types in China, conducted to investigate the
effect, rate and ratio of N, P and K fertilizers
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图例
■ 双季稻区试验点；
■ 水旱两熟区试验点；
▲ 旱作两熟区实验点
▲ 旱作一熟区试验点
全国定位试验点分布示意图

16. Gray dessert soil
Black soil
Drab fluvo-aquic soil
Fluvo-aquic soil
Loess soil
Paddy soil
Paddy soil
Red soil
Purple soil
China Long-term
Soil Fertility Experiment
Network (CSFEN)
CSFEN was established in 1990
There are 9 experimental sites
in the network all over China

17. Ongoing LTEs Net work in China
形成遍布全国的：
农田长期试验协助网！
40个长期试验，
40 long-term Exps
(longer than 25 Years)
10个主要土壤类型；
Ten Major soil Types
10个主要耕作模式；
覆盖主要粮食作物
10 Rotational Systems
水旱轮作
水稻
旱作
单季
双季
旱作

18. Red Soil LTEs (1990- ), Qiyang, Hunan
Wheat-Maize, two crops, annually

19. Wheat in filling period in Zhengzhou of Henan Province
Chao Soil LTEs (1990- ), Zhengzhou, Henan
Wheat-Maize, two crops, annually

20. 2018年9月10日
图1. 耕层土壤全磷的变化
Fig 1.Change of soil total P in plough layer
500
600
700
800
900
1000
1990 1994 1996 2000 2002
时间 Year
全磷含量
TotalP（g/kg）
CK NP
PK NPK
a
Loess Soil LTEs(1990-), Yangling, Shaanxi.
Wheat-Maize, two crops, annually

21. Paddy Field
Long-term Exp.
（1983-）,
Nanchang,
Jiangxi.
Rice-Rice, two
crops annually

22. Paddy Field LTEs（1981-) Wuchang, Hubei
Rice-Rape rotation, Two crops annually

23. Black soil Long-term Exp. In Gongzhuling
(1980-), Maize, one crop annually

24. Black soil Long-term Exp. In Harbin （1979-）
Soybean-Wheat-Maize Rotation, One crop annually

25. Usual Treatments for the Exp.
1 CK （No. Fertilization）
2 N
3 NP
4 NK
5 PK
6 NPK

26. Treatments for the Exp.
7 NPK+Manure(NPKM)
8 High NPK+Manure（1.5NPKM）
9 Straw +NPK（NPKS）
10 Manure（M）

27. Published a Book:
Evolution of soil
fertility in China
Cooperated by 50
researchers
First Edit: 2006

28. Evolution of soil fertility in China
Cooperated by 300 researchers
Second Edit: 2015

29. Part Two
Relationship SOC and crop
production

30. Soil fertility
Crop
production
Climate
change
Soil fertility, SOC pool, and food security
food
security
SOC
Environment
-friendly

31. SOM or SOC is the basis and core of
the soil fertility!
The improvement of SOC and soil
fertility is fundamental of ensuring
food security!
SOC pool － Soil fertility －
Soil productivity

32. SOM increase with crop yield for four
soil types in China
y = 8E-05x + 8.1621
R
2
= 0.565
8.0
8.5
9.0
9.5
10.0
7000 11000 15000 19000
Crop yield (wheat+corn) (kg/ha)
Organicmatter(g/kg)
灰潮土
y = 0.8909Ln(x) + 1.4013
R
2
= 0.996
6
7
8
9
10
11
12
13
14
15
0 1000 2000 3000 4000 5000 6000
Wheat yield (kg/ha)
OC(g/kg)
1/2OM
OM
CF
y = 3.5361Ln(x) - 16.087
R2
= 0.6917
14
15
16
17
18
19
7000 11000 15000 19000
Crop yield (wheat+corn) (kg/ha)
Organicmatter(g/kg)
砂姜黑土
y = 1.4992Ln(x) - 4.3345
R2
= 0.7167
8
9
10
11
7000 11000 15000 19000
Crop yield (wheat+corn) (kg/ha)
Organicmatter(g/kg)
白散土
河南潮土
SOM
SOM
SOMSOM
Fluvo-aquic soil Lime concretion black soil
Gray fluvo-aquic soil Whitish soil

33. CROP YIELD INCREASE WITH
INCREASE IN SOC BY 1 Mg C/Ha
(LAL, 2005)
Crop Yield Increase (Kg/Ha/Mg C)
Maize 100 - 300
Soybeans 20 - 50
Wheat 20 - 70
Rice 10 - 50
Sorghum 80 - 140
Millet 30 - 70
Beans 30 - 60

34. CROP YIELD INCREASE IN CHINA
WITH SOC INCREASING 1 g C/KG
Region and crop Yield (Kg/ha)
Northeast (Spring maize) 176
Northern China(Wheat and
summer maize)
454
Northwest (Spring maize) 328
Middle China (Rice)
Southeast (Rice-Rice)
Southwest (Wheat-Rice)
185
266
229
(QIU ET AL, CHINA AGRICULTURE SCIENCE, 2009)

35. Different Regions of LTEs of China

36. Average relative yield from different treatments in different regions
Numbers in parentheses are standard deviation and numbers with the same
lowercase (for wheat) or capital (for maize) letter are not significantly (P < 0.01)
different among four treatments in each column. N/A: no data available.
Crop Treatment
Average relative yields
North East North West North South
Wheat Control 0.63(0.06) b 0.35(0.02) c 0.29(0.01) c 0.52(0.14) c
NP/NPK 0.97(0.06) a 0.97(0.01) b 0.90(0.02) b 0.82(0.06) c
NPM /NPKM /hNPKM 1.05(0.02) a 1.11(0.02) a 1.04(0.01) a 2.53(0.59) a
NPS/ NPKS N/A 1.06(0.02) a 0.94(0.03) b 1.21(0.05) b
Maize Control 0.50(0.02) D 0.39(0.03) C 0.43(0.01) C 0.12(0.02) C
NP/NPK 0.94(0.01) C 1.02(0.03) B 0.91(0.02) B 0.59(0.07) C
NPM /NPKM /hNPKM 1.08(0.01) A 1.13(0.02) A 1.06(0.01) A 2.53(0.27) A
NPS/ NPKS 1.01(0.03) B 1.04(0.03) B 1.07(0.02) A 1.26(0.08) B

37. Treatment Period
Average SOC storage (t C ha-1)
North East North West North South
Control before 2000s 31.3(1.0) c 19.5(0.5) de 19.1(0.8) de 20.6(0.5) d
after 2000s 30.1(1.3) c 18.5(0.3) e 18.0(1.2) e 19.8(0.6) d
NP/NPK before 2000s 33.6(0.7) bc 20.9(0.4) cd 21.5(0.7) cd 23.1(0.4) cd
after 2000s 33.3(0.9) c 21.8(0.4) c 22.2(0.7) c 23.2(0.5) cd
NPM/NPKM/hNPKM before 2000s 37.6(0.7) b 25.4(0.6) b 27.3(0.6) b 28.1(1.4) b
after 2000s 43.6(1.1) a 35.8(0.9) a 30.6(0.6) a 34.1(1.3) a
NPS/NPKS before 2000s 32.8(0.3) c 21.1(0.5) cd 22.7(0.5) c 22.8(1.0) cd
after 2000s 34.3(1.0) bc 25.7(0.7) b 26.6(1.4) b 25.1(0.9) bc

38. 







)(
)<(
optSmax
optSS
SOCSOCYP
SOCSOCBSOCA
YR
linear-plateau
model:
Increases beyond 21.8-
46.2 t C ha-1 in the top
20 cm soil would not
provide any more
benefit to increasing
grain yields when SOC
reaches this threshold.
Critical SOS
(SOCopt)

39. Region
Relative yield (%) Equivalent to crop yield (kg ha-1)
Wheat Maize Wheat Maize
North East 6.4 2.9 160.0 159.5
North 6.1 3.9 112.8 216.5
North West 10.5 9.9 105.1 165.8
South 6.4 10.3 89.6 252.4
Change rate of crop relative yield and equivalent crop
yield with an increment of 1.0 t C ha-1 in C storage before
its SOCopt in the top 20 cm soil depth in different regions

40. An increasing of 1 t C ha-1 during the experimental
period could reduce the average variability by 1.1,
2.3 and 3.8% for wheat and 1.0, 1.7 and 3.4% for
maize in the North West, the North and the South
region, respectively.

41. There is a close correlation between the average grain
yield in normal years and SOC content in cropland in
the major grain-producing areas
In China, the SOC storage increased by 1 t C/ha could get
the grain productivity of 100-260 kg /ha
On average, with the increase of 1 t /ha of SOC, the increase
of grain yield stability would increase by 2% to 4%.
Enhancing of soil carbon sequestration to ensure
crop productivity and stability in China
Summary this part

42. Part Three
Critical SOC level for high
crop production
(A case study in Black soil)

43. Long-term experiment site
 The selected long-term field experiment：
located in Gongzhuling city, Jilin province,
started in 1980
 Cropping system：rainfed continuous corn
 Soil type：black soil

44. Main-
treatment
(Manure)
Sub-treatment (Chemical fertilizer)
M0 CK N P K NP NK PK NPK
M2 CK N P K NP NK PK NPK
M4 CK N P K NP NK PK NPK
Split-plot design: three main-treatments (manure)
and eight sub-treatments (chemical fertilizers)
Application rate
Manure Chemical fertilizer
M0 –0 m3/ha (no manure) Pure N -- 150 kg/ha
M2 --30 m3/ha P2O5 -- 75 kg/ha
M4 --60 m3/ha K2O -- 75 kg/ha
Experimental design

45. After 29 years in 2009,
Still big differences
for chemical
fertilizers in Mo Plot

46. After 29 years in 2009,
However, no
significant
differences for
chemical fertilizers
in M2 and M4 Plots
When and
Why?

47. Dynamic of yield increment due to fertilizer
under different manure rates
-50
0
50
100
150
200
250
1980 1985 1990 1995 2000 2005 2010
年份 Year
增产率(%)
Incrementofyield（%）
N P K NP
NK PK NPK
-50
-25
0
25
50
75
100
1980 1985 1990 1995 2000 2005 2010
年份 Year
增产率(%)
Incrementofyield（%）
N P K NP
NK PK NPK
-50
-25
0
25
50
75
100
1980 1985 1990 1995 2000 2005 2010
年份 Year
增产率(%)
Incrementofyield（%）
N P K NP
NK PK NPK
M0 M2
M4

48. SOC dynamic under different manure rates
10
15
20
25
30
35
1980 1985 1990 1995 2000 2005 2010
年份 Year
土壤有机碳（g/kg）
Soilorganiccarbon(g/kg)
CK N P K
NP NK PK NPK
10
15
20
25
30
35
1980 1985 1990 1995 2000 2005 2010
年份 Year
土壤有机碳（g/kg）
Soilorganiccarbon(g/kg)
CK N P K
NP NK PK NPK
10
15
20
25
30
35
1980 1985 1990 1995 2000 2005 2010
年份 Year
土壤有机碳（g/kg）
Soilorganiccarbon(g/kg)
CK N P K
NP NK PK NPK

49. Relationship between yield increment due to
fertilizer and SOC
-50
0
50
100
150
200
250
10 15 20 25 30 35
土壤有机碳 Soil organic carbon (g/kg)
增产率(%)
Incrementofyield(%)
y1 = -30.14x + 543.64
R2 = 0.3745**
y2 = -1.6295x + 43.034
R2 = 0.1596**
SOC=17.6g/kg
SOM=30.3g/kg

50. Major Conclusions for this part
1) When the SOM content reached to 30 g/kg，the chemical
fertilizer can be completely replaced with the manure for
achieving the expected high yield!
2) The results obtained from 170-yr Roth experimental
station show that proper chemical fertilizer application
can maintain high yield. However, our results indicate
that manure alone can also produce the equivalent high
yield when the soil fertility is high enough.
3) This is very important for Organic Agriculture or
Organic Framing and agricultural sustainable
development!

51. Part Four
Future Research
for SOC and crop production

52. Water &
Nutrient
Holding
Look for the Critical SOC
keeping good soil function
Soil OM
SoilQuality
Aggregation &
Infiltration Productivity
Air & Water
Quality,Wildlife
Habitat
Critical Soil Carbon

53. Long-term
Exps.
Lab.
Anal.
Short
Field Exp.
Green
house
Exp.
Model
Exp.
Simulate SOC
by Modified
Model
SOC Research approaches
Based on long-term Exps

54. SOC Research Areas
SOC
Research
2. SOC
Quality
and
Infuencing
Factors
1.Total SOC
Evolvement
and
Sequestration
3.SOC
Modeling
and
estimation
4.Mitigation
CO2 and
N2O by
fertilization

55. Major publications-SCI Papers
 Soil organic carbon active fractions as early indicators for total carbon change
under straw incorporation. Biology and Fertility of Soils. 2011;47: 745-752
(IF=2.07)
 Effects of organic amendments on soil carbon sequestration in paddy fields of
subtropical China. Journal of soil and sediments, 2012,12:457-470 (IF=2.57)
 Long-Term Evaluation of Manure Application on Maize Yield and Nitrogen Use
Efficiency in China. Soil Science Society of America Journal, 2011; 75(4):1562-
1573 (IF=2.59)
 Return rate of straw residue affects soil organic C sequestration by chemical
fertilization, Soil & Tillage Research, 2011; 113(1): 70-73 (IF=2.78)
 Soil organic carbon dynamics under long-term fertilizations in arable land of
northern China. Biogeosciences, 2010, 7: 409-425 （IF=3.6)
 Soil organic carbon, total nitrogen and grain yields under long-term fertilizations
in the upland red soil of southern China. Nutr. Cycl. Agroecosyst. 2009. 84:59-69
(IF=1.81)

56. Thanks for attention!
Welcome you to visit
China Long-term
Experiments
Do Collaborations!