Soil Organic Carbon Sequestration

and Crop ProductionMinggang XU

Wenju Zhang, Yilai Lou, Hui Li(Institute of Agricultural Resources and

Regional Planning, CAAS, China)

Soilproductivity

Contribution fromBasic Soil Fertility

Effects of Management: Fertilization,

irrigation, …...

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 

<2020~3030~4040~5050~6060~7070~8080~90>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

<2020~3030~4040~5050~6060~7070~8080~90>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Soil Fertility

FertilitySoil 

W‐F

W‐F

Same Varity

Yield

USA

China

Low SOMIn 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%

Outline

Long-term experiments in cropland of China

SOC, soil fertility, and crop production

Part One

SOC, soil fertility and crop

production

Soil fertility

Crop production

Climate change

Soil fertility, SOC pool, and food security

food security

SOC

Environment-friendly

Three questions

Relationship soil fertility, Soil Organic Carbon (SOC) and crop production

Critical SOC for high crop production

Principle and technology for increasing SOC

Question Ⅰ

Relationship of SOC, soil fertility

and crop production

What is soil fertility?

Soil fertility-

An important characteristic of soil quality

The ability to supply the essential nutrients and water for plant growth

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

SOM increase with crop yield for four soil types in China

河南潮土

SO

MS

OM

SO

MS

OM

Fluvo-aquic soil Lime concretion black soil

Gray fluvo-aquic soil Whitish soil

SOC, crop yield and yield sustainability in cropland of China

SOC increase by 10%，

Wuchang wheat：74%Nanchang rice: 42%Jinxian corn：110%

Yiel

d

SOC

Wuchang wheat

Nanchang rice

Jinxian corn

SOC

Suining riceNanchang rice

Wuchang riceJinxian corn

Suining

Nanchang

Wuchang

Jinxian

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 upland area in north China, the SOC content of 1 g/kg is equivalent to the grain productivity of 0.3 -0.5t/ha

In paddy area in south China, the SOC content of 1 g/kg is equivalent to the grain productivity of 0.4-0.6 t/ha.

On average, with the increase of 1 g/kg of SOC content, the increase of grain yield stability ranges from 10% to 20%.

Statistical results

Year (a)

15

17

19

21

23

25

1980 1985 1990 1995 2000 2005

CK NPK NPKS

SOC

（g/kg

）

Hunan0

5

10

15

20

25

1980 1985 1990 1995 2000 2005

CK NPK50F+50M 30F+70M70F+30M

Jiangxi

10

12

14

16

18

20

1990 1995 2000 2005

CK NPKNPK+M1 1.5(NPK)+M1

Sichuan 141516171819202122

1990 1992 1994 1996 1998 2000 2002

CK NPKNPKM NPK‵M

Zhejiang

SOC trend under different fertilization in Paddy field

Change trend: Yield VS. SOC

Region Land use Crop yield change SOC change rate t/ha/yr

Northeast upland decreased -0.11 to-0.27

Northwest upland decreased -0.17 to -0.42

Huanghuaihai upland decreased -0.10 to 0.10

South China upland decreased maintained

paddies75% of sites maintained -0.28 to 0.26

(1) Non-fertilization

(2) Chemical fertilization

Region Land use Yield increased(%)

SOC changed(t ha-1 yr-1)

Northeast upland Wheat:48Corn:58 maintained

Northwest upland Wheat:95Corn:72 -0.19 to -0.23

Huanghuaihai upland Wheat:168Corn:78 0.07 to 0.4

South China upland Wheat: 120Corn:491 0.05 to 0.13

paddies Rice:54 0.03 to 0.16

(3) With manure and straw

Region Land use Yield increased(%)

SOC changed(t ha-1 yr-1)

Northeast upland Wheat:66Corn:77 0.77-1.03

Northwest upland Wheat:268Corn:109 0.09-1.29

Huanghuaihai upland Wheat:309Corn:141 0.4-0.7

South China upland Wheat:278Corn:1326 0.6-1.0

paddies Rice:75 0.15-0.88

Major conclusions from the long-term experiments：

SOC content can be significantly accumulated under the long-term manure application alone or combined with fertilizer；

The increase in SOC content can improve soil fertility and thus enhance crop yield;

Manure application is an useful option for increasing soil fertility, ensuring food security and promoting agricultural sustainability.

Question Ⅱ

Critical SOC level for high crop

production

(A case study in Black soil)

Long-term experiment site

The selected long-term field experiment：located in Gongzhuling city, Jilin province, started in 1980Cropping system：rainfed continuous cornSoil type：black soil

Main-treatment(Manure)

Sub-treatment (Chemical fertilizer)

M0 CK N P K NP NK PK NPKM2 CK N P K NP NK PK NPKM4 CK N P K NP NK PK NPK

Split-plot design: three main-treatments (manure) and eight sub-treatments (fertilizers)

Application rate

Manure Chemical fertilizerM0 –0 m3/ha (no manure) Pure N -- 150 kg/haM2 --30 m3/ha P2O5 -- 75 kg/haM4 --60 m3/ha K2O -- 75 kg/ha

Experimental design

After 29 years in 2009, Still big differences

for chemical fertilizers in Mo Plot

After 29 years in 2009, However, no significant

differences for chemical fertilizers in M2 and M4 Plots

When and Why?

Dynamic of yield increment due to fertilizer under different manure rates

M0 M2

M4

SOC dynamic under different manure rates

Relationship between yield increment due to fertilizer and SOC

y1 = -30.14x + 543.64 R2 = 0.3745**

y2 = -1.6295x + 43.034 R2 = 0.1596**

SOC=17.6g/kgSOM=30.3g/kg

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 160-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!

Question Ⅲ

Principle and quantitative

technology for increasing SOC

SOC change is determined by the balance of the C input and output

SOC usually shows a linear increase with C input when the SOC has no saturation limitation

0

5

10

15

20

25

1990 1995 2000 2005

CK NPKNPKM 1.5NPKMM

Hunan

Xinjiang

Jiangsu

Henan

Year (a)

SOC

（g/kg

）

SOC trend under different fertilization in Upland

SOC

changed

（t/ha/yr

）

C input （t/ha/yr）

Regression between SOC changed and C input in upland of China

SOC0=15.43 SOC0=13.05SOC0=9.49 SOC0=11.54

SOC0=6.5 SOC0=6.67 SOC0=8.58

SOC

Changed

（t/ha/yr

）

C input （t/ha/yr）

Conversion coefficient of

C input

C input to

maintain SOC

SOC Response to C Input

The relations are used to guide the application of manure and straw to improve soil fertility for sustainable agriculture

C input to maintain SOC

Site Initial SOC(g/kg)

C input to maintain

SOC( t C/ha/yr)

Manure/ straw needed to maintaining SOC

(t/ha/yr)

Fresh pig manure

Rice straw

祁阳QY 8.6 0.8 18 2.3

遂宁SN 9.2 0.8 16 2.0

武昌WC 15.9 2.2 23 5.4

南昌NC 14.9 2.5 26 5.8

望城WC 19.7 1.4 29 3.6

SiteInitial SOC(g/kg)

TargetSOC(g/kg)

C input to increase

SOC by 10%

( t C/ha/yr)

Manure/ straw needed toincreasing SOC by 10%

(t/ha/yr)

Fresh pig manure Rice straw

祁阳QY 8.6 9.4 1.89 33.5 4.2

遂宁SN 9.2 10.1 1.49 36 3.3

武昌WC 15.9 17.5 3.69 46 8.2

南昌NC 14.9 16.7 3.33 48 7.4

望城WC 19.7 21.7 4.05 60 9

C input to increase SOC by 10%

Part Two

Long-Term Experiments (LTEs)

in Cropland of China

Importance of LTEs

Long-term experiment: an important research means of soil science

Revealing the change in soil quality, guiding rational fertilization, and protecting ecological environment and agricultural sustainable development

LTEs In the World

Longer than 100 years: around 20 sites

The Longest One: Rothamsted, established in 1843, 168-year history

The classical experiments at Rothamsted

N, P, K, Manure

Broadbalk ContinuousWheat ExperimentFirst sown 1843

LTEs In the World

The 2nd Longest One: Morrow Plots, located in University of Illinois at Chamigan-Urbana, established in 1876

135-year history, Foundation of USA Agri.

2011年11月11日

Effects of Rotation and Fertilization on Crop Productivity and Soil Quality, National Historical Landmark

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

National long-term fertilizer experiment netFrom 1980, about 80 long-term fertilizer experiments through 22

provinces and 10 soil types in China, conducted to investigate theeffect, 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

Gray dessert soil

Black soil

Drab fluvo-aquic soil

Fluvo-aquic soil

Loess soilPaddy soil

Paddy soil

Red soilPurple 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

Ongoing LTEs in China started in 1980s

90

60 sites, including10 soil classification；10 rotation systems

Collected data from long-term experiments in China (more than 20 yrs)

Published a Book:

Evolvement of soil fertility in

China

Cooperated by 50 researchers

Major Publications-SCI Papers

Soil organic carbon dynamics under long-term fertilizations in arable land of

northern China. Biogeosciences， 2010, 7: 409-425 （IF 3.5）

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 1.8）

Long-term effects of manure application on grain yield under different cropping

systems and ecological conditions in China. The Journal of Agricultural

Science . 2009, 147, 31-42. （IF 1.3）

Trends in grain yield and soil organic carbon in a long-term fertilization

experiment in the China Loess Plateau. J. Plant Nutr. Soil Sci. 2008,171:448-457.

（IF 1.6）

Crop Yield and Soil Responses to Long-Term Fertilization on a Red Soil in

Southern China. Pedosphere. 2009, 19 (2): 199 – 207. （IF 0.81）

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