-- CHAPTER 3 - CROPLANDS AND PASTURES
TABLE OF CONTENTS
(3-A) - Arable Lands In General
[1] Fallowed Croplands, [2] Land Areas Subject to Physical and Chemical Constraints for Use as Croplands, [3]
Potentially Cultivatable Lands, [4] Conservation- and No-Till Croplands, [5]
Slope Distribution of Croplands, [6] Current Inventories, [7]
Cropland Distribution by Climate, [8] Loess Soil Regions
(3-B) - Irrigated Croplands
[1] Global, [2] Regional, [3] Historical, [4]
Drip Irrigation, [5] Groundwater Issues, [6]
Salination and Waterlogging Issues, [7] Abandonment
(3-C) - Rainfed Croplands
(3-D) - Pastures
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(3-A) - ARABLE LANDS IN GENERAL - [1] Fallowed Cropland, [2] Land Areas Subject to Physical and Chemical Constraints for Use as Croplands, [3] Potentially Cultivable Lands, [4] Conservation- and No-Till Croplands, [5] Slope Distribution of Croplands, [6] Current Inventories, [7] Cropland Distribution by Climate, [8] Loess Soil Regions
Arable land in use, cropping intensities, and harvested land in tropical climates
(Table 4.8 of (se03B3)) (la)Fallowed Cropland in Several Nations with Large Inventories (in millions of km2 ) (la)
Summer fallow in Canada (as a percent of the prairie province's cultivated land) (se84S2)
USSR summer fallow: 170-180,000 km2 (late 60s-early 1970s) (se84B2). (la)
USSR summer fallow: 120,000 km2 (mid-1970s) (se84B2). (la)
Comments: Reductions in amount of fallowed land can often be interpreted as being due to increased pressures on the land to produce.
[2] Land Areas Subject to Physical and Chemical Constraints for Use as Croplands
Less than 300,000 km2 (less than 4%) of Australia's
land are of good, or very good, quality in terms of broad scale cropping potential (og02C1). (la) Comments: Australia's soil is very old and of low quality. Erosion rates are high, and salinity is a major problem in the western part of Australia.
(See Chapter 1 [B] for some relevant data on this topic.)
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[3] Potentially Cultivatable Lands
(See the document on topsoil loss for large amounts of data on this topic. Despite the data there, the general consensus (FAO studies after around 2000) seems to be that increases in global food production will come mainly from increased productivities of existing croplands, and very little from increases in the area of croplands. )
[4] Conservation- and No-Till Croplands
Cropland Area Under No-Till in 1998-99, (Areas are in units of km2 ) (Rolf Derpsch, "Frontiers in Conservation Tillage and Advances in Conservation Practice", in D. E. Stott, R. H. Mohtar, and G. C. Steinhardt (eds.) Sustaining the Global Farm
(2001) pp. 248-254).
[5] Slope Distribution of Croplands
NOTE: In general, the higher the slope of land that is cropped, the greater the human pressure on the land, i.e. farmers tend to crop the most level lands first, and then resort to cropping on increasingly steep lands as the availability of unused level land diminishes.
45% of the world's agricultural (cropland + pasture -- not range) land is "steep" (slope over 8%) (se00W1). (la) Comments:
This fact is not very useful, since "steep" pasture is of minor concern, while "steep" cropland is of significant concern.
Cumulative Distribution of Cropland Slopes in Rwanda (se88L1) (la)
US cropland slope profile (se83L1) (Also see (se80U2): 0-2% on 45%; 2-6% on 70%; 6-12% on 90%; 12-20% on 97%.
Distribution of US Croplands by Slope (la)
0-2% 48%| 2-6% 23%|6-12% 19%|12-20% 7%|20-45% 2%|45%+ 1%
0-2% 45%| 2-6% 25%|6-12% 20%|12%+ 10%
Line 1 is from (se80U2): Line 2 is from (se83L1)
(20-25% slopes (9-11 degrees) are considered the maximum that can be cropped in the US ((se74C1), p. 70).).
100 million acres (405,000 km2) of US cropland (out of 460 million acres (1.86 million km2 ) of US lands suitable for crops) are flat, alluvial lands of negligible erosion hazard (se53L1). (la)
20% of all Mexican croplands are on "steep" slopes (Ref. 16 of (se97R1)). (la)
87% of Serbia's cropland is on slopes over 5 degrees (se90D3). (la)
79% of Serbia's cropland is on slopes over 10 degrees (se90D3). (la)
58% of Philippine cropland is on slopes over 11% (se85C5). (la) (Ref. 1 of (se95P1)).(la)
As much as 75% of Venezuela's highlands cultivated land is on slopes over 25% (se77L1). (la)
Greece, Italy, and Spain have 65, 56, and 42%, respectively of land in the moderately steep (15- 25+% slope) - and steep slope (25+% slope) category (se87L3).
25% of Jamaica's surface area has slopes over 30%; 52% of Jamaica's land has slopes over 20% ((se82B3), Ref. 1 of (se95P1)). (la)
25% of EEC-12 is level (0-8% slope), 14% level/ sloping (0-15% slope). About 26% is moderately steep/ steep (15- 25+% slope) (se87L3). (la)
Comments: "EEC-12" means European Economic Community of 12 nations
Comments: Presumably the above data refer to croplands, not to land in general. This presumption could possibly be false.
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[6] Current Inventories of Arable Land
[6A] Global, [6B] USA, [6C] Africa, [6D]
Russia
[6A] Global
Global grain-harvested area (se88B4): 6 million km2 (1950); 6.5 (1960); 6.9 (1970); 7.2 (1980), 6.9 in 1988. (la)
(Left Panel) Total arable land: past and projected (Table 4.7 of (se03B3)) (la)
(1998 is an average of 1997-99) (Areas are in units of millions of km2
)
~~ ~ ~ ~ ~ ~ ~ ~ ~ | Arable land in use
Year ~ ~ ~ ~ ~ ~ ~ |1961 |1979 |1997 |1998 |2015 |2030
Range~ ~ ~ ~ ~ ~ ~ | /63 | /81 | /99 |adj. | ----| ---
~~ ~ ~ ~ ~ ~ ~ ~ ~ | (1) | (2) | (3) | (4) | (5) | (6)
Sub-Saharan Africa | 1.19| 1.38| 1.56| 2.28| 2.62| 2 88
Near East/N. Africa| 0.86| 0.91| 1.00| 0.86| 0.89| 0.93
Latin Amer./ Carib.| 1.04| 1.38| 1.59| 2.03| 2.23| 2.44
South Asia ~ ~ ~ ~ | 1.91| 2.02| 2.05| 2.07| 2.10| 2.16
---excl. India ~ ~ | 0.29| 0.34| 0.35| 0.37| 0.38| 0.39
East Asia~ ~ ~ ~ ~ | 1.76| 1.82| 2.27| 2.32| 2.33| 2.37
---excl. China ~ ~ | 0.72| 0.82| 0.93| 0.98| 1.05| 1.12
Developing ~ ~ ~ ~ | 6.76| 7.51| 8.48| 9.56|10.17|10.76
---excl. China ~ ~ | 5.72| 6.52| 7.13| 8.22| 8.89| 9.51
--excl.China/India | 4.10| 4.83| 5.43| 6.52| 7.17| 7.74
Industrial ~ ~ ~ ~ | 3.79| 3.95| 3.87| ----| ----| ----
Transition*~ ~ ~ ~ | 2.91| 2.80| 2.65| ----| ----| ----
World~ ~ ~ ~ ~ ~ ~ |13.51|14.32|15.06| ----| ----| ----
* Former Soviet Union
Global Cropland Inventories ((se00W1) Table AF.2, p. 272-73) (la)
Data below are broken down by nation in Table AF.2 of (se00W1)
- ~ ~ ~ ~ ~ ~ ~ ~ ~ | ~1000 km2 | ha/ capita
Region ~ ~ ~ ~ ~ ~ | 1987| 1997| 1987| 1997
Asia(excl. Mideast)| --- | 4828| --- | .147
Europe ~ ~ ~ ~ ~ ~ | --- | 3112| --- | .427
Mideast/ N. Africa | ~950| 1023| .320| .270
Sub-Saharan Africa | 1595| 1714| .349| .288
Canada ~ ~ ~ ~ ~ ~ | ~460| ~457|1.726|1.510
U. S.~ ~ ~ ~ ~ ~ ~ | 1878| 1790| .761| .659
Cent. Amer./Caribb.| ~395| ~434| .287| .263
South America~ ~ ~ | 1065| 1162| .381| .351
Oceania~ ~ ~ ~ ~ ~ | ~521| ~578|2.065|1.972
Totals ~ ~ ~ ~ ~ ~ |14891|15104| .297| .259
Devloped World ~ ~ | 4877| 4769| .397| .369
Developing World ~ | 8130| 8540| .215| .189
Comments: The difference between TOTALS and the sums of the last two lines (Col. 2 and 3) could not be determined.
[6B] United States
NRI 1992 Estimates of land uses and land-use changes in the US (Alaska excluded, Puerto Rico and Virgin Islands included) (se94K2) (Areas are in 1000 km2)
|
CATEGORY |
AREA |
AREA |
% |
% of land- |
|
Total Surface Area |
7851.2 |
7851.2 |
0.0 |
N.A. |
|
Water Area |
194.3 |
197.9 |
1.9% |
N.A. |
|
Land Base |
7657.0 |
7653.3 |
0.0 |
100% |
|
- Federal Land |
1637.8 |
1651.1 |
0.8 |
21.6 |
|
- Non-Federal Land |
6019.1 |
6002.2 |
-0.3 |
78.4 |
|
----Developed Land |
317.2 |
373.8 |
17.8 |
4.9 |
|
----Non-Fed. Rural Land |
5702.0 |
5628.5 |
-1.3 |
73.5 |
|
------Cropland |
1703.6 |
1547.2 |
-9.2 |
20.2 |
|
-------- Cultivated |
1482.0 |
1317.1 |
-11.1 |
17.2 |
|
-------- Irrigated |
194.9 |
193.0 |
-1.0 |
2.5 |
|
-------- non-Irrig. |
1287.1 |
1124.2 |
-12.7 |
14.7 |
|
-------- Non-Cultivated |
221.6 |
230.1 |
3.8 |
3.0 |
|
---------- Irrigated |
54.9 |
58.7 |
6.8 |
0.8 |
|
---------- Non-Irrig. |
166.7 |
171.4 |
2.8 |
2.2 |
|
------ Pastureland |
533.8 |
509.6 |
-4.5 |
6.7 |
|
------ Rangeland |
1654.8 |
1614.6 |
-2.4 |
21.1 |
|
------ Forest land |
1596.0 |
1598.4 |
0.2 |
20.9 |
|
------ CRP area |
0.0 |
137.8 |
N.A. |
1.8 |
|
------ Other Rural land |
213.8 |
220.9 |
3.3 |
2.9 |
1992 NRI Estimate of US Prime Farmlands
(Areas are in units of 1000 km2) (se94K2) (la)Comments
: The above table means that the US inventory of prime farmland in the US is being used as cropland, pastureland, rangeland, forestland, CRP area and in other rural land uses.In 1977 the US had 1.68 million km2 (649,000 sq. mi.) in crop production (se83L1). Of the 421 million acres (1.70 million km2) of US cropland, 327 million acres are cropped, 165 million acres are affected by the highly-erodible-land conservation provisions of the 1985 farm bill (se88M2). 118 million acres (478,000 km2) of US cropland are highly erodible (se88M2). (la)
100 million acres (405,000 km2) of US cropland (out of 460 million acres of US lands suitable for crops) are flat, alluvial lands of negligible erosion hazard (se53L1). (la)
[6C] Africa
Africa's land area = 29.7 million km2 (se87L1). In early 1980s, 1.81 million km2 were cultivated. (se87L1). (la)
Only 0.2% of Mauritania's 1,000,000 km2 is arable (df88L1) (la). (The remainder is largely desert land.)
[6D] Russia
Russia has managed (agricultural) land covering 2.12 million km2
(Land of Russia, 1995), including 1.30 million km2 of cropland. The rest (0.80 million km2) falls into the category of so-called "other agricultural land" -- hay land (se03S2). (la)
[7] Cropland Distribution by Climate
Arable Land Areas ("No inherent soil constraints") of five tropical regions categorized by climate.
(Areas are in units of 1000 km2); (la) (se90W1)
Region ~ ~ |Arable| Arid|Semi-arid|Humid|Cold
Africa ~ ~ | 4427 | 3745| ~441~ ~ | 236 | ~6
Cent. Amer.| ~586 | ~425| ~ 91~ ~ | ~69 | ~1
S. America | 2076 | ~676| ~523~ ~ | 813 | 65
S.E. Asia~ | ~331 | ~ ~9| ~102~ ~ | 199 | 21
S.W. Asia~ | ~456 | ~388| ~ 59~ ~ | ~ 9 | ~0
Totals ~ ~ | 7876 |=5243|+1216~ ~ |+1326|+93
Comments: "Arable" apparently refers to land that could be cropped by irrigating, since arid lands that are not irrigated cannot possibly be used as croplands, and semi-arid lands are only marginally suitable as croplands without irrigation - they are usually best left as grasslands to avoid wind erosion ("Dust Bowls").
Comments: See Ch. 1 [B] for more data on these same five regions.
China's loess (wind-deposited soil) plateau covers 500,000 km2 (se92D1). (la) Comments: Loess soil contains low organic content and is therefore not very fertile and is subject to high rates of erosion. The US has a large area of Loess soil - the Palouse in the Pacific Northwest.
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(3-B) - IRRIGATED CROPLANDS
[1] Global, [2] Regional, [3] Historical, [4]
Drip Irrigation, [5] Groundwater Issues, [6]
Salination and Waterlogging Issues, [7] Abandonment
[1] Global
Global Irrigated-Area data (FAO data) (la)
Year~ ~ ~ ~ ~ | 1992 | 1993 | 1994 | 1995
million km2 ~ | 2.45 | 2.47 | 2.49 | 2.55
ha/1000 people| 44.8 | 44.5 | 44.1 | ----
Reference ~ ~ |ir97B1|ir97B1|ir97B1|ir99P1
Global Irrigated Area (1000 km2)
((ir94B1), Ch. 8 of Ref. 2) (ir94P2) (la)Return to Table of Contents of this Chapter 3 - Go to Table of Contents of this Document
[2] Regional
Gross Irrigated Areas of the Top 15 Countries as of 1986 (ir90P1) (la)
(Data of W. Robert Rangeley) 1995 data are from UN FAO, 1996 Production Yearbook (Rome, 1997) (These are areas equipped for irrigation whether or not they are in actual use.)
(Areas are in units of 1000 km2 and in percent of cropland area.)
Year~ ~ ~ ~| 1986~ ~ |1995
Country~ ~ |Area|Pct.|Area|Pct.
India ~ ~ ~| 550| 33 | 501| 29
China ~ ~ ~| 466| 48 | 498| 52
USSR~ ~ ~ ~| 210| ~9 | ---| --
Russia~ ~ ~| ---| -- | ~54| ~4
Uzbekistan~| ---| -- | ~40| 89
Romania ~ ~| ~30| 28 | ~31| 31
US~ ~ ~ ~ ~| 190| 10 | 214| 11
Pakistan~ ~| 160| 77 | 172| 80
Indonesia ~| ~73| 34 | ~46| 15
Iran~ ~ ~ ~| ~58| 39 | ~73| 39
Iraq~ ~ ~ ~| ---| -- | ~35| 61
Mexico~ ~ ~| ~53| 21 | ~61| 22
Spain ~ ~ ~| ~33| 16 | ~35| 17
Turkey~ ~ ~| ~33| 12 | ~42| 15
Egypt ~ ~ ~| ~32|100 | ~33|100
Bangladesh~| ---| -- | ~32| 37
Brazil~ ~ ~| ---| -- | ~32| ~5
Thailand~ ~| ~32| 16 | ~50| 24
Afghanistan| ---| -- | ~28| 35
Italy ~ ~ ~| ~30| 25 | ~27| 25
Japan ~ ~ ~| ~30| 63 | ~27| 62
Other ~ ~ ~| 522| ~9 | 524| --
World ~ ~ ~|2502| 17 |2555| 17
Irrigated Area by Region, 1995
(ir99P1) (la)Cropland Inventories (Total and Irrigated)
((ir00W1) Table AF.2) (la)Comments:
Presumably "irrigated land" does not included irrigated pastures. Columns 6 and 7 were obtained by multiplying other columns. "Oceania" apparently includes Australia and New Zealand.Arable land in use, cropping intensities, and harvested land in tropical climates (Table 4.8 of (se03B3)) (la)
NOTE: Lands in temperate climates are not included in the table below.
NOTE: This table is also in the "Rainfed Croplands" section of this compilation.
(1998 is an average of 1997-1999)
A = Arable land in millions of km2
CI = Cropping Intensity in % (Net result of fallowing and double-cropping)
H = Harvested land in millions of km2 = A * CI
~ ~ ~ ~ ~ ~| ~ ~| ~ ~Total~ ~ ~ | Rain-Fed ~ ~| Irrigated
~ ~ ~ ~ ~ ~|Year| ~A ~| CI| ~H ~| A ~| CI| H ~| A ~| CI| H
Sub-Saharan|1998| 2.28| 68| 1.54|2.23| 67|1.50|0.05| 86|0.05
--Africa~ ~|2030| 2.88| 76| 2.17|2.81| 75|2.10|0.07|102|0.07
Near East/ |1998| 0.86| 81| 0.70|0.60| 72|0.43|0.26|102|0.27
--N.Africa~|2030| 0.93| 90| 0.83|0.60| 78|0.46|0.33|112|0.37
Latin Amer/|1998| 2.03| 63| 1.27|1.85| 60|1.11|0.18| 86|0.16
--Caribbean|2030| 2.44| 71| 1.72|2.22| 68|1.50|0.22|100|0.22
South Asia~|1998| 2.07|111| 2.30|1.26|103|1.31|0.81|124|1.00
------- ~ ~|2030| 2.16|121| 2.62|1.21|109|1.31|0.95|137|1.31
East Asia ~|1998| 2.32|130| 3.03|1.61|120|1.93|0.71|154|1.10
------- ~ ~|2030| 2.37|139| 3.28|1.51|122|1.84|0.85|169|1.44
All above ~|1998| 9.56| 93| 8.85|7.54| 83|6.28|2.02|127|2.57
------- ~ ~|2030|10.76| 99|10.63|8.34| 87|7.22|2.42|141|3.41
All but ~ ~|1998| 8.22| 83| 6.79|6.72| 76|5.08|1.50|114|1.71
--China ~ ~|2030| 9.51| 90| 8.53|7.69| 81|6.22|1.82|127|2.30
All but ~ ~|1998| 6.52| 75| 4.89|5.59| 70|3.92|0.93|105|0.97
--C./India |2030| 7.74| 83| 6.41|6.62| 77|5.07|1.12|119|1.34
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[2A] - Africa
The Nile River irrigates 30,000 km2 of cropland (ir95P2). (la)
Less than 120,000 km2 were irrigated in Africa in 1984 (Ref. 41 of (ir87L1)). (la)
[2B] - Asian Sub-Continent
Irrigated area in India (km2) (Refs. 16, 23, 2, and 62 of (ir81G1)) (la)
Year| 1950/51| 1960/61| 1968/69| 1978/79
Area| 226,000| 278,900| 359,300| 510,000
Irrigated Area in Bangladesh (1000 km2)
(Plotted on p. 207 of (ir99P1)) (la)[2C] - North America
2223 km2 of irrigated land are in Arizona's Santa Cruz-San Pedro area (ir81S3). (la)
Breakdown of 1982 US irrigated lands by state (ir87E1) (la)
State| ~ Acres | km2~ | Pct. of Croplands
AZ~ ~|1,153,478| 4,670| 74
CA~ ~|8,460,508|34,253| 75
CO~ ~|3,200,942|12,959| 30
NV~ ~| ~829,761| 3,359| 96
NM~ ~| ~807,206| 3,268| 36
TX~ ~|5,575,553|22,573| 14
UT~ ~|1,082,328| 4,382| 56
Source: Agricultural Census (1981) and Ref. 24 of (ir87E1).
Irrigated Land in the US (from a plot) (ir95B3) (1000 km2) (la)
Year |1954|1960|1965|1970|1975|1980|1985|1990|1994
Area | 120| 140| 150| 160| 180| 200| 190| 200| 210
[2D] - Latin America
Cultivated land under irrigation in Chile's Atacama Desert = 134 km2 (ir70C2).
A description of Chile's Atacama Desert is found in Ref. (ir70C2). (la)
Mexico's total cropland covers 167,000 km2, its irrigated cropland covers 53,000 km2 (ir76W1). (la)
[2E] - Central Asia
180,000 km2 of Russia are irrigated (ir85B2). (la)
Kazakhstan's Irrigated cropland = 18,560 km2 (ir93M3). (la)
[2F] - Southeast Asia
13% of Thailand's 240,000 km2 of cultivated land are irrigated (ir88P2). (la)
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[3] Historical Data
[3A] Historical - Global
History of Global Irrigated Area (Areas are in units of 1000 km2) :
Year~ | Area | References
1800~ | ~ 80 | (ir85B2) (ir88S1)
1880~ | ~ 89 | (ir70W1), p.413
1880~ | ~ 80 | (ir76E1)
1900~ | ~400 | (ir70W1), p.413 (ir76E1) (ir85B2)
1900~ | ~480 | (ir88S1)
1949~ | ~920 | (ir88S1)
1950~ |1,050 | (ir76E1)
1950~ | ~940 | (ir85B2)
1959~ |1,490 | (ir88S1)
1966~ |1,530 | (ir00F1)
1967~ |1,500 | (ir70W1), p.413 (10% of these in the US)
1967~ |1,627 | (ir71R1)
1970~ |1,900 | (ir76E1)
1980~ |2,000 | (ir88S1)
1982~ |2,610 | (ir85B2)
(1986)|3,000 | (ir87W1)
(1991)|2,350 | (ir92P1)
(1993)|2,370 | (Ref.28 of (ir94P1)) (16% *) (1/3 *#)
(1998)|2,710 | (ir00F1) (17% * (ir97W1), p.9)
* percent of total cropland
*# fraction of global harvest
Irrigated areas in 1900 (ir88S1) (in km2) (la)
Indian Subcontinent|154,900| Japan 27,200| Spain| 10,000
USSR (former) ~ ~ ~| 38,000| Egypt 20,000| Chile| ~3,000
US~ ~ ~ ~ ~ ~ ~ ~ ~| 36,100| Italy 13,000| Total|301,200
Growth in Irrigated Area
((ir85P1), p. 47) (la)[3B] - Historical - U.S.
US irrigated land: 100,000 km2 in 1950, 210,000 km2 in 1995 (ir99P1). (la)
Irrigated Cropland Area in Texas (ir92P1) (la)
Some US Irrigated Cropland Inventories
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[4] Drip Irrigation
Micro-irrigation (km2) (e.g. drip irrigation) and fraction of total irrigated under micro-irrigation in 1991
(ir92P1) (ir93P2) (la)
US ~ ~ ~ |6060| 3.0% | Portugal~| 236| 3.7%
Spain~ ~ |1600|48.0% | Italy ~ ~| 217| 0.7%
Australia|1470| 7.8% | Brazil~ ~| 202| 0.7%
Israel ~ |1043|48.7% | China ~ ~| 190|<0.1%
S. Africa|1023| 9.0% | India ~ ~| 170|<0.1%
Egypt~ ~ | 685| 2.6% | Jordan~ ~| 120|21.1%
Mexico ~ | 606| 1.2% | Taiwan~ ~| 100| 2.4%
France ~ | 510| 4.8% | Morocco ~| ~98| 0.8%
Thailand | 412| 1.0% | Chili ~ ~| ~88| 0.7%
Colombia | 295| 5.7% | Other ~ ~| 394| ---%
Cyprus ~ | 250|71.4% | World ~ ~|15766| 0.7%
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[5] Groundwater Issues - [5A] Global, [5B] Far East, [5C] Africa, [5D] U.S.
[5A] Groundwater - Global
5-8% of present global irrigated area depends, to some degree, on over-pumped groundwater (Ref. 32 of (ir96G2)). (la)
[5B] Groundwater - Far East
(Groundwater Use) Groundwater wells irrigate 88,000 km2 in China
- 18% of China's irrigated land (ir99P1). (la)
[5C] Groundwater - Africa
WEST AFRICA: Saving Lake Chad 3/21/03 [www.irinnews.org/wwd.asp]
The size (surface area) of Lake Chad has gone from 30,000 km2 to 3,000 km2 in 40 years, according to some sources - from 25,000 km2 to less than 1,500 km2 between 1966-97. Its basin extends over 967,000 km2. (la)
[5D] Groundwater - US
(Ground water Depletion) The Ogallala Aquifer is being drawn down 15-18 times faster than nature is replacing it (ir80F1). The Ogallala Aquifer supports irrigated agriculture on more than 44,500 km2 of arid land (Ref. 24 of (ir81S2)). Mean thickness of the Ogallala Aquifer is 700 ft. (p. 31 of (ir86S3)). (la)
In Texas, water tables are falling 15 cm/ year beneath 15,400 km2
-- 72% of the irrigated area of Texas (ir90P1). (la)
The High Plains Aquifer underlies 174,000 mi2 (451,000 km2) in CO, KS, NB, NM, OK, SD, TX and WY. 134,000 (347,000 km2) of this are the Ogallala Aquifer (ir86S3). (la)
Ground-water overdrafts are now the major desertification force at work in the 42,700 km2. Santa Cruz-San Pedro Basin. Abandonment of irrigation projects is spreading (Ref. 223, 224 of (ir81S1)). (la)
(Ground water Inventory Data) The Northern Midwest Regional Aquifer System (Cambrian-Ordovician Aquifer System) covers 161,000 mi.2 (417,000 km2) (p. 72 of (ir86S3)). (la)
(Ground water Inventory Data) The Northern Great Plains Aquifer System covers 250,000 mi.2 (648,000 km2) (p. 50 of (ir86S3)). (la)
21% of irrigated US cropland is fed by drawing down water tables (USDA data) (ir91B3). (la)
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[6] Salination and Waterlogging Issues
[6A] Salinity/Waterlogging - Global Data
Salination severe enough to remove land from production claims 15-25,000 km2/ year worldwide. (Ref. 52 of (ir96G2)). (la)
Nearly 4 million acres (16,000 km2) of the world's irrigated farmland is lost to excessive salt every year. (Stanley Wood et al, report released by International Food Policy Research Institute, 2/9/01 [satellite data]). (la)
Irrigated Land Damaged by Salination in the late 1980s (la)
Region~ ~ ~ |Area(km2| % of irrigated land
India ~ ~ ~ | 70,000 | 17%
China ~ ~ ~ | 67,000 | 15%
Pakistan~ ~ | 42,000 | 26%
US~ ~ ~ ~ ~ | 42,000 | 23%
Uzbekistan~ | 24,000 | 60%
Iran~ ~ ~ ~ | 17,000 | 30%
Turkmenistan| 10,000 | 80%
Egypt ~ ~ ~ | ~9,000 | 33%
Sub-Total ~ |281,000 | 21%
World Est.~ |477,000 | 21%
Source: F. Ghassemi, A. J. Jakeman, H. A. Nix, "Salinization of Land and Water Resources", University of New South Wales Press, Sydney, 1995.
250,000 km2 (over 10% of the world's irrigated area) are suffering from salt buildup sufficient to reduce yields (Ref. 10 of (ir92P1)). (la)
(Salination) 200,000-300,000 km2 of the world's irrigated area suffer serious salination (ir94P2). (la)
(Salination) Salinity seriously affects productivity on 200,000 km2
of the world's irrigated lands (Ref. 14 of (ir85E1)). (la)
(Salination) The UNEP estimates global irrigated area damaged by salination
at 400,000 km2 (Ref. 15 of (ir89P3)). (la)
More than 50% of the world's irrigated soils are affected by secondary salination and/or alkalization (Ref. 355, 356, p. 207 of (ir88S1)). (la)
(Salination) A 1995 study, drawing on the global data of the 1980s, estimated that 20% of the world's irrigated area suffers from salination
(Ref. 52 of (ir96G2)). (la)
(Salination) 250,000 km2 of the world's irrigated lands appear to suffer from salt buildup enough to lower crop yields (Ref. 12 of (ir96P1)). (la)
Waterlogging affects over 100,000 km2 (globally?) (ir91O1) (ir03N1). (la)
(Salinity and waterlogging) 26% of the world's irrigated area suffers from some degree of waterlogging and salinity (ir91B3). Comments: 0.26 * 2.4 million = 624,000 km2 (la)
(Salination and waterlogging) The FAO estimates that salt build-up in soil has severely damaged 300,000 km2 of the world's 2.4 million km2
of irrigated land. Another 800,000 km2 are affected by a combination of salinization and waterlogging (ir98H1). (la)
(Salination) Oldeman, Hakkeling and Sombroek (ir91O1) estimate the total global
area affected by salination to be over 760,000 km2, but they do not differentiate between irrigated and rain-fed areas. It seems possible that 20% of the total irrigated area is affected, and 120,000 km2 of irrigated land may have gone out of production (ir01N1) (ir03N1). (la)
150,000 km2 in developing countries are experiencing serious reductions in crop yields because of salt buildup in irrigated soil (Ref. 9 of (ir92P1)). (la)
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[6B] Salinity/ Waterlogging - Regional Data
China has 70,000 km2
of saline and alkaline agricultural land (ir90P1). (la)
20-25% of all US irrigated land (40,000 km2) suffers from salt-caused yield reductions (Ref. 2 of (ir85E1)). (la)
Over 10,000 km2 of irrigated land in the Arab states region suffer from salination (ir96M2). (la)
Pakistan has 32,000 km2 of saline and alkaline agricultural land (ir90P1). (la)
Salination affects 160,000 km2 of Iran's agricultural land, and has forced over 80,000 km2 out of production (ir96G2). (la)
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[7] Abandonment
[7A] Abandonment - Global Data
20,000 km2/ year of irrigated land are lost to salination worldwide (Ref. 29 of (ir94P1)). (la)
Soviet agronomist Victor Kovda estimates a global rate of irrigation system abandonment of 10,000-15,000 km2/ year (Ref. 12 of (ir90B1)). (la)
Research puts current rate of loss of world farmland due to salination at 15,000 km2/ year (Ref. 60 of (ir94K1)). (la)
[7B] Abandonment - Regional Data
India has lost a total of about 70,000 km2 of once-irrigated area (ir93U1) (ir94F1) (ir99F2). (la)
70,000 km2 have been abandoned as salty wasteland in India
(ir90P1). (la)
Over 20,000 km2 of India's salinated land have been abandoned (ir96G2). Comments: Note the disparity between the two estimates. (la)
Of the 2223 km2 of irrigated land in the Santa Cruz-San Pedro area, 215 km2 have been abandoned due to lack of water (Ref. 33 of (ir81S3)). The 15-20% decrease in water supply projected for 2000 will cause abandonment of an additional 332-445 km2 of irrigated cropland (Ref. 35 of (ir81S3)). (la)
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(3-C) - RAINFED CROPLANDS
[1] Global Data
9% of the world's "dry" land area of 51 million km2 is rain-fed croplands (4.6 million km2 ) (se97C1). (See Section (5-A)) Comments: "dry" land is semi-arid, arid, or hyper-arid land.
Arable land in use, cropping intensities, and harvested land in tropical climates (Table 4.8 of (se03B3)) (la)
NOTE: Lands in temperate climates are not included in the table below.
NOTE: This table is also in the irrigated croplands section of this compilation.
(1998 is an average of 1997-1999)
A = Arable land in millions of km2
CI = Cropping Intensity in % (Net result of fallowing and double-cropping)
H = Harvested land in millions of km2 = A * CI
~ ~ ~ ~ ~ ~| ~ ~| ~ ~Total~ ~ ~ | Rain-Fed ~ ~| Irrigted
Region~ ~ ~|Year| ~A ~| CI| ~H ~| A ~| CI| H ~| A ~| CI| H
Sub-Saharan|1998| 2.28| 68| 1.54|2.23| 67|1.50|0.05| 86|0.05
--Africa~ ~|2030| 2.88| 76| 2.17|2.81| 75|2.10|0.07|102|0.07
Near East/ |1998| 0.86| 81| 0.70|0.60| 72|0.43|0.26|102|0.27
--N. Africa|2030| 0.93| 90| 0.83|0.60| 78|0.46|0.33|112|0.37
Latin Amer/|1998| 2.03| 63| 1.27|1.85| 60|1.11|0.18| 86|0.16
--Caribbean|2030| 2.44| 71| 1.72|2.22| 68|1.50|0.22|100|0.22
South Asia~|1998| 2.07|111| 2.30|1.26|103|1.31|0.81|124|1.00
------- ~ ~|2030| 2.16|121| 2.62|1.21|109|1.31|0.95|137|1.31
East Asia ~|1998| 2.32|130| 3.03|1.61|120|1.93|0.71|154|1.10
------- ~ ~|2030| 2.37|139| 3.28|1.51|122|1.84|0.85|169|1.44
All above ~|1998| 9.56| 93| 8.85|7.54| 83|6.28|2.02|127|2.57
------- ~ ~|2030|10.76| 99|10.63|8.34| 87|7.22|2.42|141|3.41
All but ~ ~|1998| 8.22| 83| 6.79|6.72| 76|5.08|1.50|114|1.71
--China ~ ~|2030| 9.51| 90| 8.53|7.69| 81|6.22|1.82|127|2.30
All but ~ ~|1998| 6.52| 75| 4.89|5.59| 70|3.92|0.93|105|0.97
--C./India |2030| 7.74| 83| 6.41|6.62| 77|5.07|1.12|119|1.34
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(3-D) - PASTURES
[1] Africa, [2] U.S., [3] Northern/ Central Asia
[1] Africa
Africa's land area = 29.7 million km2 (se87L1). In early 1980s, 7.84 million km2 were permanent pasture (se87L1). (la)
[2] U. S.
51 million acres (206,000 km2) of pastureland
(of 134 million acres of current US pasture land) have potential for conversion to croplands (og82W1) (USDA data). Comments: Much high-grade grazing land is being converted to low-grade cropland, e. g. in eastern Colorado. (la)
Cropland used as pasture in the US (og80H1) (la)
Year |1910|1959|1969|1975
Area | ~84| ~66| ~88| ~84 million acres
Area | 340| 267| 356| 340 x 1000 km2
Comments:
To be meaningful, we need to know the total cropland area in the US.
[3] Northern and Central Asia
Reindeer pastures occupy 501,000 km2 in Russia's Chukchi Peninsula (og03S1). (la)
Reindeer pastures occupy 603,000 km2 in Eastern Siberia (og03S1). (la)
Reindeer pastures occupy 564,000 km2 in the European and West-Siberian parts of the Arctic tundra, tundra, and forest steppe (og03S1). (la)
The area of mountain pastures in Southern Siberia is 168,000 km2
(og03S1). (la)
The area of mountain pastures in the Northern Caucasus is 31,000 km2
(og03S1). (la)
The total area of pastures and hayfields in Russia is 899,000 km2
(National Report ...2000). In addition, 2.82 million km2 are used for reindeer grazing (og03S1). This type of land is characterized by the fact that only a small part of the area is "improved". Only about 15% of Russia's hayfields and 6% of its pastures are "improved" (og03S1). (Comments:
Could "improved" mean irrigated?) (la)
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