Introduction

Southwest Asia (figure 5.5) is spatially organized aroundIndia (IND) and includes the countries from Pakistan (PAK) to Bangladesh (BGD)as well as Nepal (NPL) and Bhutan (BHU) in the north and Sri Lanka (LKA) in thesouth. Most of the north of India, Nepal, and Bhutan belongs to the Indo-Gangeticplain, named after the Indus (Pakistan) and Ganges (India) rivers, whereelevation rarely exceeds 250 meter. The common delta of three of Asia's largestrivers (the Ganges, the Brahmaputra, and the Meghna)—and one of the largestdeltas in absolute terms[1]—iswhere Bangladesh is located, resulting in the country’s rather peculiarlithology in which sediments predominate and “hard stone” is a rare occurrence(except in some peripheral areas such as the Chittagong Hills in the southeast).Punjab (meaning, “land of five rivers”[2])constitutes the west of the low-lying areas of the Indo-Gangetic plain, whichis delimited to the west by the Baluchistan plateau along the Iranian (IRN)border. Beyond the Indo-Gangetic crescent, elevation rises rapidly to the northin the Himalayan foothills and to the south of India, centered around theDeccan Plateau at elevations around 500 meter. In Sri Lanka, elevations arehighest in the south, which markedly affects and conditions climate and agriculturalpatterns.

Just over one-fifth of the world population lives insouthwest Asia, where India, Pakistan, and Bangladesh are among the eight mostpopulated countries in the world. Together with Europe and the eastern Gulf ofGuinea, southwestern Asia also includes some of the highest national populationdensities (table 5.5): With more than 1100 people per square kilometer,Bangladesh has the record of the most densely populated non-urban country inthe world. The high density also accounts for the country’s large fraction ofarable land (60%, followed by India at 53% and, to a lesser extent, by Pakistanwith 39%). In all three countries, the values point at a relative shortage ofland when compared with other countries in the region.

With the exception of Pakistan, where 2015 population growthrates remain close to 2% (2.1%), all other countries in the region now haverates close to 1% (1.2% in Bangladesh, India, and Nepal) or below (0.9% in SriLanka.[3]For the sake of comparison with some agricultural production statistics, Table5.5 shows the increase of population over the last 12 years or so (percentagechange between the averages of 1998-2002 and 2010-2014). Among all countries,Pakistan shows the largest population growth (31%) and Sri Lanka the smallest(9%). The contradiction between the World Bank growth rates and the FAO datareflects a well-known debate about Bhutanese population statistics,[4]involving population movements from neighboring countries and cultural issues.

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Altogether, in spite of its very high population densities,Bangladesh is doing well in terms of food supply, with cereal productiongrowing faster than population (44% vs 20%) and the highest per capita cerealproduction (343 kg per year). In India, values are comparable (25% vs 21%), whilethe situation is most favorable in Sri Lanka (49% vs 9%). This last country,which has often been used to illustrate a successful family planning policy[1](Abeykoon, 2011), also displays increases in agricultural production that wellexceed population growth, especially for soybean and maize (in terms ofunder-nutrition levels (25%), however, the country is comparable with othercountries in the region). Bangladesh too has massively switched to maize,mostly at the expense of pulses and in particular spring wheat, which is atraditional crop in the region but with a lower production potential than maizeunder the prevailing climate.

Agricultural environment

Most areas of Southwest Asia suffer from large rainfalldeficits when compared with potential evapotranspiration (PET), particularly forsome water demanding crops such as maize or rice for which water requirementsexceed PET by 20% to 50% (figure 5.6a). As shown in the same figure, the regionis also characterized by some of the wettest climates in the world (e.g., innortheast India and the western Ghats bordering the Deccan Plateau on thesouthwestern coast of India) where low temperature due to elevation contributesto low PET. Capture of monsoon rainfall by the Himalayan relief constitutes themain source of water for the Indo-Gangetic plain. Particularly for southernPakistan, where near-desert prevails in most of Sind province, the combinationof high sunshine with a usually reliable water supply and a pest and diseaseadverse low air moisture, constitute a very favorable environment for crops.Together, India, Pakistan, and Bangladesh make up the largest contiguous areaof irrigated agriculture in the world. If central Asia and China (Yangtze) arealso considered, the rivers that flow from the Himalayas contribute to feedingabout 20% of the global population (Allison, 2012). Because of this, however,and as illustrated in recent CropWatch bulletins, floods are among the majorhazards affecting the region. Some traditional varieties of rice (e.g., thefloating rice type known as B-aman in Bangladesh) are adapted to floods withstem elongations that can sometimes reach 20 cm per day, but they cannot easilyaccommodate modern farming techniques, including the development of highyielding varieties.

Table 5.5. Some basic statisticsfor Bangladesh (BDG), Bhutan (BHU), India (IND), Nepal (NPL), Pakistan (PAK)and Sri Lanka (LKA)

Notes: Population %change refers to the % change between the 1998-2002 average and the 2010-2014average when available (otherwise, the second period was taken as 2009-2013);-, + and = signs after numbers indicate that the variable is decreasing, stableor increasing; n.a. stands for "not available" or "meaningless."
Sources: (1) FAOSTAT or computedbased on FAOSTAT (http://faostat3.fao.org/); (2) World Bank, http://data.worldbank.org/indicator;(3) http://data.un.org/Data.aspx; (4) FAO/Aquastat http://www.fao.org/nr/water/aquastat/maps/World-Map.ww.trwr_eng.htmand http://www.fao.org/nr/water/aquastat/water_use_agr/ IrrigationWaterUse.pdf;(5)  https://en.wikipedia.org/wiki/List_of_countries_and_territories_by_population_density;(6) World Bank (same as 2). Agricultural land includes rangeland and forests,while arable land is normally cultivated with temporary crops (i.e., fieldcrops as opposed to trees); (7) same source as (1); 2010-14 averages were usedinstead of 2009-2013 when available.

The annual water balance of the region undergoes markedseasonal changes from the temperate mountains in the north to the equatorialhighlands in Sri Lanka. In India, Nepal, and Pakistan, seasons are oftenreferred to as either Rabi or Kharif, with Rabi including mostly rainfed wintercrops grown from October to March (wheat, sesame, various Brassicas, andtemperate legumes) and Kharif describing rainfed summer crops in monsoon areasor irrigated crops, from May to November (rice, sugarcane, cotton, maize,soybean, and tropical legumes). In Bangladesh, rice is grown throughout theyear under different scenarios of water control in three seasons: early monsoonAus season (March-July), late monsoon Aman (July-December), and mostlyirrigated Boro season (January -June) (Dey and Norton 1992). In Sri Lanka,cropping seasons tend to be similar to those in maritime Southeast Asia; theyare commonly referred to as Maha (greater monsoon), sown between August andOctober and harvested five or six months later, and Yala, sown between Apriland May and harvested about four or five months later.[2]