This chapter looks at water’s role in sustainable agriculture intensification focusing on three main ideas: how water is used globally in food production and agriculture, climate and water sensitivity, and the stresses of water systems globally as relate to agriculture. ‘Green water’ refers to water that is used in agriculture from rainfall, while ‘blue water’ comes from irrigation or surface water sources. Rain-fed agriculture accounts for 80% of agriculture globally, but only 60% of global product; irrigated agriculture makes up for deficits in rainfall and is more productive. Groundwater is particularly concerning as a blue water source because it is depleted at higher rates than it is stored. Irrigation improved productivity in agriculture enormously in the 1970s, mostly to improve yields during periods of drought. The FAO predicts that the most promising areas for future productivity are the ones that have the lowest water productivity. Looking most specifically at India, because that is where irrigation intensity is the highest, groundwater is being depleted very quickly because electricity for farmers is subsidized. There are a few types of irrigation listed in order of increasing efficiency and cost; furrow irrigation, sprinkler irrigation, drip irrigation, and subsurface irrigation. Precision irrigation detects how much moisture is in the soil to control how much water is applied. Policy changes are necessary to support irrigational system changes, and examples are given.
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