Most Value Per Drop & Which Crop For Scarce Water?

Rank your candidate crops by economic water productivity — value per cubic metre of water — which equals yield (kg/ha) divided by seasonal water use (m³/ha) multiplied by the farm-gate price. High-value horticulture such as tomato, onion and potato typically tops the list at well over the calculator's 'best' band of about 30 currency units per m³, while bulk cereals sit lower and paddy rice and sugarcane sink to the bottom. Enter your water budget and prices and the tool names the winner and the runner-up.

Crop water productivity (WP) is the marketable yield produced per unit of water consumed: WP = yield in kg/ha ÷ seasonal evapotranspiration in m³/ha. It is the 'more crop per drop' number popularised by FAO. Wheat sits around 1.1 kg/m³, maize around 1.6, while vegetables like tomato reach 10 or more kg/m³ because they pack a lot of saleable fresh weight into modest water use.

One millimetre of water depth spread over one hectare equals ten cubic metres. So a crop using 450 mm of seasonal ET consumes 4,500 m³ per hectare. The calculator stores each crop's seasonal ET in mm and multiplies by ten to get the water needed per hectare, then divides your total supply by that figure to show how many hectares the water covers.

Because they consume enormous amounts of water for the saleable output they produce. Paddy rice uses roughly 900 mm of ET and yields about 6 t/ha, giving only ~0.67 kg/m³; sugarcane uses around 1,500 mm. When water — not land — is the binding constraint, these thirsty crops return the least value per cubic metre, so the tool ranks them last and suggests deficit-irrigating them after the high-WP crops are watered.

Use value per drop when your goal is income from scarce water — it weights the ranking by farm-gate price, favouring high-value crops. Use food per drop (kg/m³) when your goal is maximum tonnage or household food security regardless of price, which favours high-yield vegetables and forages. Toggle between the two; the winner can change because a crop can be cheap but very productive in kilograms.

The tool divides your seasonal water supply (m³) by each crop's water need per hectare (ET mm × 10). With 5,000 m³ and wheat at 4,500 m³/ha, you can irrigate about 1.11 ha; the same water covers far less area of a thirsty crop like rice. The bar under each crop shows the area its supply covers, so you can see the area–water trade-off at a glance.

Yes. Each crop carries an editable farm-gate price and a planning yield; change the price for any crop in the basket and the value-per-drop ranking re-sorts instantly. The defaults are attainable-irrigated means, so refine them with your local mandi or market price and the yield you actually achieve for a result tuned to your farm.

The reference WP values come from FAO Irrigation & Drainage Paper 66, 'Crop yield response to water' (Steduto, Hsiao, Fereres and Raes, 2012), and the seasonal crop-ET ranges from FAO-56 (Allen et al., 1998) and FAO AquaCrop documentation. Each crop's computed kg/m³ is checked to fall inside its published FAO-66 band, so the ranking is grounded in authoritative data.

Not blindly. Water productivity is the right lens when water is the scarcest resource, but you must still consider market demand, rotation and soil health, labour, price volatility and whether you can sell a perishable high-value crop. Use the value-per-drop ranking to shortlist crops that use scarce water well, then layer in agronomy and market realities before deciding.

Cut the water lost without yield: switch flood to drip or sprinkler, mulch to reduce evaporation, level fields, fix leaks, irrigate at critical growth stages and apply controlled deficit irrigation outside them, and use a variety bred for water-limited conditions. Better agronomy — adequate nutrition, weed control and plant stand — also raises the kilograms produced per cubic metre by lifting yield without raising ET.

Cubic metres (m³) for the water supply, which is the standard volume unit; 10,000 m³ equals one hectare-metre of depth. Crop water use is stored in millimetres of ET and converted internally (1 mm over 1 ha = 10 m³). Results show the area covered in both hectares and acres so you can plan in whichever land unit you use.