The potato is the fourth crop in the world in terms of production after grain, rice and wheat, and is grown everywhere. Current world production is around 321 million tonnes from 19.5 million hectares of cultivated land.
Asia and Europe together reach over 80% of world production. China is now the main producer; previously, Northern America was the undisputed leader with more than 40 tons per hectare.
The potato is cultivated in about 100 countries, in climates ranging from temperate, subtropical and tropical, although it is basically considered a warm climate crop. Crops depend significantly on temperature, and the optimal daily average should be between 18°C and 20°C.
The potato needs a dissolved, sufficiently drained and aerated soil, with pH between 5 and 6. Softer soils have a negative effect on radical penetration, water and nutrients absorption, and growth of the tuber. This crop is moderately sensitive to soil salinity with a yield decrease at different EC levels (which is the electrical conductivity of a saturated soil extract). In order to optimize the irrigable supplementation on this crop with a drop-plant, recommended spacing is between 0.75 and 0.90 m in rows and between 0.15 and 0.3 m among plants, with a sown depth varying between 5 cm and 10 cm. Agronomic procedures, during the growing period, must avoid damage to both roots apparatuses and tubers, and in temperate climates it is necessary to crush the earth in order to avoid greening of the tubers themselves. Drop irrigation and fertilization in the potato were technically and economically advantageous both in developed and developing areas. Drop irrigation in several cases has resulted in more substantial yields (from 40 to 60 tons per hectare) in addition to water (from 30% to 40%), fertilizers (from 20% to 25%) saving and increase in tuber quality (size and organoleptic qualities) compared to conventional irrigation methods such as targeted, flooding and pivoting.
In Turkey and India, drop irrigated potatoes accounted for 50 and 42 tonnes of tubers per hectare with an NPV (total project value) of 2.085 $/hectare and 2.692 $/hectare, respectively, and a return on the investment in one year.
In order to obtain high yields, seasonal water requirements are estimated between 150 mm and 750 mm at various climatic conditions and different growth periods (70 to 180 days) with a daily evaporation-transpiration value of 4-5 mm/day, considering an average crop life of 70 to 150 days. Irrigation scheduling with the use of tensiometers has allowed for efficient use of water, fertilizers and energy.
The potato is an important source of nutrients, its root system is superficial and fibrous, therefore it is recommended to use fertilization-irrigation for greater nutrients availability and efficiency. The purpose of the fertilization-irrigation program is to reduce the difference between potato supply and demand. Nutrients requirements for drop irrigated potatoes are relatively high. Other good management practices include earthing up, protecting the crops from harmful animals and diseases, correct weed management and harvest and post-harvest operations, in order to minimize losses.