A study held by the University of Turin explains which is the best corn irrigation system, one of the most widespread crops in the world and with yields above 10t/ha in Italy.

Corn cultivar

Maize commonly known as corn, from the Gramineae family, was discovered in America and today in one of the most common cereal in the world, both in industrial agriculture and in our plantation.

The major worldwide producers of corn are USA (37%) and China (21%) while in Europe he major producer and Germany, France and Poland with a medium yield of 5,2t/ha. Corn, turns out to be the most cultivated cereal compared to the other cereals crops. It is also one of main crop Italy with yields over 10t/ha and 45 millions tons per year. The culture is mainly cultivated in the Po valley.

Climate

Maize, of tropical origin, fears frost and extreme cold but also excessive warm and aridity. The seed requires 12°C to germinate and at least 18°C for the blooming.

Soil

The plant requires a well-drained soil, rich in nutriments. The soil before the sowing must be deep digged but is not necessary to have a fine soil. This deep work on the soil makes the corn a renewal crop and it can  be alternated to many vegetables.

Sowing and planting layout

Sowing in open field has to be done in late spring when temperature are a little bit higher. Seeds has to be positioned at 2cm depth with a distance of 15cm between them.

The corn plant have to be ideally placed at 30-40cm from each other, with a distance between the rows of half meter.

The plant

Period hoeing are recommended since the wide spread of weed. Maize needs to be irrigated, to an increasing extent from the blooming, in order to prevent the soil to dry out. To reduce the irrigation demand, some mulching can be used.

After more or less 6 months from the sowing, corn is harvested.

Recommendation: sugars on the grain decreases with the increase of temperatures therefore for a sweeter yield it is recommended to harvest the cobs in the morning. By leaving the cobs in the plant until they dry out, we can use it to obtain corn flour or otherwise it can become pop-corns.

Irrigation need of the crop

As stated before, cron has to be irrigated from the planting phase but in which quantities? It all depends from climate, soil and other variables related to the crop that should be studied before the sowing.

The average requirement of the plant is of 60mm of water during its whole life cycle. The major sensitivity period for the plant is from 15-20 days before the blooming and at 30 days from it; a water stress in this period will bring yield reduction of 50-60%.

Drip irrigation on corn help us prevent the possibility of water stress not only in the critical time of blooming but even during the upcoming week thanks to a consistent use of the available water source.

We can see here below a comparison made by University of Turin, between costs and efficiency of the four irrigation system more used on corn: flow irrigation, pivot irrigation, hose-reel irrigation, localized irrigation.

From the results here above, it might seem that PIVOT system would be the best one we could use, from an agronomical and economical point of view, but unfortunately this kind of irrigation hardly adapts to our territorial realities.

Localized irrigation with drip tape, even if implicate higher costs it turns out to be the winning solution especially when we have reduced irrigation availability and on difficult and uneven surfaces. This irrigation system, has reasonable costs that can be supported by the crop and it adapt easily to our soil, also helping us to improve yields and quality.

Furthermore these studies demonstrate that drip tape, together with fertigation results in a productive advantage for about 10% compared to flow and hose-reel irrigation. There will be also a quantitative water saving of 45%.

Localized irrigation on corn: recommendations

Drip irrigation helps us increase yield and corn quality give the increase of temperature over the past decade, which implies an increased irrigation demand on the plant.

Localized irrigation, compared to the flow one allows us to provide the plant with the right amount of water and fertilizer (if required) without a water stress.

Valducci is recommending you drip tapes 1.5m away from each other (every two rows) with a spacing between drippers of 0.3m and 1.0l/h flow rate. Once it is calculated the irrigation capacity of the plant, this value should be divided by the value of daily evapotranspiration therefore we will obtain as result the total hours we would need to ideally irrigate our entire plant.

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