Only possible at temperatures above ten degrees, the cultivation of corn requires compliance with strict and precise regulations, in-depth knowledge and a lot of patience. It is a plant of tropical origin, originally brevidiurna and typically macroterma. It needs high temperatures during its overall life cycle: not only does it not germinate and grow with temperatures below ten degrees, but it needs at least twelve degrees to avoid random or too slow birth. It must be known, on the other hand, that a drop in temperature to three or four degrees risks becoming fatal, killing the plant or leaving it stressed. For flowering, the ideal condition is twenty-six degrees centigrade, while for growth it is twenty-two degrees. The thermal threshold of seventeen degrees, instead, indicates the end of the vegetative season. This does not, however, detract from the fact that thermal excesses can also be harmful: in particular, temperatures higher than thirty-two degrees during flowering, combined with low humidity, can cause water stresses and consequent caryopsis failures; the result results in an incomplete graying of the ears, especially in the apical area which obviously blooms last. As for the administration of water, maize grows better in the regions that in summer are characterized by regular and frequent rains: in Italy, they correspond to the areas of the North East, where even sometimes irrigation is not necessary. Plant able to adapt without difficulty to soils of different types, it grows in the clayey substrates as in the sandy ones, in the brown, gray, peaty, red lands, in alkaline conditions and in acidic conditions. Cultivation, however, cannot disregard the availability of many nutrients and an excellent aeration of the rhizosphere: the most obvious intolerances occur against soils that are too compact, therefore very crackable and asphyxiated, poorly structured.
How to prepare the soil
In spite of its great adaptability, this plant prefers a soil prepared a few weeks before proceeding to the plant, through digging and fertilization to be carried out at the end of the previous autumn. The digging can be done by hand, with a pickaxe, or with a motor hoe. Of course, fertilization must be carried out with about two or three kilos of manure per square meter. Using a pitchfork, the manure is distributed in the furrows, the manure placed in the first furrow should be covered with the soil deriving from the preparation of the parallel furrow, and so on. Once the processing is complete, in the spring, with a rake or a hoe, the clods of earth must be refined and weed is to be ground by leveling it and eliminating weeds. Sowing, therefore, takes place in the spring, when the temperature has stabilized above the degrees. The seeds, available in any specialized store, must be positioned two or three centimeters deep, in rows between them about forty centimeters apart. Inside the same row, on the other hand, the holes, which can be made with an awl, must be placed twenty centimeters from each other.
About a month after sowing, when three or four leaves are already present, the plants can be thinned out. In practice, it is necessary to eradicate the excesses, leaving only the most vigorous seedlings, in such a way as to ensure them sufficient space and nourishment to develop. Maize needs abundant watering, in the absence of rains on a weekly basis. The soil, instead, must be prepared in advance with manure or compost, and then fertilized with mineral fertilizer with a high content of potassium and phosphorus during the production cycle. Weeding should be put into practice every two months, to allow the soil to have sufficient air and oxygen, while mulching, which consists of placing straw, hay and leaves at the base of the plant, prevents or limits the growth of weeds, and facilitates a favorable humidity situation. Finally, during the summer, it can be harvested before the beard, that is apical vegetation, acquires an excessively dark color. The most widespread harvesting method is that of spike, which is done by hand; after which the panicle is dried, and finally the grains are extracted. Alternatively, you can opt for grain collection, which involves the use of a special machine that collects and shells at the same time.