**3. Βiofuels**

*Maize - Production and Use*

*2.1.1.1 Maize production*

optimum pH of 6.8 [30].

9 days [31, 32].

ance to salts [35].

range, 13–28°C).

226 kg ha<sup>−</sup><sup>1</sup>

per plant.

of bioenergy [37].

ha<sup>−</sup><sup>1</sup>

its main bulk grows in the first 60 cm of soil.

N, resulting in 13.647 kg ha<sup>−</sup><sup>1</sup>

significantly less than with sugar cane [43].

biomass. This biomass presents an energy potential of 11.050 kWh ha<sup>−</sup><sup>1</sup>

use of only husks and cobs into consideration, it is possible to generate 2712 kWh

Like energy crops, maize is mainly used for two reasons: (i) for the starchy raw material contained in seeds and the material from which bioethanol is mainly produced [38, 39] and (ii) for the biomass (crop residues) resulting from the removal of the seeds and consisting of leaves, stems and a cone of the blade. Biomass can be used for combustion or production of second-generation bioethanol [27, 40, 41]. The appropriate time of harvesting is when the moisture content of the seeds is between 20 and 30% [42]. Late maturation and flowering of maize cause a greater accumulation of lumps with reduced grain yields and a reduced number of cores

Maize requires more nitrogen and pesticides than many other crops, thus affecting its energy balance. Increasing the energy potential with ethanol from maize is

The choice of varieties with a dry matter content of 30–32% is very important for harvesting date to facilitate the process. Based on the system, FAO maize needs about 45 units of heat to form a new real leaf and about 300 units of heat to fully populate the plant. Early varieties (FAO 150–160) require about 2100 heat units, late (FAO 180–210) approximately 2400 units, while biogas crude maize hybrids

(FAO 240–260) require a longer period of 2800–3000 heat units.

The main root system of maize is rich and can reach a depth of 2.5 m, although

The water requirements of maize range from 744 to 901 mm. The irrigation frequency affects the yield of corn seed as they propose an irrigation program where a dose of 15% of the water capacity of the soil will be applied irrigation every

Increased salinity results in reduced plant leaves, decreased green weight, fresh weight, shorter shoots and root lengthening. However, varieties that are ideally adapted to conditions of high salinity have been developed, as they have particular durability [33, 34]. Still hybrids with respect to pure maize rows show greater toler-

Corn seed germination may be affected even slightly from 28°C or above as the activity of certain protein-producing enzymes is inhibited by this critical temperature and then [36]. When the temperature increases (in the range of 13–38°C), there is a similar increase in leaf growth rate and photosynthesis rate. Also it was found an increase in photosynthesis rate by increasing the temperature (study

The nutrition of the cobbler in continuously cultivated soil suggests 17–23 kg of nitrogen per hectare, while when there is an increase in organic matter, the addition may be twice as low. For high yields, it is necessary to add potassium as a mature crop of maize which may contain up to 30 kg of potassium per hectare in its plant parts. An experiment in Brazil showed that nitrogen application increased the productivity of grains and dry matter, the calorific power, and the potential for energy generation from maize. Maximum grain yield was obtained with an application of

of grain yield and 10.968 kg ha<sup>−</sup><sup>1</sup>

of total

. Taking the

The pH range for ideal yields is 6–6.5 while a range of 5.8–7 is generally shown, and there are reports that mention an even greater range of 5–8. Generally, attempts have been made to create varieties that adapt to high or low pH in acidic pH, expecting only 35% of ideal yields and being defined as an

**6**

The use of corn-based biofuels was first introduced into the US as a food additive, but ethanol-maize production increased drastically when conventional fuel prices doubled between 2004 and 2007. Biofuels and rising food prices have contributed to the accumulation of wealth in the agricultural sector, thus increasing the income of farmers, potential value to agricultural land and shifting the relative allocation of resources to the agricultural sector in relation to the rest of the economy [44].

The use of biofuels in the transport sector has become very timely recent years.

In **Tables 1** and **2** below, we can see the liquid biofuel production globally and in each continent separately, up to 2017.
