Бурение грунтовых зондов, установка энергетических колодцев

3.1.1 Corn Stover

Corn or maize (Zea mays L) is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times and is widely culti­vated throughout the world. The United States produces 40% of the world’s harvest, and about 85% of this is genetically modified vari­eties of corn. Other top corn producing countries are: China, Brazil, Mexico, Indonesia and India. The leafy stalk of corn produces ears which contain seeds called kernels. Though technically a grain, corn kernels can be cooked as a whole, or ground to produce corn starch, and used to produce corn oil as well. Many forms of corn are used for food, sometimes classified as various subspecies related to the amount of starch in these varieties. Corn is the most widely grown crop in the Americas with 332 million metric tons grown annually in the United States. As the world’s leading fuel ethanol producer of 13.9 billion gallons/year (in 2011) approximately 40% of the corn grown in the US (130 million tons) is used for corn etha­nol production.

Corn stover is the agricultural waste left in a field after harvest and consists of the residue: stalk, leaves, husk, and cob remaining in the field following the harvest of cereal grain. Corn stover is a very common agricultural product in areas of large amounts of corn production. The stover can also contain other weeds, grasses, and the non-grain part of harvested corn, and has low water con­tent and is very bulky.

Stover can be grazed as forage or collected for use as fodder, but is commonly not utilized in many parts of the world. The corn pro­ducers who also raise cattle are the most common users of corn

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stover as cattle feed. In addition to the stover, cobs remaining in the field and kernels of grain may also be left over from harvest. These leftover kernels, along with the corn stover, serve as an additional feed source for grazing cattle. Over time, the stalks will decrease in value as feed, so it is important to graze the corn stover as soon as possible after harvest. The amount of grazing possible on a field of corn stover is between one and two months of grazing per cow per acre. As we discussed earlier, corn stover is not widely utilized or completely removed after grazing, and in many regions of the world is not harvested at all and left in the field for natural bio­degradation. In fact, some agronomists believe that taking all corn stover out of the field annually may have a negative impact on soil fertility and structure.

Composition of corn stover

The detailed composition analysis of corn stover is shown in Table 3.4 [16, 17]. This analysis shows high percentages for glucan and xylan, which can be hydrolyzed to sugars for fermentation to ethanol in the aqueous-phase saccharification-fermentation path.

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