Residues of grain corn production consist of (Fig. 1):
- stalks which make up about 52.5% of the whole mass of the residues. At that, the stalk makes up 27.3% of the mass of the whole plant including grain (the same indexes are presented below for other parts of corn residues);
- leaves – 20.0 % (10.6%);
- cobs – 17.5% (9.0%);
- wrap of ear – 8.5% (4.3%);
- other parts – 1.5% (0.8%).
Fig. 1 Main corn parts and their mass ratio.
Residue factor (mass ratio between crop residues and grain of the crop) depends on many factors, primarily on a crop hybrid, but on average, it is 1.3 for corn.
Grain corn harvesting periods
Production of agricultural residues, including corn residues, is seasonable and depends on harvesting periods. Grain corn is harvested during different time frames, depending on the variety, the place of cultivation and the time of sowing. Usually, time frame for harvesting corn is determined by the level of grain moisture, so before harvesting, they determine the moisture content of the grain and its ripeness, taking into account the terms of sowing and the hybrid ripeness group. By the beginning of harvesting, the corn grain must have a high dry matter content (at least 45%).
As a rule, grain corn is harvested in September-November. For example in Ukraine in 2016, corn was harvested from 24.4% of the total area by the beginning of October (20.4% of the annual production), and from 65.7% of the area by the beginning of November (61.4% of the annual production) (Fig. 2). By 2 December 2016, the share of harvested area under corn came to 95-100% in 10 oblasts, and the rest had the index mainly over 80%. At that, corn harvesting was carried out more dynamically in the central and southern regions of the country.
Fig. 2 The dynamics of corn harvesting in the regions of Ukraine (2016) 
It should be noted that in recent years, some farmers have harvested corn in December, January and even later. However, it is not due to agro-technical requirements but owing to some production needs and economic feasibility. According to the existing harvesting periods, a typical “schedule” of the corn residues production is as presented in Table 1.
Table 1. Seasonable production of corn residues in Ukraine
Authors: Tetiana Zheliezna, Semen Drahniev
 L. Kocsis, Z. Hudoba and T. Vojtela. Investigation of the corn stalk gathering for energetic use www.tankonyvtar.hu/…/publikacio_67.pdf
 The value given by Ukraine’s National Academy of Agrarian Sciences in its letter to the Institute of Engineering Thermophysics (N 5-2/256 of 16.11.2012).
 Report on “Analysis of utilisation of corn straw as an energy source” (2018). Prepared by SEC Biomass for EBRD against Contract C38842/1018/5362.