Materials 2022 , 15 , 4542
4of 27
2018 [20]. Only in 2019, about 3.4 million tons of jute and 0.2 million tons of sisal were produced worldwide [19]. Flax and hemp are mainly cultivated because of their seeds to produce oil in the food industry [21,22], while their fiber, together with kenaf and sisal, are used in textiles (clothes, mattresses, ropes, etc.) due to their high length, strength, and durability [23,24]. Kenaf fibers are commercially used as an insulating material in constructions. The NWLM category also includes ornamental plants that are grown for decorative purposes, such as rhododendrons or alternatives like bamboo. The fast-growing grass bamboo is used for various applications, such as construction, food, biofuel, pulp, and panel making. This diversity is mainly due to its considerable growing number annually, which is over 0.32 million km 2 worldwide [25]. Grow care residues are the first group of agricultural residues from plant materials and arise during crop maintenance. When fruits grow, the plants are pruned to allow the fruit bodies to reach the ideal growth [26]. There is no economic use proposed for this biomass type rather than burning, i.e., thermal use of apple and olive tree pruning [27,28], or an attempt to produce ethanol from it, i.e., ethanol production from olive tree pruning [29]. There are no accurate numbers for available existing materials from grow care residues as they are not measured in most cases. Harvest residues or primary residues are mainly stalks, straws, leaves, sticks, and roots. These materials are collected during the harvest of cereals or other crops, and they are mainly used for animal feed, bedding animals, or in pallet form as an energy source [30]. However, most of this material type is left in the field without further application, which can sometimes lead to disposal problems for farmers [31]. The terms stalks, straw, and sticks are named stalks hereafter. A ton of rice, wheat, oat, and rye harvest produces about 1.3–1.6 tons of stalks. These numbers for cotton and sorghum harvesting are about 3.4 and 2.4 tons, respectively [19]. The quantity of harvest residues can be assessed by considering the residue-to-crop ratio through a ton of the produced main product, i.e., wheat grain, of a specific cultivated plant. The average residue-to-crop ratio of available harvest residues in Europe and worldwide is presented in Table 2.
Table2. Residue-to-crop ratio and amount of crop production in 2018 (million tons, [19]).
Crop
Residue-to-Crop Ratio
Production
Stalks
Husks
Leaves
Stalks
Husks
Leaves
World Europe World Europe World Europe World
Sugarcane
0.26 1.96 1.33 1.28 0.25 1.53 0.25
-
0.2
1907.0 1147.6
2.3
495.8
0.6
-
-
381.4
Corn Rice
0.22 0.25
- - - - - - - - - - - - - - -
128.6
2249.3 1040.1
252.0
252.5 195.5
28.3
- - - - - - - - - - - - - - -
782.0 734.0 368.2 348.7 274.9 272.1
4.0
5.4
1.0
Wheat Potato
- - - -
242.1 105.2
939.6
309.9
- - - -
- - - - - - - - - - - - -
92.0
26.3 18.4 46.3
Soybean
1.09
12.1
533.5
380.1
13.1
Sugar beet
185.1
68.7 84.3
Oil palm 0.31
2.6
0.1
- -
707.3
Coconut
-
0.49
0.47
61.9 59.3 46.0 41.2 31.0 23.1 14.1 11.3 10.3
-
-
30.3
29.1
Sorghum 2.44
-
1.1
144.8
2.6
-
Groundnut
-
0.47 0.26
-
-
-
21.6 10.7
Cotton Millet
3.4
0.5 0.4
140.0
1.9 1.0
0.1
2.54 1.42 1.35 1.61
- - - -
78.8 32.7 19.1 18.2
- - - -
Oat
13.5 83.1
19.2
Barley
112.2
Rye
9.1
14.7
Coffee Cacao
- -
1.32
- -
- -
- -
13.6
1.5
5.3
7.9
Total
6137.9
787.3
5936.9
810.6
912.2
42.6
1117.8
Made with FlippingBook - Online magazine maker