An Essay on Some Biotechnological Interventions in Agricultural Waste Management

ABSTRACT

The human population is growing rapidly throughout the globe. To feed the growing population; there has been a rapid increase in intensive agricultural practices. As a result, the volume and types of agricultural waste biomass have gone up. Hie coimnon traditional approach to manage agro-waste has been its release to the environment either with or without any treatment. Such practices increase the risk of environmental pollution and public health hazards. With the advancement of biotechnology, many new techniques for the management of agricultural wastes (AWs) have been developed, which had enabled one to reduce the toxic and hazardous effects of waste. These techniques convert the agro-waste into eco-friendly and value-added products having the potential of providing sustainable raw material for utilization of living organisms, including humans. Some of the potential applications of agricultural residues that had been exploited with the aid of biotechnology had been discussed in this review.

INTRODUCTION

Globally human population growth increases to 1.1% annually. The population has grown from 1 billion from 1800 to 7.616 billion in 2018. To feed the gr owing population; there has been a rapid increase in intensive agricultural practices. As a result, the volume and types of agricultural wastes (AWs) biomass have gone up. Globally, 140 billion metric tonnes of biomass is generated every year from agriculture (Singhania et al., 2017). The AWs exist in variety of forms like solid, liquid, and slurries (Table 13.1). The composition of the waste varies with the type of agricultural activity. Agricultural waste most commonly belongs to the following three categories: food processing waste, crop waste (field residue), and hazardous and toxic agricultural waste like pesticides, insecticides, and herbicides (Obi et al., 2016). Among the three, crop waste and processing residues contribute to a considerable proportion of total waste. Field residues or crop waste are remains of the crop that are left in an agricultural field during the practice of crop harvesting. These residues comprises of stalks and stubble or stems, leaves, and seedpods. Such residues either are plowed with the soil or are burnt to add to the fertility of the field. During the processing of crops in the valuable foim, some residues such as husks, seeds, bagasse, molasses, and roots are taken out. This unusable crop processing waste is most commonly used to feed the livestock. In some alternative cases, such waste are dumped and kept stagnant for some months which are later on used as soil amendment to add the fertility of soil. This waste can be used as irrigation control which proves quite helpful in prevention of soil erosion (Sadh et al., 2018).

TABLE 13.1 Different Types of Agricultural Waste

Agricultural Waste

SL.

No

Crop Waste (Field Residue)

Food Processing Residues

Toxic Agricultural Waste

1.

Leaves

Husks

Pesticides

2.

Stems

Seeds

Insecticides

3.

Stalks

Roots

Herbicides

4.

Seed pods

Bagasse

Manure

5.

Stubble

Molasses

Fertilizer waste

The composition of AWs varies from being starch or cellulose rich to the ones quite rich in nitrogen. The majority of the agricultural biomass is rich in cellulose (40% approx.), followed by hemicelluloses (almost 30%) and lignin (25%). The composition of the most commonly generated crop waste is shown in Table 13.2.

TABLE 13.2 Chemical Composition of Commonly Used Agricultural Waste

Type of Crop

Chemical Composition (% w/w)

Cellulose

Hemicellulose

Lignin

Ash

References

Sugarcane bagasse

30.2

56.7

13.4

1.9

Nigam et al. (2009)

Rice straw

39.2

23.5

36.1

12.4

El-Tayeb et al. (2012)

Com stalks

61.2

19.3

6.9

10.8

El-Tayeb et al. (2012)

Cotton stalks

58.5

14.4

21.5

9.98

Nigam et al. (2009)

Wheat straw

32.9

24.0

8.9

6.7

Martin et al. (2012)

Barley stalks

33.8

21.9

13.8

11.0

Nigam et al. (2009)

Soya stalks

34.5

24.8

19.8

10.39

Motte et al. (2013)

Sunflower stalks

42.1

29.7

13.4

11.17

Motte et al. (2013)

This agr icultural waste has attractive potential of providing sustainable raw material for utilization of living organisms including humans. Most of starch rich agricultural biomass is being utilized as animal fodder. Starches are polysaccharides with a large number of glucose molecules linked together by alpha 1-4 linkages as well as alpha 1-6 linkages at branching points. These energy storage compounds are easily digestible. Cellulose is most abundant organic biomass utilized as animal feed and an energy source. The field residue rich in cellulose are burnt directly and the remaining amount available can be used as raw material for conversion into value-added products. As a result, cellulosic AWs had gained much interest of environmental engineers.

 
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