Chapter 20: Biotechnology, Environmental Technology, and Agribusiness
Biotechnology in practice
Plant tissue culture (micropropagation) grows many plants from a small piece of tissue (an explant) on a sterile nutrient medium with growth regulators: a higher ratio of cytokinin to auxin promotes shoots, and a higher auxin ratio promotes roots. Stages: initiation, multiplication, rooting, and acclimatization. It produces disease-free, uniform planting material (banana, orchid, ornamental plants).
Fermentation technology: microorganisms convert substrates to useful products. Yeast converts glucose to ethanol: . Lactic acid bacteria make yoghurt and curd; Acetobacter makes vinegar. Industrial fermenters control temperature, pH, aeration, and sterility.
Biofertilizers and biopesticides: Rhizobium, Azotobacter, mycorrhizae, Trichoderma, Bacillus thuringiensis.
Molecular tools: PCR (copying DNA), DNA markers for breeding, and genetic engineering, which should be applied with careful assessment of safety and ethics.
Enzymes in baking, brewing, juice clarification, and detergents.
Waste and bioenergy
Biogas is produced by anaerobic digestion of manure and organic waste in four stages: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Biogas is about 55–65% methane and has an energy content of roughly 20–25 MJ per cubic metre; the leftover digestate is an excellent fertilizer. Composting is the aerobic decomposition of organic waste; good compost needs a carbon-to-nitrogen ratio of about 25–30:1, moisture of 50–60%, and air, and it passes through a hot (thermophilic) phase of about 55–65 °C that kills pathogens and weed seeds. Other bioenergy: biodiesel, bioethanol, and biomass briquettes.
Environmental technology
Solid waste management follows the hierarchy: reduce, reuse, recycle, recover, dispose. Segregation at source is the foundation.
Wastewater treatment: preliminary (screening, grit removal), primary (sedimentation), secondary (biological treatment such as activated sludge, trickling filters, or constructed wetlands), and tertiary (nutrient removal, disinfection) (Tchobanoglous et al., 2014).
Water and air quality monitoring: pH, dissolved oxygen, biochemical oxygen demand (BOD), turbidity, and particulates.
Environmental impact assessment (EIA) evaluates the likely effects of a project before it is approved, and in Sri Lanka it is administered under national environmental law by the Central Environmental Authority and related agencies.
Climate change affects rainfall, temperature, and sea level. Mitigation (reducing greenhouse gases) and adaptation (drought-tolerant varieties, water harvesting, climate-smart practices) are both needed. The United Nations Sustainable Development Goals provide a global framework (United Nations, 2015).
Agribusiness and farm management
Value chains link input suppliers, farmers, processors, transporters, wholesalers, retailers, and consumers; improving the whole chain, not just production, raises farmers’ incomes. Marketing considers product, price, place, and promotion; cooperatives, farmer organizations, and contract farming improve bargaining power; certification schemes (Good Agricultural Practices, organic, fair trade) open markets and demand records and discipline.
Farm budgeting: ; the break-even yield is . Example: if the total cost of growing a crop is Rs 250 000 per hectare and the price is Rs 100 per kg, the break-even yield is kg/ha; any yield above this gives profit. The benefit–cost ratio is (above 1 means profitable). Records of inputs, labour, yields, and sales allow a farmer to see where money is made or lost. Risk arises from weather, pests, prices, and finance; it is managed by diversification, insurance where available, storage, and good planning.
Digital agriculture includes weather and price apps, soil and moisture sensors, drones, GPS, and farm management software, and it connects well to the ICT of SFT (Chapter 10). Entrepreneurship rests on identifying a need, testing a product, costing, marketing, and keeping honest records.
Common mistakes
Selling without knowing the cost of production.
Ignoring environmental rules and impacts.
Treating biotechnology as either miracle or menace instead of judging each application on evidence.
Practice questions
A farmer’s costs are Rs 180 000 per hectare and the price is Rs 90 per kg. Find the break-even yield. [2000 kg/ha]
State the four stages of anaerobic digestion in order.
Describe the stages of wastewater treatment.