MEVE 011: Unit 09 – Agriculture

 UNIT 9: AGRICULTURE

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9.1 Introduction

Agriculture is one of the most important human activities as it ensures food production and supports rural livelihoods. However, agriculture also significantly affects the environment and is itself highly sensitive to changes in climate. This unit discusses how agricultural practices impact the environment, how climate change affects agriculture, and how agriculture can both contribute to and help mitigate climate change.

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9.2 Objectives

The main objectives of this unit are:

• To understand how agriculture affects air, water, and biodiversity
• To explore agriculture's role in greenhouse gas (GHG) emissions
• To study the impact of climate change on agricultural systems
• To identify how agriculture can act as a sink for GHGs
• To learn about mitigation and adaptation strategies for climate-resilient agriculture

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9.3 Impacts of Agriculture on Environment

Agriculture influences the environment in several ways. It contributes to water pollution through the runoff of fertilizers and pesticides into rivers and groundwater. These chemicals can cause eutrophication and contaminate drinking water. Air pollution from burning crop residues, use of chemical fertilizers, and methane emissions from livestock further degrade air quality. Agricultural expansion often leads to loss of biodiversity as forests and natural habitats are converted into farmlands, reducing the number of plant and animal species.

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9.4 Agriculture and Greenhouse Gas Emissions

Agriculture is a significant source of greenhouse gases. Methane (CH₄) is emitted from rice paddies and livestock digestion, nitrous oxide (N₂O) is released from fertilized soils, and carbon dioxide (CO₂) is emitted during land-use changes like deforestation for farming. These gases contribute to global warming and climate change.

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9.5 Changing Climate

As the climate changes, agriculture faces new challenges. Rising temperatures, changing rainfall patterns, and increasing frequency of extreme weather events can reduce crop yields and affect farming practices. Some areas may become less suitable for farming, while others may see new opportunities.

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9.6 Effects of Climate Change on Agriculture

Climate change has several direct and indirect effects on agriculture:

• 9.6.1 Monsoon Dependent Agriculture: In countries like India, farming depends heavily on the monsoon. Any change in its timing or intensity can lead to crop failures or delayed sowing.
• 9.6.2 Enhanced CO₂ on Crop Growth: Increased CO₂ can improve photosynthesis in some crops, but the benefit may be offset by heat stress or nutrient imbalance.
• 9.6.3 Weeds, Pests, and Diseases: Warmer temperatures and erratic rainfall promote the growth of weeds, pests, and crop diseases.
• 9.6.4 Crop Quality: Climate change may reduce the nutritional value of food crops, such as protein and iron content in wheat and rice.
• 9.6.5 Livestock: Animals suffer from heat stress, reduced productivity, and higher disease risks under a changing climate.
• 9.6.6 Prices, Production, and Food Consumption: Changes in production affect market prices, impacting food availability and affordability.
• 9.6.7 Per Capita Calorie Consumption and Child Malnutrition: Declining crop yields and food shortages can lead to hunger, reduced calorie intake, and increased child malnutrition.

9.6 Effects of Climate Change on Agriculture

9.6.1 Monsoon‑Dependent Agriculture
The South Asian summer monsoon delivers up to 75 percent of annual rainfall within 100 days. Delays of just one week can reduce rice yields by 10 percent; erratic onset creates a USD 2–3 billion loss in India alone.

9.6.2 Elevated CO₂ (CO₂ fertilisation)
FACE (Free‑Air CO₂ Enrichment) trials show yield boosts of 8–15 percent for C₃ crops (e.g., wheat, rice) at 550 ppm CO₂, but nutrient dilution lowers protein and micronutrient density (iron, zinc) by 5–10 percent.

9.6.3 Weeds, Pests, Diseases
Warmer winters expand pest overwintering survival (e.g., fall armyworm in East Africa). Fungal pathogen range shifts threaten coffee, cocoa, and banana belts.

9.6.4 Crop Quality
Heat stress during grain filling increases chalkiness in rice, reduces oil quality in sunflower, and triggers mycotoxin contamination in maize.

9.6.5 Livestock
Each 1 °C rise above a 20 °C THI (temperature–humidity index) zone cuts dairy milk yield by 0.5 kg cow⁻¹ day⁻¹. Heat stress also lowers fertility and elevates mortality in poultry.

9.6.6 Prices, Production & Food Consumption
Climate shocks in breadbasket regions (e.g., 2010 Russian heatwave) can spike global wheat prices by 30 percent, increasing food import bills for low‑income nations.

9.6.7 Calorie Intake & Child Malnutrition
IFPRI projects that without adaptation, climate change could leave an additional 90 million people at risk of hunger by 2050, exacerbating stunting in children under five.

 

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9.7 Agriculture as a Sink for Greenhouse Gases

While agriculture emits GHGs, it also has the potential to act as a carbon sink. By adopting sustainable practices, carbon can be captured and stored in soils and plants.

• 9.7.1 Mitigation of GHG Emission from Agriculture: Methods include using organic fertilizers, avoiding burning crop residues, practicing agroforestry, improving manure management, and adopting no-till farming. These reduce emissions and improve soil health.

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9.8 Adaptation to Climate Change

To cope with climate change, farmers must adapt by changing cropping patterns, using climate-resilient seeds, improving irrigation methods, and adopting smart farming techniques. Governments and institutions should support adaptation through policies, research, and access to credit and insurance.

 

9.7 Agriculture as a Sink for Greenhouse Gases

• Soil carbon sequestration: Conservation tillage, cover crops, and biochar can store 0.3–0.8 t C ha⁻¹ yr⁻¹—enough to offset ~10 percent of global agricultural CO₂‑eq emissions under the “4 per 1000” initiative.
• Agroforestry: Integrating trees with crops or pasture sequesters 2–4 t CO₂ ha⁻¹ yr⁻¹, increases biodiversity, and provides shade for livestock.

9.7.1 Mitigation options

1. N management: Split applications, nitrification inhibitors, and precision sensors cut N₂O emissions up to 40 percent.
2. Rice water management: Alternate wetting and drying reduces CH₄ by 30 percent while saving water.
3. Enteric CH₄ inhibitors: 3‑NOP or red seaweed (Asparagopsis) can slash cattle methane by 30–80 percent.
4. Renewable energy & biogas on farms replace diesel pumps and capture manure CH₄ for cooking.

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9.8 Adaptation to Climate Change

• Climate‑smart cultivars: Drought‑tolerant maize (DTMA) raises yields 25 percent in sub‑Saharan Africa under dry spells.
• Water‑saving irrigation: Drip and micro‑sprinkler systems boost water productivity two‑ to threefold.
• Index‑based insurance: Satellite rainfall triggers payouts, protecting smallholders from climate shocks (e.g., Kenya’s “Kilimo Salama”).
• Digital advisory services: SMS weather alerts and AI‑based crop models guide sowing dates, fertiliser use (e.g., India’s “FARMER” app).
• Livestock adaptation: Heat‑tolerant breeds (e.g., Sahiwal cattle), shade sheds, and evaporative cooling.
• Supply‑chain diversification: Storage, cold chains, and shorter value chains reduce post‑harvest losses—currently 14 percent of global food production.

 

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9.9 Let Us Sum Up

Agriculture and climate change are closely linked. While farming contributes to environmental degradation and climate change, it is also vulnerable to its effects. However, with sustainable practices and proper adaptation strategies, agriculture can be made more resilient and climate-friendly. A balance between food production and environmental protection is essential for future food security.