Soil Fertility and Plant Nutrition - Learning Unit 2 Notes

Levels of Crop Production

  • Soil Fertility, Quality, and Productivity: Understanding the meaning of each.

  • General Concept: Fertility potential, production costs, and risks involved.

  • Practices: Soil fertility improvement and maintenance, both traditional and modern.

  • Role: Soil organic matter and the carbon cycle.

Student Overview

  • Physical: Soil texture, structure, and resilience.

  • Chemical: Nutrient supply and cycling.

  • Biological: Organic matter, animals, and micro-organisms.

Crop Production

Production Situation

  • Potential Production:

    • Defining factors:

      • CO2CO_2

      • Radiation

      • Temperature

      • Crop characteristics: physiology, phenology, canopy architecture

    • Yield-increasing measures:

      • Water

      • Nutrients (Nitrogen, Phosphorus)

  • Attainable Production:

    • Limiting factors:

      • Weeds

      • Diseases

      • Pests

      • Pollutants
        *Yield-protecting measures

Soil Fertility (SF)

  • Definition: The capacity of soil to support plant growth on a sustained basis under given climate conditions and land properties (Young, 1989).

  • Alternative Definition: The productive potential of the soil system that allows the accumulation of energy in the form of vegetation (Stocking, 1984).

  • SF is more than just the capacity of soil to supply nutrients to plants.

Factors Influencing SF

  • Infiltration of water

  • Content of organic matter

  • Active soil life

  • Soil structure

  • Exploitable depth

  • Acidity (pH)

  • Water retention

  • Sufficient drainage

  • Release of nutrients

  • Parent soil

  • Groundwater

  • Minerals (K)

Soil Productivity (SP)

  • Definition: The capacity of a soil in its normal environment to produce a particular plant or sequence of plants under a specified management system (NSESPRPC, 1981).

Impact of SF and SP

  • Decrease in SF or SP leads to a loss in future economic returns on production and yield.

Soil Quality (SQ)

  • Soil health refers to the physical, chemical, and biological properties of soil.

  • Goal: To maintain productivity, not just yield.

  • Soil quality and its ability to support plant growth.

SQ Interrelation

  • Biological

  • Chemical

  • Physical

  • Food Quality

  • Soil productivity

  • Environmental quality

  • Health

Maintenance of SP

  • Traditional methods: Crop rotation, intercropping, and fallowing.

  • Modern methods: Use of fertilizers, irrigation, and conservation tillage.

Traditional Method: Fallowing/Shifting Cultivation (Pertanian Pindah)

  • Involves leaving land unplanted for a period to rest and regain fertility.

  • Process:

    • Choose new site

    • Slashing

    • Burning

    • Cultivation

    • Harvesting

    • Abandonment of old site after two to three years

Advantages of Fallowing/Shifting Cultivation

  1. Burning releases nutrients from ash.

  2. Regeneration of forest stability.

  3. Soil fertility is restored.

    • High biomass = High nutrient

Disadvantages of Fallowing/Shifting Cultivation

  1. Loss of organic C/SOM to the atmosphere.

  2. Loss of nutrients in ash through wind and water erosion.

  3. Restriction to open burning.

Traditional Method: Crop Rotation (Rotasi Tanaman Atau Pertanaman Bergilir)

  • Involves the systematic planting of different crops on a piece of land over time.

  • Examples:

    • Legumes: Add nitrogen to soil (Green beans, Peas, Soy beans, Lupin, Fava beans, Alfalfa, Chickpeas, Peanuts)

    • Root Veggies: Light feeders, need potassium and phosphorus (Carrot, Radish, Onion, Garlic, Leeks, Parsnip, Turnip, Beet)

    • Greens/Brassicas: Need ample nitrogen (Lettuce, Kale, Spinach, Cabbage, Brussels, Broccoli, Cauliflower, Herbs, Bok Choy, Collards)

    • Fruiting Veg: Need ample phosphorus (Tomato, Eggplant, Squash, Cucumber, Melons, Potatoes, Peppers, Corn)

Advantages of Crop Rotation

  1. Helps to replenish soil nutrients.

  2. Reduces soil-borne diseases.

  3. Helps in weed control.

Disadvantages of Crop Rotation

  1. Requires planning and management.

  2. Requires more land.

  3. Labor-intensive.

  4. Reduced short-term profits.

Traditional Method: Organic Manures

  • Farmyard Manure: Mixture of animal dung, urine, bedding material collected from farms.

    • Production:

      • Collecting raw materials

      • Protection from rain and run on water

      • Protection from direct sunlight

    • Utilization of cattle urine: Collection of cattle urine in a tank, Adding of cattle urine in FYM

  • Compost: Mixture of decomposed plant matter and other organic waste materials.

    • Production:

      • Collecting raw materials

      • Effective Microorganism (EM) to hasten microbial activity in FYM and compost

      • EM Bokashi™: Organic Fermentation Starter

  • Green Manure: Specific plants grown then plowed into the soil to add nutrients and organic matter.

  • Slurry: Created from cow manure and water, used as natural fertilizer.

Modern Method: Sewage Sludge (Lumpur Kumbahan)

  • Semi-solid or liquid residue from domestic wastewater treatment.

  • Goes through processes to remove solid materials and contaminants.

  • Increases soil organic matter, improves soil structure, and water-holding capacity.

Modern Method: Inorganic Fertilizer (Chemical)

  • Any inorganic material added to the soil to enhance crop growth and yield.

  • Widely available for agricultural use in Malaysia.

  • Subsidized fertilizer for rural agricultural development.

Issues with Subsidized Fertilizer

  • Lack of complete farmer data leads to misuse of fertilizer subsidies.

Impacts of Climate Change on Agriculture and Food Security in Malaysia

  • Climate change impacts agricultural productivity, crop choice, and food security.

  • Phenomena like natural disasters, drought, flood, pest attack, plant disease, and changing crop cycles adversely affect Malaysian agriculture.

  • Despite government subsidies and focus on paddy production, the paddy planting area decreases due to climatic variation.

  • Climate change impacts food security among farmers.

  • Adaptation and mitigation strategies are needed to sustain agricultural productivity.

Maintenance of Soil Productivity

  • Production system: Sustainable agriculture and Precision agriculture. Organic farming. Balancing of inorganic organic inputs. Conservation farming/ mixed/ integrated farming Agroforestry

Supporting Processes

  • Ecosystem Function:

    • Soil organic matter

    • Water retention

    • Aeration

    • Soil structure

    • Promotion of Soil life

    • Aggregation

  • Elemental Cycles:

    • NPS mineralisation

    • C sequestration

    • Compound retention

  • Soil Biodiversity:

    • Erosion protection

    • Primary production

    • Climate regulation

    • Water quality

    • Plant health

    • Weeds

Formation of Soil Organic Matter

  • Dry leaves, cow dung $\rightarrow$ half decomposed $\rightarrow$ decomposed material $\rightarrow$ humus

  • Soil poor in organic matter

Role of OM in managing SF

  • Improves soil structure

  • Enhances soil nutrient availability

  • Increases soil water holding capacity

  • Supports soil microbial activity

Role of Carbon Cycle in Managing SF

  • Carbon sequestration

  • Nutrient cycling

Conclusion

  • Soil fertility is crucial for healthy plant growth, providing essential nutrients and conditions.

  • It involves the biological, physical, and chemical properties of soil that interact to support plant growth.

  • Maintaining and improving soil fertility is crucial for sustainable agriculture and food security for the future.

  • Crop rotation, cover cropping, and the use of organic fertilizers are important management practices to prevent soil degradation and maintain soil health.