Manures and fertilizers

Manure

Manure is an organic compound that supplies plant nutrients required for proper growth, productivity, and protection against diseases.

Advantages of organic manure

1. Supplies all essential plant nutrients, unlike fertilizers, which are selective.
2. Cost-effective compared to expensive fertilizers.
3. Helps maintain soil structure.
4. Requires less expertise for application.
5. Supports microbial activity in the soil.
6. Maintains soil color and retains moisture.
7. Lasts longer in the soil without causing acidity.

Disadvantages of organic manure

1. Bulky and occupies large storage space.
2. Difficult to transport due to high moisture content.
3. Risk of spreading pests or diseases if infected plant remains are used.
4. Loses nutrients easily if poorly handled or stored.

Fertilizers

Fertilizers are chemical substances (inorganic compounds) that provide nutrients required for plant growth, productivity, and disease protection.

Examples of fertilizers

1. Urea
2. Ammonium nitrate
3. Ammonium sulfate
4. Calcium phosphate
5. Calcium nitrate
6. NPK (Nitrogen, Phosphorus, Potassium)

Types of fertilizers

1. Straight Fertilizer: Contains one primary nutrient (e.g., nitrogen, phosphorus, or potassium).
2. Compound Fertilizer: Contains two or more nutrients.
3. Complete Fertilizer: Contains all three primary nutrients (N, P, K).

Straight fertilizers

1. Nitrogenous Fertilizer: Contains nitrogen as the primary nutrient. Examples: Ammonium sulfate, NPK, Ammonium nitrate, CAN.
2. Phosphate Fertilizer: Contains phosphorus as the primary nutrient. Example: $\text{Ca}_3(\text{PO}_4)_2$.
3. Potassium Fertilizer: Contains potassium as the primary nutrient.

Properties of nitrogenous fertilizers

1. Contain high nitrogen content.
2. Can scorch plants due to their acidic nature.
3. May lead to the accumulation of toxic substances in the soil.

Effects of repeated nitrogenous fertilizer use

1. Causes soil acidity.
2. Leads to the accumulation of toxic substances harmful to plants.

Consumption of nitrogen by plants

Plants cannot use molecular nitrogen ($\text{N}_2$) directly as it is insoluble. They convert nitrogen into soluble nitrates ($\text{NO}_3^-$), which are easily absorbed by roots.

Application of fertilizers

Fertilizer application depends on the type of fertilizer, timing, and soil nature. Methods include:

Methods of application

1. Placing: Fertilizer is placed at a specific distance (6-9 cm) from the plant stem to prevent scorching, commonly used for nitrogenous fertilizers.
2. Broadcasting: Fertilizer is spread evenly over the soil surface, often before planting.
3. Band Strip: Fertilizer is applied in rows for crops planted in straight lines.
4. Spraying: Fertilizer is applied in solution form using spray equipment.

Timing of application

1. Basal Dressing: Fertilizer is applied before planting or seed germination.
2. Top Dressing: Fertilizer is applied after seed germination.