Weather and disaster measures
Weather is the part of the environment we cannot control, but we can prepare. Common dangers and simple measures:
- Strong wind: windbreak trees, staking tall plants.
- Frost (freezing night): cover plants, light irrigation in the evening, smoke or small fires in orchards.
- Heavy rain and flood: raised beds and drainage channels so water runs away.
- Drought: mulch, drip irrigation, drought-tolerant varieties, rain-water storage.
- Heat: shade net and extra irrigation.
- Hail: nets in orchards, crop insurance to share the loss.
Good habits: listen to weather forecasts, sow at the right season, and keep a plan before the disaster comes.
Soil management and improvement
Healthy soil has the right pH, good structure and enough organic matter.
- pH tells acid (below 7) or alkaline (above 7). Most crops like pH 6 to 7.5. Acid soil: add lime. Alkaline or salty soil: add gypsum and wash with good water.
- Structure: clay holds water but packs hard; sand drains fast but holds little. Adding compost improves both.
- Organic matter: compost and green manure feed microbes and hold water.
- Erosion control: contour ploughing, cover crops and bunds stop rain washing soil away.
- Soil testing: test every few years and act on the report.
pH scale note: each pH step is 10 times in acidity. pH 5 is 10 times more acidic than pH 6.
Fertiliser properties and application
Plants need three big nutrients: N (nitrogen, for green leaves), P (phosphorus, for roots and flowers) and K (potassium, for strong stems and fruit). A bag marked 20-10-10 has 20% N, 10% P2O5, 10% K2O by weight.
- Organic (compost, manure): slow, improve soil, low risk.
- Chemical (urea, DAP, MOP): fast, exact amounts, but can pollute water if overused.
How to apply: basal dose before sowing, top dressing during growth, placement near roots, drip fertigation (in irrigation water), foliar spray on leaves. Rules: test the soil first, apply the right dose, avoid just before heavy rain, keep fertiliser away from seeds and water bodies.
Pesticide properties and pest-control methods
A pest is any insect, fungus or weed that damages the crop. Controls, from gentlest to strongest:
- Prevention: clean seeds, crop rotation, resistant varieties.
- Physical: sticky traps, nets, hand picking.
- Biological: helpful insects (ladybirds), birds, neem products.
- Chemical: insecticide, fungicide, herbicide. Quick, but can harm bees, water and people, and pests can become resistant.
Using all of these in order is integrated pest management (IPM): watch the field, spray only when pests pass a damage limit. Safety: read the label, use the right dose, wear gloves and mask, spray when there is no wind, keep out of children's reach, and wait the stated days before harvest.
Growing environment in protected horticulture
Protected cultivation grows crops inside a structure: greenhouse, polyhouse, net house or low tunnel. It controls temperature, humidity, light, wind, rain and pests.
- Greenhouse effect inside: glass or plastic lets sunlight in but traps heat. On sunny days it gets too hot, so we use vents, fans, shade nets and fogging. On cold nights we close vents or add heating.
- Water and food: drip lines and fertigation give exact amounts.
- Soil or soilless: hydroponics or cocopeat pots avoid soil diseases.
- Good side: more yield per m², crops out of season, fewer pests, less water.
- Limits: high set-up cost, needs skill, can get too humid and cause fungus.
Try it: a pH test with red cabbage
Boil some red cabbage leaves and keep the purple water. Pour a little into 3 cups. Add lemon juice to one (acid: turns pink), plain water to another (stays purple), and a pinch of baking soda to the third (alkaline: turns blue-green). Then test the water from a pot of soil mixed with distilled water. What colour do you get? Compare with the pH strip in the 3D.
Key formulas and definitions
- pH < 7 acid, pH = 7 neutral, pH > 7 alkaline
- Fertiliser grade N-P-K: 20-10-10 means 20 kg N per 100 kg bag
- Nutrient (kg) = bag weight (kg) × grade % ÷ 100
- Spray mix = dose per litre × tank volume (L)
Worked examples
1. A 50 kg bag is graded 20-10-10. How much nitrogen is in it?
N = 50 × 20 ÷ 100 = 10 kg.
2. A pesticide label says 2 mL per litre of water. How much goes into a 15 L sprayer?
2 mL × 15 = 30 mL, mixed into 15 L of water.
3. Soil A has pH 5 and soil B has pH 7. How many times more acidic is A (in hydrogen ion strength)?
Difference is 2 pH steps. Each step is 10 times, so 10 × 10 = 100 times more acidic.
Common mistakes
- Adding extra fertiliser "to be safe". Too much burns roots and pollutes water.
- Spraying pesticide without a label dose or protective gear, or just before harvest.
- Adding lime to alkaline soil. Lime raises pH; use it only on acid soil.
- Closing a greenhouse fully on a sunny day. It overheats; open the vent.