Explanation

• In a septic tank, anaerobic bacteria decompose organic matter in sewage in the absence of free oxygen.

Additional information:

• Anaerobic decomposition: These bacteria break down organic waste without requiring free oxygen.
• Sludge reduction: This process helps decompose accumulated organic solids and reduces the amount of sludge.
• Biogas production: Anaerobic decomposition can produce gases such as methane and carbon dioxide.

Last verified on 16-10-2026

Explanation

• Suppressed weir: A rectangular weir whose crest length spans the full width of the channel, so there is no lateral contraction of the flowing water.

Additional information:

• Contracted weir: The crest length is less than the channel width, allowing water to contract at the sides.
• Broad-crested weir: A weir with a relatively wide, flat crest over which water flows.

Last verified on 16-10-2026

Explanation

• Onion seeds have a relatively short storage life and lose viability quickly under unsuitable storage conditions.
• Onion seeds are sensitive to moisture and high temperatures. Cool, dry storage helps maintain their germination capacity.
• Properly dried onion seeds stored under suitable conditions can remain viable longer than seeds kept in warm, humid environments.

Last verified on 16-10-2026

Explanation

• The suitable pH range for most plant tissue culture media is approximately 5.8–6.5.
• The pH affects nutrient availability, nutrient uptake, and the growth and development of plant cells and tissues.
• In many protocols, the culture medium is adjusted to around pH 5.6–5.8 before sterilization.

Last verified on 16-10-2026

Explanation

• The man-hours required for dibbling are approximately 200–250 man-hours.
• Dibbling is a method of sowing in which seeds are placed manually in holes at specific spacing and depth.
• It requires considerable labour because workers make holes and place seeds individually.
• The labour requirement varies with crop type, seed spacing, soil conditions, and workers’ efficiency.

Last verified on 16-10-2026

Explanation

• Base period is the time between the first watering and the last watering of a crop, usually expressed in days.
• Crop period is the time from sowing to harvesting (or, in some irrigation references, from sowing to crop maturity).
• The base period is generally shorter than the crop period because the crop may be sown before the first irrigation and remain in the field after the last irrigation.

Last verified on 16-10-2026

Explanation

• The Pakistan Agricultural Research Council (PARC) divided Pakistan into 10 agro-ecological zones.
• This classification considers factors such as climate, rainfall, temperature, soils, and agricultural potential.
• The zones help researchers and planners identify suitable crops and develop region-specific agricultural practices.

Last verified on 16-10-2026

Explanation

• An experimental unit is the smallest unit of experimental material to which a treatment is independently applied.
• In agricultural experiments, it may be a plot of land, an individual plant, or a group of animals, depending on the study.

Last verified on 16-10-2026

Explanation

• An auger is a screw-shaped mechanism that moves and meters granular materials such as fertilizer.
• In fertilizer applicators, it helps deliver fertilizer at a controlled rate to the soil.
• The application rate depends on factors such as auger speed, design, and the material being handled.

Last verified on 16-10-2026

Explanation

• Phosphorus fixation occurs when phosphorus reacts with soil minerals and forms compounds that plants cannot readily absorb.
• In acidic soils, phosphorus commonly reacts with iron and aluminium compounds; in alkaline or calcareous soils, it may precipitate with calcium.

Last verified on 16-10-2026