NSSCO Agricultural Science 6115 cheat sheet

Agriculture is classified into crop production, animal production, forestry and fisheries; a farm system combines these enterprises with the household and its resources.

Sustainable farming requires four simultaneous conditions: profitable production, conservation of soil and water, maintenance of biodiversity, and social acceptability to the farming household and community.

Input-output analysis of a farm: gross output value minus purchased inputs equals gross margin; fixed costs are then deducted to give net farm income.

Mixed farming spreads risk because crop and livestock income rarely fail in the same season; monoculture gives higher returns per hectare but higher variance.

Subsistence farming directs most output to household consumption; commercial farming sells the majority of output and depends on market prices.

Crop rotation with legumes fixes atmospheric nitrogen through Rhizobium bacteria, reducing the nitrogen fertiliser requirement of the following cereal crop.

Integrated pest management uses resistant varieties, crop rotation, biological control and economic thresholds before chemical pesticides are applied.

Land tenure determines whether a farmer can invest in long-term improvements such as terracing, tree planting or boreholes; insecure tenure discourages such investment.

Carrying capacity is the maximum stocking rate a pasture can support indefinitely without degradation; exceeding it causes overgrazing and bush encroachment.

Soil texture refers to the proportion of sand, silt and clay; soil structure refers to how these particles are bound into aggregates.

Clay particles carry negative surface charge and hold cations such as Ca2+, Mg2+, K+ and NH4+; this is cation exchange capacity, measured in cmol/kg.

A pH below 5.5 limits nutrient availability and aluminium becomes toxic; liming with agricultural lime raises pH and is applied according to soil test results.

Soil erosion by water begins as sheet erosion, then rill erosion, then gully erosion; splash erosion is the detachment of particles by raindrop impact.

Contour ploughing, terracing, strip cropping, mulching and grassed waterways are the main structural measures against soil erosion on sloping land.

Organic matter improves water-holding capacity, structure and nutrient supply; it is maintained by crop residues, manure, compost and cover crops.

Nitrogen is lost from soil by leaching of nitrate, denitrification in waterlogged conditions, volatilisation of ammonia and erosion of topsoil.

Legumes such as groundnut, cowpea and lucerne form root nodules with Rhizobium and add nitrogen to the soil when residues are incorporated.

Soil sampling for analysis must be done with a zigzag pattern across the field, mixing subsamples from the top 0–20 cm to form one composite sample.

Germination requires viable seed, adequate moisture, suitable temperature and, for many small seeds, light; sowing depth is roughly two to three times the seed diameter.

Photosynthesis converts carbon dioxide and water into carbohydrates using light energy; respiration uses oxygen and releases energy for growth and maintenance.

Transplanting should be done in the cool part of the day with the root ball intact and watered in, to reduce transplant shock and wilting.

Pruning removes diseased or overcrowded branches to improve light penetration and airflow; it must be done with clean, sharp tools to avoid disease spread.

Spacing determines plant population per hectare; population equals 10 000 divided by (row spacing in metres x plant spacing in metres).

Irrigation scheduling by tensiometer or by crop water requirement avoids both waterlogging, which causes root rot, and drought stress at flowering.

Pests are controlled by cultural, mechanical, biological and chemical methods; pesticide application must follow label rate, pre-harvest interval and protective equipment.

Harvest maturity is judged by indices such as colour, firmness, sugar content, dry matter and days after flowering, varying with crop and market.

Nursery management includes sterilised media, raised beds, shade netting, thinning and hardening off seedlings before field transplanting.

Ruminants digest fibre through microbial fermentation in the rumen; non-ruminants such as pigs and poultry cannot digest large amounts of roughage.

Ration formulation balances energy, protein, minerals, vitamins and water; a maintenance ration supports no production, while a production ration supports growth, milk or eggs.

Poultry layer feed typically contains 16–18% crude protein and a calcium source such as limestone; broiler starter contains about 22% crude protein.

Pregnancy diagnosis and breeding records determine calving interval; a target calving interval for cattle is about 12–13 months.

Common livestock diseases include foot-and-mouth disease, lumpy skin disease, Newcastle disease, anthrax and rabies; vaccination schedules follow veterinary advice.

Housing must provide ventilation, dry bedding, shade and protection from predators; stocking density affects growth, disease and cannibalism in poultry.

Colostrum must be fed to newborn animals within the first hours of life because it supplies antibodies before the gut closes.

Castration, dehorning, ear tagging and dipping are routine husbandry operations; they must be done humanely and at the recommended age.

Feed conversion ratio equals feed consumed divided by live weight gain; a lower ratio indicates more efficient production.

Farm structures include animal housing, stores, silos, sheds, fences, dips, boreholes and irrigation works; each is designed for its specific function and load.

A store for grain must be dry, rodent-proof, well ventilated and raised above ground to prevent moisture uptake and aflatoxin development.

Hand tools such as hoes, rakes, secateurs and knapsack sprayers require cleaning after use and sharpening; blunt tools increase labour and injury risk.

Tractor implements are matched to tractor power; a plough for primary tillage is followed by a disc harrow or rotavator for secondary tillage.

The three-point linkage and power take-off connect and drive implements; incorrect hitching causes poor depth control and implement damage.

Daily maintenance of a tractor includes checking engine oil, coolant, fuel, tyre pressure and air filter; neglect shortens engine life.

Fencing types include wire, barbed wire, electric and game fencing; electric fencing requires a charger, insulators and a well-earthed circuit.

Drip irrigation delivers water to the root zone and saves water compared with overhead sprinklers, but requires filtration to prevent emitter blockage.

Gross margin equals gross output value minus variable costs; it is used to compare enterprises because fixed costs are excluded.

Fixed costs include land rent, depreciation, insurance and permanent labour; variable costs include seed, fertiliser, fuel and casual labour.

Break-even yield equals total costs divided by price per unit; break-even price equals total costs divided by expected yield.

Depreciation is calculated as (purchase cost minus salvage value) divided by useful life in years.

Partial budget analysis compares the added returns and reduced costs of a change against the added costs and reduced returns.

Opportunity cost is the value of the best alternative forgone when a resource is used in one enterprise rather than another.

Farm records include physical records (stock, yields) and financial records (cash book, ledger, balance sheet, profit and loss account).

Labour efficiency is measured by output per labour day; mechanisation raises output per worker but raises capital cost and reduces employment.

Risk management tools include enterprise diversification, insurance, forward contracts, irrigation and storage to avoid selling at harvest-time low prices.

The marketing chain runs from producer to assembler, wholesaler, processor, retailer and consumer; each link adds cost and margin.

Value addition includes grading, cleaning, packaging, processing, branding and certification; it raises unit price but requires investment and market access.

Price is determined by supply and demand; at harvest, supply peaks and prices fall, so storage can raise returns if storage costs are lower than the price gain.

Grading and standardisation allow produce to be sold by description and reduce disputes; grades are based on size, colour, defect and moisture.

Market information systems reduce information asymmetry between farmers and traders and improve bargaining power.

Cooperatives allow smallholders to bulk produce, access credit, buy inputs in bulk and negotiate better prices.

Post-harvest losses arise from poor handling, inadequate drying, insect pests, rodents and lack of cold storage; losses can exceed 30% in grains.

A marketing margin is the difference between the price paid by the consumer and the price received by the producer.

Natural resources include soil, water, vegetation, wildlife, air and minerals; renewable resources can regenerate if harvesting stays within the regeneration rate.

Deforestation causes soil erosion, loss of biodiversity, reduced rainfall infiltration and increased carbon dioxide in the atmosphere.

Agroforestry combines trees with crops or livestock; benefits include shade, fodder, fuelwood, nitrogen fixation and wind protection.

Water conservation measures include contour banks, check dams, infiltration pits, mulching and rainwater harvesting from roofs.

Bush encroachment and overgrazing reduce grass cover, expose soil to erosion and lower the grazing capacity of rangeland.

Wetlands act as water filters and sponges; draining them for cropping removes these services and is restricted in many countries.

Biodiversity conservation on farms uses hedgerows, buffer strips, retention of indigenous trees and reduced pesticide use.

Climate-smart agriculture includes drought-tolerant varieties, conservation tillage, early planting and crop diversification to adapt to variable rainfall.

Environmental impact assessment is required before large agricultural projects such as irrigation schemes or intensive livestock units are established.

The research process follows problem identification, literature review, hypothesis, experimental design, data collection, analysis and dissemination.

A randomised complete block design controls field variation by grouping plots into blocks; replications are needed to estimate experimental error.

A control treatment is the untreated comparison; a treatment is the factor applied, and replication is the number of independent plots per treatment.

Precision agriculture uses soil maps, GPS, variable-rate application and sensors to match inputs to within-field variability.

Conservation agriculture rests on three principles: minimum soil disturbance, permanent soil cover and crop rotation.

Improved seed varieties are developed by selection, crossing and, where permitted, biotechnology; they must be adapted to local conditions.

Extension transfers research results to farmers through demonstrations, field days, farmer field schools and radio; feedback from farmers informs research priorities.

Mobile phone technology supports market price information, weather alerts, mobile money payments and remote veterinary advice.

Data analysis of experiments uses mean, standard deviation and analysis of variance to test whether treatment differences are significant.

Pesticide handling requires gloves, boots, overalls, eye protection and a respirator; re-entry intervals and pre-harvest intervals must be observed.

Pesticide poisoning symptoms include headache, nausea, sweating, blurred vision and muscle twitching; remove the person from exposure and seek medical help.

Pesticide containers must never be reused for food or water; they are rinsed, punctured and disposed of according to regulations.

Zoonotic diseases such as brucellosis, anthrax and rabies pass from animals to humans; protective clothing and vaccination reduce risk.

Machinery safety includes guards on power take-offs and belts, safe tractor operation on slopes and never carrying passengers on implements.

Noise, dust and vibration in farm workshops cause hearing loss and respiratory disease; hearing protection and dust masks are required.

Ethical practice includes honest record keeping, fair labour treatment, no use of banned substances and respect for animal welfare.

First aid kits, fire extinguishers and clear emergency contacts should be present on every farm; workers should be trained in basic first aid.

Child labour restrictions prohibit hazardous farm work by children while allowing light, supervised family work consistent with the law.