BGCSE Field Crop Production 1256 cheat sheet

Photosynthesis: 6CO2 + 6H2O + light → C6H12O6 + 6O2; chlorophyll absorbs mainly red and blue wavelengths, reflecting green.

C3 crops (wheat, rice, soybean) use RuBisCO directly; C4 crops (maize, sorghum, sugarcane) pre-fix CO2 into a 4-carbon acid, raising water-use efficiency roughly two to three times.

Monocots: one cotyledon, parallel leaf veins, fibrous roots, scattered vascular bundles. Dicots: two cotyledons, net veins, taproot, ringed bundles.

Crop families to know: Poaceae (cereals), Fabaceae (legumes, nitrogen-fixing), Solanaceae (tomato, potato, pepper), Brassicaceae (cabbage, rape), Malvaceae (cotton).

Legume root nodules host Rhizobium bacteria that convert atmospheric N2 to ammonia; the symbiosis supplies most nitrogen needs of pulses.

Seed parts: embryo (radicle, plumule, cotyledons), endosperm (stored food), testa (seed coat). Germination needs water, oxygen and suitable temperature.

Plant hormones: auxins (elongation, rooting), gibberellins (stem elongation, bolting), cytokinins (cell division), abscisic acid (dormancy, stomatal closure), ethylene (ripening).

Alternation of generations: the sporophyte plant produces flowers and seeds; meiosis in anthers and ovules produces haploid gametes for sexual reproduction.

Growth stages of a cereal: germination, emergence, tillering, stem elongation, booting, heading, flowering (anthesis), grain filling (milk to dough), ripening.

Growth is irreversible increase in dry mass; development is the sequence of ordered morphological stages. Both are driven by temperature, light and water.

Growing degree days (GDD) = Σ[(Tmax + Tmin)/2 − Tbase]; Tbase is commonly 10 °C for maize and 5 °C for wheat. Accumulated GDD predicts stage timing.

Photoperiodism: long-day plants (wheat, barley) flower when day length exceeds a critical value; short-day plants (sorghum, soybean) flower when nights are long.

Vernalisation: a cold period (often 0–10 °C for several weeks) is required for flowering in winter cereals and some brassicas.

Critical growth stages most sensitive to stress: flowering and grain filling in cereals; tuber initiation in potato; pod set in legumes.

Leaf area index (LAI) peaks near canopy closure; a crop LAI of about 3–5 in cereals maximises light interception without excessive self-shading.

Crop duration is set by genetics and environment; late planting shortens vegetative growth and reduces yield because the crop matures in a fixed calendar window.

Soil texture classes by particle size: sand 2.0–0.05 mm, silt 0.05–0.002 mm, clay <0.002 mm. Loam is a balanced mixture and is generally the most workable.

Soil structure: granular (good arable), blocky, prismatic, platy, massive. Aggregates are stabilised by organic matter, roots and fungal hyphae.

Field capacity is water held after free drainage; permanent wilting point is water held too tightly for roots. Available water = FC − PWP.

Soil pH scale 0–14. Most field crops perform best at pH 5.5–7.0; legumes favour pH 6.0–7.0 because Rhizobium is acid-sensitive.

Cation exchange capacity (CEC) rises with clay and organic matter content; sandy soils have low CEC and leach nutrients readily.

Soil profile horizons: O (organic), A (topsoil), B (subsoil accumulation), C (weathered parent material), R (bedrock).

Bulk density = oven-dry mass / total volume. Compaction raises bulk density and reduces porosity, root penetration and drainage.

Soil water erosion is controlled by cover, contour tillage, terracing and strip cropping; wind erosion by shelterbelts, mulching and maintaining surface roughness.

Essential macronutrients: N, P, K, Ca, Mg, S. Micronutrients: Fe, Mn, Zn, Cu, B, Mo, Cl, Ni.

Nitrogen deficiency: pale yellow older leaves, stunted growth. Phosphorus deficiency: purplish leaves, poor root development. Potassium deficiency: scorched leaf margins.

Fertiliser grades are given as N–P2O5–K2O percentages. A 50 kg bag of 20–10–10 supplies 10 kg N, 5 kg P2O5 and 5 kg K2O.

Nutrient requirement (kg) = crop yield target × nutrient content per unit yield ÷ nutrient-use efficiency.

Legumes fix nitrogen biologically; a preceding legume crop can supply part of the N requirement of the following cereal.

Law of the minimum: yield is limited by the most deficient nutrient, not by the most abundant one.

Fertiliser placement rules: band or place phosphorus near the seed zone; split nitrogen applications to reduce leaching and volatilisation losses.

Liming raises pH on acid soils; dolomitic lime also supplies magnesium. Over-liming can induce micronutrient (Fe, Mn, Zn) deficiencies.

Primary tillage (ploughing) breaks and inverts soil; secondary tillage (harrowing, levelling) refines the seedbed.

Seedbed requirements: fine tilth, adequate moisture, firm sub-surface, level surface, free of weeds and residues.

Plant population = (target plants per hectare) ÷ (germination fraction × field establishment fraction).

Seed rate (kg/ha) = (target plant density × 1000-grain weight) ÷ (germination % × establishment %).

Planting geometry: row spacing × within-row spacing gives the area per plant; 1 ha = 10 000 m².

Sowing depth rules: small seeds shallow (1–2 cm), large seeds deeper (3–6 cm); moisture and soil texture govern the choice.

Transplanting reduces the field period and seedling competition with weeds; direct seeding is cheaper but needs better seedbed preparation.

Conservation tillage (minimum or zero tillage) retains residue cover, reduces erosion and conserves moisture but may require adapted seeders and weed control.

Crop rotation benefits: breaks pest and disease cycles, restores soil nitrogen via legumes, improves structure and spreads labour demand.

Intercropping combines crops in the same field; cereal–legume systems use complementary canopy and root niches and fix nitrogen.

Thinning removes excess plants to reach the target population; weeding reduces competition during the critical early growth period.

Earthing up (ridging) supports stems, improves drainage and encourages tuber or root development in crops such as potato.

Mulching suppresses weeds, conserves soil moisture and moderates soil temperature; organic mulch also adds nutrients as it decomposes.

Pruning and training shape the canopy and improve light penetration and air movement, reducing disease in orchards and vegetables.

Application of manure or compost should be timed before planting; immature manure can burn seedlings and introduce weed seeds.

Record of management operations (date, field, input, rate) supports traceability and allows comparison of treatment effects across seasons.

Crop water requirement (ETc) = reference evapotranspiration (ETo) × crop coefficient (Kc); Kc changes with growth stage.

Irrigation scheduling: irrigate when soil moisture falls to the allowable depletion (often 50% of available water for sensitive crops).

Irrigation efficiency = water stored in root zone ÷ water delivered to the field. Drip is highest, then sprinkler, then surface furrow.

Drip irrigation delivers water near the root zone, cuts evaporation and foliar disease, and suits high-value crops and water-scarce areas.

Furrow irrigation suits row crops on graded land; basin irrigation suits rice paddies and level fields.

Drainage is the counterpart of irrigation: waterlogging causes oxygen deficiency in roots, yellowing and yield loss.

Critical irrigation stages: tillering and flowering in cereals, flowering and pod fill in legumes, tuber bulking in potato.

Water-harvesting structures (tied ridges, contour bunds, farm ponds) capture rainfall and extend the effective growing season.

Integrated pest management (IPM) hierarchy: prevention, monitoring, cultural and biological control, then chemical control as a last resort.

Economic threshold: pest density at which control cost equals the value of crop loss avoided; control is justified only above this level.

Weed classification: grasses (monocots), broadleaves (dicots), sedges (triangular stems, e.g. nutgrass); each needs different control.

Critical weed-free period is usually the first third to half of the crop season; early competition causes the greatest yield loss.

Disease triangle: a disease requires a susceptible host, a virulent pathogen and favourable environment simultaneously.

Fungal diseases often show lesions, rusts or wilts; bacterial diseases show water-soaked spots and oozing; viral diseases cause mosaic, mottling and stunting.

Pesticide safety: read the label, wear protective clothing, observe the pre-harvest interval, and never spray into wind or near water sources.

Resistance management: rotate active ingredient groups (mode-of-action codes) and avoid repeated applications of a single chemical.

Harvest at physiological maturity: cereals when grain moisture is about 20–25% for mechanical harvest, lower for storage.

Moisture content for safe storage is commonly 12–14% for cereals and pulses; above this, moulds and insects multiply.

Post-harvest losses arise from shattering, threshing damage, spillage, pests, mould and poor storage; each step should be measured.

Drying reduces moisture to the safe level; sun drying is cheap but slow, while mechanical dryers give faster, more uniform results.

Storage conditions: cool, dry, dark, well-ventilated, rodent-proof. Hermetic (airtight) storage reduces insect activity and chemical use.

Grain quality grading considers moisture, foreign matter, broken grains, pest damage and discolouration.

Perishable crops need cooling and rapid marketing; ethylene-producing crops should not be stored with ethylene-sensitive produce.

Threshing and cleaning remove chaff and foreign matter; poorly cleaned grain stores badly and loses market value.

Hand tools by function: cutting (machete, sickle), digging (hoe, spade, fork), levelling (rake), planting (dibber, jab planter).

Maintenance rules: clean after use, dry and oil metal parts, sharpen cutting edges, replace cracked handles, store under cover.

Tractor implements: plough (primary tillage), harrow and rotavator (secondary tillage), seed drill (planting), sprayer (crop protection).

Power take-off (PTO) drives implements from the tractor engine; guards must be in place and loose clothing avoided near moving shafts.

Machinery safety: stop the engine before servicing, lower implements to the ground, use wheel chocks, and never carry passengers.

Calibrate sprayers before use: nozzle output, spray pressure, walking or forward speed and swath width determine the application rate.

Personal protective equipment for chemical work: gloves, boots, coveralls, goggles and a respirator; wash after handling.

Sharpening an edge restores tool efficiency; a dull blade increases effort and injury risk because it slips.

Gross margin = gross output (yield × price) − variable costs. Fixed costs are excluded from gross margin but included in whole-farm profit.

Break-even yield = total costs ÷ price per unit; break-even price = total costs ÷ yield.

Farm records: physical records (yields, inputs, livestock), financial records (receipts, payments, inventories) and enterprise accounts.

Depreciation (straight line) = (purchase cost − salvage value) ÷ useful life in years.

Marketing channels range from farm gate to local markets, cooperatives, wholesalers and processors; each adds costs and margins.

Price seasonality: prices often fall at harvest and rise in the lean season, so storage decisions depend on storage cost and expected price gain.

Partial budget analysis compares the added returns and added costs of a proposed change to decide whether it is worthwhile.

Cost of production per unit = total enterprise cost ÷ total output; it is the benchmark for pricing and competitiveness.

Sustainability pillars: economic viability, environmental protection and social equity; all three must be satisfied.

Soil conservation practices: contour ploughing, terracing, cover cropping, mulching, agroforestry and reduced tillage.

Biodiversity benefits: natural enemies control pests, pollinators improve fruit set, and diverse rotations suppress soil-borne pathogens.

Nutrient budgeting: balance nutrient inputs (fertiliser, manure, fixation) against outputs (harvest, leaching, erosion) to avoid surpluses.

Water quality protection: buffer strips along waterways, careful timing of fertiliser and pesticide application, and avoiding over-irrigation.

Agroforestry and shelterbelts reduce wind erosion, provide shade and fodder, and diversify farm income.

Organic matter management: add compost and manure, retain crop residues, and minimise burning to maintain soil carbon and structure.

Climate-smart practices: early maturing varieties, water harvesting, residue retention and diversified cropping reduce risk under variable rainfall.