Crop science, seeds, soil nutrients, fertilisers, organic and natural farming, and pest management on one page. For explanations, go back to the [chapter](/science-technology/agricultural-science/).

{{< callout type="tip" title="How to use this sheet" >}}
Scan it top to bottom before Mains. **Bold** entries are the facts and distinctions that most often decide an answer.
{{< /callout >}}

## Crop Science and Cropping Systems

| Fact | Detail |
|------|--------|
| **C3 crops** | Rice, wheat, pulses, oilseeds; RuBisCO only; high photorespiration in heat |
| **C4 crops** | **Maize, sugarcane, sorghum, millets**; Kranz anatomy; PEP carboxylase; better water-use efficiency |
| CAM | Pineapple, agave; stomata open at night |
| Photoperiod | Rice and soybean short-day; wheat and mustard long-day; HYVs mostly photoperiod-insensitive |
| Most sensitive rice stage | Flowering (heat or drought causes spikelet sterility) |
| Legume N fixation | *Rhizobium* in nodules; **nitrogenase**; leghaemoglobin |
| LER | Above 1 means intercropping beats sole cropping |
| **SRI** | Madagascar, 1980s, Henri de Laulanié; young single seedlings, wide spacing, alternate wetting and drying |
| DSR | No nursery or puddling; saves water and labour; weeds are the main problem |
| Paddy methane | Methanogenic archaea in flooded, anaerobic soil; AWD, SRI and DSR reduce it |
| **Conservation agriculture** | Minimum tillage + permanent soil cover + crop diversification (FAO) |
| **Biasi** | Cross-ploughing standing broadcast paddy (Chhattisgarh) |
| **Utera** | Relay sowing of lathyrus, linseed, gram into ripening paddy |
| Lathyrus toxin | β-ODAP, causes neurolathyrism |

## Seeds and Crop Improvement

| Fact | Detail |
|------|--------|
| **Seed tag colours** | Breeder **golden yellow** · foundation **white** · certified **azure blue** · truthfully labelled opal green |
| Hybrid | F1; heterosis; saved seed segregates |
| Seeds Act | **1966**; draft Seeds Bill 2025 to replace it (not enacted as of 2026) |
| **PPV&FR Act** | **2001**; farmers may save, use, exchange and sell seed, but not as branded seed |
| GM regulator | **GEAC**, Ministry of **Environment**; EP Act 1986, Rules 1989 |
| **Bt cotton** | **2002**; *Bacillus thuringiensis* cry genes; pink bollworm resistance later |
| Bt brinjal | Moratorium, February 2010 |
| GM mustard DMH-11 | Environmental release approved Oct 2022; split Supreme Court verdict July 2024 |
| Genome-editing exemption | **March 2022**: SDN-1 and SDN-2 (no foreign DNA) |
| **Genome-edited rice** | **May 2025**: DRR Dhan 100 (Kamala), IIRR Hyderabad; Pusa DST Rice 1, IARI New Delhi |
| **Chhattisgarh Zinc Rice-1** | IGKV Raipur, 2015; India's first zinc-biofortified rice |
| Rice germplasm | IGKV Raipur, over 23,000 accessions; Dr R.H. Richharia |

## Soil Fertility and Fertilisers

| Fact | Detail |
|------|--------|
| Essential elements | **17**: C, H, O; N, P, K; Ca, Mg, S; Fe, Mn, Zn, Cu, B, Mo, Cl, Ni |
| Law of the Minimum | Liebig: scarcest nutrient limits growth |
| N deficiency | Older leaves yellow first (mobile) |
| P deficiency | Purple leaves, poor roots |
| K deficiency | Scorched leaf margins |
| **Khaira (rice)** | **Zinc** deficiency |
| Whiptail (cauliflower) | Molybdenum deficiency |
| Acidic soil / sodic soil | **Lime** / **gypsum** |
| **Urea / DAP / SSP / MOP** | **46% N / 18-46 / 16% P₂O₅ / 60% K₂O** |
| MOP | Wholly imported |
| N losses | Volatilisation (NH₃), leaching (NO₃⁻), denitrification (N₂O), runoff |
| **Benchmark NPK** | **4:2:1**; actual seasonal ratios near 10:4:1 (kharif 2023–24) |
| NBS | 2010; urea outside it |
| **Neem-coated urea** | Mandatory 2015; nitrification inhibitor |
| Nano urea / nano DAP | IFFCO, June 2021 / 2023; yield claims debated |
| **Soil Health Card** | 19 Feb 2015, Suratgarh (Rajasthan); 12 parameters |
| PM-PRANAM | 2023; rewards states for cutting chemical fertiliser use |
| World Soil Day | 5 December |

## Manures and Biofertilisers

| Fact | Detail |
|------|--------|
| FYM | About 0.5% N, 0.2% P₂O₅, 0.5% K₂O |
| Vermicompost earthworm | ***Eisenia fetida*** |
| Green manures | Sunhemp, dhaincha; *Sesbania rostrata* has stem nodules |
| ***Rhizobium*** | Symbiotic; **legumes only** |
| *Azotobacter* | Free-living, aerobic |
| *Azospirillum* | Associative; cereals and millets |
| *Acetobacter* | Endophyte; **sugarcane** |
| BGA (cyanobacteria) | *Anabaena*, *Nostoc*; paddy |
| ***Azolla*** | Water **fern** + cyanobacterium *Anabaena azollae*; paddy |
| PSB / mycorrhiza | Phosphorus availability / phosphorus and water uptake |
| Regulation | Fertiliser Control Order, 1985 |
| Godhan Nyay Yojana | Chhattisgarh, 20 July 2020 (Hareli); cow dung at ₹2/kg; vermicompost in gauthans |

## Organic and Natural Farming

| Fact | Detail |
|------|--------|
| **Organic vs natural** | Organic = certified standard, bought organic inputs allowed · Natural = on-farm inputs, soil microbes, mulching |
| ZBNF | **Subhash Palekar** |
| **Four wheels** | Beejamrit (seed), Jeevamrit (soil microbes), Achhadana (mulch), Whapasa (air–water balance) |
| **NPOP** | 2001; **APEDA, Commerce Ministry**; third-party; exports |
| **PGS-India** | Agriculture Ministry; participatory; domestic |
| Large Area Certification | From 2020–21; traditionally organic areas |
| Jaivik Bharat logo | FSSAI, Organic Foods Regulations 2017 |
| PKVY / MOVCDNER / BPKP | 2015 / 2015–16 / 2020–21 |
| **NMNF** | **Nov 2024**; ₹2,481 crore; 15,000 clusters; 1 crore farmers; 7.5 lakh ha; 10,000 Bio-input Resource Centres |
| Sikkim | First fully organic state, January 2016 |
| Dantewada | About 110 villages, about 65,000 ha certified under LAC (early 2020s) |
| Sri Lanka | Chemical fertiliser ban April 2021, reversed late 2021 |

## Pest Management and IPM

| Fact | Detail |
|------|--------|
| **IPM goal** | Keep pests **below economic levels**, not eradicate |
| **ETL vs EIL** | ETL (start control) is set **below** EIL (damage = control cost) |
| **Label colours** | **Red** extremely · **yellow** highly · **blue** moderately · **green** slightly toxic |
| **3R problem** | Resistance, resurgence, residue |
| Pesticide law | Insecticides Act 1968; CIB&RC; Directorate of PPQS, Faridabad |
| Endosulfan | Supreme Court ban, 2011 |
| ***Trichogramma*** | Egg-parasitoid wasp (Tricho-cards) |
| ***Trichoderma*** | Antagonistic fungus against soil-borne diseases |
| NPV / *Beauveria* / *Metarhizium* | Virus / fungus / fungus (locusts) |
| Parthenium / water hyacinth biocontrol | *Zygogramma bicolorata* / *Neochetina* weevils |
| Fall armyworm | *Spodoptera frugiperda*; first reported 2018, Karnataka, maize |
| Desert locust | Outbreak 2019–20; Locust Warning Organisation, Jodhpur |
| Rice gall midge | **Gangai (गंगई)**; silver shoot |
| Yellow stem borer / BPH | Dead heart and white ear / hopper burn |
| **NIBSM** | Baronda, **Raipur**; approved 2012 |
| NCIPM | ICAR, New Delhi |

## Don't Confuse

| This | vs | That |
|------|----|------|
| Intercropping (rows, planned) | vs | Mixed cropping (seeds mixed, insurance) |
| Biasi (ploughing young paddy) | vs | Utera (relay sowing into ripening paddy) |
| Biofortification (bred into crop) | vs | Fortification (added in processing) |
| GM / transgenic (foreign gene) | vs | SDN-1/2 genome editing (no foreign DNA) |
| GEAC (Environment Ministry) | vs | PPV&FR Authority (Agriculture Ministry) |
| Azolla (fern) | vs | Anabaena (cyanobacterium inside it) |
| Liming (acid soils) | vs | Gypsum (sodic soils) |
| NPOP (Commerce, exports) | vs | PGS-India (Agriculture, domestic) |
| Conservation agriculture (may use chemicals) | vs | Organic farming (no synthetic chemicals) |
| *Trichoderma* (fungus, diseases) | vs | *Trichogramma* (wasp, insect eggs) |
| Resistance (pest adapts) | vs | Resurgence (enemies killed, pest rebounds) |

{{< callout type="warning" title="Favourite traps" >}}
- **Rice is C3**, not C4.
- **Azolla is a fern**; the nitrogen is fixed by *Anabaena azollae*.
- **Khaira is zinc deficiency**, not a disease.
- **IPM does not ban pesticides**; it uses them only above the ETL.
- **Green label = slightly toxic**, not safe.
- **NPOP is under the Commerce Ministry** (APEDA), not Agriculture.
{{< /callout >}}

---
Source: https://cgpscnotes.in/science-technology/agricultural-science/quick-revision/

Science & Technology Agricultural Science

Agricultural Science — Quick Revision

One-page CGPSC quick revision for Agricultural Science: crop physiology, seeds, NPK and fertilisers, biofertilisers, organic farming and IPM in tables.

5 min read Updated Oct 2026 #quick revision#cgpsc#agricultural science

Crop science, seeds, soil nutrients, fertilisers, organic and natural farming, and pest management on one page. For explanations, go back to the chapter.

How to use this sheet

Scan it top to bottom before Mains. Bold entries are the facts and distinctions that most often decide an answer.

Crop Science and Cropping Systems

Fact	Detail
C3 crops	Rice, wheat, pulses, oilseeds; RuBisCO only; high photorespiration in heat
C4 crops	Maize, sugarcane, sorghum, millets; Kranz anatomy; PEP carboxylase; better water-use efficiency
CAM	Pineapple, agave; stomata open at night
Photoperiod	Rice and soybean short-day; wheat and mustard long-day; HYVs mostly photoperiod-insensitive
Most sensitive rice stage	Flowering (heat or drought causes spikelet sterility)
Legume N fixation	Rhizobium in nodules; nitrogenase; leghaemoglobin
LER	Above 1 means intercropping beats sole cropping
SRI	Madagascar, 1980s, Henri de Laulanié; young single seedlings, wide spacing, alternate wetting and drying
DSR	No nursery or puddling; saves water and labour; weeds are the main problem
Paddy methane	Methanogenic archaea in flooded, anaerobic soil; AWD, SRI and DSR reduce it
Conservation agriculture	Minimum tillage + permanent soil cover + crop diversification (FAO)
Biasi	Cross-ploughing standing broadcast paddy (Chhattisgarh)
Utera	Relay sowing of lathyrus, linseed, gram into ripening paddy
Lathyrus toxin	β-ODAP, causes neurolathyrism

Seeds and Crop Improvement

Fact	Detail
Seed tag colours	Breeder golden yellow · foundation white · certified azure blue · truthfully labelled opal green
Hybrid	F1; heterosis; saved seed segregates
Seeds Act	1966; draft Seeds Bill 2025 to replace it (not enacted as of 2026)
PPV&FR Act	2001; farmers may save, use, exchange and sell seed, but not as branded seed
GM regulator	GEAC, Ministry of Environment; EP Act 1986, Rules 1989
Bt cotton	2002; Bacillus thuringiensis cry genes; pink bollworm resistance later
Bt brinjal	Moratorium, February 2010
GM mustard DMH-11	Environmental release approved Oct 2022; split Supreme Court verdict July 2024
Genome-editing exemption	March 2022: SDN-1 and SDN-2 (no foreign DNA)
Genome-edited rice	May 2025: DRR Dhan 100 (Kamala), IIRR Hyderabad; Pusa DST Rice 1, IARI New Delhi
Chhattisgarh Zinc Rice-1	IGKV Raipur, 2015; India’s first zinc-biofortified rice
Rice germplasm	IGKV Raipur, over 23,000 accessions; Dr R.H. Richharia

Soil Fertility and Fertilisers

Fact	Detail
Essential elements	17: C, H, O; N, P, K; Ca, Mg, S; Fe, Mn, Zn, Cu, B, Mo, Cl, Ni
Law of the Minimum	Liebig: scarcest nutrient limits growth
N deficiency	Older leaves yellow first (mobile)
P deficiency	Purple leaves, poor roots
K deficiency	Scorched leaf margins
Khaira (rice)	Zinc deficiency
Whiptail (cauliflower)	Molybdenum deficiency
Acidic soil / sodic soil	Lime / gypsum
Urea / DAP / SSP / MOP	46% N / 18-46 / 16% P₂O₅ / 60% K₂O
MOP	Wholly imported
N losses	Volatilisation (NH₃), leaching (NO₃⁻), denitrification (N₂O), runoff
Benchmark NPK	4:2:1; actual seasonal ratios near 10:4:1 (kharif 2023–24)
NBS	2010; urea outside it
Neem-coated urea	Mandatory 2015; nitrification inhibitor
Nano urea / nano DAP	IFFCO, June 2021 / 2023; yield claims debated
Soil Health Card	19 Feb 2015, Suratgarh (Rajasthan); 12 parameters
PM-PRANAM	2023; rewards states for cutting chemical fertiliser use
World Soil Day	5 December

Manures and Biofertilisers

Fact	Detail
FYM	About 0.5% N, 0.2% P₂O₅, 0.5% K₂O
Vermicompost earthworm	Eisenia fetida
Green manures	Sunhemp, dhaincha; Sesbania rostrata has stem nodules
Rhizobium	Symbiotic; legumes only
Azotobacter	Free-living, aerobic
Azospirillum	Associative; cereals and millets
Acetobacter	Endophyte; sugarcane
BGA (cyanobacteria)	Anabaena, Nostoc; paddy
Azolla	Water fern + cyanobacterium Anabaena azollae; paddy
PSB / mycorrhiza	Phosphorus availability / phosphorus and water uptake
Regulation	Fertiliser Control Order, 1985
Godhan Nyay Yojana	Chhattisgarh, 20 July 2020 (Hareli); cow dung at ₹2/kg; vermicompost in gauthans

Organic and Natural Farming

Fact	Detail
Organic vs natural	Organic = certified standard, bought organic inputs allowed · Natural = on-farm inputs, soil microbes, mulching
ZBNF	Subhash Palekar
Four wheels	Beejamrit (seed), Jeevamrit (soil microbes), Achhadana (mulch), Whapasa (air–water balance)
NPOP	2001; APEDA, Commerce Ministry; third-party; exports
PGS-India	Agriculture Ministry; participatory; domestic
Large Area Certification	From 2020–21; traditionally organic areas
Jaivik Bharat logo	FSSAI, Organic Foods Regulations 2017
PKVY / MOVCDNER / BPKP	2015 / 2015–16 / 2020–21
NMNF	Nov 2024; ₹2,481 crore; 15,000 clusters; 1 crore farmers; 7.5 lakh ha; 10,000 Bio-input Resource Centres
Sikkim	First fully organic state, January 2016
Dantewada	About 110 villages, about 65,000 ha certified under LAC (early 2020s)
Sri Lanka	Chemical fertiliser ban April 2021, reversed late 2021

Pest Management and IPM

Fact	Detail
IPM goal	Keep pests below economic levels, not eradicate
ETL vs EIL	ETL (start control) is set below EIL (damage = control cost)
Label colours	Red extremely · yellow highly · blue moderately · green slightly toxic
3R problem	Resistance, resurgence, residue
Pesticide law	Insecticides Act 1968; CIB&RC; Directorate of PPQS, Faridabad
Endosulfan	Supreme Court ban, 2011
Trichogramma	Egg-parasitoid wasp (Tricho-cards)
Trichoderma	Antagonistic fungus against soil-borne diseases
NPV / Beauveria / Metarhizium	Virus / fungus / fungus (locusts)
Parthenium / water hyacinth biocontrol	Zygogramma bicolorata / Neochetina weevils
Fall armyworm	Spodoptera frugiperda; first reported 2018, Karnataka, maize
Desert locust	Outbreak 2019–20; Locust Warning Organisation, Jodhpur
Rice gall midge	Gangai (गंगई); silver shoot
Yellow stem borer / BPH	Dead heart and white ear / hopper burn
NIBSM	Baronda, Raipur; approved 2012
NCIPM	ICAR, New Delhi

Don’t Confuse

This	vs	That
Intercropping (rows, planned)	vs	Mixed cropping (seeds mixed, insurance)
Biasi (ploughing young paddy)	vs	Utera (relay sowing into ripening paddy)
Biofortification (bred into crop)	vs	Fortification (added in processing)
GM / transgenic (foreign gene)	vs	SDN-1/2 genome editing (no foreign DNA)
GEAC (Environment Ministry)	vs	PPV&FR Authority (Agriculture Ministry)
Azolla (fern)	vs	Anabaena (cyanobacterium inside it)
Liming (acid soils)	vs	Gypsum (sodic soils)
NPOP (Commerce, exports)	vs	PGS-India (Agriculture, domestic)
Conservation agriculture (may use chemicals)	vs	Organic farming (no synthetic chemicals)
Trichoderma (fungus, diseases)	vs	Trichogramma (wasp, insect eggs)
Resistance (pest adapts)	vs	Resurgence (enemies killed, pest rebounds)

Favourite traps

Rice is C3, not C4.
Azolla is a fern; the nitrogen is fixed by Anabaena azollae.
Khaira is zinc deficiency, not a disease.
IPM does not ban pesticides; it uses them only above the ETL.
Green label = slightly toxic, not safe.
NPOP is under the Commerce Ministry (APEDA), not Agriculture.

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