Green manure is a natural fertilizer for Class 9 science, where specific green plants are grown in fields and then ploughed back into the soil before sowing the main crop. This process enriches the soil with organic matter and essential nutrients like nitrogen, improving fertility without chemicals.

Definition Breakdown

Green manure involves turning undecomposed green plant tissues directly into the soil to boost its structure and nutrient content. It's especially effective with leguminous crops (like peas or beans family), which fix atmospheric nitrogen via root bacteria called Rhizobium.

For Class 9 students, think of it as "living fertilizer"—plants like sunn hemp or dhaincha are grown quickly (30-45 days), cut, and mixed into the soil to decompose naturally.

Preparation Steps

Here's how green manure is prepared, tailored for CBSE Class 9 Chapter 12 (Improvement in Food Resources):

  1. Select and sow : Choose fast-growing legumes (e.g., Sesbania aculeata or Crotalaria juncea) during the off-season or alongside the main crop.
  2. Grow phase : Let them mature for 6-8 weeks, building biomass and fixing 20-40 kg nitrogen per acre.
  3. Plough under : Before flowering, till the green plants into the top 15-20 cm of soil while moist.
  4. Decompose : They break down in 20-30 days, releasing nutrients as the next crop is sown.

This method mimics nature's recycling, much like leaves falling in a forest to feed new growth.

Key Benefits

  • Soil health boost : Adds organic matter (15-18 quintals dry matter/acre), enhances water retention, and fights erosion.
  • Nutrient supply : Primarily nitrogen, plus phosphorus, potassium, and micronutrients; C:N ratio under 30:1 ensures quick breakdown without robbing soil nitrogen.
  • Eco-friendly : Reduces chemical fertilizer needs by 20-30 kg N/ha, supports organic farming, and suppresses weeds/pests naturally.
  • Sustainable edge : In 2026's push for regenerative agriculture, it's trending in India for climate-resilient crops amid erratic monsoons.

Limitations : Takes land/time (not ideal for intensive farming), and poor timing can tie up nitrogen temporarily.

Common Green Manure Crops

Crop Name| Family| Key Traits| Nitrogen Fix (kg/ha)
---|---|---|---
Sunn Hemp (Crotalaria juncea)| Legume| Drought-tolerant, fast growth| 100-150 1
Dhaincha (Sesbania aculeata)| Legume| Water-loving, high biomass| 150-200 1
Cluster Bean (Guar)| Legume| Heat-resistant, dual-purpose| 80-120 1
Pillipesara| Legume| Short-duration, easy to plough| 90-130 1

These are staples in Indian curricula and farms.

Real-World Example

Imagine a wheat farmer in Punjab: After rice harvest (March 2026), they sow dhaincha. By May, it's ploughed in, adding nitrogen for kharif crops—boosting yields by 10-15% naturally, as seen in sustainable trials. From multiple views, agronomists praise it for carbon sequestration, while smallholders value cost savings over urea.

TL;DR : Green manure = grow legumes → plough green → soil gets nutrient- rich! Perfect for Class 9 exams and eco-farming.

Information gathered from public forums or data available on the internet and portrayed here.