🎹Agrisilviculture Systems -- Trees with Crops

When a Forest Department Planted Teak — and Got Rice Too

In the previous lesson, we defined agroforestry and explored its principles, benefits, constraints, and management practices. Now we move to the first major system type: agrisilviculture — the combination of trees with agricultural crops.

In 1850s Burma, forest officers discovered that tribal labourers clearing land for teak plantations could grow rice between the young teak seedlings. The trees got weeded for free, the labourers got food, and the government got its plantation established at minimal cost. This Taungya system became one of the world’s first formally recognized agroforestry practices — and it all started because someone saw the logic in combining trees with crops.

This lesson covers:

1. P.K. Nair’s classification of agroforestry systems (1987)
2. Shifting cultivation (Jhum) — the oldest system
3. Taungya system — origin, types, and rainfall requirements
4. Alley cropping — hedgerow intercropping with nitrogen-fixing trees
5. Shelterbelts and windbreaks — protection zone calculations
6. Hortisilviculture — fruit trees with timber trees

All sub-systems are high-yield for IBPS AFO, NABARD, and RRB-SO exams.

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Classification of Agroforestry Systems

Before diving into individual agrisilviculture sub-systems, it is essential to understand how all agroforestry systems are classified. P.K. Nair’s framework provides the standard taxonomy used across textbooks and exams.

P.K. Nair (1987), widely regarded as the father of modern agroforestry, classified agroforestry systems based on four criteria:

• His book An Introduction to Agroforestry is the foundational text for the discipline.

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Structural Classification — Based on Nature of Components

The structural basis is the most commonly used classification in exams because it directly describes what you see on the ground — which components are present and how they are arranged.

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Agrisilviculture Sub-systems

Having established the classification framework, we now examine each agrisilviculture sub-system in detail. Agrisilviculture (Trees + Crops) includes several important sub-systems:

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1. Shifting Cultivation (Jhum)

Shifting cultivation is the oldest known agroforestry system, dating back thousands of years.

The cycle:

1. Select a forest patch and clear-fell it
2. Burn the slashed vegetation (slash and burn)
3. Cultivate crops for 2-3 years until soil fertility declines
4. Abandon the site (fallow period) and move to a new patch
5. Return after the fallow period when soil has recovered

The problem: Earlier, the fallow cycle was 20-30 years — enough for full recovery. Due to population pressure, it has reduced to 2-3 years, causing ecological degradation, soil erosion, and conversion of forests to wasteland.

Improved Fallow System: Planting nitrogen-fixing trees during the fallow period to restore soil fertility faster, allowing either shorter fallows or better yields.

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2. Taungya System

The Taungya system is a modified form of shifting cultivation used primarily to establish timber plantations at low cost.

How it works: Labourers are given forest land to grow food crops (rice, millets, vegetables) alongside newly planted tree seedlings. They weed the plantation as part of crop cultivation. After 3-5 years, when the tree canopy closes, they move to a new area.

Types of Taungya

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3. Multi-species Tree Gardens

• Various tree species are grown in a mixed arrangement
• Provides ecological resilience and year-round supply of different products
• Main function: production of food, fodder, and wood for home consumption and sale
• Common in Kerala (home gardens with coconut, arecanut, pepper, jackfruit, mango)

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4. Alley Cropping (Hedgerow Intercropping)

One of the most well-researched agroforestry systems in the tropics.

How it works:

• Perennial, preferably leguminous trees/shrubs are grown as hedgerows in wide rows
• Agricultural crops are planted in the “alleys” between the hedgerows
• During cropping, trees are pruned and the biomass is used as mulch on the alleys — this reduces evaporation, suppresses weeds, and adds nutrients

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5. Agroforestry for Fuelwood Production

• Multipurpose fuelwood species are planted on or around agricultural lands
• Over 70% of rural India depends on fuelwood for cooking
• Trees also serve as fencing, shelterbelts, and boundary markers
• Common species: Acacia nilotica, Albizia lebbek, Cassia siamea, Casuarina equisetifolia, Dalbergia sissoo, Prosopis juliflora, Eucalyptus tereticornis

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6. Shelterbelts

A wide belt of trees, shrubs, and grasses planted in rows at right angles to prevailing winds to protect crops from wind erosion and hot desiccating winds.

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7. Windbreaks

• Windbreaks protect livestock from cold winds; shelterbelts protect crops from hot drying winds
• An agroforestry system suitable for small orchards prone to wind damage is a windbreak

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8. Soil Conservation Hedges

• Trees planted on bunds and terraces to stabilize soil and reinforce conservation structures
• Intercept rain and obstruct wind, reducing soil erosion
• Common species: Grevillea robusta, Acacia catechu, Pinus roxburghii, Prosopis juliflora, Leucaena leucocephala (often with grasses)

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9. Hortisilviculture

• Integration of horticultural trees (fruit) with timber trees on the same land
• Combines short-term returns from fruits with long-term returns from timber
• Timber trees on orchard bunds act as windbreaks, protecting fruit trees from high winds
• Example: Mango orchard with Teak on boundaries

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Comparison of Wind Protection Systems

Shelterbelts, windbreaks, and soil conservation hedges all use trees to protect land — but they differ in scale, width, and primary purpose. This comparison is a common exam question.

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Exam Tips

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Summary Table

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Summary Cheat Sheet