Plantation Crop I – Chapter 2 Notes

Land Preparation

• Scope: Encompasses all physical works carried out before a perennial crop (rubber, in this lecture) is established.
• Core elements
  • Clearing • Road construction • Drainage construction • Lining • Terracing
• Why clear the existing vegetation?
  • Removes potential hosts of root‐disease fungi (old rubber trees, jungle species)
  • Gives clear, obstacle-free work space for subsequent terracing, lining, holing and planting
  • Facilitates access for machinery and labour
• Clearing techniques
  • Manual felling (chainsaws)
  • Mechanical felling (bulldozers, winches)
  • Burning = traditional but discouraged; destructive to soil structure and microorganisms
  • Recommended → “Zero-burn” system: all biomass left in situ to rot and recycle nutrients, minimising CO₂ emissions and wildfire risk

New-Planting Operations (chronology)

1. Construct or service drainage (where needed).
2. Under-brush ground vegetation.
3. Fell jungle trees (chainsaw / bulldozer).
4. Allow felled timber to dry; prune & stack.
5. Construct estate roads.
6. Optional tillage of compacted soils.
7. Field lining (straight or contour).
8. Terrace building on hill slopes.
9. Establish leguminous cover crop (LCC).
10. Holing ($45\,\text{cm}\times45\,\text{cm}\times45\,\text{cm}$) + $120\,\text{g}$ rock-phosphate per hole.
11. Transplant polybag or other nursery plants.

Re-Planting Operations (chronology)

• Same general flow but begins with removal or poisoning of old rubber stand rather than jungle felling.
• Additional servicing of existing drains, terraces and roads in lieu of constructing new ones.

Road Construction in Plantations

• Importance
  • Ensures timely movement of people, latex, agro-inputs → lowers production cost
  • Enhances supervision & communication; considered a KPI of estate “progress”.
• Design objectives
  • Maximise overall field efficiency.
  • Minimise in-estate travel time.
  • Facilitate connection to public infrastructure.
• Hierarchical classes
  • Main road – links estate HQ ↔ public road / parent estate.
  • Subsidiary road – links HQ ↔ divisions.
  • Minor road – connects individual field blocks ↔ HQ.

Drainage Construction

• Physiological rationale
  • Excess water ↓ soil aeration → root suffocation, pathogens, young-plant mortality.
  • Goal : keep water table ≥ $100\,\text{cm}$ below surface yet conserve enough moisture for crop use.
• Functional objectives
  • Evacuate surplus water
  • Enable adequate soil air
  • Maintain plant health, prevent water-logging diseases
  • Raise yield via improved root environment
• Drainage network (start at lowest outlet – river, stream, lake, or excavated sump)
  • Main drains: $150\,\text{cm}$ deep, spaced $100{-}200\,\text{m}$, gradient drop $30\,\text{cm}$ per $100\,\text{m}$.
  • Subsidiary drains: $120\,\text{cm}$ deep, spacing $50\,\text{m}$.
  • Intermediate drains: $100\,\text{cm}$ deep, run between subsidiary drains.
• Manual vs. mechanical digging – back-hoe commonly used.
• Labour norms (Table 4.6)
  • Main: top width $150\,\text{cm}$, bottom $100\,\text{cm}$, depth $150\,\text{cm}$ → 5 m per man-day
  • Subsidiary: $120\times80\times120$ cm → 7 m per man-day
  • Intermediate: $100\times60\times60$ cm → 10 m per man-day

Lining & Planting Design

• Target stand: $500\,\text{trees ha}^{-1}$ (approx.)
• Basic geometry
  • Square : $4.5\,\text{m}\times4.5\,\text{m} \Rightarrow 494\,\text{SPH}$
  • Typical inter-cropping row: $2.5\,\text{m}\times8\,\text{m} \Rightarrow 500\,\text{SPH}$
• General formulae
  $\text{Area per tree}=\text{Row spacing}\times\text{Tree spacing}$
  $\text{Trees ha}^{-1}=\frac{10\,000}{\text{Area per tree}}$
• Comparative layouts (Table 4.7)
  1. Square – regular crowns, early ground shading, balanced growth.
  2. Rectangular – longer row length; advantages for inter-cropping/shading vary with aspect ratio.
  3. Avenue – shorter rows, easier tapping rounds.
  4. Hedge – delayed shading, suits longer inter-cropping windows.
  5. Triangular/Quincunx – maximum land use, very uniform crowns, longest rows.

Terracing (Hill Slopes)

• Definition: Horizontal “steps” cut along contour to host planting rows.
• Purposes
  • Minimise soil erosion & surface runoff.
  • Enhance soil moisture retention.
  • Simplify holing, manuring, maintenance & movement.
• Standard cross-section (Fig 3.6)
  • Bench width $100{-}200\,\text{cm}$; riser $25{-}30\,\text{cm}$.
  • Excavated soil dumped on terrace edge to reinforce platform.

Planting Systems

1 Inter-cropping

• Rubber canopy sparse during first 3–5 years ⇒ intense sunlight in alley ways.
• Inter-spaces monetised through short-cycle crops planted ≥ $1.5\,\text{m}$ from rubber stem.
• Example intercrops: banana, pineapple, ginger, vegetables, tuber crops.
• Benefits: early cash-flow, weed suppression, more efficient land use, farmer livelihood support.

2 Leguminous Cover Crops (LCC)

• Objectives
  • Living mulch shielding soil from sun-bake & splash erosion.
  • Organic-matter addition via degenerated biomass; acts as in-situ compost.
  • Nitrogen fixation through root nodules ⇒ reduced fertiliser bill.
  • Moisture conservation, erosion control, weed germination check, improved trunk growth & yield.
• Common species
  • Calopogonium mucunoides, C. caeruleum, Centrosema pubescens, Pueraria phaseoloides, Mucuna cochinchinensis, M. bracteata.
• Seed-mix recipe (per ha) – 3 standard blends (A, B, C) each totalling $6\,\text{kg}$; e.g., mix $2.9\,\text{kg}$ C. mucunoides + $1.2\,\text{kg}$ C. pubescens + $1.9\,\text{kg}$ P. phaseoloides = Blend A.
• Pre-sowing treatment
  1. Mix seeds in pail.
  2. Scarify via hot-water soak (≈$75^{\circ}\text{C}$; 2 parts boiling : 1 part cool) for 2 h.
  3. Drain; inoculate with Rhizobium slurry ($50\,\text{g}$ inoculum : $10\,\text{kg}$ seed).
  4. Add equal weight rock-phosphate (e.g., $10\,\text{kg}$ seed + $10\,\text{kg}$ RP) and sow.

Method of Planting

1 Holing

• Hole size: $45\,\text{cm}\times45\,\text{cm}\times45\,\text{cm}$.
• Functions
  • Loosen soil for rapid root exploration.
  • Remove stones, old stumps (disease sources).
  • Facilitate accurate placement of nursery stock.
• Soil amendment: $120\,\text{g}$ rock-phosphate per hole for P-starter.

2 Planting Material Categories & Key Techniques

3 Pollarding / Branch Induction

• Not detailed in slides, but generally involves pruning main stem at set height (≈$2\,\text{m}$) to stimulate manageable branching for future tapping panels.

Field Development Stages (Rubber)

1. Young seedlings in field – vulnerable; heavy shade & weed control critical.
2. Immature plantation – canopy closing; emphasis on panel training, LCC management, and girth monitoring.
3. Mature plantation – commencement of tapping, road upkeep, fertilizer & disease management pivot to maximise latex yield.

Environmental, Ethical & Practical Considerations

• Zero-burn clearing addresses climate-change concerns, conserves soil biota, reduces haze episodes common in SE Asia.
• Contour drains & terraces align with sustainable land management, meeting certification criteria (RSPO, FSC, etc.).
• LCC & inter-cropping provide biodiversity corridors and smallholder income diversification—mitigate price shocks in rubber markets.
• Good road design reduces fuel use & accidents—socially responsible practice benefiting worker safety.

Key Formula Recap

• Area per tree: $A = S<em>r \times S</em>t$ (row × tree spacing, in $\text{m}^2$).
• Stand density: $N = \dfrac{10\,000}{A}$ trees ha$^{-1}$.
• Drain gradient: $0.3\,\text{m}\,/\,100\,\text{m}$ linear drop.

Quick Revision Checklist

• Can you list the 3 road categories & their functions?
• Specify hole dimensions & rock-phosphate rate.
• Compute SPH for $5.25\,\text{m}\times3.75\,\text{m}$ rectangular layout ($\approx509$ trees ha$^{-1}$).
• Name four benefits of LCC beyond N-fixation.
• Outline the sequence from under-brushing to transplanting in new planting.
• Why orient polybag scion to the north-east?