Introduction and Fundamental Concepts of Multiple Cropping
Multiple cropping is defined as the practice of growing more than one crop on the same piece of land during one agricultural calendar year. It represents an advanced intensification strategy designed to maximize land, solar radiation, water, and nutrient utilization efficiency.
- Temporal Intensification: Involves growing crops sequentially (sequential cropping), where the succeeding crop is planted only after the preceding crop has been harvested.
- Spatial Intensification: Involves growing two or more crops simultaneously during all or part of their life cycle (intercropping or mixed cropping).
- Cropping Intensity Index (CII): Calculated as the total gross cropped area divided by the net sown area, multiplied by 100. High multiple cropping index signifies superior agro-ecosystem productivity.
Classification and Types of Multiple Cropping Systems
Agronomically, multiple cropping systems are categorized based on spatial and temporal overlaps into distinct functional groups:
- Sequential Cropping: Growing crops in quick succession within a year. Examples include Oryza sativa (Rice) followed by Triticum aestivum (Wheat) followed by Vigna radiata (Green gram).
- Intercropping: Growing two or more crops simultaneously in distinct row arrangements. Sub-types include row intercropping, strip intercropping, relay intercropping, and mixed intercropping.
- Relay Cropping: A special form of sequential intercropping where the succeeding crop is planted before the harvesting of the preceding crop (e.g., planting lentil or soybean into standing rice crop).
- Ratooning: Raising a crop from the regrowths coming out of the roots or stalks after harvest of the main crop, widely practiced in Saccharum officinarum (Sugarcane) and Sorghum bicolor (Sorghum).
Indices of Competition and Efficiency in Multiple Cropping
Quantifying the biological and economic advantage of multiple cropping over sole cropping requires specialized mathematical and agronomic indices:
- Land Equivalent Ratio (LER): Measures the relative land area under sole crops required to produce the yields achieved in intercropping. LER > 1.0 indicates yield advantage. Formula: ext{LER} = rac{Y_{ab}}{Y_{aa}} + rac{Y_{ba}}{Y_{bb}} where Y_{ab} is yield of crop A in association with B.
- Competitive Ratio (CR): Indicates the degree of competition between intercropped species and calculates which crop is more competitive.
- Aggressivity (A): Determines how much the relative increase in yield of component crop 'A' is greater than that of component crop 'B'.
- Monetary Advantage Index (MAI): Evaluates the economic profit of the cropping system by incorporating economic value and LER.
Nutrient, Water, and Weed Management in Intensified Systems
Multiple cropping increases nutrient and water demands, requiring precise agronomic interventions:
- Nutrient Management: Legume-cereal systems reduce nitrogen fertilizer requirements due to biological nitrogen fixation (BNF) by Rhizobium species. Fertilizer recommendations must account for residual nutrient effects.
- Water Management: Synchronizing critical irrigation stages (e.g., CRI stage in wheat, flowering in legumes) prevents moisture stress in intercropped setups. Micro-irrigation systems are highly advantageous.
- Weed Suppression: Dense canopy closure in multiple and intercropping systems smothers weed emergence, significantly reducing weed dry matter and minimizing herbicide dependency.
- Allele-Chemical Interactions: Certain crops release allelochemicals that inhibit weed growth or affect companion crops, necessitating careful species selection.
Socio-Economic Importance and Constraints in UP Agriculture
Adopting multiple cropping systems in the Indo-Gangetic plains of Uttar Pradesh offers profound socio-economic benefits alongside notable challenges:
- Employment Generation: Continuous cropping operations increase annual labor utilization and reduce seasonal unemployment.
- Risk Mitigation: Diversified cropping buffers against total crop failure caused by aberrant weather or pest outbreaks.
- Machinery Constraints: Timely turnaround between sequential crops (e.g., rice-wheat rotation) requires robust mechanization, such as zero-till seed drills and happy seeders.
- Soil Health Maintenance: Continuous intensive tillage without organic recycling can cause structural degradation, demanding integrated nutrient management (INM) and residue retention.
Comparison Between Sequential Cropping and Intercropping
| Parameter | Sequential Cropping | Intercropping |
|---|---|---|
| Temporal Arrangement | Crops grown one after another in sequence | Crops grown simultaneously on the same land |
| Spatial Arrangement | Single crop stands occupy the land at any given time | Multiple crops occupy the land simultaneously in rows or strips |
| Competition Level | Inter-plant competition is minimal or absent between crops | Interspecific competition occurs for light, water, and nutrients |
| Machinery Operation | Easier mechanization for single-species fields | Requires specialized inter-row cultivators and seed drills |
| Primary Objective | Maximum annual production per unit area per unit time | Risk minimization and enhanced resource use efficiency |
Memory Trick / Mnemonic
Types of Multiple Cropping (S-I-R-R)
Some Intelligent Rats Run
S = Sequential Cropping, I = Intercropping, R = Relay Cropping, R = Ratooning. Use this to quickly recall the four major pillars of multiple cropping systems.
Memory Trick / Mnemonic
Intercropping Efficiency Indices (L-C-A-M)
Let’s Cultivate All Maize
L = Land Equivalent Ratio (LER), C = Competitive Ratio (CR), A = Aggressivity, M = Monetary Advantage Index (MAI). Essential acronym for competitive and biological efficiency indices.
⚡ High-Yield Exam Points (UP TGT / PGT Focus)
- Cropping Intensity Index (CII) formula: ( ext{Gross Cropped Area} / ext{Net Sown Area}) imes 100.
- Relay cropping involves planting the succeeding crop before harvesting the preceding crop, such as sowing lentil in standing paddy fields.
- Land Equivalent Ratio (LER) greater than 1.0 indicates a biological advantage of intercropping over sole cropping.
- The Rice-Wheat cropping system is the predominant sequential cropping system of the Indo-Gangetic Plains in Uttar Pradesh.
- Ratooning is commercially practiced in Sugarcane (Saccharum officinarum) and Napier grass (Pennisetum purpureum).
- Biological Nitrogen Fixation (BNF) in legume-cereal intercropping systems significantly reduces inorganic nitrogen fertilizer requirements.
- Competitive Ratio (CR) measures the ratio of individual LERs of two crops and reflects their competitive ability.
- Allelopathy refers to the chemical inhibition of one plant species by another through the release of secondary metabolites into the environment.
⚠️ Common Mistakes & Exam Pitfalls
- Confusing mixed cropping with intercropping: Mixed cropping involves sowing seeds without distinct row arrangements, whereas intercropping involves definite row proportions.
- Assuming LER measures economic profit directly: LER measures biological efficiency; Monetary Advantage Index (MAI) or Net Returns must be used for economic evaluation.
- Treating relay cropping as sequential cropping: Relay cropping has temporal overlap between crops, whereas sequential cropping has zero overlap.