Intercrop Competition & Find Who Wins
Quantifies aggressivity
LER tells you the intercrop is worth it; the competition indices tell you which component is winning. From sole and intercrop yields and the row ratio, get aggressivity, competitive ratio, crowding, yield loss and a row-ratio recommendation.
Enter your intercrop yields
Sown proportions: Maize 50% · Soybean 50%
Next: Maize is out-competing Soybean (A = +0.39, CR 1.39 > 1). Cut a row of Maize or add a row of Soybean — move from 2:2 toward a ratio that favours Soybean — then re-check that LER stays above 1.
Aggressivity (Willey & Rao 1980): A=0 means equal competition; the sign shows which crop is dominant and the magnitude how strongly. Competitive Ratio CR>1 = dominant. K is the relative crowding coefficient; AYL is the actual yield loss vs sole crops at the same proportion. Sources: Willey & Rao (1980) Expl. Agric.; ICAR-AICRP cropping-systems methodology.
Competition indices — key facts
- Partial LER
- La = Ya ÷ Sa
- LER
- La + Lb (> 1 = advantage)
- Aggressivity
- Ya÷(Sa·Za) − Yb÷(Sb·Zb)
- Competitive ratio
- (La÷Lb)·(Zb÷Za)
- Crowding
- Kab = Ya·Zb ÷ ((Sa−Ya)·Za)
- Actual yield loss
- (Ya÷Za)÷Sa − 1
- Dominant if
- |aggressivity| > 0.1
- Privacy
- Runs in your browser; nothing uploaded
Reference intercrop pairs and row ratios
Sole-crop yields and recommended row ratios from AICRP and ICRISAT cropping-systems trials. Pick a pair to pre-fill, or use the custom option for your own figures.
| Component A | Component B | Sole A | Sole B | Row ratio | Source |
|---|---|---|---|---|---|
| Maize | Soybean | 5.2 t/ha | 1.6 t/ha | 2:2 | AICRP maize-based systems |
| Maize | Cowpea | 5 t/ha | 1.2 t/ha | 1:1 | AICRP |
| Sorghum | Pigeonpea | 3.6 t/ha | 1.1 t/ha | 2:1 | ICRISAT classic |
| Pearl millet | Groundnut | 2.8 t/ha | 1.8 t/ha | 1:3 | AICRP rainfed |
| Cotton | Greengram | 2.2 t/ha | 0.9 t/ha | 1:1 | AICRP cotton systems |
| Sugarcane | Onion | 80 t/ha | 18 t/ha | 1:2 | AICRP sugarcane |
| Wheat | Mustard | 4.4 t/ha | 1.5 t/ha | 6:2 | AICRP wheat systems |
| Groundnut | Pigeonpea | 1.9 t/ha | 1.1 t/ha | 4:2 | ICRISAT |
| Maize | French bean | 5 t/ha | 1.4 t/ha | 1:1 | hill-zone AICRP |
| Redgram | Blackgram | 1.2 t/ha | 0.8 t/ha | 1:2 | AICRP pulses |
Sources: Willey & Rao (1980), Expl. Agric. 16:117-125; de Wit relative crowding coefficient; ICAR-AICRP on Cropping Systems methodology manual; ICRISAT intercropping trials.
Beyond LER: who is out-competing whom
The Land Equivalent Ratio is the headline number for intercropping — above 1 and the mixture beats sole crops on land use. But LER alone hides what is happening between the two crops. A high LER can come from one component thriving while the other is badly suppressed, which is fragile and unbalanced. The competition indices — aggressivity, competitive ratio, the de Wit relative crowding coefficient and actual yield loss — open that black box and tell you which component is winning, by how much, and whether the row ratio is feeding that imbalance.
This tool computes all of them from sole and intercrop yields and the row ratio, then translates them into a plain recommendation: keep the ratio if the crops are balanced, or shift rows toward the suppressed crop if one dominates. The competition seesaw visualises the tilt live. Use it with the Intercropping LER and Alley Cropping tools to design a stand that is both productive and balanced.
See who dominates
Aggressivity and CR name the winning crop and by how much.
Tune the row ratio
Get a clear keep-or-shift recommendation for the stand.
Confirm the advantage
LER and crowding K together confirm a real land-use gain.
Audit the loss
Actual yield loss shows each crop's true cost in the mixture.
Frequently Asked Questions
What is the difference between LER and aggressivity?+
LER (Land Equivalent Ratio) tells you whether the intercrop is more productive than sole crops overall — it is the sum of each component's partial LER (intercrop yield ÷ sole yield), and a value above 1 means a yield advantage. Aggressivity tells you which component is winning the competition: Aab = (Ya ÷ (Sa·Za)) − (Yb ÷ (Sb·Zb)). LER answers 'is it worth it', aggressivity answers 'who is dominating'.
How do I read the aggressivity value?+
If aggressivity (Aab) is positive, component A is the dominant, more competitive crop; if negative, component B dominates; near zero, the two are evenly matched. The further from zero, the stronger the imbalance. The tool flags A or B as dominant when the magnitude exceeds 0.1 and recommends shifting the row ratio toward the suppressed component.
What is the competitive ratio?+
The competitive ratio (CR) refines aggressivity by accounting for the sown proportions: CRa = (La ÷ Lb) × (Zb ÷ Za). A CRa above 1 means component A is more competitive per unit area sown than B. Unlike aggressivity, CR is a ratio, so it is easy to say 'A is 1.8 times as competitive as B'. The dominant crop has CR above 1 and the suppressed crop below 1.
What is the relative crowding coefficient?+
The relative crowding coefficient (K), from de Wit, measures how much a component crowds out its partner relative to itself. Kab = (Ya·Zb) ÷ ((Sa−Ya)·Za). If a component's K is above 1 it produced more than expected in the mixture; the product K = Kab × Kba above 1 indicates a yield advantage from the combination, consistent with LER above 1.
What is actual yield loss (AYL)?+
AYL compares each component's intercrop yield per unit area it occupied against its sole yield: AYLa = (Ya ÷ Za) ÷ Sa − 1. A positive AYL means that component actually yielded more per unit of its land than as a sole crop; negative means it lost. The total AYL sums both and shows the net behaviour of the system beyond the simple LER.
How does the row ratio enter the calculation?+
The row ratio sets the sown proportions Za and Zb. A 2:1 maize-to-pigeonpea stand gives Za = 0.667 and Zb = 0.333. These proportions appear in aggressivity, competitive ratio, crowding and actual yield loss, because each index asks how a component performed relative to the share of land it was given. Change the ratio and every competition index changes.
Should I change my row ratio if one crop dominates?+
Usually yes, if the goal is a balanced harvest of both crops. When one component is strongly dominant, reducing its rows or adding rows of the suppressed crop re-balances the stand and often raises the total LER by letting the weaker crop contribute more. If you only want the dominant crop and the legume is a bonus, you may keep the ratio — the tool's recommendation assumes you value both.
What does an LER above 1 actually mean?+
It means you would need more than one hectare of sole crops to produce what the intercrop produces on one hectare. An LER of 1.3 means a 30 percent land-use advantage — the same yields would need 1.3 ha as monocultures. This is the classic justification for intercropping, and it usually comes from the two crops using light, water and nutrients at different times or depths.
Which crop pairs are built in?+
The tool includes ten reference pairs from AICRP and ICRISAT cropping-systems trials — maize-soybean, maize-cowpea, sorghum-pigeonpea, pearl millet-groundnut, cotton-greengram, sugarcane-onion, wheat-mustard, groundnut-pigeonpea, maize-French bean and redgram-blackgram — each with sole yields and a recommended row ratio, plus a custom option for your own figures.
Do the two crops need the same yield unit?+
Yes. As long as both sole and intercrop yields for the two components share a consistent unit (t/ha or kg/ha), the indices are ratios and the unit cancels out. Do not mix tonnes for one crop and kilograms for the other, or the partial LERs and every derived index will be wrong.
Can intercropping ever lose compared with sole crops?+
Yes — if the LER falls below 1, the intercrop produced less than the sole crops would on the same land, usually because one crop suppressed the other too severely. A strongly negative aggressivity with a low LER is the warning sign. In that case widen the gap, change the ratio toward the weaker crop, or reconsider the pairing.