Intercropping and the land equivalent ratio

Q: Can the LER be above 2?

In principle, yes, if both crops yield as much in the intercrop as alone, which needs almost no competition. In practice, values between 1.1 and 1.5 are typical for good intercrops.

Q: Is mixed cropping the same as intercropping?

Mixed cropping is one form of intercropping, with no row arrangement. "Intercropping" covers mixed, row, strip and relay systems.

Q: Why do intercrops help most when fertiliser is scarce?

A legume partner supplies nitrogen, and complementary roots explore more soil, which matter most when nutrients are limiting. With generous fertiliser, sole cereals often close the gap.

Why growing two crops together can out-yield growing them apart, the main types of intercropping, and how to calculate and read the land equivalent ratio.

Exam essential7 min readUpdated 19 October 2026

On this page

Kinds of multiple cropping
Why an intercrop can produce more
The land equivalent ratio
Designing an intercrop
Key points
What the exams ask
Questions people ask
Sources
Related on Laisha
Discussion

Intercropping is growing two or more crops in the same field at the same time, close enough that they interact. It is one of the oldest farming practices in the world and is still how a large share of smallholder fields are planted in Africa, Latin America and Asia.

The land equivalent ratio (LER) is the standard way to judge whether an intercrop is worth it: it tells you how much land you would need to grow the same harvest as separate sole crops. Both the idea and the arithmetic are examined in agronomy papers almost everywhere.

Kinds of multiple cropping

Multiple cropping means growing more than one crop on the same land in a year. It has two branches:

Sequential cropping: one crop after another, with no overlap: for example rice followed by wheat or a pulse in the same year. Two crops a year is double cropping; three, triple cropping.
Intercropping: crops overlap in time and share the field.

Intercropping itself comes in four common arrangements:

Type	Arrangement	Example
Mixed intercropping	no distinct rows; seeds mixed and broadcast or sown together	traditional cereal–pulse mixtures in dry regions
Row intercropping	at least one crop in rows, in a regular pattern	maize with beans or cowpea in alternate rows
Strip intercropping	strips wide enough to manage each crop separately, narrow enough to interact	strips of maize and soybean several rows wide
Relay intercropping	the second crop is sown into the first before it is harvested	cotton or wheat sown into a standing crop; lentil sown into rice before harvest

A crop with a different, longer life can also be interplanted into a plantation or orchard, as with legumes or vegetables between young fruit trees. When intercrops include trees, the system is agroforestry.

Why an intercrop can produce more

If two crops simply competed for exactly the same resources, an intercrop could never beat the better sole crop. It can, because the crops differ.

Complementarity in time. A short crop and a long one use the season differently. A fast-maturing bean harvested at 90 days and a pigeonpea that keeps growing for six months use light and water at different times, so the field's resources are used for longer.

Complementarity in space. Different canopy heights capture light at different levels; a tall cereal and a short legume intercept more light together. Different rooting depths draw water and nutrients from different layers.

Facilitation. One crop improves conditions for the other. A legume fixes nitrogen, and the cereal, competing strongly for soil nitrate, pushes the legume to fix more. Some species mobilise phosphorus that their neighbour can then use. In the classic Mesoamerican milpa ("three sisters"), maize gives climbing beans a support, beans add nitrogen, and squash covers the ground against weeds.

Protection. Mixtures slow the spread of pests and diseases, which find their host less easily, and support more natural enemies. The push–pull system developed in East Africa intercrops maize with a repellent legume (Desmodium) and surrounds it with an attractive trap grass, cutting stemborer and Striga weed damage.

Insurance. If one crop fails in a drought or to a pest, the other may still yield. For a smallholder, a more stable harvest can matter more than the highest average.

The disadvantages are real too: management is more complex, mechanised harvesting is harder, and if the crops are badly chosen or too dense, competition outweighs complementarity.

The land equivalent ratio

The LER compares the intercrop with the sole crops grown under the same conditions:

Land equivalent ratio for two crops

LER = (Y_a,intercrop ⁄ Y_a,sole) + (Y_b,intercrop ⁄ Y_b,sole)

Each term is a partial LER: the intercrop yield of that crop as a fraction of its sole-crop yield.

LER = 1: no advantage; the intercrop yields exactly what the same land divided between sole crops would.
LER > 1: the intercrop uses land more efficiently. An LER of 1.25 means that 1.25 ha of sole crops would be needed to match 1 ha of intercrop.
LER < 1: competition outweighs complementarity; sole cropping would be better.

A worked LER. Each crop yields less in the intercrop than alone, but together they produce more than the same hectare divided between the two sole crops.Diagram: Laisha, original.

Worked example

Calculating and interpreting an LER

In a trial, sole maize yields 6.0 t/ha and sole bean 2.0 t/ha. The maize–bean row intercrop yields 4.8 t/ha of maize and 0.9 t/ha of bean.

Partial LER for maize = 4.8 ⁄ 6.0 = 0.80.
Partial LER for bean = 0.9 ⁄ 2.0 = 0.45.
LER = 0.80 + 0.45 = 1.25.

To produce 4.8 t of maize and 0.9 t of beans as sole crops, the farmer would need 0.80 ha of maize and 0.45 ha of beans: 1.25 ha, compared with 1 ha intercropped.

The partial LERs also show the balance. Maize, the taller and more competitive crop, kept 80 per cent of its sole yield; bean, shaded, kept 45 per cent. Whether this is a good intercrop depends on what the farmer wants: if beans are the more valuable crop, a different design may be better even with a lower LER.

Reading an LER honestly

Sole crops must be at their best. An LER is only meaningful if each sole crop was grown at its optimum density and management; comparing with a poorly grown sole crop inflates the ratio.
Duration matters. If one crop occupies the land much longer, the LER can exaggerate the advantage. The area–time equivalent ratio (ATER) weights each partial LER by the crop's duration.
Value matters. The LER compares harvests in biological terms. Farmers compare money: the monetary advantage is often calculated as the value of the intercrop × (LER − 1) ⁄ LER. With an intercrop worth 1,000 currency units per hectare and an LER of 1.25, that is 1,000 × 0.25 ⁄ 1.25 = 200 currency units, the gain over sole cropping on the same land.
Competition indices such as aggressivity and competitive ratio describe which crop dominates; they complement the LER.

Large reviews of field experiments around the world have found average LERs for cereal–legume and other intercrops of roughly 1.2 to 1.3, with wide variation by crop pair, design and nitrogen supply. Gains tend to be largest where the crops differ most in timing and form, and where inputs, especially nitrogen, are limited.

Designing an intercrop

Choose complementary crops: different heights, rooting depths, durations, or a legume with a non-legume.
Set the population. In a replacement design, rows of one crop replace rows of the other, so each is below its sole density. In an additive design, the second crop is added to the full stand of the main crop. Additive designs are common when the main crop must not lose yield.
Arrange for light. Orient rows and choose row ratios (1:1, 2:1, 2:2 and so on) so the shorter crop is not shaded for its whole life.
Stagger sowing where one crop would otherwise overwhelm the other early.
Fertilise for both: the legume's nitrogen is not a full substitute for the cereal's needs.

Key points

Multiple cropping is sequential (one crop after another) or intercropping (crops overlapping in time and space).
Intercropping types: mixed, row, strip and relay.
Advantages come from complementarity in time and space, facilitation (legume nitrogen), pest suppression and yield stability.
LER = sum of partial LERs (intercrop yield ÷ sole yield for each crop); above 1 means more efficient land use.
An LER of 1.25 means 1.25 ha of sole crops would be needed to equal 1 ha of intercrop.
Use optimally grown sole crops for comparison; ATER corrects for duration; monetary advantage converts the gain to money.

What the exams ask

School-leaving and entrance papers: definitions of multiple, sequential, mixed, row, strip and relay cropping, with examples, and the advantages of intercropping.
Degree and research-fellowship entrances: calculating LER and partial LERs, interpreting values above and below 1, competition indices, and the role of legumes.
Professional and licensing examinations for agronomists: designing row ratios and populations, replacement versus additive designs, and economic evaluation of an intercrop.

Described in general terms: the kind of examination, not a past paper. Laisha never reproduces exam questions.

Questions people ask

Can the LER be above 2?

In principle, yes, if both crops yield as much in the intercrop as alone, which needs almost no competition. In practice, values between 1.1 and 1.5 are typical for good intercrops.

Is mixed cropping the same as intercropping?