How to Evaluate Crop Yield: Understanding Crop Equivalent Yield and Land Equivalent Ratio

When a farmer grows two or more crops together on the same piece of land, a key question arises – how do you measure the overall productivity of such a system? You can’t simply add the yields of wheat and mustard or maize and soybean and compare them with a sole crop. Different crops have different values, different growth habits, and different land requirements. That’s where standardised metrics like Crop Equivalent Yield (CEY) and Land Equivalent Ratio (LER) step in. These two tools allow farmers, researchers, and agricultural planners to evaluate whether intercropping is actually paying off – both economically and in terms of land use efficiency.

Why evaluating crop yield matters 🔗

Crop yield evaluation goes beyond simply counting how many kilograms you harvested per hectare. In modern agriculture, especially where intercropping is practised, the real challenge lies in comparing the productivity of mixed cropping systems against sole cropping. A farmer growing maize alongside groundnut needs to know: did growing two crops together give a better return than dedicating the entire field to just one crop?

Without proper evaluation tools, this comparison remains guesswork. CEY answers this from an economic standpoint by converting all crop outputs into a single standard crop’s equivalent. LER answers it from a biological and land-use standpoint by measuring how efficiently the land is being used. Together, they form the foundation of sound crop management decisions – from choosing which crops to intercrop, to deciding how to allocate limited resources like land, labour, and capital.

What is crop equivalent yield (CEY)? 🔗

Crop Equivalent Yield is a method of converting the yields of all crops in an intercropping system into the yield equivalent of one chosen standard crop, using their respective market prices. Crop yield measurement typically uses units like kilograms per hectare or bushels per acre, but when multiple crops are involved, a price-based conversion creates a common currency for comparison.

The CEY formula 🔗

The general formula for Crop Equivalent Yield is:

CEY = Yield of main crop + (Yield of intercrop × Price of intercrop ÷ Price of main crop)

In a system with more than two crops, the formula simply extends to include each additional crop’s yield and price ratio. The key idea is straightforward – every intercrop’s yield is converted into the equivalent yield of the main (or standard) crop based on prevailing market prices.

A worked example of CEY 🔗

Suppose a farmer grows wheat as the main crop and mustard as an intercrop. Here are the figures:

Wheat yield: 3,000 kg/ha at ₹25 per kg
Mustard yield: 500 kg/ha at ₹50 per kg
Standard crop: Wheat (₹25 per kg)

CEY = 3,000 + (500 × 50 ÷ 25) = 3,000 + 1,000 = 4,000 kg/ha of wheat equivalent

This means the intercropping system produced the economic equivalent of 4,000 kg of wheat per hectare. If the farmer’s sole wheat crop on a similar field yielded 3,500 kg/ha, the intercropping system clearly performed better in economic terms.

When is CEY most useful? 🔗

CEY is particularly valuable when you need to compare the economic performance of different cropping combinations. It helps with crop planning, insurance assessment, and communicating productivity to lenders or buyers in standardised terms. However, because CEY depends entirely on market prices, its value can shift with commodity fluctuations. A combination that looks highly productive when mustard prices are high may appear less attractive if prices drop. It’s wise to calculate CEY using both current and average historical prices for a more reliable picture.

What is land equivalent ratio (LER)? 🔗

While CEY focuses on money, the Land Equivalent Ratio focuses on land-use efficiency. LER is defined by the FAO as the ratio of the area under sole cropping to the area under intercropping needed to produce equal amounts of yield at the same management level. In simpler terms, it answers the question: how much land would I need if I grew these crops separately to match what I produced through intercropping?

The LER formula 🔗

For a two-crop intercropping system, LER is calculated as:

LER = (Ya ÷ Yaa) + (Yb ÷ Ybb)

Where:
Ya = Yield of crop A in the intercropping system
Yaa = Yield of crop A when grown alone (sole crop)
Yb = Yield of crop B in the intercropping system
Ybb = Yield of crop B when grown alone (sole crop)

Each fraction (Ya/Yaa or Yb/Ybb) is called the partial LER for that crop. The sum of all partial LERs gives the total LER for the system.

A worked example of LER 🔗

Consider a farmer who grows groundnut and sesame. Here are the yields:

Sole groundnut yield: 1,200 kg/ha
Sole sesame yield: 1,000 kg/ha
Intercropped groundnut yield: 1,000 kg/ha
Intercropped sesame yield: 600 kg/ha

LER = (1,000 ÷ 1,200) + (600 ÷ 1,000) = 0.83 + 0.60 = 1.43

An LER of 1.43 means that growing these crops separately would require 43% more land to produce the same total output. In other words, the intercropping system is 43% more land-efficient than sole cropping.

How to interpret LER values 🔗

The interpretation is simple and direct:

LER greater than 1: Intercropping has a yield advantage. The higher the value above 1, the greater the benefit. For instance, an LER of 1.30 means 30% more land would be needed under sole cropping to match the intercrop’s production.
LER equal to 1: No advantage or disadvantage – intercropping and sole cropping are equally efficient.
LER less than 1: Sole cropping is more efficient, and the intercropping system is underperforming.

Research published in Proceedings of the National Academy of Sciences (PNAS) confirms that intercropping widely leads to higher LER values, with the metric being the most commonly used index for assessing land-use efficiency of intercrops compared with sole crops.

CEY vs LER: key differences 🔗

Though both CEY and LER evaluate intercropping performance, they measure fundamentally different things. CEY is a price-based economic metric – it tells you how much your combined harvest is worth in terms of a single standard crop. LER is a biological efficiency metric – it tells you how well the land is being used regardless of what crops are worth in the market.

A system could have a high LER (excellent land use) but a moderate CEY if the intercrop fetches a low price. Conversely, a high-value intercrop could boost CEY even if the land-use efficiency is not exceptional. This is precisely why agronomists recommend using multiple indices together rather than relying on any single metric for evaluating cropping systems.

Factors that influence CEY and LER 🔗

Market price fluctuations 🔗

Since CEY directly depends on the price of each crop, volatile markets can significantly alter results. A crop combination that appears highly profitable during a season of high prices may look average when prices normalise. Calculating CEY over multiple seasons using average prices gives a more reliable picture.

Weather and growing conditions 🔗

Both metrics are sensitive to seasonal variation. A drought year might favour one crop in the intercrop over the other, skewing both CEY and LER. Research from Iowa State University notes that strip intercropping of maize and soybean in the Midwest showed LER values ranging from just above 1 in drought years to higher values under good growing conditions, confirming that multiple years of data are needed for sound conclusions.

Management practices 🔗

LER values are only valid when compared at the same management level. If the sole crop and the intercrop receive different levels of fertiliser, irrigation, or pest management, the LER comparison becomes unreliable. For instance, studies have shown that nitrogen application rates can significantly alter LER – intercropping may show high LER at zero nitrogen but only modest advantage with moderate nitrogen inputs, because the sole crop’s yield responds differently to fertiliser than the intercrop does.

Crop selection and spatial arrangement 🔗

The choice of crops and their planting pattern matter enormously. Crops with complementary root depths, canopy structures, and nutrient demands tend to produce higher LER values. For example, a tall cereal paired with a short legume can optimise light capture and soil nutrient use across different layers.

Practical applications of CEY and LER 🔗

Choosing the right crop combinations 🔗

Before the planting season, farmers can use previous CEY data to identify which crop combinations have consistently delivered the highest economic returns. If a maize-soybean intercrop shows a higher CEY than maize-groundnut in your region, that data directly supports your planting decision.

Optimising land allocation 🔗

LER helps identify which fields are best suited for intercropping and which may perform better under sole cropping. Fields that consistently show LER values well above 1 with a specific combination are strong candidates for continued intercropping. Fields where LER hovers near or below 1 may be better utilised with a single crop or an alternative combination.

Resource allocation and investment decisions 🔗

Both metrics guide how to allocate limited resources. If certain intercropping combinations consistently produce high LER and CEY values, it may justify investing in specialised planting or harvesting equipment. Research from a study on cotton-legume intercropping found that LER values ranging from 1.34 to 1.63 in cotton-legume systems increased net economic profit by 37 to 226% compared to sole cotton – a clear signal that the investment in intercropping management was worthwhile.

Supporting intercropping adoption 🔗

Intercropping offers several well-documented benefits beyond just yield. According to a review published in the Journal of Economic Entomology, intercropping strengthens agroecosystems by improving resource use efficiency, enhancing soil water holding capacity, and increasing habitat diversity for beneficial insects. When these advantages are quantified through CEY and LER, they provide compelling evidence for farmers, extension workers, and policymakers to promote intercropping more widely.

Other related indices worth knowing 🔗

While CEY and LER are the most commonly used tools, several other indices add depth to intercropping evaluation:

Relative Yield Total (RYT): Similar to LER but measured on a per-plant population basis rather than per-unit area. It accounts for differences in planting density between sole and intercropping systems.

Area Time Equivalent Ratio (ATER): This adjusts LER by factoring in the time each crop occupies the land. It is useful when intercropped species have very different growth durations, since a standard LER might overestimate the advantage of a system where one crop occupies the field much longer.

Aggressivity (A): Measures which crop in the intercropping system is dominant and which is suppressed. A positive value for crop A means it is outcompeting crop B for resources.

Competition Ratio (CR): Provides a measure of the competitive ability of each component crop. A CR greater than 1 for a particular crop means it is more competitive than its partner in the intercrop.

Using a combination of these indices alongside CEY and LER gives a comprehensive picture of how an intercropping system is performing – biologically, economically, and in terms of inter-species competition.

Limitations to keep in mind 🔗

No evaluation metric is perfect. CEY is entirely dependent on market prices, which means it reflects economic conditions at a point in time rather than the inherent biological productivity of the system. Two identical fields with the same physical output can show different CEY values simply because crop prices changed between calculation dates.

LER, while a powerful measure of land-use efficiency, does not account for differences in input costs, labour requirements, or the quality of produce. A system with an LER of 1.3 sounds efficient, but if it requires significantly more labour or management effort, the net benefit to the farmer may be marginal. Additionally, LER values should be interpreted cautiously when management levels differ between the intercrop and sole crop treatments – the comparison is only valid at equal management intensity.

Both metrics also rely on accurate yield data. In smallholder settings, where precise field measurements are rare, estimates can introduce significant error. A guide from Agriculture Victoria emphasises that the accuracy of yield estimation depends on adequate sampling across the field to get a representative average.

The bigger picture: why these metrics matter for Indian agriculture 🔗

India has a long tradition of intercropping, particularly in rainfed and dryland farming systems. Combinations like pigeonpea + sorghum, maize + soybean, and wheat + chickpea are widely practised across different agro-climatic zones. Yet, adoption of formal evaluation tools like CEY and LER remains limited among smallholder farmers.

As agriculture in India moves toward more data-driven approaches, understanding and applying these metrics can directly improve decision-making. With shrinking per capita arable land and increasing pressure to produce more from less, quantifying the advantages of intercropping through CEY and LER is not just an academic exercise – it is a practical necessity for improving profitability and sustainability.

What do you think? If you are already practising intercropping, have you ever calculated the CEY or LER for your cropping system? And do you think price-based metrics like CEY or land-efficiency metrics like LER should carry more weight when making planting decisions?

References

1. https://en.wikipedia.org/wiki/Crop_yield
2. https://en.wikipedia.org/wiki/Land_equivalent_ratio
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC9926256/
4. https://www.slideshare.net/slideshow/tools-for-evaluation-of-cropping-systems/248577026
5. https://masters-sms.agron.iastate.edu/Content/Students/sample/classes/Sample/lesson09/9.4.html
6. https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2025.1527256/full
7. https://www.sciencedirect.com/science/article/abs/pii/S0378429025000541
8. https://academic.oup.com/jee/article/115/5/1350/6572575
9. https://agriculture.vic.gov.au/crops-and-horticulture/grains-pulses-and-cereals/crop-production/general-agronomy/a-brief-guide-to-estimating-crop-yields