Monocropping

Imagine you're hiking through a forest, and you begin to notice that every single tree looks the same. You then look down at your feet to see only soil—no shrubs, no flowers. You might begin to feel a bit unsettled...where did all the other plants and animals go?

Unless you've hiked through a monocropped tree plantation, this has likely never happened to you. It's very uncommon to find a natural environment where only one type of plant is growing. The practice of monocropping has intensified agriculture through the planting of a single crop type. But what happens when other organisms are removed from the agricultural ecosystem? Read on to learn why monocropping is used and how it negatively impacts the environment.

Fig. 1 - Monocropped field with potatoes.

Monocropping Definition

The industrialization of agriculture began during the Second Agricultural Revolution and was further developed as part of the Green Revolution that later occurred in the 1950s and 60s. The shift to this commercialization of agriculture and export-driven crop production required a spatial reorganization of agriculture.

This readjustment often came in the form of monocropping, a practice that is now widely executed across the world. It is most common to find monocropping practiced on large scales, in contrast to smaller family farms or subsistence agriculture.

Natural environments typically have a variety of plants growing, and the lack of biodiversity in monocropping means that many of the functions provided by diverse plant and soil interactions must be supplemented with fertilizers and pesticides. While monocropping has undoubtedly allowed cash crop production to become more standardized through mechanization, it has brought with it many impacts on agricultural soils and the greater environment.

Monocropping vs Monoculture

Monocropping involves continuously planting the same crop for multiple seasons, while monoculture is planting a field with a single crop for a season.

Continuous monoculture is equivalent to monocropping, and the two often go together in industrialized agriculture. However, it is possible to practice monoculture without practicing monocropping.

Benefits of Monocropping

The benefits of monocropping are primarily related to increases in efficiency.

Standardization

In monocropping, standardization is achieved through the planting of a single crop variety and through mechanization. Just as an assembly line can streamline production in a factory, monocropping allows for farming practices to be standardized all for a single crop. As a result, labor and capital efficiency are increased.

Selecting a single crop variety is essential to standardization in monocropping. By selecting only one seed variety, all practices from sowing to harvesting can be optimized for the growth of that one crop variety. This also allows for machinery to be specialized for a single crop.

A farmer investing in expensive farm machinery only has to buy specialized equipment for sowing, spraying, irrigating, and harvesting a single crop variety. This simplification can greatly reduce capital costs.

In addition, mechanization results in reduced labor costs. A field with five different crops growing at once is likely too complex for harvesting with large machinery; as a result, many hours of manual labor might be necessary. Every seed can be planted with precision and in a standardized fashion, making later processes of fertilizing and harvesting more straightforward and less labor-intensive.

Fig. 3 - This row-crop cultivator relies on consistent row measurements to remove weeds with greater efficiency than manual labor.

Land Use Efficiency

The standardization involved in monocropping can result in increased land-use efficiency. Every inch of a single plot of land can be optimized for maximized yields, which can reduce the overall need for agricultural land. Ideally, this frees up that land for alternate uses or natural vegetation. The price of land is a noteworthy cost for commercial farmers to consider, so increased land-use efficiency is another economically attractive benefit of monocropping.

Disadvantages of Monocropping

The benefits of increased efficiency in monocropping do not come without a host of concerning disadvantages.

Reliance on Agrochemicals

Agrochemical fertilizers and pesticides are applied to supplement the lost services provided by soil microbes and the larger food web. These agrochemicals can cause the accumulation of heavy metals in soil and can pollute water through runoff.

Soil microbes are responsible for decomposing organic matter and releasing those locked-up nutrients for plant absorption. Reducing plant diversity to just one crop variety in monocropping disrupts the symbiotic plant-soil microbe relationships that control nutrient availability. As a result, overall soil health is compromised and nutrients must be supplemented with agrochemical fertilizers. These can be very costly inputs for farmers.

In addition to providing plants with nutrients, symbiotic microbes offer plants protection from soil pathogens. Because these symbiotic relationships become strained with only one crop variety present, pathogens can more easily infect plants. Monocropping also increases the vulnerability of the crop to other types of pests, as the lack of plant diversity disrupts local food chains and predator-prey relationships.

Soil Erosion

Monocropping is known to degrade soil health over time, which contributes to increased rates of soil loss through erosion. The use of heavy machinery in tilling, planting, fertilizing, and harvesting causes soil to become compacted. The reduced pore space in the soil then leads to increased water runoff, as water is unable to percolate down into the compacted soil.

In addition, machinery and the use of agrochemicals break down soil aggregates into smaller and smaller sizes. Smaller soil aggregates are then more susceptible to being carried away by the increased water runoff caused by compaction.

Fig. 4 - Soil piles have formed at the edge of this monocropped field due to erosion. Runoff water travels down the dugout furrows between crop rows and carries away soil.

Furthermore, soil erosion can be accelerated when soil is left bare after harvest season and before planting occurs. With no cover crop roots holding the soil in place, bare fields create conditions where erosion is greatly increased. As soil is continually lost to erosion in monocropping, the organic matter and nutrients supplied by the soil must be supplemented.

Crop Yields and Genetic Diversity

Because commercial agricultural practices like monocropping have proliferated in recent decades, the overall genetic diversity of crops has been greatly reduced. Genetic diversity in crops allows for natural variations to occur, as plants with different characteristics reproduce with each other and pass on favorable traits to their offspring. This process of recombination drives the ability of crop plants to adapt to local environmental conditions and stresses like droughts.

In monocropping, if a drought causes crop failure, there are no backup crops to rely on. The entire yield could be lost, and food security can be compromised as a result. With greater crop diversity, complete yield loss is much less likely; some crops may be affected by the drought, while others survive. Even in the absence of environmental stressors, monocropping does not always lead to greater yields when compared to practices with multiple crops in one field.¹

Monocropping Examples

The environmental destabilization caused by monocropping has resulted in numerous social impacts throughout the history of this agricultural practice.

Irish Potato Famine

The Irish Potato Famine refers to the period between 1845 and 1850 when around one million Irish people died from starvation and disease due to a pest outbreak that plagued potato crops.

Potatoes were a cash crop in Ireland, and monocropping was used to maximize potato production. Fields of potatoes were planted in proximity to one another, which proved disastrous in aiding the potato blight pathogen, P. infestans, to spread rapidly.² Entire yields were lost to P. infestans, and food insecurity increased with no backup crops to rely on.

Maize

Maize was first domesticated in southern Mexico. Maize is important both as a food source and as a cultural symbol, appearing in the religions and legends of Indigenous groups in the region. Today, Mexico and Guatemala grow the highest diversity of maize in the world. However, monocropping has negatively affected the overall genetic diversity of maize crops.³

Fig. 5 - Many native maize varieties have been replaced with genetically engineered hybrids that are most often grown with monocropping.

The gradual loss of maize genetic diversity due to monocropping has led to reduced food varieties available in the market. Loss of genetic diversity of such a culturally important plant can have cascading effects on indigenous societies and cultures.