Study the chart below which shows data relevant to the following scenario. A farmer is deciding whether to plant a monoculture or a polyculture on a 10-hect...

(a) Definition of monoculture [1]

Monoculture is the practice of growing a single crop species over a large area of land. [1]

The entire field is planted with the same plant, harvested at the same time, and often replanted with the same crop season after season.

(b) Two advantages of polyculture compared with monoculture [2]

1. Polyculture supports higher biodiversity because a variety of plant species provides different habitats, food sources and microenvironments for a wider range of insects, birds and other organisms. [1]
2. Polyculture reduces the risk of total crop failure because if one crop species is affected by disease, drought or pest attack, the other crops may still survive and produce a harvest. [1]

(c) Why monoculture is more vulnerable to pest outbreaks [3]

1. In a monoculture, the entire field is planted with the same crop, providing a continuous, uniform and abundant food source for any pest species that feeds on that crop. [1]
2. Pests can spread rapidly and without barriers because every plant in every direction is a suitable host. There are no different plant species to interrupt or slow the spread of the pest population. [1]
3. In polyculture, the mixture of crops disrupts pest populations. Pests specific to one crop cannot spread as easily when different, non-host crop species are planted between their host plants. The physical separation and chemical diversity of a polyculture create natural barriers to pest movement. [1]

(d) Discussion: polyculture as a practical alternative for meeting global food demand [5]

Arguments for polyculture:

1. It is more sustainable in the long term because different plants have different root depths and nutrient requirements. This maintains soil structure and fertility without heavy reliance on chemical fertilisers. [1]
2. It provides natural pest control: the diversity of plants supports populations of beneficial predatory insects and breaks up pest habitats, reducing or eliminating the need for expensive and environmentally harmful pesticides. [1]
3. It reduces the risk of total harvest failure, providing greater food security for small-scale farmers who depend on their harvest for food and income. If one crop fails, others may still produce. [1]

Arguments against polyculture:

1. Monoculture is more efficient for large-scale commercial production because modern agricultural machinery (combine harvesters, seed drills, sprayers) is designed for uniform fields of a single crop. Polyculture is harder to mechanise and manage at scale. [1]
2. The high yields achieved by monoculture are currently essential for feeding the growing global population. Polyculture typically produces lower yields of any individual crop, and converting large-scale monoculture areas to polyculture could reduce total food output in the short term. [1]