Exercises: Food production and sustainability

State two factors that can reduce the amount of food produced on a farm in Ireland. Explain briefly how each affects the crop or animals.

Define the terms "fertiliser" and "pesticide". Give one benefit and one environmental drawback of each.

Explain what is meant by "sustainable food production". Suggest two things a farmer could do to be more sustainable.

A farmer in Tipperary grows barley on a field of $12\ \text{ha}$ and harvests $96\ \text{tonnes}$. The following year, after changing to a different variety and using a better crop rotation, she harvests $114\ \text{tonnes}$ from the same field.

1. a) Calculate the yield per hectare in each year.

1. b) Calculate the percentage increase in yield.

1. c) Suggest two reasons why crop rotation can improve yield.

Producing $1\ \text{kg}$ of beef requires about $15,000$ litres of water, while $1\ \text{kg}$ of wheat requires about $1,500$ litres.

1. a) Calculate how many times more water beef needs than wheat.

1. b) A family wants to reduce its water footprint. Using these data, suggest one change to its diet and justify it.

1. c) Explain why energy is lost at each trophic level and how this relates to the efficiency of producing meat compared with plant crops.

Run-off from fields with excess nitrate fertiliser enters a lake in the Midlands. Over several weeks, algae grow rapidly on the surface and later fish die.

1. a) Name the process described.

1. b) Explain the sequence of events from fertiliser run-off to fish deaths.

1. c) Suggest two ways to reduce this problem.

By 2050 the global population is projected to reach about $9.7$ billion, compared with about $8.0$ billion today.

1. a) Calculate the percentage increase in population.

1. b) Discuss three strategies that could help to increase global food production without large increases in agricultural land.

1. c) Evaluate one social or ethical concern related to one of these strategies, such as genetic modification.

A study compares two farms of the same size in County Kerry. Farm A uses intensive methods (high fertiliser, pesticide, monoculture) and gets $9\ \text{t/ha}$. Farm B uses organic methods (crop rotation, natural predators, compost) and gets $6\ \text{t/ha}$. Farm B has twice the number of species of insects and birds as Farm A.

1. a) Calculate the percentage difference in yield of B compared with A.

1. b) Explain the link between monoculture, pesticide use and biodiversity.

1. c) Evaluate which farm is more sustainable in the long term, giving reasons and recognising any limitations of the data.

Selective breeding has increased the milk yield of Irish dairy cows from about $3,500$ litres per year in 1980 to about $5,500$ litres per year today.

1. a) Calculate the percentage increase.

1. b) Describe the process of selective breeding in terms of selection, breeding and repetition over generations.

1. c) Explain why reduced genetic variation can be a risk to a herd, using an example of disease.