Crop and Grass Production

Grass is the biggest crop in Northern Ireland

More land here grows grass than everything else put together, so "crop production" on this specification means grass first and cereals second. There are three parts to this topic: - **Identifying** the grasses, weeds and crops, and choosing varieties that suit NI - **Grass into silage**: when to cut, how the clamp preserves it, and how to judge the result - **Yield**: what moves it, whether GM crops help, and how a crop is grown start to finish One idea runs through all three, and it is worth holding on to: **almost every decision here is a trade-off about timing.** Cut early or cut heavy. Seal now or lose the fermentation. Rotate the field or take the better price this year.

Know your grasses

What a farmer sows, and why. Note that one of these is not sown at all.

Identify the four plants

Four plants from this topic are drawn here. Drag the right name onto each. Two of the labels are plants from the specification that are not drawn, so you will not use them.

Which of these are weeds?

Select the TWO plants a farmer would be trying to get rid of.

• Docks
• Creeping buttercup
• White clover
• Timothy

Match each weed to where it thrives

Cut early or cut heavy

This is the most examinable idea in the whole topic, and it is a single trade-off. **Young leafy grass** is highly digestible, high in protein and low in fibre. An animal gets a great deal from every kilogram. But there is not much of it yet. **Grass left to head out** produces far more bulk. But as it matures the fibre content rises, and digestibility and protein both fall. Every kilogram is worth less. **So cutting date decides silage quality before anything else does.** Cutting at or just before heading is the usual compromise: enough bulk to be worth harvesting, before the feeding value has dropped away. A weather forecast can override all of it, which is why the decision is genuinely difficult rather than a rule to memorise.

Making silage, in order

Put the stages of silage-making into the order they happen.

• The sward is grown and fertilised, and a cutting date is chosen
• The grass is mown and left to wilt, losing some of its water
• It is picked up and chopped, then carted to the clamp or baled
• It is rolled to squeeze out the air and sealed under sheeting, or wrapped
• Bacteria ferment the sugars into acid, the pH falls, and the crop is preserved

Why the clamp must be sealed

A clamp is rolled hard and covered with sheeting. What is that actually for?

• To exclude air, so the bacteria that ferment the sugars into acid can work. Without those airless conditions the crop spoils instead of preserving
• Only to keep the rain off
• To keep the grass warm enough to dry out
• To keep birds and vermin off the crop

Work out the dry matter

A sample of fresh grass weighs **200 g**. After oven-drying it weighs **36 g**. What is its dry matter, as a percentage?

Good silage and bad silage

You can tell a great deal at the clamp face before any sample goes to a laboratory.

A year in the crop

The main sown grass in Northern Ireland is _____, while _____ is a legume that fixes nitrogen from the air. As grass matures its fibre content rises and its _____ falls, so cutting date decides silage quality more than anything else. In the clamp the grass is rolled and sealed to exclude _____, allowing bacteria to ferment the sugars and lower the _____. Growing different crops in successive years, known as _____, helps break pest and disease cycles.

GM crops in an answer

**"Discuss the advantages and disadvantages of growing genetically modified crops. (9 marks)"** "The agricultural case is real. GM varieties can be given resistance to particular pests, which cuts the pesticide a grower has to apply, or tolerance of a herbicide so weeds can be controlled without damaging the crop. Others are bred for drought or salt tolerance, which matters where conditions are marginal, and yields can be higher as a result. Against that, the seed is expensive and usually controlled by the company that developed it, so a grower becomes dependent on a supplier. Pests can develop resistance in time, as they do to any single control measure. There are concerns about cross-pollination with wild relatives. And consumer resistance can close markets regardless of the agronomy. **The practical position matters here**: GM crops are not grown commercially in Northern Ireland or the rest of the UK, so for a farmer here this is a question about what regulation and the market permit as much as about what the technology can do." **Notice the last paragraph.** It does not just list points; it says what actually decides the question for the farmer being asked about. That is what turns a list into a discussion.

Spot the yield factors

A grower describes a poor barley harvest. Tap the TWO details that explain the low yield.

• The variety was taken from the Recommended Varieties List and the seed bed was well prepared.
• The field lay waterlogged for three weeks in spring, and the crop never recovered its early growth
• . Fertiliser was applied at the planned rate and the machinery was in good order.
• Barley had been grown in the same field for four years running, and disease had built up in the soil
• . Harvest weather in August was dry and settled.

Write a balanced line on GM

Build a sentence that gives both sides and then names what settles it for a farmer here.

Planning the crop year

You are planning next season on a field that grew barley this year. Work through the decisions.

• Barley did well here and prices are good. Should you grow it again?
• You are choosing a variety. What is the Recommended Varieties List for?
• Silage cutting is planned for next week, and the grass is just at heading. The forecast turns wet. What is the trade-off?

Your turn: the production study

Choose one crop grown in Northern Ireland and explain how it is produced and what limits its yield.

• Name your crop and say how the site, soil and seed bed would be prepared for it
• Explain two factors that could reduce its yield, giving the mechanism in each case
• Explain what crop rotation does and why a grower might still choose not to rotate
• For a grass crop, explain how cutting date affects silage quality, using the words digestibility and fibre