In which form do plants take in nitrogen from soil?

nitrate ions. Nitrate ions are dissolved in soil water.

Which soil is a mixture of sand, silt and clay?

loam. The mixture gives it the best of each particle size.

Why do crops grow badly in waterlogged soil?

the roots cannot get oxygen. Water has filled the pore spaces where air should be.

the day-to-day condition of the atmosphere in a place. The long-term pattern is climate.

Which soil pH suits most crops?

close to neutral. Nutrients are most available near neutral.

In a region with a wet season and a dry season, when are most crops planted?

at the start of the wet season. The crop then has water for the whole of its growth.

Soil, weather and crop growth · Cambridge IGCSE Environmental Management

In plain words

A seed needs the same things wherever it is planted: food, water, air around its roots, warmth and light. Whether it gets them depends on two things the farmer cannot easily change, the soil and the weather.

8 things to know

Plants take in nutrients as inorganic ions dissolved in soil water: nitrogen as nitrate ions (NO₃⁻), phosphorus as phosphate ions (PO₄³⁻) and potassium as potassium ions (K⁺).
The organic content matters too. As it decomposes it releases these ions, and it helps the soil to hold water.
Soil pH can be acidic, neutral or alkaline. Most crops grow best in soil close to neutral. In very acidic or very alkaline soil, some nutrients cannot be taken up.
Pore spaces hold air and water. Roots need oxygen from the air for respiration. In waterlogged soil the pores are full of water, so roots are starved of oxygen.
Soil needs to hold enough water for the crop while letting the excess drain away. It should also be easy to cultivate, which means easy to dig and plough.
Loam is a soil with a mixture of sand, silt and clay. It has an ideal combination of mineral particles and pore spaces. It retains moisture, lets excess water drain, contains organic content and inorganic ions, and is easy to cultivate.
Weather is the day-to-day condition of the atmosphere in a place. Some parts of the world have a wet season and a dry season, and crops there are timed to grow during the rains.
Crops grow fastest when photosynthesis is at its optimum rate. That depends on the length of the growing season, how close the weather is to the best conditions for that crop, and the number of daylight hours.

Worked example

Explain why a loam soil gives a better crop than a clay soil.

Loam has a mix of particle sizes, so it has pore spaces that hold both air and water. Clay has tiny pores and becomes waterlogged.
Excess water drains from loam, so roots get oxygen for respiration.
Loam still retains enough moisture and holds nutrients, and it is easier to plough than heavy clay.

Tips and tricks

Write the ions correctly: nitrate NO₃⁻, phosphate PO₄³⁻, potassium K⁺. Plants do not take in nitrogen gas from the soil.
Weather is day to day. Climate is the pattern over many years. The two definitions are asked for separately.

6 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Soil, weather and crop growth: 6 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

In which form do plants take in nitrogen from soil?
- nitrate ions (the answer)
- nitrogen gas
- ammonia gas
- protein
Nitrate ions are dissolved in soil water.
Which soil is a mixture of sand, silt and clay?
- loam (the answer)
- chalk
- peat
- gravel
The mixture gives it the best of each particle size.
Why do crops grow badly in waterlogged soil?
- the roots get too many nutrients
- the roots cannot get oxygen (the answer)
- the soil becomes too hot
- the soil becomes alkaline
Water has filled the pore spaces where air should be.
What is weather?
- the average conditions over many years
- the temperature of the soil
- the number of daylight hours in a year
- the day-to-day condition of the atmosphere in a place (the answer)
The long-term pattern is climate.
Which soil pH suits most crops?
- strongly acidic
- close to neutral (the answer)
- strongly alkaline
- pH does not matter
Nutrients are most available near neutral.
In a region with a wet season and a dry season, when are most crops planted?Stretch
- at the end of the wet season
- in the middle of the dry season
- at the start of the wet season (the answer)
- at any time of year
The crop then has water for the whole of its growth.

6 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

3 questions, 8 marks. Write your answers on paper, then check them.

Soil, weather and crop growth

Cambridge IGCSE Environmental Management 0680 · 8 marks · papermunch.org

Name ______________________________ Date ______________

Name the three inorganic ions that crops take from the soil, and the element each supplies.[3]
Show answerHide answer
Nitrate ions supply nitrogen. Phosphate ions supply phosphorus. Potassium ions supply potassium.
I got this one
Explain three reasons why loam is a good soil for growing crops.[3]
Show answerHide answer
Any three: it has an ideal mixture of mineral particles and pore spaces; it retains moisture; it allows excess water to drain; it contains organic content and inorganic ions; it is easy to cultivate.
I got this one
Explain why crop growth is faster in a season with long days.[2]
Show answerHide answer
More daylight hours give more time for photosynthesis each day. More glucose is made, so the crop grows faster.
I got this one

Answers: Soil, weather and crop growth

1. Nitrate ions supply nitrogen. Phosphate ions supply phosphorus. Potassium ions supply potassium.
2. Any three: it has an ideal mixture of mineral particles and pore spaces; it retains moisture; it allows excess water to drain; it contains organic content and inorganic ions; it is easy to cultivate.
3. More daylight hours give more time for photosynthesis each day. More glucose is made, so the crop grows faster.