35. Soil

Why is humus a beneficial component of soil?

How might roots react when they encounter a region of the soil that is low in nitrates?

The American Dust Bowl of the 1930s resulted from __________.

Soil can easily become deficient in __________ because these ions are negatively charged and do not stick to negatively charged soil particles.

The particles in soil are important because they __________.

Fertilizers are usually enriched in __________.

Which of the following would be considered a sustainable agricultural practice?

What is the goal of phytoremediation?

Why do farmers need to be concerned with the pH level of soil?

At low soil pH levels (5 or less), what can happen?

Phytoremediation is showing promise as a sustainable, cost-effective way to decontaminate soil and water. In the case of a hyperaccumulater such as Thlaspi caerulescens, however, what might be a drawback of the technology?

The biological process that produces 96% of the dry mass of a plant is called __________.

A botanist claims to have discovered a new macronutrient required for plant growth. Most of this scientist's colleagues are skeptical of her claim. Why might they consider it unlikely?

If a plant's leaves are yellowing, it may be that the plant is deficient in the elements needed to make chlorophyll, one of which is __________.

If a plant is deficient in __________, it will not be able to make DNA.