Lecture 7 - Crop Rotation

Flashcards about Crop Rotation

What is the definition of crop rotation?

Sequentially planting crops of different species on a parcel of land for specific purposes.

What were the three components that the Roman's crop rotation system was based on?

Food, feed, and fallow.

What crop did the Romans plant for human consumption?

Wheat.

What crop did the Romans plant to feed their horses and livestock?

Oats.

What was the purpose of the fallow period in the Roman crop rotation system?

To increase nutrient levels as organic matter in the soil was decomposed by microbes.

Who introduced the European four-field rotation system to the UK in the 1700s?

Turnip Townsend.

What were the four crops in the European four-field rotation system?

Wheat, barley, turnips, and clover.

Why was clover important in the four field rotation system?

Clover has high protein levels, quite nutritious for livestock grazing which is converted to manure, benefiting the soil.

What was a key benefit of turnip crops?

Voluminous root system is quite effective at burrowing down through the soil. So this could alleviate any of soil compaction.

What was a result of the introduction of the four-field crop rotation system in the UK?

Wheat exports increased by about ninefold within sixty years; quantity and quality of livestock increased.

Why was monoculture common in the UK in 1970s?

Incentives for high productivity, ability to use wheat for multiple purposed, farmer perceptions that yield was high regardless.

What is meant by break crop benefit?

The increased yield in a primary crop when it is planted after a different crop is planted the year before.

Why might there be reluctance to have diverse crop rotations?

The market prices for break crops, oilseeds, legumes, are just not as great.

Name some ways break crop benefits can be assessed?

Monocultural continuous cropping, crop growth models and experimental approach is best.

Name a variety of ways that Break crops could assist yields?

Fallow treatment for nutritional value, destroying all soborn organisms, including pests and diseases and beneficials

Name some reasons that a monoculture decreases yields.

Buildup of soborne diseases, Mycorrhizal fungi have been suggested to be parasitic, acidification of the soil, depletion of soil organic matter and specific nutrients, changes in the rhizosphere.

What is a significant variable that dissuades farmers from adopting crop rotation?

Variability in prediciting the magnitude of yield benefits.

What is Farmers relying on if they plant their wheat seed after there has been rain?

There will be some residual soil moisture at depth within the soil profile that hasn't been used by the preceding crop.

What is one potentially adverse impact of crop rotations?

Waterlogging of the soil.

Give one concept Lucent has been proposed to do

Biological drilling (break the plough pan), by getting its roots through the plough pan and potentially change the pore structure in the subsoil.

What term descirbes the particle size distributions of the soil

Texture.

What does each crop change in terms of soil?

Structure or how the soil particles aggregate in its immediate environment.

What is key to promoting structural stability of the soil?

Turnover of roots introducing organic matter to the soil.

Name the two possibilities Legumes have to acquire nitrogen?

Directly fix nitrogen if the nodulation process works within their nodules or take up nitrogen directly from the soil.

What can inhibit the nodulation process in Legumes?

Loading up the soil with nitrates.

How can nitrogen content be lost from legume residues?

Denitrified; losses of nitrous oxide to the atmosphere.

What do legumes provide in terms of boosting soil nitrogen levels directly?

Decomposition of their residues. Also, less nitrogen is taken from the soil when biological nitrogen fixation is successful, resulting in nitrogen sparing.

What can be done to use legume crops more effectively in European agriculture?

Understanding the regulation of legume nitrogen fixation is absolutely critical if they are going to be deployed in crop rotations.

What can disrupt the life cycle of weed species in crop rotation?

A change in the crop rotation.

How can crops suppress weed species?

Physical and chemical/allelopathic effects.

What term describes the exuding a chemical into the soil that can either suppress weed seed germination or have other impacts preventing seedling establishment?

Allelopathic effect.

How is the rice crop and Burseem clover grown in Egypt?

Rice crops grown around the Nile on flooded sores are typically grown after Burseem clover.

What pest is perhaps the most challenging that UK Potato Farmers have to deal with?

The potato cyst nematode.

What is a common way in which UK Potato Farmers avoid potato cyst nematode?

By not planting potato sequentially year on year in the same parcel of soil.

What induces hatching and enhances them in Nematodes eggs?

Soil temperature

What is the name of the soilborn bacteria that are antagonistic towards the take off fungus?

Pseudomonad bacteria.

What does allelopathy cause?

Suppression of weeds

What does the rhizosphere community promote?

Growth of the plant and/or causes suppression of diseases.

What is one of the more critical, if less interesting, elements to crop rotation?

Time; the populations of pests and diseases that build up in soil will die off over time.

What affects the root distribution, particularly by allowing biopores to develop?

The preceding crop