Summary
Summary WIND PROTECTION
- Course
- Institution
- Book
wind protection using windbreaks
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
Seller
Follow
letholetheophilus
Content preview
THEME 11: WIND PROTECTION11.1 INTRODUCTION
We all know that the environment is not optimal and must be changed
under certain circumstances, for example, a windy area needs to have
some type of windbreak to protect crops.
A windbreak is any structure that decreases the wind speed.
A shelterbelt is a row of trees planted for shelter.
Both can change the environment and this benefits crop growth.
Farmers have always used them.
The main purpose of using windbreaks is to conserve soil water
ET wind speed
Decrease wind => decrease ET and
increase in wind => increase ET.
ETpot α ↑wind speed
So if wind speed is low, then soil water is conserved.
It is difficult to predict effect of wind speed.
The advantage is that for low wind speed, seed germination is good,
because soil surface stays moist longer,
but plants grow quicker, roots & foliage is larger and this then
⇒ use of soil water more quickly.
This in turn can lead to water stress behind windbreak.
WUE ↑ behind windbreak and T: Es ↑
⇒↑ biomass, ↑ yield /unit water.
254
, Experimental results for Canadian wheat yields (t ha-1). Height of windbreak
is h.
Heavy snow Med. Snow
Distance (of sheltered zone) 0-15 h 15h-25 h 0-15 h 15h-25 h
Yield +1.82 +1.35 +1.61 +1.48
According to the above table, the highest yields for wheat were attained in
heavy snow in the zone 0 to 15 x height of the windbreak. For example, if
the windbreak was 2 m high, then the zone would measure 0 to 30 m.
Wheat yields were thus highest (+1.82) in the zone nearer to the
windbreak, although yields were still high (+1.35) in the 30 to 50 m zone
WUE of beans, rye, oats, potatoes, also ↑ with use of windbreaks in
studies in Poland.
Even under irrigation, windbreaks still influence plant water relations,
therefore it is the windbreak’s influence on soil and plant water relations
that is the critical factor.
Very complex relationships-
influenced by geometry, spacing, age, height, density of wind break.
11.2 WIND SPEED & TURBULENCE IN SHELTERBELT
Aim: to reduce force of wind.
Design is very difficult if to function properly.
Flow patterns very complex around barriers.
Effectiveness – depends on height, porosity, length.
↑ Height (h) => ↑ distance of effect up & downwind.
A thick barrier => shelter distance of 10-15 * h.
But an ↑ Porosity ≅ => influence 20-25 * h.
255
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller letholetheophilus. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $2.85. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
64438 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now