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  • Writer's pictureMauricio Sagastuy

Windbreaks - Can they improve your yields? (Agroforestry)

Updated: Apr 9

Windbreaks, also called hedges or shelterbelts, are rows of trees or shrubs that are being planted in order to protect crops and animals from the wind and snow. Windbreaks can decrease soil erosion, reduce evapotranspiration, increase farmers yields, and provide many more benefits to the farm. Additionally, windbreaks can be established with relatively low establishment and management costs, and without trees taking too much space in your farm.


In this post, I will give you an overview about windbreaks in agroforestry by covering the following topics:



Windbreaks in a farm in Sweden

Windbreaks protecting the crops in a farm in the region of Västra Götaland, Sweden.


1. The different functions of a windbreak


A great way to think about windbreaks is to see them as the green infrastructure of your farm. By strategically placing windbreaks in your farm, you will be able to create a web of trees that improves the health of the whole agroecosystem (agricultural ecosystem) without the trees taking too much land in your farm. 


As you can see in the image below, windbreaks can be planted for many different purposes [1]. The four main functions that windbreaks usually have are: (1) wind protection (2) snow management (3) habitat for beneficial organisms, and (4) new products from the trees and shrubs. Other functions that windbreaks may have are: blocking unpleasant smells, blocking chemical spray particles, reducing nutrients leaching and water management. The functions you are trying to get from your windbreaks will determine where you should place them in your farm. 


The most common functions of a windbreak © Mauricio Sagastuy

The most common functions that windbreaks have in farming

Wind protection is the most evident function of a windbreak. Protecting your crops and livestock from the wind will allow them to grow better and produce better yields. The health of the soils in your farm will also improve by reducing evapotranspiration and soil erosion. Additionally, you can use windbreaks to protect the buildings in your farm from the wind, which reduces the heating costs.


Another function that windbreaks can have is to control the movement of snow in your farm. By protecting your crops and livestock from the snow you reduce the stress they are exposed to. Additionally, you can use windbreaks in order to avoid snow from accumulating on the feedlot or to protect your barn from heating loss. 


A third function that windbreaks can have is to provide habitat for the wildlife, which increases the biodiversity in your farm. Windbreaks can attract certain beneficial organisms to your farm, such as pollinators or predators to insects that damage your crops. 


The fourth main function that windbreaks can have in your farm is to produce new products from the trees and shrubs. There are many different products you can produce from your trees as shrubs. Some products have well established markets, such as fruits, berries, nuts, firewood, biofuel or timber. Other products may have more niche markets, for example flowers for florists, or christmas products (e.g. Christmas trees, holly, mistletoe). You can either sell these products or use them for yourself and your family.


As you can see in the image above, there are many other functions that windbreaks can have. Windbreaks can be planted in order to block unpleasant smells coming from the livestock and its manure, or to block chemical sprays, such as pesticides or herbicides, that are blowing to or from your field. Strategically placed windbreaks can reduce the leaching of nutrients coming from your fields. Additionally, windbreaks can help you manage the presence of water in your fields and redirect its movement, for example by absorbing water through their roots, preventing soil erosion, or by increasing the moisture in the soils due to a reduction in evapotranspiration.  



2. The effects that windbreaks have on your land


The image below shows the effect that windbreaks have on the lee side (the side of your field that is protected by wind) [2]. The higher your windbreak is, the wider its impact gets on the lee side of your field. A good rule of thumb is that for every meter of height of the windbreak, you get 10 times the shelter in width. Thus, a 10 meter high windbreak provides 100 meters of wind protection. As you can see in the image below, the effect that windbreaks have on the microclimate is not evenly distributed throughout the field. The longer the distance from the windbreak the less effect it has on the microclimate. 


Patterns of microclimate and crop production

Patterns of microclimate and crop production as a result of windbreaks

Source: Marshall, J.K. (1967), 'The effect of shelter on the productivity of grasslands and field crops', Field Crop Abstracts, Vol. 20, pp 1-14. “H” stands for multiples of windbreak height.


Windbreaks are in general beneficial for crop and livestock production in a temperate climate. However, there may be some situations where windbreaks can harm crop or livestock production. Below, I am listing the main benefits and limitations of having windbreaks in your farm [1, 2, 3]. 


The benefits of windbreaks:

  • Higher concentrations of soil moisture 

  • Higher daytime air-temperatures and lower evening air-temperatures

  • Higher soil temperatures

  • Higher relative humidity during the day

  • Significant reductions in evapotranspiration

  • Significant reductions in wind speed

  • Habitat for beneficiary organisms & increased biodiversity

Negative side-effects to the areas adjacent to the windbreaks - often within 1H of the windbreak:

  • Shading

  • Higher competition for water and nutrients with the roots of the trees 

  • Reduction in rainfall reaching the ground due to interception by the trees

Be mindful about the following aspects:

  • Fungi thrives in humid environments. Too little airflow can create a more humid environment that increases the risk for fungal diseases.

  • Windbreaks may create a beneficial environment for damaging organisms, such as certain insect species, certain bird species, or damaging fungi.

  • Windbreaks should not block cold air flowing downhill, thereby increasing the risk for frost.

  • Windbreaks will remove some land from production.

  • Windbreaks will require intensive management in the early years and a slow return on investment.


3. How do these effects affect your crop yields?  


After reading all the information above you may be wondering… so, what does this mean in practical terms? How will these effects affect my current production?


To begin with, we should be aware that the shading, the interception of rainfall, and the competition for water and nutrients will most likely negatively affect the yield of the crops in the area closest to the windbreaks, which is approximately within 0 - 1 H on both sides of the windbreak (see figure below). The rest of your field that gets wind protection and isn't too close to the windbreaks will experience the positive effects listed above. The area that will experience most of the positive effects is the leeward area that is approximately between 1-10 H of your windbreak (as seen in the figure below). Additionally, you can also expect your yields to increase in the windward side of -1 to - 5 H and in the leeward side area of 10 - 15 H, even though these increases in yields won´t be as significant as for the leeward area between 1-10 H. To sum up, you should expect the total yield of your crops to be higher with windbreaks in most cases, even when taking its negative side-effects into consideration. 



Crop field response for a field windbreak


Typical crop response to a windbreak

Source: Osorio, R. J. (2018), GIS approach to estimate windbreak crop yield effects in Kansas–Nebraska [3].


Another important aspect you should take into consideration when planning for a windbreak is to know how much your specific crops or livestock will benefit from wind protection. Not all crops benefit equally as much from wind protection. In order to calculate the expected yield increases for your specific crop, you should look for scientific studies that analyze the yield increases of your crop when they get protection from the wind. Below, I am attaching a table with the best information I could find on the yield increases of different crops with wind protection (table 1).


Yield increase of different crop species with wind protection

Different crop yield increases due to windbreaks

Source: Data from Bagley (1964), Baldwin (1988), Brandle et al. (2009), Norton (1988), Kort (1988), and Osorio et al. (2018) [4 - 9].


As you can see in the table above, some crops are more sensitive to wind than others (table 1). In general, one can say that fruit, nuts and berries are the agricultural crops that benefit most from wind protection. The creation of a more stable microclimate is especially beneficial during flowering and fruit development. Additionally, reduced wind speeds can improve pollination and minimize damage to delicate fruit and reduce fruit drop. Vegetables are the second group of agricultural crops that benefit most from windbreaks, particularly those with large and vulnerable fruits. Cereals, root vegetables and legumes are the third group of agricultural crops that benefit from windbreaks. These crops are in general less vulnerable to wind damage and exposure. Nonetheless, you should be aware that this classification is a broad generalization. In the table above, you can see for example that millet is more sensitive to wind than plums or raspberries (table 1).


You can calculate how much your yields will increase or decrease by establishing windbreaks by doing the following calculation:


  1. Write down how much percentage (%) of your productive land you will lose due to the establishment of windbreaks.

  2. Multiply the rest of your productive land by the increase in yields shown in the table above (table 2).

  3. Compare your current production to step nr 2 to see how much higher or lower your yields will be with wind protection.


For example, a reasonable scenario would be to plant a 10m thick windbreak every 200m. This means you would reduce your crop production area by 5%. To maintain previous productivity you need to aim for a 5% increase in yields. In other words, even if you “lose” 5% of your productive area, you should expect your yields to be higher with any crop listed in the table above, even with the ones which experience the least benefit with wind protection.


What is mind-blowing is that the benefits listed above do not even take into consideration that your windbreaks will also provide a variety of ecosystem services such as reduced wind erosion, improvements in insect biodiversity, reduced nutrient run-off, etc.



4. How do these effects affect your livestock yields?  


Windbreaks can be very beneficial for your livestock as well. By protecting your livestock from the wind you will reduce the cold stress they are exposed to. Reducing their cold stress will have several positive effects on their health and their stress levels. This is beneficial both in terms of animal welfare and increased productivity. Studies have demonstrated that sheltered areas can increase dairy milk production by 17%, and increase sheeps live weight by 10-21% [10]. Windbreaks can also significantly decrease livestock mortality rates at birth or in extreme weather conditions. Trials in south/east Australia demonstrated that losses of newborn lambs were reduced by 50% where there was effective shelter in place [10]. Another study in New Zealand showed that wind protection decreased twin mortality by 14 - 37% and overall mortality by 10% [10]. Shelter also reduces the risk of ewe mastitis [10]. Additionally, livestock need substantially more energy to maintain their health in exposed conditions. Sheltered animals use less energy to maintain their core body temperature than those without wind protection, resulting in lower feed costs.


As you can imagine, calculating the increase in yields when livestock are being protected from the wind is not as straightforward as with crops. Animals can move around the field to find the most sheltered areas and they can also find shelter within themselves, which complicates the wind exposure calculations. Additionally, in order to estimate your improved profitability, you will need to calculate the reduction in feed costs and the reduction in livestock mortality. However, you can still make good estimations on how much your livestock is being affected by the wind and how much you can save in feed costs with windbreaks. Below, I explain this in more detai.


To begin with, it is important for you to understand what “wind chill” is and how it affects your livestock. “Wind chill” is the effective air temperature that animals experience as a result of both the actual air temperature and the wind (see table 2 below). When wind speed increases, a greater amount of heat is lost from the animal to the environment. 



Table 2. Wind chill temperatures based on air temperature and wind speed


Table showing the wind chill effect

Source: Adapted from the United States National Weather Center (https://www.weather.gov/)


Different animal species and breeds have different tolerance levels to cold stress (see table 3 below). Animals with thicker or more insulating fur/coats, as well as those with increased metabolic rates, will be more tolerant to cold stress. Sheeps or goats will be more tolerant to wind exposure than pigs or chicken, for example. Cattle with winter coats will also be more tolerant to cold exposure than cattle with summer coats (see table 3 below).


The more tolerant an animal is to cold stress, the lower their “lower critical temperature” (LCT) will be (see table 3 below). The “lower critical temperature” (LCT) refers to the effective temperature below which an animal must increase its metabolic rate to maintain a constant body temperature. In other words, when the effective air temperature is below the LCT, animals experience cold stress and they will need extra energy, in form of feed or energy reserves (body fat), in order to maintain their core body temperature.



The lower critical temperature of different cattle breeds 


Table showing the lower critical temperature of different cattle breeds

Source: Adapted from Ames, D.R. 1978. The concept of adjusting energy level in maintenance rations for cold weather [11].


Table 4 below shows the percentage increase in maintenance energy requirements for cattle per °F degree below the LCT. By using table 2-4 you will be able to know how much your livestock is affected by wind chill and how much feed costs you can save by providing wind protection. Below, I show you how to calculate the feed needs of your livestock (maintenance energy requirements) with and without shelter:


Table 4. Percentage increase in maintenance energy requirements for cattle per °F degree below Lower Critical Temperature


Table showing how much energy different cattle breeds need to expend per Fahrenheit degree of coldness

Source: Adapted from Simms, D.D. 2009. Feeding the Beef Cowherd for Maximum Profit [12]


Maintenance energy requirements = (Effective air temperature (windchill) - Lower Critical Temperature) x Percentage increase in maintenance energy per degree of coldness (for your livestocks breed and weight)


For example, a 1000-pound (~450kg) animal, with its winter coat, has a lower critical temperature of 32 °F (0°C) (Table 3) and requires 1.1 percent more feed per °F degree of cold (Table 4). If the temperature is 10 °F (-12°C) and the wind speed is 10 mph (16 km/h), the windchill temperature would be - 9 °F (-23°C) (Table 2). By following the formula above, you will realize that in this case your livestock would need 45% more feed. 


If your livestock would be protected by a windbreak providing a 70 percent reduction in wind speed, the windchill factor would change from -9°F (-23°C) degrees to +2°F (-17°C) . The difference between the “effective air temperature” and the “lower critical temperature” would thus be 30°F. This would result in an increased feed requirement of only 33 percent, which saves you 12% costs in feed. Colder temperatures or higher wind speeds would result in larger savings due to windbreak protection.


5. Conclusion


To summarize, windbreaks can be a great tool to improve your current farming practice. Windbreaks can be used for multiple purposes and they can provide many beneficial effects to your land. Many scientific studies have been done in order to analyze the increase in yield for several crops and animal species. You can use the information provided by these studies to get a good estimate of how much your farm can benefit from windbreaks. 


The increases in yield shown in this blog post are very significant for most crop and livestock species. This means that establishing windbreaks is a smart economic decision in most cases. You should outweigh yourself, if the expected benefits make up for the land that will be lost from production, the money you will have to invest, and the time you will put into its management. As mentioned in the beginning of this blog post, windbreaks are the type of agroforestry systems that will require less management time and investments. Therefore, windbreaks should be a great option for you if you are concerned about your time and money.


If you want to make a more nuanced analysis for yourself or if I didn't present any information on your specific crop or livestock species, then you can do your own analysis by following these steps: 


1) Look for scientific studies that analyze the effect that windbreaks have on your specific crop or livestock species. 

2) Preferably, look for studies that are also analyzing the specific crop cultivar or livestock breed you have in your farm. 

3) Try to look for studies that are analyzing your crop or livestock in a climate similar to yours. 


-> A free search engine that will allow you to do this is Google Scholar.


There are also software programs that can help you make these calculations even more accurately. They can take into account even more specific factors in the equation, such as your soil type, the tree species in your windbreaks, and the weather conditions in your farm. Two organizations that offer these software programs are Regenfarmer and Propagate. They can even help you design your agroforestry system, propose different tree and bush species, and make predictions for your future income!


In future blog posts, I will be covering the topic of “how to design windbreaks for more productivity and biodiversity, and how to do this in a cost-effective way?”. I will also cover the topic of economic calculations with windbreaks in more detail.


Comment below on what are your experiences with windbreaks. Do you have any experiences, insights or scientific papers you want to share?



References:

[1] Smith, M. et. al. (2021) Windbreaks in the United States: A systematic review of producer-reported benefits, challenges, management activities and drivers of adoption.


[2] Marshall, J.K. (1967), 'The effect of shelter on the productivity of grasslands and field crops', Field Crop Abstracts, Vol. 20, pp 1-14.


[3] Osorio, R. J. (2018), GIS approach to estimate windbreak crop yield effects in Kansas–Nebraska


[4] Bagley, W. T. (1964). Responses of tomatoes and beans to windbreak shelter. J. Soil Water Conserv, 19(2), 71-73.


[5] Baldwin, C. S. (1988). 10. The influence of field windbreaks on vegetable and specialty crops. Agriculture, Ecosystems & Environment, 22, 191-203.


[6] Brandle et al., (2009) Windbreak practices. P. 75-104


[7] Norton, R. L. (1988). 11. Windbreaks: Benefits to orchard and vineyard crops. Agriculture, Ecosystems & Environment, 22, 205-213.


[8] Kort, J. (1988). 9. Benefits of windbreaks to field and forage crops. Agriculture, Ecosystems & Environment, 22, 165-190.


[9] Osorio, R. J., Barden, C. J., & Ciampitti, I. A. (2019). GIS approach to estimate windbreak crop yield effects in Kansas–Nebraska. Agroforestry Systems, 93, 1567-1576.


[10] The Agroforestry Handbook: Agroforestry for the UK 1st Edition (2019) https://www.soilassociation.org/media/19141/the-agroforestry-handbook.pdf#page=143&zoom=100,0,0 


[11] Ames, D.R. (1978). The concept of adjusting energy level in maintenance rations for cold weather. Cattlemen’s Day Report. pp. 94-97. Kansas State University, Manhattan, KS


[12] Simms, D.D. (2009). Feeding the Beef Cowherd for Maximum Profit. SMS Publishing, Amarillo, TX.



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