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  <div class="title"><h3>5.32 -Drought Tolerant Bean Varieties (Phaseolus vulgaris) Utilized to Overcome the Negative Effects of Climate Change </h3><br><h3 class="ch-owner">Jordan Candido, University of Guelph, Canada </h3></div>
  <div class="title"><h3>5.32 -Morning Dew Collection on Terrace Walls to Mitigate Climate Change </h3><br><h3 class="ch-owner">Karleigh Litt, University of Guelph, Canada </h3></div>
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<p>Suggested citation for this chapter.</p>
<p>Suggested citation for this chapter.</p>
<p>Candido,J. (2022) Drought Tolerant Bean Varieties (Phaseolus vulgaris) Utilized to Overcome the Negative Effects of Climate Change, In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org</p>
<p> Litt,K. (2022) Morning Dew Collection on Terrace Walls to Mitigate Climate Change , In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org</p>
       <h3 class="title-bg">Background</h3>
       <h3 class="title-bg">Background: Regions Where Terrace Wall Collection Would be Useful</h3>
         <div class="cont-bg">
         <div class="cont-bg">
           <p>During the formation of the International Centre for Tropical Agriculture, or CIAT, in 1967, headquartered in Colombia, the vast majority of starving and malnourished people residing in tropical and sub-tropical regions were smallholder farmers (CIAT, 2017). Thus, the goal of increasing yield potential became a primary priority for CIAT (CIAT, 2017). The current areas of concern are in regard to common bean (Phaseolus vulgaris) production systems, the landscapes where its production occurs, and its yield potential (CIAT, 2015). Millions of farmers within Africa and Latin America depend on high yield outcomes from their bean crops not only to provide food but also to provide an income for themselves and their families. However, due to the high demand of the crop and the drastic effects of climate change, farmers continue to struggle to meet the needs of consumers (CIAT, 2015).</p>  
           <p>It is estimated that there are 300 million people globally that rely on terrace farming (Kidron 2000).  Tens of millions of smallholder terrace farmers are located in the dry subtropics, and they are increasingly susceptible to droughts associated with climate change (Chapagain and Raizada, 2017). An innovation that can combat climate change is a terrace wall dew collection system scaled for smallholder subsistence farmers. Farmers can place a low-cost polytetrafluoroethylene lining sheet on terrace walls that will collect atmospheric vapor and transform it into a potable liquid form for boiling (Takena, 2003). Farmers can also use the more low-labor approach of placing slow growing crops directly against the wall for the condensate to seep into the soil (Chapagain and Raizada, 2017). The target regions for this innovation have an extended dry season and lack of rainfall, increasing chances of drought, like East Africa, Yemen, Central America, Nepal, and India. This innovation will be a low-labor and low-cost alternative source of water for subsistence farmers, livestock and slow growing crops on terraces.</p>
<p>The occurrence of dew collection relies on a few different factors, first of which is capitalizing on fog, uphill nearby locations, and daily temperature. Morning dew is a natural process that happens through the formation of water vapor as the hot daytime temperatures cool down at night – which is typical in drylands and desert environments. Wind speed, air pressure and humidity are factors that create the formation of morning dew. When the maximum vapor pressure is reached in the atmosphere from the temperature transition, the air become full of water molecules that will connect with a hydrophobic surface to create a liquid (Josh and Paini, 2010).</p>  
<p>Throughout the previous several decades, the impacts of climate change have been worsening (IFPRI, 2009). Climate change projections state that regions in Sub-Saharan Africa, Latin America, and the Caribbean will be greatly affected by an increase of drought conditions and a rise in average annual temperatures. Due to these conditions, the threats to agricultural production within these land areas are escalating (IFPRI, 2009). Within these regions, the common bean is a staple crop; beans are often referred to as “the meat of the poor” (CIAT, 2016). They contain high levels of protein, fibre, vitamins and micronutrients. An estimated 400 million people residing in the tropics consume beans in their daily diet due to their high nutritional content (CIAT, 2016).</p>  
<p>Dew formation is dependent on the amount of humidity in the air. If temperatures remain relatively constant, times of the day when dew formation occurs can be predicted. Examined through the climates of distinct habitats in the Negev Highlands of Israel, clear mornings had collected greater amounts of morning dew, rather than windy and cloudy mornings (Josh and Paini, 2010). Continuous condensation in this climate creates continuous dew formation from sundown to after sunrise. Paired with the north and west facing habitats blocked form high winds, and the hilltop location of Negev, demonstrated an ideal climate and location for a terrace wall morning collection system.</p>
</p>
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       <h3 class="title-bg">Benefits of Drought Tolerant Bean Varieties to Small Scale Farmers </h3>
       <h3 class="title-bg">Operation of the Terrace Wall Dew Collection System: Synthetic sheets or rock alternatives </h3>
         <div class="cont-bg">  
         <div class="cont-bg">
 
<p>It is important to undertake this practice in locations with cool nights and humidity which are needed for dew formation (Jin and Wang, 2017). Once a location is found close to the subsistence farmer, the next step is to introduce a collection surface. According to the Journal of Hydrology, an ideal material for dew collection would be a sheet of polytetrafluoroethylene foil, which is a low-cost hydrophobic material to which water does not adhere but rather beads and drips down (Takenanka, 2003). The challenge is obtaining this material. The sheets can be bought from the international online retail site, Alibaba.com, costing $14.40 US dollars per 24 rolls of 25 square feet. The polytetrafluoroethylene foil is easily mouldable and ideal for shaping on the terraces, but they are recommended to be protected against harsh weather. Due to the lack of durability of the sheets they will need to be replaced often if experiencing high winds and sand. This particular hydrophobic surface would bring in higher yield of water short term but suffer from long term damage that can be costly to a subsistence farmer. These materials would not be the easily accessible for subsistence farmers without the help of an aid or government organization.</p>  
<p>The world’s largest and most diverse collection of beans is preserved by CIAT (CIAT, 2015). Beans were domesticated within the neo-tropics thousands of years ago, which is where the majority of CIAT’s germplasm originated. With such an extensive range of beans available, the seed bank contains many options for farmers; a variety of colours, nutritional content, and production requirements can be found within these different strains (CIAT, 2015).</p>
<p>An easily accessible and efficient alternative to a hydrophobic surface on a terrace wall are porous rocks (Agnoletti, 2012). Rocks have a natural hydrophobic surface, aside from a small initial absorption of the first wetting. The concept of dew collection from porous rocks has been traditionally practiced on the island of Pantelleria, a volcanic island in the Mediterranean (Agnoletti, 2012). The volcanic presence on the island creates a large access to porous, stone materials for terrace walls which increases the surface area and crevices for dew collection. Many terrace walls around the world are already reinforced using rocks, so the only innovation here is to switch to more porous rocks.</p>
<p>Once the landscapes are established, the smallholder farmer can proceed to place crops on the steps of the terrace against the walls for overnight dew formation. If the plants are planted so that the soil is directly against the hydrophobic surface, the liquid vapor will trickle into the soil and provide water for those plants (Agnoletti, 2012). In terms of collecting the morning dew from the hydrophobic surfaces, the farmer should plant the crops such as slow growing fruit trees directly against the terrace wall so the dew is directly beneficial. Creating a trench in the soil closer to the wall could potentially promote collection of the dew water as it drips. Therefore, the labor involved with this system diminishes greatly once the initial setup is complete. The terrace wall dew collection system essentially creates a low labor irrigation system for plants that thrive in large dew forming conditions for moist soil, an ideal concept for a hot and dry subtropical climate endangered with drought.</p>
<p>Within the previous 15 years, researchers at the Consortium of International Agricultural Research Centres (CGIAR), CIAT’s umbrella organization, have created incredible advances towards solving issues surrounding drought, and increasing the heat-tolerance and nutritional content levels within common bean varieties (CIAT, 2015). CIAT researchers have been able to identify lines that display a tolerance to a 3˚C increase in temperature. These lines derive from a variety of crosses between common and tepary bean species (Phaseolus acutifolius). Currently cultivated traditional bean varieties have been projected to suffer a 20-50% loss by 2050, whereas heat-tolerant bred beans are projected to suffer minimal losses within that same time period (CIAT, 2015).</p>
</div>
 
<p>In order for the new bean varieties to have drought resistant qualities, different traits from different genetic groups were required (Beebe, 2014). Many of the traits which are linked to drought resistance were found within both bean roots and shoots. In order to guarantee a higher success rate of the bean plant, a lengthy root system was required. Additionally, early maturation of the bean crops was a common tactic to combat drought tolerance. A total of 36 genotypes were tested in 2009 during a growing season with significant drought stress. Table 1 shows the field trial results of 5 genotypes grown under different field conditions (Beebe, 2014).</P>
 
<p>Table 1. Drought associated traits associated with improved bean genotypes </p>
[[File:Capture 672.JPG]]
<p>The crops were managed by the irrigation systems for up to 25 days following planting. In order to induce drought stress, the crops were fed a total of 105 mm of water initially followed by an allotted amount of 59 mm of rainwater. An analysis of these trials recommended that the most elite drought tolerant lines expressed heightened stomatal control of transpiration and contained Mexican genetics (Beebe, 2014).</p>
 
<p>Since 1996, The Pan-Africa Bean Research Alliance (PABRA) has released over 550 new drought resistant bean varieties to many of the countries within Africa in co-ordination with assistance from CIAT (CIAT, 2016). Utilizing germplasm available, the new varieties of beans (known as BIO101 and BIO107) contain 60% more iron and 50% more zinc than those of traditional bean crops. Following the creation of these specially bred beans, a trial with pregnant and young women in Rwanda discovered that the new varieties of beans reduced iron-deficiency and increased immune system strength in each of the women (CIAT, 2016). With these new advances, PABRA will assist future production by making the crops more resilient to climate change threats while simultaneously targeting direct effects on the human population (CIAT, 2015).</p>
 
<p>The regions within Latin America, Oceania and Sub-Saharan Africa contain the highest percentage of women participating in the agricultural sector. It is within these regions that 60% of the total agricultural production is completed by women (Huyer, 2016). In the world’s least developed regions, 79% of the women contributing to their national economy report that they work in the agriculture sector (Huyer, 2016). When women engage in the agricultural production (with new technologies such as heat-tolerant bean varieties) it creates a sense of empowerment and thus builds essential assets, which the women are then able to use in all other aspects of their lives (Muriel, 2019). With the climate change innovations available within common bean variety crops, female farmers are considered to be important influences (Huyer, 2016). When the women’s knowledge of available innovative resources and access to information increases, it establishes an increase in food supply as well as a more resilient community. Likewise, an attempt is made to close the gender gap, thus providing a higher chance for equal opportunities between both men and women (Huyer, 2016), which would in turn help to positively shape the future of those regions affected.</p>  
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       <h3 class="title-bg">Gender Issues Associated with Production of Drought Tolerant Bean Varieties </h3>
       <h3 class="title-bg">Steps to Guide a Subsistence Farmer </h3>
         <div class="cont-bg">
         <div class="cont-bg">
<p>If the farmers, though especially female farmers, are not able to utilize and benefit from these new seed varieties, the food supply decreases and the gender gap increases, which diminishes the resiliency of the community (Huyer, 2016). Additionally, since very little information is available with regards to how poor regions with higher gender discrepancy respond to the threats and impacts of climate change within agricultural production, it is difficult to forecast results for future decades (Huyer, 2016).</p>
<p>1. The small-scale farmer will locate terrace walls which already drip water from dew.
<p>2. Then they will use the hydrophobic surface chosen and line the terrace walls. Stacking porous stones or propping up foil.
<p>3. If the farmer chooses to gather the dew themselves, the sheets should be left overnight, and dew is expected to form 30 minutes before sunrise. This method would require the collection of dew from the surface before the sun rises. The alternative would be to plant the crops/plants directly against the hydrophobic surface so the dew can run down into the soil directly.<p>
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       <h3 class="title-bg">Production of Drought Tolerant Beans (Phaseolus Vulgaris) in Arid Regions </h3>
       <h3 class="title-bg">Benefits of Combining Dew Collection with Annual Himalayan Plants</h3>
         <div class="cont-bg">
         <div class="cont-bg">
<p>It is necessary that farmers are equipped with all of the relevant information required to achieve the highest quality results from their newly adapted bean varieties (PABRA, 2016). Becoming knowledgeable about land preparation, crop management and harvesting is vital to ensuring success within production systems. Integrated crop management (ICM) is a holistic approach utilized by PABRA that assists farmers throughout their cultivation. The desired outcome from ICM is to give smallholder farmers access to cost-effective, climate change resistant crops. This is achieved by working with many international partners. Multiple techniques exist within ICM such as pest management, soil quality, planting and intercropping. With such techniques, approximately six million farmers have been able to improve their bean yields. The ICM research encompasses a variety of areas:</p>
<p>There are large numbers of terrace farmers in the Himalayas. The subtropical Himalayas presents heavy dew formation from the months of October to February, resulting in plants that have adapted to the lengthy periods of dew they are used to growing in (Josh and Paini, 2010). Large amounts of exposure to dew formation can negatively affect a plant’s transpiration rates, photosynthetic rates, and efficient use of water. Local plants derived from the Himalayan regions would be ideal to combine with terrace dew collection systems. For example, the perennial plant Optiva, a small tree that can be used for wood and fuel, reacts well to high dew forming growing conditions. It stands out as having a small reduction in photosynthetic rate and transpiration rate (Josh and Paini, 2010). As well as being a high fibre plant for fuel, Optiva is highly digestible and makes a preferred feed for livestock. This would be a substantial resource for subsistence farmers, because they can use it for cooking, heating, feeding, and resale for family income. This Himalayan plant represents an opportunity on cool mountains and hillsides to effectively use the collection of morning dew (Pant et al, 2018). Similarly adapted plants may exist in other mountainous regions of the world.</p>  
<p>-    Cropping systems: Assessing the different varieties of beans while comparing the benefits of intercropping and rotation.</p> 
</div>
<p>-    Inputs: Evaluating the varieties of fertilisers available which are best suitable for the farmer’s chosen bean variety.</p>
<p>-    Water Management: In order to combat the negative effects of climate change and drought, improved practices regarding irrigation and water conservation are fundamental. </p>
<p>-    Soil Fertility: By working with the technologies available within the private sector, this promotes biological nitrogen fixation capabilities which increases yield potential.</p> 
<p>-    Pest and Disease Management: Bean varieties are frequently affected by an array of pests and diseases which have very negative effects on crop yields. PABRA analyses integrated pest management systems with utilization of both biological and chemical methods (PABRA, 2016).</p>  
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       <h3 class="title-bg">Helpful Links to Get Started </h3>
       <h3 class="title-bg">Helpful Links to Get Started </h3>
         <div class="cont-bg">
         <div class="cont-bg">
<p>Resource for Requesting Seeds:</p>
<p>The materials needed for this terrace wall system can be purchased on international trade websites Alibaba.com: https://www.alibaba.com/product-detail/Pure-tin-foil-ptfe-reusable-non_62204925724.html?spm=a2700.galleryofferlist.0.0.78b9617eMQsJnN&s=p
<p>https://genebank.ciat.cgiar.org/genebank/inforequestmaterial.do</p>
  and Indiamart.com: https://www.indiamart.com/proddetail/aluminum-foil-tape-15368158212.html.</p>  
<p>CIAT innovations on heat-tolerant beans:</p>
 
<p>https://blog.ciat.cgiar.org/heat-tolerant-wild-beans-tapped-to-breed-commercial-beans-for-hotter-climates/</p>
<p>The following article from Frontiers in Plant Science Agroecology will be useful to understanding the general challenges and opportunities of terrace agriculture: https://www.frontiersin.org/articles/10.3389/fpls.2017.00331/full</p>
<p>What is ‘Seed Security’?</p>
 
<p>https://www.youtube.com/watch?v=xvqSaw49wnE</p>
<p>To educate terrace farmers on the process of dew collection and inexpensive enhancements on the procedure that has been previously discussed, refer to this short video accessible through Youtube.com : https://youtu.be/ajbodAFqNbA</p>
<p>Agricultural Business Skills for seed-producers:</p>
<p>https://cgspace.cgiar.org/bitstream/handle/10568/54569/handbook_3_english.pdf</p>
<p>Crop Management:</p>
<p>https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/newsroom/features/?&cid=nrcs143_023350</p>
<p>Smallholder Farmers Stories Who Have Adopted Drought Tolerant Bean Varieties:</p>
<p>https://www.youtube.com/watch?v=O2UqFbnOc6U</p>
<p>https://www.youtube.com/watch?v=x3D3DiZ4I-8</p>
<p>https://www.youtube.com/watch?v=Qd4RS66FMJM&t=8s</p>
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       <h3 class="title-bg">References </h3>
       <h3 class="title-bg">References </h3>
         <div class="cont-bg">
         <div class="cont-bg">
 
<p>1. Agnoletti, M. (2012) Italian Historical Rural Landscapes (page 522), Springer.</p>
<p>1. Beebe, S.E., et al. (2014) Common beans, biodiversity, and multiple stresses:  
<p>2. Jin, Y., Zhang, L., & Wang, P. (2017). Atmospheric Water Harvesting: Role of Surface </p>
a. challenges of drought resistance in tropical soils. Crop and Pasture Science 65, 667-675. Retrieved from https://www.publish.csiro.au/cp/cp13303</p>
<p>3. Wettability and Edge Effect. Global Challenges, 1(4), 1700019. doi:
<p>2. Buruchara, R. (2011). Development and Delivery of Bean Varieties in Africa: The Pan-
10.1002/gch2.201700019</p>
a. African Bean Research Alliance (PABRA) Model, p.227-245. African Crop Science Journal. Retrieved from https://www.ajol.info/index.php/acsj/article/view/74168/64827</p>
<p>4. Chapagain T and Raizada MN (2017) Agronomic Challenges and Opportunities for Smallholder </p>
<p>3. Huyer, S, et al. (2016). CCAFS Gender and Social Inclusion Strategy, p.8-11. The
<p>5. Terrace Agriculture in Developing Countries. Front. Plant Sci. 8:331.
a. Consortium of International Agricultural Research Centres. Retrieved from https://cgspace.cgiar.org/handle/10568/72900</p>
doi:10.3389/fpls.2017.00331</p>
<p>4. International Food Policy Research Institute (IFPRI). (2009). Climate Change: Impact
<p>6. Josh, S.C. and Paini, L.M.S. (2010) Is dew useful for Himalayan plants? Current Science 99,  
a. on Agriculture and Costs of Adaptation. Retrieved from https://books.google.ca/books?hl=en&lr=&id=1Vpe0JvYTJYC&oi=fnd&pg=PR7&ots=Xmu2c8Swla&sig=GX4sDC1DiDa7I5408r0a3nz2sJo&redir_esc=y#v=onepage&q&f=false</p>
1434-1437.</p>
<p>5. Muriel, J., et al. (2019). The Abbreviated Women’s Empowerment in Agriculture Index
<p>7. Khahil, B. et al. (2016) A review: dew water collection from radiative passive collectors to
a. (A-WEIA). Project Results for ‘His and Hers, Time and Income: How Intra Household Dynamics Impact Nutrition in Agricultural Households’. The International Centre for Tropical Agriculture. Retrieved from https://cgspace.cgiar.org/handle/10568/101141</p>
recent developments of active collectors. Sustainable Water Resources Management 2,71-86</p>
<p>6. The International Centre for Tropical Agriculture (CIAT). (2015). Developing Beans that
<p>8. Kidron, G.J. (2000) Analysis of dew precipitation in three habitats within a small arid drainage</p>
a. Can Beat the Heat. The Consortium of International Agricultural Research Centres. Retrieved from https://ciat-library.ciat.cgiar.org/articulos_ciat/biblioteca/DEVELOPING_BEANS_THAT_CAN_BEAT_THE_HEAT_lowres%20(2).pdf</p>
<p>9. basin, Negev Highlands, Israel. Atmospheric Research 55, 257-270.</p>
<p>7. The International Centre for Tropical Agriculture (CIAT). (2016). Beans. Retrieved from  
<p>10. Lekouch, I. et al. (2010, May 4). Dew, fog, and rain as supplementary sources of water in south-
a. https://ciat.cgiar.org/what-we-do/breeding-better-crops/beans/.</p>
western Morocco. Energy, 36(4), 2257-2265. Retrieved October 3, 2019, from  
<p>8. The International Centre for Tropical Agriculture (CIAT). (2017). Fifty Years and Fifty
    https://www.sciencedirect.com/science/article/pii/S0360544210001362.</p>
a. Wins, p.4-18. The Consortium of International Agricultural Research Centres. Retrieved from https://cgspace.cgiar.org/bitstream/handle/10568/89145/50_WINS_WEB02.pdf?sequence=1&isAllowed=y</p>
<p>11. Pant, G.B., Pradeep Kumar, P., Revadekar, J.V., Singh, N. (2018) Climate Change in the
Himalayas, Springer Publishing.</p>
<p>12. Muselli, M. (2009) Dew and Rain Water Collection in the Dalmatian Coast, Croatia.</p>
<p>13. Atmospheric Research, 92(4), 455-46. Retrieved from  
https://www.sciencedirect.com/science/article/pii/S0169809509000209.</p>
<p>14. Tarolli, P. (2014) Terraced Landscapes: From an Old Best Practice to Potential Hazard for Soil </p>
<p>15. Degradation Due to Land Abandonment. Anthropocene, 6, 10-25. Retrieved from  
https://www.sciencedirect.com/science/article/pii/S2213305414000113</p>
<p>16. Takenaka, N. (2003). Difference in Amounts and Composition of Dew from Different Types of
Dew Collectors. Graduate School of Engineering, Osaka Prefecture University, 147(1-4), </p>
<p>17. 51-60. Retrieved from https://link.springer.com/content/pdf/10.1023/A:1024573405792.pdf</p>
<p>18. Werby, Christopher. (2011) DRIPS Dew Collection Project Video. Retrieved from  
https://youtu.be/ajbodAFqNbA</p>  
<p>19. XiChena, & YinYipab, N. (2019, June 20). Low-temperature heat utilization with vapor </p>
<p>20. pressure-driven osmosis: Impact of membrane properties on mass and heat transfer Journal of Membrane Science, 588 (1-2) Retrieved October 3, 2019, from  
https://www.sciencedirect.com/science/article/pii/S0376738819307240</p>

Revision as of 23:05, 1 July 2022

5.32 -Morning Dew Collection on Terrace Walls to Mitigate Climate Change


Karleigh Litt, University of Guelph, Canada

4.jpg

Suggested citation for this chapter.

Litt,K. (2022) Morning Dew Collection on Terrace Walls to Mitigate Climate Change , In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org

Background: Regions Where Terrace Wall Collection Would be Useful

It is estimated that there are 300 million people globally that rely on terrace farming (Kidron 2000). Tens of millions of smallholder terrace farmers are located in the dry subtropics, and they are increasingly susceptible to droughts associated with climate change (Chapagain and Raizada, 2017). An innovation that can combat climate change is a terrace wall dew collection system scaled for smallholder subsistence farmers. Farmers can place a low-cost polytetrafluoroethylene lining sheet on terrace walls that will collect atmospheric vapor and transform it into a potable liquid form for boiling (Takena, 2003). Farmers can also use the more low-labor approach of placing slow growing crops directly against the wall for the condensate to seep into the soil (Chapagain and Raizada, 2017). The target regions for this innovation have an extended dry season and lack of rainfall, increasing chances of drought, like East Africa, Yemen, Central America, Nepal, and India. This innovation will be a low-labor and low-cost alternative source of water for subsistence farmers, livestock and slow growing crops on terraces.

The occurrence of dew collection relies on a few different factors, first of which is capitalizing on fog, uphill nearby locations, and daily temperature. Morning dew is a natural process that happens through the formation of water vapor as the hot daytime temperatures cool down at night – which is typical in drylands and desert environments. Wind speed, air pressure and humidity are factors that create the formation of morning dew. When the maximum vapor pressure is reached in the atmosphere from the temperature transition, the air become full of water molecules that will connect with a hydrophobic surface to create a liquid (Josh and Paini, 2010).

Dew formation is dependent on the amount of humidity in the air. If temperatures remain relatively constant, times of the day when dew formation occurs can be predicted. Examined through the climates of distinct habitats in the Negev Highlands of Israel, clear mornings had collected greater amounts of morning dew, rather than windy and cloudy mornings (Josh and Paini, 2010). Continuous condensation in this climate creates continuous dew formation from sundown to after sunrise. Paired with the north and west facing habitats blocked form high winds, and the hilltop location of Negev, demonstrated an ideal climate and location for a terrace wall morning collection system.

Operation of the Terrace Wall Dew Collection System: Synthetic sheets or rock alternatives

It is important to undertake this practice in locations with cool nights and humidity which are needed for dew formation (Jin and Wang, 2017). Once a location is found close to the subsistence farmer, the next step is to introduce a collection surface. According to the Journal of Hydrology, an ideal material for dew collection would be a sheet of polytetrafluoroethylene foil, which is a low-cost hydrophobic material to which water does not adhere but rather beads and drips down (Takenanka, 2003). The challenge is obtaining this material. The sheets can be bought from the international online retail site, Alibaba.com, costing $14.40 US dollars per 24 rolls of 25 square feet. The polytetrafluoroethylene foil is easily mouldable and ideal for shaping on the terraces, but they are recommended to be protected against harsh weather. Due to the lack of durability of the sheets they will need to be replaced often if experiencing high winds and sand. This particular hydrophobic surface would bring in higher yield of water short term but suffer from long term damage that can be costly to a subsistence farmer. These materials would not be the easily accessible for subsistence farmers without the help of an aid or government organization.

An easily accessible and efficient alternative to a hydrophobic surface on a terrace wall are porous rocks (Agnoletti, 2012). Rocks have a natural hydrophobic surface, aside from a small initial absorption of the first wetting. The concept of dew collection from porous rocks has been traditionally practiced on the island of Pantelleria, a volcanic island in the Mediterranean (Agnoletti, 2012). The volcanic presence on the island creates a large access to porous, stone materials for terrace walls which increases the surface area and crevices for dew collection. Many terrace walls around the world are already reinforced using rocks, so the only innovation here is to switch to more porous rocks.

Once the landscapes are established, the smallholder farmer can proceed to place crops on the steps of the terrace against the walls for overnight dew formation. If the plants are planted so that the soil is directly against the hydrophobic surface, the liquid vapor will trickle into the soil and provide water for those plants (Agnoletti, 2012). In terms of collecting the morning dew from the hydrophobic surfaces, the farmer should plant the crops such as slow growing fruit trees directly against the terrace wall so the dew is directly beneficial. Creating a trench in the soil closer to the wall could potentially promote collection of the dew water as it drips. Therefore, the labor involved with this system diminishes greatly once the initial setup is complete. The terrace wall dew collection system essentially creates a low labor irrigation system for plants that thrive in large dew forming conditions for moist soil, an ideal concept for a hot and dry subtropical climate endangered with drought.

Steps to Guide a Subsistence Farmer

1. The small-scale farmer will locate terrace walls which already drip water from dew.

2. Then they will use the hydrophobic surface chosen and line the terrace walls. Stacking porous stones or propping up foil.

3. If the farmer chooses to gather the dew themselves, the sheets should be left overnight, and dew is expected to form 30 minutes before sunrise. This method would require the collection of dew from the surface before the sun rises. The alternative would be to plant the crops/plants directly against the hydrophobic surface so the dew can run down into the soil directly.

Benefits of Combining Dew Collection with Annual Himalayan Plants

There are large numbers of terrace farmers in the Himalayas. The subtropical Himalayas presents heavy dew formation from the months of October to February, resulting in plants that have adapted to the lengthy periods of dew they are used to growing in (Josh and Paini, 2010). Large amounts of exposure to dew formation can negatively affect a plant’s transpiration rates, photosynthetic rates, and efficient use of water. Local plants derived from the Himalayan regions would be ideal to combine with terrace dew collection systems. For example, the perennial plant Optiva, a small tree that can be used for wood and fuel, reacts well to high dew forming growing conditions. It stands out as having a small reduction in photosynthetic rate and transpiration rate (Josh and Paini, 2010). As well as being a high fibre plant for fuel, Optiva is highly digestible and makes a preferred feed for livestock. This would be a substantial resource for subsistence farmers, because they can use it for cooking, heating, feeding, and resale for family income. This Himalayan plant represents an opportunity on cool mountains and hillsides to effectively use the collection of morning dew (Pant et al, 2018). Similarly adapted plants may exist in other mountainous regions of the world.

Helpful Links to Get Started

The materials needed for this terrace wall system can be purchased on international trade websites Alibaba.com: https://www.alibaba.com/product-detail/Pure-tin-foil-ptfe-reusable-non_62204925724.html?spm=a2700.galleryofferlist.0.0.78b9617eMQsJnN&s=p and Indiamart.com: https://www.indiamart.com/proddetail/aluminum-foil-tape-15368158212.html.

The following article from Frontiers in Plant Science Agroecology will be useful to understanding the general challenges and opportunities of terrace agriculture: https://www.frontiersin.org/articles/10.3389/fpls.2017.00331/full

To educate terrace farmers on the process of dew collection and inexpensive enhancements on the procedure that has been previously discussed, refer to this short video accessible through Youtube.com : https://youtu.be/ajbodAFqNbA

References

1. Agnoletti, M. (2012) Italian Historical Rural Landscapes (page 522), Springer.

2. Jin, Y., Zhang, L., & Wang, P. (2017). Atmospheric Water Harvesting: Role of Surface

3. Wettability and Edge Effect. Global Challenges, 1(4), 1700019. doi: 10.1002/gch2.201700019

4. Chapagain T and Raizada MN (2017) Agronomic Challenges and Opportunities for Smallholder

5. Terrace Agriculture in Developing Countries. Front. Plant Sci. 8:331. doi:10.3389/fpls.2017.00331

6. Josh, S.C. and Paini, L.M.S. (2010) Is dew useful for Himalayan plants? Current Science 99, 1434-1437.

7. Khahil, B. et al. (2016) A review: dew water collection from radiative passive collectors to recent developments of active collectors. Sustainable Water Resources Management 2,71-86

8. Kidron, G.J. (2000) Analysis of dew precipitation in three habitats within a small arid drainage

9. basin, Negev Highlands, Israel. Atmospheric Research 55, 257-270.

10. Lekouch, I. et al. (2010, May 4). Dew, fog, and rain as supplementary sources of water in south- western Morocco. Energy, 36(4), 2257-2265. Retrieved October 3, 2019, from https://www.sciencedirect.com/science/article/pii/S0360544210001362.

11. Pant, G.B., Pradeep Kumar, P., Revadekar, J.V., Singh, N. (2018) Climate Change in the Himalayas, Springer Publishing.

12. Muselli, M. (2009) Dew and Rain Water Collection in the Dalmatian Coast, Croatia.

13. Atmospheric Research, 92(4), 455-46. Retrieved from https://www.sciencedirect.com/science/article/pii/S0169809509000209.

14. Tarolli, P. (2014) Terraced Landscapes: From an Old Best Practice to Potential Hazard for Soil

15. Degradation Due to Land Abandonment. Anthropocene, 6, 10-25. Retrieved from https://www.sciencedirect.com/science/article/pii/S2213305414000113

16. Takenaka, N. (2003). Difference in Amounts and Composition of Dew from Different Types of Dew Collectors. Graduate School of Engineering, Osaka Prefecture University, 147(1-4),

17. 51-60. Retrieved from https://link.springer.com/content/pdf/10.1023/A:1024573405792.pdf

18. Werby, Christopher. (2011) DRIPS Dew Collection Project Video. Retrieved from https://youtu.be/ajbodAFqNbA

19. XiChena, & YinYipab, N. (2019, June 20). Low-temperature heat utilization with vapor

20. pressure-driven osmosis: Impact of membrane properties on mass and heat transfer Journal of Membrane Science, 588 (1-2) Retrieved October 3, 2019, from https://www.sciencedirect.com/science/article/pii/S0376738819307240

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