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| Kiva Mahoney
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| Agriculture in Parras de la Fuente México
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| As you travel through the hot deserts of Northern Mexico you will happen upon a paradise blooming-up in the middle of the arid landscape. Growing out of the high desert are groves of avocados and pomegranates surrounded by a backdrop of green lush vegetation. Here lies the small town of Parras de la Fuente. Parras is unique in this region because of the large amount of underground water, which has turned it into an oasis of teeming life. Due to this water there is a lot of agriculture occurring in this area. Even though there is a vast amount of water comparatively to the surrounding area, it is still a desert and the conservation of this water is vital.
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| One of the focuses of my major is sustainable organic agriculture. Although I have a lot of knowledge in the subject for the Northern Coast of California, I do not know much about agriculture in the desert. I will be spending the summer months of 2006 in Parras with a program from HSU teaching students about Appropriate Technology and learning from the locals how they have utilized appropriate technologies for centuries. My personal emphasis while working there will be to observe the local agriculture and work directly with farmers to see what different farming practices they are applying to the desert land. Before going down to Parras I would like to gain as much knowledge about the areas as I can so I will know what to expect while I am down there. This paper examines the location of Parras, its climate conditions, soil conditions, what crops grow in the area and when they should be planted, as well as, ways of conserving water.
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| The city of Parras is an oasis, completely surrounded by desert. There is a lot of underground water that flows out of the earth from near by mountains. When this water surfaces it turns into rivers and is collected in huge pools within the city. As a result of this water there is a much wider array of plants that can be grown within the city and the agricultural production of non-xerophytes, plants that have distinct adaptations to arid lands, is more realistic. Lonny Grafman a lecturer at HSU who spent last summer in Parras says that, “The water is piped around the city and is used on an honor system. Each farmer gets to irrigate his fields twice a month or three times a month depending on what type of crop they are growing.”
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| Parras de la Fuente is located in Northern Mexico in the state of Coahuila. It is 237 KM west of Monterrey, which is the nearest large city. It is at 25º 16’ latitude and 102º 11’ longitude with an elevation of 1,520 meters above sea level. The rainy season extends between the summer months of June- September. Following is a table of the average rainfall and temperatures throughout the year in Parras.
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| Mean Temperature (ºC)
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| JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
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| 13.8 15.0 18.3 21.3 25.0 25.2 25.2 24.0 22.1 19.5 17.1 13.8
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| Monthly Rainfall (Mm)
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| JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
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| 16.4 10.0 16.7 11.3 26.6 44.3 72.3 59.4 58.0 21.1 14.8 15.5
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| Source: Comisión Nacional del Agua (National Water Commission) (CONAGUA ) 2000.
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| °C degrees centigrade.
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| *Mm. Measurement determined in millimeters.
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| Furthermore Parras is a B climate classification. There are two different B categories; one is a BW, which is arid desert and the other is a BS, which is semi-arid grasslands. According to the Municipal Profiles of Parras the climate is semi-arid. Once out of the city and away from the underground water, the climate changes to a BW arid desert. This part of the region is considered a “Hot and Dry Desert” meaning just how it sounds; it is hot and dry. The precipitation in a “Hot and Dry Desert” is very low or happens all at once in a short period of time, usually the summer, leaving the rest of the year dry. Because of this Parras also only gets rain for a few months in the summer. Due to the amount of rainfall a year and the vegetation of the surrounding regions which are a combination of grasses and xerophytes, I believe that Parras is somewhere between the two B categories. Temperatures are warm throughout the fall, winter, and spring and hot in the summers; around 25 ºC. This is also the case in town although I have been told that the temperatures in town are lower then that of the outlying area due to the greater amount of water and vegetation.
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| The vegetation is very mixed in this area. According to Grafman, “In town there are a lot of avocado trees and pomegranates, as well as, more water dependent plants. Outside of town you find plants that have developed ways to survive the heat and lack of rain, as well as annual grasses”. Most plants grow low to the ground or are woody trees. Almost all of their leaves have the ability to store water and nutrients for the long dry spells when they do not receive much rain. “Some examples of these kinds of plant are Turpentine Bush, Prickly Pears, and Brittle Bush.” FAO-SDRN-Agrometeorolgy Group.
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| The soil conditions of Parras are variable. In arid climates the soils is usually an Aridisols. This is also the case in some parts of Parras however there is some diversity of soil types. Aridisols have an alkaline soil which, “is due to the calcium carbonate content of the soil which is not leached through the soil because of…limited rainfall” The University of Arizona. They also lack good humus content because of the continuously high temperatures which increase decomposition rates of organic matter, as well as, a lack of vegetation to provide the material that would be broken down and turned into humus. A benefit to this type of soil is the lack of leaching because of the small amount of rain fall. This usually means the soil is high in mineral nutrient content. Yet when you start applying an external watering source, such as irrigation, this lack of leaching is no longer the case. When outside water is applied to these types of soils you can have a problem with salinization. As discussed by Chris Haynes in Agricultural Geography, this happens for a couple of reasons: “1) as a result of evaporation creating a white crusty layer of the surface of the soil from left over nutrients, minerals, and salts. 2) There is often a hard pan that the water does not go through a few feet under the soil surface. By constantly adding water to this area it builds up on top of this hard layer and because of the alkaline soil and water it makes a saline water table that eventually hits the roots of the plants and makes it so they can no longer grow.” It is very important when gardening in these types of soils to pay close attention to this. It is almost impossible to fix or do anything once salinization has occurred.
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| Aridisols tend to have a high mineral nutrient content which makes them very desirable for agriculture, but they can become unproductive very quickly. This is one of the main concerns when trying to garden in this area. The care and maintenance of the soil has to be thought out well and implemented without fail. One way to take care of the soil as suggested by Bill Mollison is to use, “Mulches or litter on top of the soil [which] prevents both soil cracking and the lethal effect of rapid temperature gains.”
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| In the town of Parras some of the soils could be consider a Mollisol. I have deducted this through investigation of where these soils occur in the world, as well as, talking with people who have been to Parras. The soil is described by Lonny Grafman to have, “a rich dark color with so much vegetation that you can not see the ground”. The Natural Resources Conservation Services states that, “The central concept of Mollisols is that of soils that have a dark colored surface horizon.” United States Department of Agriculture. According to Dr. Paul McDaniel, from the University of Idaho, these soils are a, “results from the long-term addition of organic materials derived from plant roots.” They have much higher levels of humus then the Aridisols and are the “the most important and productive agricultural soils in the world.” There are six different Mollisol classifications. The one that is most likely to be in Parras is an “Ustolls” which is found in “semiarid and subhumid climates”. This type of soil is found trough out the middle of the United States of America extending from Texas and into Mexico, University of Idaho Collage of Agriculture and Life Sciences. Having this type of soil greatly increases the agriculture productivity of the area. It allows for a far greater variety of crops to be grown and because of the higher humus contents it holds moisture longer then an Aridisol would even though Ustolls are some of the quickest draining Mollisols. The most important thing for the soil in an area like this is to build up the humus levels and implement water conservation techniques.
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| From Humboldt County, I have no way of determining the nutrient makeup of the soils in Parras and what they may be deficient in. Deserts usually have high mineral nutrient buildups of parent material and are fairly un-leached due to lack of rain fall, which makes them some of the most targeted agricultural lands today. According to Bill Mollison one can, “Reasonably expect phosphorus and zinc deficiency, and probably iron and manganese.” when it comes to desert soils. This is something that I will have to determine when I get down there and examine how farmers deal with nutrient deficiencies on their own lands.
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| The crops that grow well in Parras are considered warm and hot weather crops, although you can still grow cool weather crops, such as cabbages and greens. Warm and hot weather crops include corn, tomatoes, melons, peppers, basil, squashes and much more. Following is a list of vegetables and when they should be planted for the specific elevation and climate of Parras.
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| Asparagus Apr 1-30 Bean, bush May 15-Jul 1
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| Bean, pole May 15-Jul 1 Bean, Lima May 15-Jul 1
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| Bean, edible soy May 25-Jul 1 Beet May 1-Jul 15
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| Broccoli Apr 1-Jul 15 Brussels sprouts Jun 1-Jul 1
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| Cabbage (seed) Mar 15 Cabbage (plants) May 1-Jun 1
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| Cantaloupe May 15-Jun 15 Carrot May 1-Jul 15
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| Cauliflower See cabbage Celery, plants Jun 1-Jul 15
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| Chard Jul 1-Aug 1 Mar 1-Apr 10 Chinese cabbage Jun 1-Jul 15
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| Collard Jun 1-Jul 15 Corn, sweet May 25-Jul 1
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| Corn, Mex June May 25-Jun 15 Cucumber May 15-Jun 15
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| Eggplant May 15-Jun 15 Endive Apr 15-Jun 15
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| Garlic Apr (cloves) Horseradish Feb 15-Mar 15
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| Kale Feb 15-Apr 10 Kohlrabi Apr 15-May 15
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| Leek April Lettuce, head Jul 1-Aug 1 Lettuce, leaf Mar 15-Apr 15 Aug 1-Sep 15 Muskmelon May 15-Jun 15 Mustard Apr 1-Jul 1 Okra May 15-Jun 15 Onion, bunch Apr 15-May 1 Onion, dry seed Oct 15-Jan 1 Feb 15-Apr 15
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| Onion, dry sets Nov 1-Feb 1 Apr 1-15 Parsley Apr 1-15
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| Parsnip Apr 1-May 20 Pea, fall not adapted Pea, spring Feb 15-Apr 15 Pepper, seed Mar 1-Apr 1 Pepper, plants May 1-May 25 Potato, Irish May 10-Jun 1 Potato, sweet May 15-20 Pumpkin May 20-Jun 15
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| Radish Apr 1-Jun 15 Rhubarb Mar 1-Apr 1
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| Rutabaga Apr 1-May 15 Salsify Apr 1-May 15
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| Spinach Apr 1-May 15 Squash, summer May 1-Jul 1 Squash, winter May 15-Jul 1 Tomato, seed Mar 1-Apr 1 Tomato, plants May 10-Jun 1 Turnip Apr 1-May 15 Watermelon May 1-Jun 1
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| http://myweb.cableone.net/tfcox/zone5.html
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| As you can see a lot of vegetables should be started in the spring. These dates do not take into consideration the over wintering of crops, which is having some crops growing all winter long. They are specific to the summer growing season and harvest. Plants that are to be over wintered should be sown late in summer with enough time to mature before days shorten and heat subsides.
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| According to Bill Mollison’s section on desert gardening, “Deep rooting and high yielding perennials (asparagus, globe artichoke) are standby crop[s], as are drought tolerant staples such as sweet potatoes and most cucurbits and the melon family.” The plants mentioned above have their edible portions in the low and mid level range of plant height. It is good to use a layer system in gardens through which plants of different heights are grown together. By doing this more can be grown in a smaller area of land and the ground is less exposed to heat from the sun and rain damage. The top layer of the garden should consist of tall trees for shade, as well as, food. As stated by Bill Mollison, desert gardening should include, “Staple trees adapted to dry periods or able to survive on minimal water. Suggested plants could be date palms, olives, doum palm, citrus, avocados, apricots, bananas, and papayas.” These can be planted at any time of the year but should be put in when there is enough water available for them to become fully established.
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| Finally, water conservation is vital to the desert region. There are a number of ways to maximize water usage and conservation techniques that should be put into practice in the desert. One of these techniques is the collection of dew. There are a number of ways this can be done. A method used by the Hohokam Indians and mention by Bill Mollison is a “Stone Mulch”. This can be done under trees or around garden beds. “Dew [is] captured by building piles of loosely-stacked stones, where low night winds cool rock surfaces and dew can accumulate to dampen the ground below.” With this type of system, “Each mound of stones may suffice to water one tree.” This is a good way to use water that otherwise is not available for agriculture. A “Stone Mulch” is a good tool but Bill Mollison also says that, “The most efficient dew-collectors are free-standing shrubs of about 1-2 m in height.” At this level the most water can be collected at night and then utilized. In the Permacultures Designers Manual it states you can use a, “metallic mesh fences 1m or so high… as initial condensers in deserts, growing shrubs along the fence drip-line, and moving the fence on after these plants are established.” In this way you are only watering right where it is needed and the same piece of fencing can be used over and over again.
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| Another way of reducing the amount of irrigation needed is by transplanting crops, instead of directly sowing them. According to John Jeavons, “Transplanting should be done whenever possible. Space and water are conserved in this way, because seedlings in flats require less of both (as little as ½ gallon of water per day for one flat, compared to 10 to 20-plus gallons for a 100-square-foot growing bed).” Another way to start small seeds, when not done through transplants, is to lay a damp burlap bag on top of them until they sprout. Both of these methods greatly reduced the amount of water needed for germination and helps prevent seeds from drying-out.
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| There are also ways of changing the topographic structure of a field so that water is preserved. One of these methods was used by Native Americans in the southwestern states. John Jeavons says that they would, “make the growing area into large square shaped diamonds on a slight slope with one point each, being at the top and the bottom of the slope. Crops are planted at the bottom ¼ to ½ of the square…” In this setup the area where the crops are grown is deeper then the land around it, so water collects were it is most needed. This process covers a lot of square footage, but the amount of the growing area is not that large in comparison to how much land is actually being used; due to this the implementation of this system is only an option for a select few. Those that do not have a vast amount of land can use a tilted bed system. In this way, beds are built to have notches cut out of them with a slope on either side. The crops are then planted at the bottom of this slope so that rain is again collected where it is most needed.
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| Another important factor in maintaining soil moisture is having humus in the soil. How to Grow More Vegetables it states, “that soil which has living compost as 2% of its volume in the upper 11 inches of soil can reduce the rainfall or irrigation required for poor soils by as much as 75%.” This is an incredible reduction in the amount of water needed to irrigate a field. Although it is harder to maintain organic matter in desert soil due to fast decomposition, it is possible, especially in conjunction with heavy mulching processes.
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| Mulch is extremely beneficial in desert gardening for water conservation and protection of the soil. A well mulched bed protects the soil from erosion and rapid drying out. There are a number of different kinds of mulches that can be used, some of which are more readably available then others. Bill Mollison has categorizes a number of these and they are as follows:
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| DOMESTIC old skins, blankets, cotton or wool clothes, cardboard boxes, newspapers, hardboard and thin planks. All of these, soaked, can be used to line sandy pits, or tiled over the ground in raised beds before mulch is added.
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| COLLECTED ashes, bones, dog, cattle, or horse manure, kept dry or pitted in circle pits for in-ground compost. Ashes and dry herbivore manure can be shredded or pounded.
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| FINES: chaff, bark, leaves, tea leaves, coffee grounds, flood detritus, rice or grain hulls, rotten wood, sawdust. All these “fines”, and shredded paper or wood ships, are ideally combined with shredded manures, sand and ashes to fill up raised beds; these can be laid as a top or coarse mulch.
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| COARSE MULCH: Logs, twigs, dry straw, thick bark, old wood. These are used as bed edges, or a 4-6cm layer over which mixed soils and “fines” are spread to 18-20 cm thick
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| TOPPINGS: Seagrass, woodchips, pine or Casua-cosmetic layer spread over the top of the early layers.
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| As you can see some of these are more easily obtain then others. It is a good idea to incorporate growing plants that are going to be used specifically for mulch, insuring that there is a sure source of available material. Bill Mollison states, “It is always essential to build-in humus and mulch production into crops, and species used for this purpose can range from edible plants such as Dolichos, edible lupin, Leucaena, or edible-seeded Acacias, to shelter, edge, weed barrier, and hedgerow species such as Echium fastuosum, Acacia, Pemgamia and clump species such as bamboo also provide shelter and leaf mulch…” He also says that, “We must largely rely on mulch to bring down the pH of alkaline soils and to make minerals available.” Therefore, all of this mulch plays an undeniable role in the health and productivity of a desert garden and should always be incorporated.
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| The last water conservation technique and a significant component to desert gardening is the growing of plants to specifically shade a garden. The less sun that hits the ground and crops directly the less transpiration and evaporation takes place. According to John Jeavons, “Even under arid conditions, soil which is shaded can reduce evaporation up to 63%, depending on soil type.” One way he suggests to do this is by closely spacing crops so that their leaves are just touching. Jeavons also expresses, “The mini-climate from closely spaced plants provides good shading.” Further more, Bill Mollison emphasizes the need for shade when he states that, “Vines have a key role to play in desert gardens. Correctly spaced and pruned they provide both a productive crop and shade cover to mulched and watered gardens.” He also gives some examples of how this can be accomplished by building a trellis over the garden that vines can clime on. He says that, “grape vines can throw a shade system over the greater part of the vegetable garden, relieving light saturation….the sides of this trellis can also be more completely closed with herbaceous vines (beans, climbing tomatoes, yams, cucurbits). It is more important to defend from the early (eastern) sun, …and soil temperatures then remain cooler for longer periods.” The use of vines for shade is only possible to do on a small scale home vegetable garden and is not really feasible for large scale agricultural systems. However, in a larger scale system the same concepts still apply. It is good to have fields somewhat shaded, which is made possible through the use of trees. By planting them either on the edges of the field, intermixed thought out the crops, or in there own rows spread out within the field, they can produce a lot of well desired shade, as well as, another product to be sold.
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| All of the above mentioned techniques can be used on their own or in conjunction with one another. Some of these methods are much more labor intensive while others are quick easy and come with added benefits. The implementation of these is dependent on the farmer and the resources that are available to him or her. Finally, Bill Mollison expresses what the, “essentials of a desert garden [are].”
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| - Small raised flooded beds, thickly mulched.
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| - Permanent hardy trees on leach fields or in swales.
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| - Semi-wild very hardy bulbs, tubers, and yams in selected sites.
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| - Every bit of waste water directed to leach fields, also surplus from roof and run-off.
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| - Vines, their roots in cool mulch or inside shady walls, a major feature of the garden. Every wall, open space, and roof vine-shaded.
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| - Mulch. Mulch. Mulch. Mulch.”
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| In conclusion, I have found that during the time that I will be in Parras the weather will be hot and the rainy season will be in full swing. The most rain Parras gets all year is throughout the months of June, July, and August. This may make it a bit harder to determine if any of the water conserving techniques examined earlier are being implemented but because a lot of these methods are built-in for long term usage I am still hoping to witness some of them in practice. The BS climate classification fits best with the town of Parras and the surrounding region is a BW.
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| I have found that there are two different soil types in the surrounding areas of Parras. These are Aridisols and Mollisols. Aridisols are a desert soil with high mineral nutrient levels, they are alkaline, and have low humus content. Mollisols on the other hand have higher humus contents, hold more moisture then Aridisols and are much more agriculturally productive. It will be interesting to see how farmers with different soil types deal with their individual locations. The two soils have such unique properties that I assume the farming practices of each will also have great differences. I am eager to find out how this is dealt with.
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| Most of the standard vegetable crops grown in the area are to be started in mid to late May. As I will be arriving right at the tail end of the planting season it will provide me the opportunity to examine what locals routinely plant and see how they handle gardens that are further along in the developmental stage. I have found that a great variety of vegetables can be grown in the desert, as well as, xerophytes. All of the hot and warm weather crops, but also some cool weather plants.
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| The most appealing part of this paper for me was discovering techniques in which water could be conserved and best utilized in a desert situation. I discussed a wide range of options for gardening in the desert, from using stones as dew collectors to shaping the land to maximize water usage. Some of the procedures were used thousands of years ago by Native Indians and are still being used today. I am eager to discus these techniques with farmers who actually practice agriculture in the desert and see what their feelings are about them. It is good to know that there are a number of things that can be done to conserve water in the desert and that gardening, as well as, larger scale agriculture is a possibility; since our prime agricultural land is quickly being buried under suburbia.
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| References
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| Arizona Desert Gardening Guide. 2005. [http://myweb.cableone.net/tfcox/]
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| FAO-SDRN-Agrometeorolgy Group. 1997. World Climates.
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| [http://www.blueplanetbiomes.org/climate.htm]
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| Grafman, L. 2006. Personal interview. Arcata, March.
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| Haynes, C. 2006. Lecture notes. Arcata, February.
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| Jeavons, J. 1995. How to Grow More Vegetables. 5th ed. Teen Speed Press.
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| Mollison, B. 1988. Permacultur: A Designers’ Manual. 2nd ed. Tagari Publications; Reprint edition.
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| Secretaria be Fomento Economico. Coahulia. El Gobierno del la Gente. [http://servidor. seplade-coahuila.gob.mx/ohs_images/seplade/files/parrasingles.pdf]
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| The University of Arizona. 2006. Cochise County Master Gardeners. [http://ag.arizona.
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| edu/cochise/mg/soils.htm]
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| United States Department of Agriculture. 2006. Natural Resources Conservation
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| Service. [http://soils.usda.gov/technical/classification/orders/mollisols.html]
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| University of Idaho Collage of Agriculture and Life Sciences. 2006. The Twelve Soil
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| Orders. [http://soils.ag.uidaho.edu/soilORDERS/mollisols.htm]
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