I lead the discussion on planting. I started this session by talking about some of the different planting methods from simple to mechanization. Planting has several processes such as tilling the soil, digging of a furrow, positioning of seeds, and burying the seeds. Different technologies take advantage of some or all of these steps in the process. For example, some large mechanized devices will dig a furrow, position seeds, and bury the seeds in one pass. Yet, this is not the required method of planting seeds. The simplest method is to just till the soil and then broadcast seeds over the freshly turned dirt. This is the cheapest way to plant a field, but is not as accurate at placing the plants at optimum spacing like the previously mentioned method. There is also room for innovation, for example a seed drill does not require and tilling and instead drills seeds into the ground at pre-defined locations.
The introduction into planting implements lead into discussion about this week’s reading in Chris Bull’s book, “Field Guide to Appropriate Technology.” The section considered had some different simple planter tools and planting technologies. We considered one simple planter device that looks like a baby carriage and with a bucket of seeds in the middle. This device had multiple actions including digging a furrow, positioning seeds, and burring them with a simple device.Read more

It has been a while since we did this last, so this is going to be pretty long. Our group is working on several projects simultaneously. We wanted to review the issues. Thus, we looked into irrigation systems, fertilizer practices, and water management practices that can increase farmer yields. Using these as our problem statements, we tried to come up with potential solutions to one or all of these issues using novel ideas and designs that are not being already tried in Kenya. Fertigation was the original concept, but the design of liquid fertilizers which can be used during irrigation or otherwise has taken the forefront. We will first discuss our problem statements, and then consider our concept and how we have tested this idea.
Water management is a large issue in Kenya. Kenya has a large amount of rainfall during the rainy season, but during the dry season there is much less. Therefore, water maintenance during this dry season is very important. One possible goal of this project would be to increase the number of crops the farmers can produce each year. Better water management would be required for this to be possible. Second, we want to deliver more water to the plants, while not wasting any water in run-off. This is important so that crops can reach their full potential, and not become stunted, but also so that water can be used for other applications such as drinking water for livestock. Selection of time to water is important, since night time delivery of water will save additional water. Water management adds a design constraint that we must use as little water as possible while still delivering as much as is required by the crop.Read more

This past week we presented our prototype design of our planting tool. Prior to the presentation and critique, we were able to perform some initial tests on the mechanism. Some of the issues we faced included difficulty finding a suitable location to carry out testing and lack of a strong frame. The spade component worked well, however, since the members of the frame were not yet glued together, the front bar that holds the spade turned as the machine moved forward. Just before presenting we applied poxy to the front member and hopefully that will prevent this from happening again.

After the presentation, we came up with a list of potential issues that we hope to be able to address in the coming weeks:Read more

Last week we completed a very rough prototype of the threshing machine. We were able to attach the two trash barrels onto our wooden structure. One was smaller than the other and rotated inside the larger barrel that was stable and had a opening to put amaranth in as well as a screen-covered opening in the bottom for amaranth seeds to be filtered out. We attached beaters to the inner barrel made of cut up sheet metal and attached them with screws. A pvc pipe runs through both barrels as well as the wooden structure to hold the materials up as well as rotate the inner barrel to thresh the amaranth. We did complete a good representation of the product that we intend to produce, however we have many alterations and optimizations that we still need to make and many problems that we encountered when creating the prototype. Some of the problems with are design are as follows:

• holes running through center of entire prototype are not exactly aligned and thus the rotation of only the inner barrel does not occur
• sheet metal beaters did not fit exactly in area between inner and outer barrel, thus further preventing rotation
• overall size of prototype is very large and thus harder to manage and optimize
• gears are currently not connected and may not work for rotating both barrel and fan because speed/direction may not coincide
• beaters may to too long and thus not actually thresh amaranth but rather carry around drum
• winnower is not yet completed or functional

Solutions that we plan to take on this semester:
• reducing size of prototype in order to be able to make an appropriate and functional model of thresher
• create larger holes and more precise measurements in structure as well as outer barrel so friction does not prevent rotation of inner barrel
• make distance between outer and inner barrel smaller
• create smaller and more frequently spaced beaters on inner barrel to more efficiently thresh, but not carry amaranth grainRead more

We have settled on materials for our prototype and have begun building our design, which will be completed by Sunday, April 9th.

The materials we are using are:

-wood as a support structure
-two trash cans as inner and outer drum for thresher
-bicycle gears for connection between fan and thresher
-pvc pipes for rods and handles
-sheet metal for blades on inner trash can
-metal screen

Additionally, we have ordered amaranth heads to test our design through the Agronomy Department at Iowa State University, which should ship in a few days. We ordered both field grown, dried amaranth heads with "break resistant amaranth" and green house grown amaranth heads.

We have now created (tentative) finalized project goals as follows:
• Minimize grain loss during threshing and winnowing
• Increase efficiency of threshing and winnowing processes
• Reduce/eliminate contamination

We have decided upon two design options (option I and option II), or for creative purposes “belt” and “drum.” Option I was described in the previous project update and is our original design. We have created technical CAD drawings illustrating the dimensions and basic structure of our proposed design and provided optimizations that we will need to further consider as we create a prototype.
The idea for our newest design came from our most recent readings on harvesting. The design is a rotating drum with “beaters” that use force to remove the grain from the amaranth head. This design idea was appealing to us because it eliminated the need for a person holding the amaranth head in the machine (like in the rotating belt idea) and then removing it that way. With this design the whole head could be placed in the rotating drum and the grain would be separated from the head then discarded through a side area. We have also created a technical CAD drawing for this design, but this only includes that internal structure and currently lacks a shell because we are unsure about how we will create an external structure around the current design.
We also created a proposed materials list with both materials that we will ideally like to use and those that are more commonly found in Kenya. Materials proposed are as follows:
• corrosive material (belt
• corrugated sheet metal (strucure/ramp)
• metal bars (belt support)
• wire mesh (removable sieve
• wood (fan and beaters)
• concrete (outside mold)

Our optimization needs are as follows:
• distance of belt to soil surface
• distance of drum to concave structure
• diameter of drum
• shape of bars
• height between belt and removable sieve
• angle of inclination
• strength of wind for winnowingRead more

We began by researching practices of amaranth planting in use today. This included everything from tilling the soil to fertilizing to sowing. Our research led us to believe that fertilizing was a matter of optimizing costs through materials research more than it was an engineering task, and that current tilling practices are adequate. Therefore, we decided it prudent to focus our efforts on constructing a device for sowing seeds.

Current seeding practices consist mostly of hand-broadcasting, which although quick, is extremely inefficient, as most of the newly budding plants have to be removed by hand to prevent crowding.

We therefore designed a device that would optimize the seeding process, taking into account these values from our research:

row spacing: 18 inches
plant to plant distance within rows: 4 inches

The device consists of a simple frame (in tentative order of preference: bamboo, wood, or pvc), attached to what looks like a giant, hollow spool (wooden "wheels", pvc drum), with 4 holes around its circumference to deliver seeds. Also attached is a spade (some kind of metal) that makes a furrow in the ground in which to deposit the seeds. The arclength of the wheels between holes determines the spacing of the deposited seeds. There is also a device, made of a durable rubber that will brush soil on top of the seeds within the furrows.

We are now concentrating on tweaking some of the device’s dimensions. Things to consider include optimal translational speed of the device (pace at which someone walks), which is related to rotational speed (and thus radius of the spool). Also, the size of the holes drilled into the cylindrical drum will be based on things like the size and shape of the seeds themselves, something that would require some degree of experimentation.

We have decided on a multipurpose threshing/separating/winnowing machine in which the input will be full amaranth heads and the output will be clean grain without shells and separated from the head. The mechanisms for removing the grains from the amaranth head itself will be a crank powered rotating belt against an surface that is adjustable as to the distance from the belt. The material of the belt is still undecided and we hope to test different materials in order to see which has the best result. Our ideas so far involve potential trying a corrosive surface that will create more friction in which to remove seeds. We research buying belts online and the prices were relatively cheap for plastic belts (about $3.50 for 10). After the belt being cranked by human power, removed the seeds they will fall through a removable screen which will sieve out the larger objects from the grain. After they fall through they will encounter the force of wind from a fan propelled by the same crank that propels the belt. This wind will blow away the lighter shells and allow the heavier seeds to fall down to their final destination. Our hopes are that this machine will reduce loss of grain and also make the process of threshing and winnowing more efficient.

The optimizations that we plan to make:
-Crank speed/resistance
-Distance of belt from surface
-Screen aperture size
-Fan/centrifuge speed
-Slope of chute

We found many of our general idea from a student thesis project on a amaranth harvesting machine shown below in the powerpoint presentation. We have also provided some of our own preliminary designs in the powerpoint.

At this point we plan to continue to research other possible methods of separating the seeds from the amaranth head that may be more efficient or simple to build.Read more

These four readings gave detailed case studies and information on the technical design of various irrigation systems designed for the developing world. The first reading, “The Design Process for the IDE Low Cost Drip Irrigation System” was a detailed case study on a drip irrigation system intended for a village in India. The farmers originally used a very successful but extremely expensive sprinkler irrigation system. Instead, Paul Polak designed a new system based on drip irrigation. Polak’s design was researched and implemented over a five year period.
In class, we discussed the cost recovery model this reading suggested of starting with a simple low-cost irrigation design and building upon it once it begins to generate more revenue for the farmer. This method is definitely a great model for overcoming the obstacle of affordability without risking the quality of the design. However, we spent some time discussing the feasibility of this idea. First, we were unsure whether this solution would work with a drip irrigation system that came in a package. Rather, the system would have to be designed on its own, piece by piece in order to allow for added pipes. Additionally, we discussed the changes that would need to occur to the whole system, including switching to either a larger water storage device, or moving the water storage tank to a greater height in order to yield a higher value of initial potential energy. Read more

Initially, we researched various forms of irrigation that have been in use and proven to be effective in developing countries, focusing on drip irrigation and
Kickstart’s treadle pumps. Drip irrigation reduces water use by delivering water directly to the roots and is inexpensive, expandable, and often can be constructed from local materials. However, it requires a lot maintenance, the drip lines are eaten by rodents, the filters and pipes clog easily, and there is a general lack of skills in installation, operation, and maintenance of the systems. Kickstart’s pumps make use of manual labor to pull water from underground or other water source. While considering design options, we kept
formulating more and more questions: If there are affordable design kits already being made, why isn’t their use more widespread? How many farmers have
irrigation? What is the source of water during the dry season? Would designing and providing these farmers with an irrigation system really be sustainable since growing more crops would further deplete the soil, further reducing crop yields in the future? With these questions in mind and considering how there are already several companies manufacturing affordable drip irrigation systems (Kickstart, Approtech, Chapin kits, IDE, etc.), we came up with a few other directions we could pursue:

1. Fertigation - Determining which of the available design kits is the best possible option and then adapting it so it could be used for liquid fertilizer; this approach would also entail finding a means for farmers to cheaply obtain their own fertilizer
2. Water conservation/management education
3. Evaluating the available design kits and optimizing the best kit so it would be ideal for amaranth farmers in Kenya
4. A combination of the above

[powerpoint attached]