Topic outline

    Module 3: Techniques needed to farm

    In the first module we explored the differences between sustainable agriculture and conventional agricultural.  This module will build on that understanding and expand your knowledge of the techniques needed to farm in a sustainably, you will learn the most important practices and principals of sustainable farming.  

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    Lesson 1.  Cover crops

    Cover crops are specific types of plants that are grown in agricultural areas which help create better soil.  Cover crops build soil fertility through a number of ways.  The most desirable characteristic of a cover crop is the ability for the plant to produce nitrogen and replenish nitrogen in the soil.  Nitrogen is the most important nutrient necessary for plant growth, and the most common nutrient that the soil is lacking.   The process where the roots of cover crops create nitrogen is called nitrogen fixation.  

    Cover crops can also be grown, then cut down and left in the garden to make a mulch layer on the surface.  This practice is illustrated by the photographs below.

    A mulch layer is beneficial for the following aspects of farming:

    • soil fertility
    • beneficial insects
    • moisture retention
    • weed control
    • pest control
    • disease control

     In sustainable and organic agriculture you cannot spray synthetic chemicals to kill weeds, pests, or use synthetic fertilizer to add nutrients, because of this, cover crops are very important.  Cover crops help prevent problems by creating healthy soil and this is of paramount importance for organic farming.

    Below is a list of cover crops for specific farming needs.   

    You can browse the CTAHR cover crop website to determine what cover crops are best in Hawaii. 

    Discussion Questions:

    Now that you are familiar with the benefits and types of cover crops, do you think that they would be beneficial for a home garden in Hawaii? Why or why not? 

     Is there a specific cover crop species that you would choose for your own garden? Why or why not?

    Post your thoughts or cover crop photos in the discussion forum.  


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    Lesson 2. Crop rotation

    Crop rotation is a practice which alternates the type of crop grown in a field.  A common cycle of crop rotation is exemplified in the photo below, where each type of crop is planted after the previous crop is completed.

    Example.  1st crop cabbage, 2nd crop carrots & 3rd crop peas.  

    This cycle of alternating the types of plants grown in the same field will help reduce nutrient deficiencies, reduce pests and build soil fertility. 

    When a farmer continuously grows the same crop year after year in the same field this is called monocropping.  Monocropping is commonly practiced in conventional agriculture because high amounts of synthetic chemicals can be used to kill pests and increase soil nutrients.  Remember that sustainable farming does not permit the use of synthetic chemicals and fertilizers, so we must use natural methods such as cover cropping and crop rotation to accomplish the same results.  

    In the 1920’s there was a high demand for farmers to grow wheat crops.  The farmers in the United States Great Plains region were producing large amount of wheat year after year to meet the demand.  But as we have learned, it is necessary to give back to the soil with crop rotation and cover crops.  Because the farmers were not practicing these sustainable methods, tragedy struck.  The 1930’s began with a drought and high winds, this combined with the poor farming monoculture practices led to the dust bowl.  The dust bowl is one of the most extreme agricultural disasters in history.  For close to ten years the land literally blew away.  The soil was so depleted and neglected that the natural structure was completely missing.  Hopefully we have learnt from these mistakes and are able to practice environmentally conscious farming that benefits us and the earth.  Reference the video below to hear the story of the dust bowl.

    Also, follow the link below to read an excerpt from a newspaper article written by  John Steinbeck during the dust bowl era.  See if you are able to make connections between 1936 when it was written and now.  Though 75 years have passed, you might find surprising similarities.

    Look at the pictures below, what do you see? One of these photos is of a farm in Hawaii today and the other is from 1930’s during the dust bowl.

    In Hawaii, everything on land eventually flows downstream in to our oceans, thus the issues of erosion and proper soil management effect more than just our resources underfoot, they also impact our ocean and fisheries. This image demonstrates this idea. 

    As you can see from the readings and what you have learned about soil management, improper treatment of the soil can lead to severe economic situations.  Below are some images of massive environmental degradation, homelessness, famine and despair during the dust bowl in the  1930’s.

    Discussion Questions:

    What do you know about monoculture in Hawaii and its environmental effects on the land?

    What effects do you think the environmental problems may pose on Hawaii’s economy and people?

    Post your ideas and thought in the discussion forum.

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    Lesson 3. Plant nutrients

    There are 20 elements necessary for healthy plant growth.   For sustainable and organic farming, these fertilizers will come from the soil or other natural sources, but because knowing about plant nutrients is so important, we are going to also cover the conventional agriculture approach so that you will understand the full spectrum.

     Air and water supply carbon, hydrogen, and oxygen.  The other 17 mineral elements must be supplied by the growing media, fertilizers and additional sources. 

    In nature, plants get nutrients from organic debris that collects at the roots.  This can be anything from decaying tree bark to bird droppings.  Complex interactions involving live bacteria, enzymes, and microbes break down this organic matter so the plant can absorb it. 

    N-P-K Ratio

    Fertilizers contain three main elements:

    • Nitrogen (N)
    • Phosphorus(P)
    • Potassium (K)

    This is called the NPK ratio. Fertilizer packages always have three numbers on the front panel that describes the NPK ratio.

    The first number is Nitrogen (N), the second is Phosphorus (P), and the third is Potassium (K). The numbers describe what percentage of each element is in the fertilizer.

    Trace Elements

    Plants need 17 elements for healthy growth.  Most fertilizers contain the three main elements (the NPK - Nitrogen, Phosphorus, and Potassium). But be on the lookout for the rest of the elements!  If your fertilizer doesn't have all the elements you're taking a hit-or-miss approach and your plants could be missing important minerals it needs to grow.  Look on the back of the package and see what's in your fertilizer.  Below is an example of what the fertilizer label will look like.  See the NPK ratio and the trace elements listed.  

    Remember, in organic farming it is not acceptable to use synthetic fertilizer.  You can use other alternatives such as:

    • cover crops
    • crop rotation
    • manure
    • compost
    • worm castings
    • and many other alternatives

    Discussion questions:

    In the discussion forum, post one environmental problem that may be caused by the use of synthetic fertilizers in farming.  Think about the nutrients running out of the field and in to streams and eventually the ocean.  Search online for “nutrient leaching” or “hypoxia dead zones” for more ideas.  

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    Lesson 4. Pest and week control

    In traditional agriculture, pest and weed control problems are easily controlled with the use of pesticide and herbicidal chemicals.  This is not the case with sustainable agriculture.  This lesson will demonstrate some of the methods of pest and weed control commonly used by organic farmers. 

    Pest control

    A pest in agriculture is an organism which causes detrimental effects to the plants you are growing. 

    There are many “home remedies” that people employ to keep pests from attacking their gardens.  Below is a list of strategies that can help prevent, reduce and remove pests from your garden. 

    • Plant diversification – This method relies heavily on the concepts covered in the previous lesson about crop rotation. Crop rotation creates different insect habitats that allow for a diverse assortment of bugs.  This bug assortment helps to build beneficial insects.
    • Promote beneficial insects (biocontrol) – Beneficial insects can be a result of crop rotation or can be directly introduced by the farmer.  Beneficial insects have many positive uses, but we will focus on pest biological control.  For example, if you have an aphid problem in your garden you could release lady bugs to eat the aphids.  There are many specific bugs which prey on pests, so it is important to first determine the pest, and then research a predatory biocontrol insect.   

    • Sanitation – Keeping plant debris off of the ground and removing any dying leaves from plants helps drastically reduce pest populations.  Pests are drawn to weakened parts of the plant, so remove dying or dead leaves. 
    • Choose resistant crops or varieties – Certain areas have long term pests.  As a response, agricultural researchers have found types of plants that resist specific pests.  You can use these plant varieties to lower the risk of pest attack.
    • Botanical pesticides – Although synthetic chemicals are not welcome in organic farming, it is still possible to use plant derived extracts.  Two of the most common plant derived sprays are listed below. 
      • Neem oil – Is a vegetable oil derived from pressing the fruits and seeds of the Neem tree.  The extract helps repel most insects, which makes it a very commonly used insecticide in organic farming. 
      • Insecticidal soaps (safer soap) – Are potassium fatty acid soaps that dissolve insect cell membranes causing death.  Insecticidal soaps work best on soft-bodied insects such as aphids, mealybugs, thrips, and whiteflies. 

    When farming, there is one thing that is guaranteed, you will have weeds.  A weed can be simply defined as a plant out of place.  It is important to control weeds because they will take needed nutrients from the garden crop and compete for space.  Follow the methods below to help prevent and kill weeds. 

    • Don’t let weeds produce seed heads – A common rhyme is “one year of seed is seven years of weed”.  We don’t want that!
    • Cover crops – Refer to the first lesson on cover crops.  You can grow cover crops to occupy the niche weeds need to grow, or you can grow and cut the cover crop to create a mulch layer.
    • Weed cloth – This is a physical layer of black plastic or similar material which is placed on the soil surface to prevent weeds by eliminating sunlight.  A similar method can be used with clear plastic to “solarize” (super heat) the soil to kill surface weed seeds. 
    • Cultivate – This practice is physically removing weeds by hand or with a machine.  Commonly large scale farms will use a tiller to scrape just above the soil surface to remove the weeds.
    • Flaming – Flaming uses gas or propane torches to produce high temperatures which burst plant cells, causing the weed to die.  This works best on small weeds just after germination.  
    • Organic herbicides – There are organic chemical alternatives used to spray and kill small weeds.  The three most common organic herbicides are clove oil, acetic acid and citric acid.

    Remember that the University of Hawaii CTAHR has plentiful resources about organic farming.  Follow this link to guide you to the CTAHR organic agriculture website.


    Discussion questions:

    Choose one method of pest and one method of weed control that you feel are important to sustainable farming.  Post in the discussion section a picture or description of the methods you choose.  

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    Who is here to help farmers in Hawaii?

    Here in Hawaii, there are many resources and assistance programs that are designed to help the local farmer.  Below are several entities which are designed to help farmers in Hawaii.  Read through and browse the various resources to help answer the questions below. 

    Every individual state in the United States has a State Department of Agriculture.  In Hawaii, this entity is the Hawaii Department of Agriculture (HDOA).  The HDOA is usually the best resource to find out information regarding Hawaii specific agriculture and financial opportunities for farmers. 

    Along with the State programs, the University of Hawaii, College of Tropical Agriculture and Human Resources (CTAHR) provides a large amount of support to local farmers.  CTAHR’s responsibility is to help all aspects of Hawaii’s farmers.

    Another resource dedicated to the advancement of Hawaii agriculture in the Hawaii Agricultural Research Center (HARC).  HARC’s mission statement is “to support a viable agricultural sector by researching and applying relevant science and technology to achieve practical solutions and by identifying new agricultural opportunities".

    The Hawaii Farm Bureau is another entity which is a dedicated non-profit organization of farming families united for the purpose of analyzing problems and formulating action to ensure the future of agriculture thereby promoting the well-being of farming and the State's economy.

    Discussion questions:

    Based on your review of the resources available to Hawaii farmers, where would you look to find out information about acquiring funding or loans to start a farm in Hawaii? 

    Where would you look to find educational opportunities in sustainable agriculture in Hawaii?  Are there any college programs and classes that focus on sustainable agriculture in Hawaii? 

    Do the resources listed above seem helpful to farmers in Hawaii?  Are they easy to understand and navigate?

    In the discussion section, post your responses to the questions above and share why at least one other response provided a new and/or interesting perspective.