Soil Health Contributors
Mulching, the addition of compost, and the establishment of complimentary ground cover can assist with soil health and improvement in coffee orchards.
Mulching
Mulching can help protect the soil surface from runoff and erosion, provide nutrients to crops over time, reduce weeds and herbicide use, as well as hold moisture in and add organic matter to the soil. There are various types of mulch including those that are organic in nature (chopped or shredded leaves, small branches, husks, grass clippings, wood chips, etc.) and those that are inorganic in nature (rocks, chopped plastic and rubber, plastic films or covers, etc.). Organic and inorganic mulches vary in lifespan with inorganic mulches lasting a year or longer depending on the material and environmental conditions. If using shredded paper, newspaper, or cardboard, consider using materials that contain environmentally friendly ink and discard the tape and staples before use.
Avoid piling, resting, or securing organic and inorganic mulch materials against tree trunks as this can cause rot. Organic mulch layered too deep can result in anaerobic decomposition and the production of alcohols and other compounds that are potentially toxic to plants so avoid piling more than 3-4 inches of organic mulch in one area and use only one layer of inorganic film or cover [109,110]. Choose materials that do not contain allelopathic chemicals, which can prevent seeds from germinating or kill young seedlings, unless this is a preferred outcome. Include a source of nitrogen with woody (high carbon) mulch materials to avoid nitrogen deficiency of young and mature trees as a result of microbes competing with the plants for nitrogen in the top 3-6 inches of the soil [112]. Also, test for unwanted pests like little fire ants and diseases before accepting mulch. Quarantine on site before distributing and spreading around the farm and under trees.
Compost
Composting is the process of aerobically decomposing brown (carbon) materials, green (nitrogen) materials, with oxygen, water, and microoganisms in a controlled environment to produce heat, carbon dioxide, water, and humus, a stable form of organic matter. The benefits of composting include providing nutrients to crops, reducing weeds and herbicide use, as well as increasing moisture retention and organic matter in the soil. Vermicomposting is a form of composting that uses earthworms to decompose raw materials [114]. Mortality composting is used to decompose animals, livestock, or aquaculture carcasses [115,116].
At the optimal 10-20:1 carbon to nitrogen (C:N) ratio [163] and with heating and turning of the compost materials, major pests and diseases are typically killed, but inspecting and testing prior to purchase and quarantining while on-site is recommended prior to use [117].
Ground cover
Ground covers can consist of living mulches, grasses, and low-growing plants that reduce the impacts of rain and erosion, reduce herbicide use while controlling weeds, and protect the roots of trees and shrubs from extremes of heat and cold. Ground covers are commonly used as substitutes for grass, especially in areas where it is difficult to maintain or grow grass, such as deep shade or steep slopes. Nitrogen fixing ground covers can help to add organic matter and nitrogen to the soil when mowed or weed whacked. Fertilization may need to be increased and modified to supply both the ground cover and coffee trees with adequate nutrition.
Mulching
Mulching can help protect the soil surface from runoff and erosion, provide nutrients to crops over time, reduce weeds and herbicide use, as well as hold moisture in and add organic matter to the soil. There are various types of mulch including those that are organic in nature (chopped or shredded leaves, small branches, husks, grass clippings, wood chips, etc.) and those that are inorganic in nature (rocks, chopped plastic and rubber, plastic films or covers, etc.). Organic and inorganic mulches vary in lifespan with inorganic mulches lasting a year or longer depending on the material and environmental conditions. If using shredded paper, newspaper, or cardboard, consider using materials that contain environmentally friendly ink and discard the tape and staples before use.
Avoid piling, resting, or securing organic and inorganic mulch materials against tree trunks as this can cause rot. Organic mulch layered too deep can result in anaerobic decomposition and the production of alcohols and other compounds that are potentially toxic to plants so avoid piling more than 3-4 inches of organic mulch in one area and use only one layer of inorganic film or cover [109,110]. Choose materials that do not contain allelopathic chemicals, which can prevent seeds from germinating or kill young seedlings, unless this is a preferred outcome. Include a source of nitrogen with woody (high carbon) mulch materials to avoid nitrogen deficiency of young and mature trees as a result of microbes competing with the plants for nitrogen in the top 3-6 inches of the soil [112]. Also, test for unwanted pests like little fire ants and diseases before accepting mulch. Quarantine on site before distributing and spreading around the farm and under trees.
Compost
Composting is the process of aerobically decomposing brown (carbon) materials, green (nitrogen) materials, with oxygen, water, and microoganisms in a controlled environment to produce heat, carbon dioxide, water, and humus, a stable form of organic matter. The benefits of composting include providing nutrients to crops, reducing weeds and herbicide use, as well as increasing moisture retention and organic matter in the soil. Vermicomposting is a form of composting that uses earthworms to decompose raw materials [114]. Mortality composting is used to decompose animals, livestock, or aquaculture carcasses [115,116].
At the optimal 10-20:1 carbon to nitrogen (C:N) ratio [163] and with heating and turning of the compost materials, major pests and diseases are typically killed, but inspecting and testing prior to purchase and quarantining while on-site is recommended prior to use [117].
Ground cover
Ground covers can consist of living mulches, grasses, and low-growing plants that reduce the impacts of rain and erosion, reduce herbicide use while controlling weeds, and protect the roots of trees and shrubs from extremes of heat and cold. Ground covers are commonly used as substitutes for grass, especially in areas where it is difficult to maintain or grow grass, such as deep shade or steep slopes. Nitrogen fixing ground covers can help to add organic matter and nitrogen to the soil when mowed or weed whacked. Fertilization may need to be increased and modified to supply both the ground cover and coffee trees with adequate nutrition.