In most traditional farming of the past, a significant amount of nutrients are removed from the soil without being replaced. Major contributing factors to the depletion of healthy soil on farms globally are:

• over-tilling the land
• monoculture (just growing one type of crop on sections of farmland, not implementing crop rotation and planting a variety of crops)
• synthetic fertilizers and pesticides

From processes like these, there is constant degradation of soil nutrients, leading to poor fertilization from year to year. On farms that use these unsustainable farming practices, there is an increase in weeds, bugs, and vermin. Basically, the farmer slowly loses control of the farm as a whole when the quality of the soil is not managed over time.

The solution to these ecological problems is sustainable agriculture. Sustainable ag. involves land-use practices that restore, protect, and maintain ecosystems and biodiversity on farms. Conventional farmlands are thus transformed into ecologically thriving carbon sinks.

Sustainable Ag. Techniques; Cover Crops, Polyculture, and more

It is important for the farmer implementing sustainable agriculture techniques to understand the relationship between all of the farm's organisms and the farm's environment; in order to optimally create biodiversity on the farm, and to focus efforts on maintaining nutrients within the farm's soil, water, and air.

A few sustainable agriculture practices that increase soil health are:

• seasonal use of cover crops
• concerted efforts to maintain proper soil nutrition
• no-till or low-till farming
• crop rotation
• polyculture (vs. monoculture)

Cover crops refer to a variety of crops grown on farmland during off-seasons in order to maintain soil health. Examples of cover crops include legumes like alfalfa, various grasses and cereal crops like rye, oats, and barley, brassicas like turnips and radishes, and turnips and non-legume broadleaves like flax and spinach.

Polyculture is also a practice of introducing a variety of crops on farmland, including multiple species of plants. In the case of polyculture, crops and plants are rotated to different sections on the farmland year-round. Even if polyculture is implemented on a farm, crop rotation and low/ no-till farming should be continually practiced year-round in order to ensure the health of a farm's ecosystems and soil.

Biodiversity of a farm's crops, plants on the farm, and other ecosystems on the farm, as well as proper soil nutrition - deter pests. Polyculture also helps maintain a farmland's healthy ecosystems; also reducing the need for synthetic fertilizers and pesticides.

Creating Carbon Sinks

Real-world examples of sustainable agriculture predominantly include farms that work to satisfy human food demand; while maintaining biodiversity and healthy ecosystems on the farmland. Sustainable agriculture transforms otherwise conventional farmland into environmentally-friendly carbon sinks.

Sustainable farms enhance environmental quality and agricultural economy through the enhancement of the health of a farmland's natural resources. For example, carbon farming is a sustainable agriculture practice that maintains healthy soils and is common practice in most organic farming. Practices to maintain soil health are found in regenerative agriculture, as well as permaculture (see the section on permaculture below, and please see Green City Times' article on Regenerative Agriculture). 

Project Drawdown recognizes these sustainable practices as top climate solutions - all of which serve to create agricultural carbon sinks:

• Land is a critical component of the climate system, actively engaged in the flows of carbon, nitrogen, water, and oxygen—essential building blocks for life. Carbon is the core of trees and grasses, mammals and birds, lichens and microbes. Linking one atom to the next, and to other elements, it’s the fundamental material of all living organisms. FROM  -  drawdown.org/sectors/land-sinks
• Plants and healthy ecosystems have an unparalleled capacity to absorb carbon through photosynthesis and store it in living biomass. In addition, soils are, in large part, organic matter—once-living organisms, now decomposing—making them an enormous storehouse of carbon. Land can therefore be a powerful carbon sink, returning atmospheric carbon to living vegetation and soils. While the majority of heat-trapping emissions remain in the atmosphere, land sinks currently return a quarter of human-caused emissions to Earth—literally.   FROM   -   drawdown.org/sectors/land-sinks
• Multistrata agroforestry systems mimic natural forests in structure. Multiple layers of trees and crops achieve high rates of both carbon sequestration and food production.    FROM  -   drawdown.org/solutions/multistrata-agroforestry
• An agroforestry practice, silvopasture integrates trees, pasture, and forage, into a single system. Incorporating trees improves land health and significantly increases carbon sequestration.    FROM   -   drawdown.org/solutions/silvopasture
• Pumping and distributing water is energy intensive. Drip and sprinkler irrigation, among other practices and technologies, make farm water use more precise and efficient.  FROM  -   drawdown.org/solutions/farm-irrigation-efficiency
• Building on conservation agriculture with additional practices, regenerative annual cropping can include compost application, green manure, and organic production. It reduces emissions, increases soil organic matter, and sequesters carbon.  FROM   -   drawdown.org/solutions/regenerative-annual-cropping