g., cover crops, compost) and soil amendments, which provide energy and nutrients to the soil organisms responsible for soil aggregate formation. The rearrangement of soil particles encourages the formation of chemical bonds that also create soil aggregates. Secondary cultivation decreases surface soil particle size to produce a quality seedbed. 2. To prevent or break up soil hard pans Deep cultivation can physically fracture compacted and otherwise impervious soil layers or hard pans, allowing more thorough aeration, the incorporation of soil amendments, and greater ease of root development. There are both naturally occurring and human created soil hard pans. a) Clay pan: Produced when clay particles leach downward and settle, forming a distinct dense soil layer (e.g., alluvial soils) b) Plow pan: Created by repeated mechanical tillage to a similar depth c) Traffic pan: Produced through repeated foot traffic or anim

To aerate the soil a) Cultivation increases soil air/gas exchange with the atmosphere. Cultivation timed to take place when beds are appropriately moist (50%75% of field capacity) immediately increases soil pore space and aeration, allowing for the rapid diffusion of atmospheric gases into the soil. These gases, which include nitrogen, oxygen, and carbon dioxide, are vital components of soil air that are critical for plant growth. Proper cultivation techniques and the addition of organic matter and soil amendments encourage the development of good crumb structure. This creates a more permanent network of pore spaces, allowing for the continual, passive exchange of atmospheric and soil gases, ease of penetration by plant roots, and water infiltration, percolation, and drainage. i. Nitrogen (N2 ): Increased atmospheric nitrogen (N2 ) levels in the soil can be used by both soil and root bacteria to fix plant-available

Oxygen (O2 ): When combined with organic matter inputs, elevated soil oxygen levels may increase soil biological diversity, stimulate soil biological activity, and increase the rate of microbial decomposition of organic matter in the soil. Soil aeration replenishes the soil oxygen reservoir that is continually being taken up through plant roots for use in respiration. iii. Carbon dioxide (CO2 ): Cultivation allows for the movement of CO2 out of the soil, to be replaced with oxygen and nitrogen b) Increase water infiltration, percolation, retention, and drainage characteristics. A soil made more permeable through proper tillage allows water to infiltrate the soil and percolate slowly downward, draining into the subsoil at rates optimal for both crop plants and soil microbes. c) Soil aeration increases the rate of mineralization and the release of plant-available nutrients into the soil solution for uptake by plant roots 4. To increase the temperature of cold soils in the spring Soil air

Soils with well-developed aggregations and adequate pore space maintain more desirable drainage characteristics and therefore dry and increase in temperature more rapidly than soils having fewer pore spaces. Biological activity and biogeochemical reactions increase at higher soil temperatures, with soil temperatures of 5055F being a threshold below which soil microbial activity rates and plant growth slow dramatically. 5. To incorporate soil amendments Cultivation is a practical means of incorporating compost and other soil amendments, including mineral and non-mineral fertilizers, cover crops, and crop residues. Cultivation may be used to incorporate soil amendments to desired soil depths in order to increase the immediate or long-term availability of essential plant nutrients or to improve the physical, biological, and/or chemical properties of the soil. a) Composts, manures, and fertilizers: Tillage and cultivation techniques are