SECONDARY TILLAGE - Tillage used (generally following primary tillage) to pulverize, level, and/or condition soil less than six inches deep to prepare or "fit" a seed bed.
SEWAGE SLUDGE - A solid, semisolid, or liquid residue generated during the treatment of domestic sewage in a treatment works. Sewage sludge includes but is not limited to: domestic septage; scum or solids removed in primary, secondary, or advanced wastewater treatment processes; and a material derived from sewage sludge. Sewage sludge does not include ash generated during the firing of sewage sludge in a sewage sludge incinerator or grit and screenings generated during preliminary treatment of domestic sewage in a treatment works.
SLURRY (MANURE) - Manure that is between solid and liquid; it flows slowly and has the consistency of a very thick soup.
SMOTHER CROP - An inter-seeded crop sown with the intent of smothering weeds; sometimes also applied to a weed suppressive cover crop grown alone.
SODIC SOIL - Soil containing excess amounts of sodium. If it is not also saline, clay particles disperse, and the soil structure may be poor.
SOIL CARNON SEQUESTRATION - The stable storage of carbon in the organic matter of soils, ultimately through the capture of atmospheric carbon by the process of photosynthesis in plants and the eventual decay and transformation of plant and animal life into stable organic compounds.
SOIL STRUCTURE - A soil physical property that is based on the arrangement of soil separates into groups of particles that adhere by cementation or cohere. Aggregates are clusters of many soil particles in a single mass. Ideally aggregates are sand-sized for good soil tilth. Large aggregates are called clods, crumbs, block, prisms, or peds.
SPADING MACHINE - A PTO-powered rotary tillage tool that has large flat blades (spades) arranged in sets of 3 on a rotor. Rotary and reciprocating spaders are described above. For rotary versions, the spades plunge into the soil, lift the dug soil and then tip to drop off the soil. The system is efficient in power use and gentle on soil structure but requires a complex and thus expensive machine. Normal forward operating speeds are slow (less than 1.5 mph). The degree of soil pulverization achieved depends on the ratio of rotor speed to forward speed, the magnitude of the speeds (rotor and forward), shape and arrangement of the spades, and the positioning of the back flap (upon which the soil will rebound). Spading machines are primarily used in preparing soil for vegetable production and are most widely used and manufactured in Europe.
SPLIT OPERATION - An operation that produces or handles both organic and nonorganic agricultural products.
STATE CERTIFYING AGENT - A certifying agent accredited by the Secretary under the National Organic Program and operated by the State for the purposes of certifying organic production and handling operations in the State.
STATE ORGANIC PROGRAM (SOP) - A State program that meets the requirements of section 6506 of the Act, is approved by the Secretary, and is designed to ensure that a product that is sold or labeled as organically produced under the Act is produced and handled using organic methods.
STRIP CROPPING: Growing two or more crops in alternating strips, usually along the contour or perpendicular to the prevailing wind direction.
STRIP TILL/ZONE TILL - Tillage system that maintains residues between rows but relocates residues out of the planting row (up to 1/3 of the row spacing) and may involve deep loosening in the row.
SUBSOILING - Tillage designed to fracture deep, compacted layers; may or may not be in-row.
SUSTAINABLE AGRICULTURE - Sustainable agriculture provides high yields without undermining the natural systems and resources that productivity depends on. Farmers who take a sustainable approach work efficiently with natural processes rather than ignoring or struggling against them - and use the best of current knowledge and technology to avoid the unintended consequences of industrial, chemical-based agriculture. One important result is that farmers are able to minimize their use of pesticides and fertilizers, thereby saving money and protecting future productivity, as well as the environment.
SWEEPS - Wings that extend out from tines on cultivation equipment to undercut weeds and lift soil causing rapid dessication.
SYNTHETIC - A substance that is formulated or manufactured by a chemical process or by a process that chemically changes a substance extracted from naturally occurring plant, animal, or mineral sources, except that such term shall not apply to substances created by naturally occurring biological processes.