Agricultural crop residues are the above ground, non-grain portion of agricultural crops (e.g., stalks, leaves, grain chaff, corn husks and cobs), which in addition to the grain or oilseed, can be collected and used as a bioenergy and bioproducts feedstock. Residues from other miscellaneous crops (such as cotton, grass seed production, orchard and vineyard pruning) could also be sources of biomass.
The quantities of agricultural crop residues that can be available depend on the quantities produced minus the quantities that must remain on the field to maintain soil characteristics (e.g., soil organic matter and soil moisture), control soil erosion and chemical runoff, and ensure long-term productivity of the soil. Sufficient residue quantities must be left to maintain these benefits and required quantities depend on a number of factors, such as the crop produced, whether it is produced in a continuous cropping system or in rotation with other crops, the timing and type of management practices used (particularly tillage operations), the physical characteristics of the soil (soil type and erodibility), field characteristics (slope), and climate.