Crop rotation:

The repetitive growing of an orderly succession of crops on the same field.

Field trial:

An on-farm trial repeated simultaneously on a number of local farms to compare a new practice or "package" of practices with the present practice or practices. It is designed to obtain information, not as a demonstration.

Fungicide:

Any pesticide that kills or halts the development of fungi.

Herbicide:

Any pesticide that kills weeds.

Hybrid:

A type of improved crop variety produced by crossing two or more inbred lines of a crop.

Legume:

Any plant belonging to the Leguminosae Family whose members all produce their seeds in pods. Legumes can satisfy part or all of their nitrogen needs through a symbiotic relationship with Rhizobia bacteria that form nodules on the roots. Beans, cowpeas soybeans, mungbeans, lima beans, chickpeas, pigeonpeas, and peas are legumes.

Monoculture:

The repetitive growing of a single crop on the same field year after year.

Multiple cropping:

The growing of two or more different crops at the same time on the same field: also referred to as intercropping.

Nematodes:

Tiny, colorless, threadlike roundworms that live in the soil and parasitize plant roots.

Nitrogen fixation:

The beneficial process by which Rhizobia bacteria convert atmospheric nitrogen into a usable form for plants. Rhizobia bacteria are associated only with legumes.

Phosphorus fixation:

The process by which added fertilizer phosphorus becomes tied-up as insoluble compounds in the soil and unavailable to plants. Phosphorus fixation is a problem on all soils but is especially severe on highly weathered, acid, red tropical soils.

Pulse:

A legume crop whose mature dry seeds are suitable for human consumption; examples are beans, cowpeas, soybeans, chickpeas, and mungbeans.

Result test:

See field trial.

Rhizobia:

A type of bacteria associated with legumes and capable of nitrogen fixation.

Soil texture:

The relative amount of sand, silt, and clay in a given soil.

Soil filth:

The current physical condition of a soil in terms of its workability and ease of moisture absorption. A soil's filth can vary markedly with its texture, humus content, and current moisture content.

Systemic insecticide:

An insecticide that is absorbed into the plant sap and translocated (transported) throughout the plant.

Threshing:

The process of separating the seeds of cereal and pulse crops from the seedheads, cobs or pods.

Tillering:

The production of sideshoots by a crop during its growth; tillering is common in millet and sorghum.

Transpiration:

The loss of soil moisture by plant root absorption and passage into the air through the leaf pores.

Winnowing:

The process of separating chaff and other light trash from threshed grain using wind, fandriven air or screens.