Agriculture Reference
In-Depth Information
Dibbling Method of seed sowing by making small holes in ground or soil and
inserting seeds into them.
Dieback A condition in woody plants in which peripheral parts are killed by par-
asites. The shoot of a plant may die many times over during the initial years in a
seasonal pattern before the plant gets established.
Ditch-cum-bund fence A fence made by excavating a ditch and forming excavated
soil into a bund with a sharp crest. The bund usually is built along the inner edge of
the ditch.
Drawdown In wells, the depth by which the saturation line in ground depresses as
a result of steady withdrawal of water. A large drawdown in a well will necessitate
a variable position of pump installation.
Drip irrigation Irrigation by means of controlled flow of water in tubing running
under or over ground but delivering water in subsoil drop by drop.
Drought A prolonged period of dryness that causes damage to crops or prevents
successful growth of crops and other vegetation. As compared to annual crops, the
perennial and woody plants are better equipped to withstand drought.
Drought tolerant A plant that can withstand drought well.
Drought-proofing Hardening of nursery-raised plants by gradually reducing the
amount water made available to them, in order to condition them for withstanding
the dry climate of field.
Dug well A type of well used as a water source. The dug well is excavated with a
large diameter, in contrast to the tube well which is bored into ground mechanically
in very small diameter usually 15 to 30 cm. A dug well is also known as an open
well.
Dumpy level An instrument fitted with a short telescope rigidly fixed and rotating
only in the horizontal plane. It is used for levelling operations, especially for sur-
veying ground profile in cross section and L-section of streams, and for computing
volumes of earthwork in embankments.
Early finish time In network analysis, the earliest time by which an activity can
be finished. It is computed by adding the time it takes to complete the activity to its
early start time.
Early start time In network analysis, the earliest time by which an activity can
start. It is determined by the early finish time of its immediate predecessors, since it
cannot start until all of them have been completed.
Earthen dam A dam on a stream made of earthen embankment and suitable spillway
arrangements. The spillway could be a natural outlet in form of a saddle on sides of
the submergence area, or a part of the embankment could be replaced with a masonry
weir for passing over the surplus discharge of water.
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