lasts from the end of November until May (from sowing to growing of ears of wheat
and barley) and water thus had to be stored and distributed gradually. The process of
carrying water from retention tanks to the fields and cereal ridges was dominated by
the effort to minimalize losses by selection of the appropriate widths, gradients and
sections for canals and conduit trenches (Hrusˇka 1988 a: 64 – 69 ). M. P. Charles ( 1988 :
11 ) believes that minor canals conveying water from the tanks to the fields could have
had flat bottoms and vertical banks. Such sections could minimize water erosion and
eliminate the sedimentation danger in cases of gradients lower than three per cent.
The essential first irrigation procedure consisted of so-called leaching.^5 The future
production area was flooded prior to sowing, up to 10 cm above the soil level, which
caused a soaking of water to the depth of 60 cm. If water was plentiful the soil could
be leached between 15 and 20 cm deep, to provide the future root system with
sufficient moisture (Charles 1988 : 32 – 33 ).The term ki-duru 5 (wet place) probably
designated a field irrigated with water after short-term fallow in order to facilitate
ploughing (tugur-si-ga). No known text can be used to identify the month of the
year in which leaching was done. LaPlaca and Powell ( 1990 : 80 ) believe that basic
ploughing went on after the harvest at the end of summer. This would nevertheless
entail two separate ploughing campaigns while the animal teams, ploughing imple-
ments, such as ploughs and seeder ploughs, seed and fodder were distributed only
once (Maekawa 1990 : 127 – 129 ). Leaching consumes some 35 – 40 per cent of the
entire water volume necessary for the whole period between sowing and harvest, since
annual precipitation does not surpass the critical minimum value of 200 mm. One
half of the remaining irrigation water was used in the time of sprouting, rooting,
and the initial stalk growing of the cereals. The other half provided for further grow-
ing phases, including the flowering and putting on ears of the grain (Charles 1988 :
14 – 15 ). Water from leaching and from soakage could have been used for the regulation
— Agricultural techniques —Figure 4. 2 Soil preparation with hoes (Butz 1980 – 83 : 478 ).