Tillage operations
Tillage operations include the cultivation practices conducted by the various tillage implements such as mouldboard, chisel, duck foot chisel, harrow, etc. The various tillage implements cause various erosion rates. For example a tandem disk may be more erosive than a mouldboard plough operation because it translocates more soil with greater variability throughout the landscape. The chisel plough may be equally erosive as the mouldboard plough. Large aggressive tillage implements, operating at excessive depths and speeds are more erosive than conventional ones. Tillage operations have been defined after contacting the land owner. The following tillage operations have been distinguished: no tillage, ploughing, disking, harrowing, and cultivator operation (Fig. 57)
Fig. 57. Tillage implement used for cultivation of hilly areas (left) preparing the soil for planting (right)
As Table 8 shows, data for this indicator have been collected in 1143 field sites, corresponding to 14 study sites. Based on the obtained data, the most important tillage operations were no tillage operations or minimum recorded in 42.2% of the study field sites, corresponding in the study sites of Secano Interior-Chile, Boteti Area-Botswana, Santiago Island-Cape Verde, Mamora Sehoul-Morocco, Guadalentin Basin Murcia-Spain, Loess Plateau-China, and Crete-Greece. No tillage operations have been defined in areas cultivated with perennial crops such as olives and in areas used as pastures. The next important class was ploughing, covering 33.5% of the study field sites (Fig. 58). Such tillage operation has been defined in all study field sites of Karapinar plain-Turkey, Eskisehir-Turkey, Cointzio Catchment-Mexico, Novij Saratov-Russia, and Djanybek-Russia, and in some cases in the study sites of Secano Interior-Chile, Boteti Area-Botswana, Rendina Basin Basilicata-Italy, Mamora Sehoul-Morocco, Zeuss Koutine-Tunisia, Loess Plateau-China, and Crete-Greece. Ploughing of the soil has been mainly conducted in areas cultivated with annual crops such as cereals, cotton, vegetables, etc. Disking and harrowing operations have been identified in 16.1% of the study field sites, corresponding to the study sites of Secano Interior-Chile, Rendina Basin Basilicata-Italy, Mamora Sehoul-Morocco, Zeuss Koutine-Tunisia, Cointzio Catchment-Mexico, Guadalentin Basin Murcia-Spain, Loess Plateau-China, and Crete-Greece. Such tillage operations have been applied mainly in perennial crops such as olives, vines, oranges, etc. Tillage operation by cultivator has been defined in very few cases (2.4%) of the study field sites (Fig. 58), corresponding mainly in the study sites of Santiago Island-Cape Verde, Mamora Sehoul-Morocco, Guadalentin Basin Murcia-Spain, and Crete-Greece. Finally other types of cultivation of the land have been defined in 5.8% of the study fields. This is a special type of cultivation applied mainly in hilly areas with very steep slopes of Santiago Island-Cape Verde in which the land is cultivated by hand in rows located parallel to the contour lines in order to conserve water and reduce soil erosion by surface water runoff (Fig.59).
Fig. 58. Distribution of various tillage operations conducted in the study field sites
Fig. 59. Cultivation of the land in rows parallel to the contour lines (left) and experimental station assessing the effectiveness of these cultivation practices in conserving water and reducing soil erosion in Santiago Island-Cape Verde
