Dry farming
The Trockenfeldbau , English dry farming is, a shape of the bottom construction , which without artificial irrigation in (semi-) arid occurs areas. As a special form of rain- fed agriculture , it is operated in areas with very little precipitation close to the agronomic dry line - regionally different at around 250–500 mm / a - whereby the precipitation can also stop over longer periods (sometimes over several years).
The aim of the cultivation method is to store rainwater for two or more years, as it rains relatively little and rarely / irregularly, but water is still needed for the whole year. The soil is plowed before the rain and rolled after the rain to reduce evaporation and prevent wind erosion. With dry farming , the fields are laid out in serpentine lines, and plants and bushes are planted around the fields to protect them from the strong wind. The parallel fields are always used alternately (English strip farming ).
The plants, which are adapted to these environmental conditions, satisfy their water requirements exclusively through water that comes from precipitation and through moisture stored in the soil. Some of the rainwater is also stored in cisterns , vessels or mud basins . Usually a humidity gradient is formed between air humidity and soil and between the surface of the earth and groundwater . The soil moisture approaches the moisture content of the air. During the night the surface of the earth cools down, humidity can condense as dew or diffuse directly into the ground.
In southern Europe, especially in Spain and Italy , this type of field management was and is traditionally practiced. Especially cereals such as barley and millet as well as olives , almonds and the carob tree are well adapted to the dry climate. Other areas in which dry field cultivation is carried out include: a. the Great Plains , the steppes in southern Russia and Argentina, and large parts of Africa.
The winemakers in La Geria on Lanzarote dig holes up to 3 meters deep and plant the vines in them. The vines grow individually in these small, walled, individual craters. The meter-thick dark lapilli layer (volcanic ash, also called picón) can be used, as it heats up during the day and absorbs moisture from the air at night. Because it rarely rains here, the water is stored in this way. The roots of the cultivated plants and the grapevines can penetrate into the ground below, which is also protected from erosion. The walls protect the hollows against the northeast passat and the drying out.
