Herbaceous crops, vineyards and olive groves. The traditional land management and its impact on water erosion

The loss of productivity and the frequent use offertilizers and pesticides in Spanish agricultural fields makes us reflect on the adequacy of the soil management used in our land. Soil erosion is one of the processes involved in this loss of productivity, showing the need/importance to evaluate its severity. Such an evaluation is essential for decision-making by society, consumers and/or farmers, and to guide the competent authorities to implement suitable measures. During the last 16 years we have been studying soil loss in the main crops in Spain (cereal, olive groves and vineyards) using different techniques. So, we can know the impact of different land management in our agricultural lands and whether the erosion rate is tolerable or not by today's standards. It has been tested in different settings that the managements with bare soil, such as tilling and/or the use of herbicides, threatens the soil conservation with average erosion rates up to 20 t ha(-1) yr(-1). These erosion rates vary from 1.3 t ha(-1)yr(-1) with rains of low erosivity, to 93.5 t ha(-1) that can be produced in a single storm event highly erosive. In the case of woody crops (olives and grapes), we have studied different soil managements. The spontaneous vegetation reduced vineyard erosion rates to 1.76 t ha(-1) yr, value limit of what is considered admissible in our circumstances. The soil managements more effective to control erosion were permanent grass cover and mown cereal cover, with soil losses of 0.24 and 0.32 t ha(-1) yr(-1) respectively. Thus, we recommend the use of groundcovers, the management of which will vary depending on the characteristics of the area.