In the Mediterranean basin there are several circumstances that have favored soil degradation. On the one hand, the Mediterranean climate itself, warm and with relatively low rainfall and highly variable from one year to the next, which produces more or less intense periods of drought. On the other, the agricultural use of the soil during the last two thousand years, which has favored the loss of organic matter and nutrients, as well as other degradation processes. Erosion in the Mediterranean region is not a continuous process, but sometimes one or two heavy rains are enough to generate high annual erosion rates.
A team of scientists, including researchers from the University of Seville, have published an article in the journal Science of The Total Environment, in which they analyze the effect of a barley straw mulch on the loss of water and sediments in vineyard soils against infrequent episodes of intense rain, characteristic of the Mediterranean climate.
“Traditional agricultural practices contribute to aggravating this situation, since they eliminate the protection of the soil and favor erosion. In risky situations, the loss of the fertile soil layer can have strong economic and social impacts. For this reason, it is necessary to investigate the agricultural management of soils at risk of erosion and find types of management that favor the protection of the soil at a reasonable cost for the farmer, such as straw mulching ”, says the professor at the University of Sevilla and one of the study authors, Antonio Jordán.
Researchers have compared the erosion produced in unprotected soils with that of soils under barley straw mulch and have calculated the application rate taking into account the economic cost of purchasing, transporting and applying the material, which must be profitable for the farmer.
To control the intensity of the rain, its duration and even the size of the drops, a portable rain simulator designed by researchers from the University of Valencia has been used.
“The use of rain simulators in erosion research is useful, because it allows easy control of all the factors involved. In this case, we simulate intense storms, relatively frequent in the area, which are the ones that originate most of the most intense erosive processes in the study area ”, explains Antonio Jordán.
For the study, 20 experiments were carried out on bare soil and as many on padded soil, and in each case hydrological parameters were calculated such as the time of ponding, the generation time of surface water flow, the infiltration rates and the formation of runoff, as well as the loss of soil produced.
From the University to the field
The application of straw mulch is very simple and cheap, and it is useful for all types of cultivated soils. In general, it is a very beneficial practice in several ways. Previous works indicate that mulching favors both the physical and chemical fertility of the soil, in addition, various researchers have found that it also contributes to reducing the risk of contamination of the soil and aquifers.
It is a system that has also been used successfully in the recovery of soils affected by fires. “However, it is necessary to know when to apply it, where and in what quantity. In addition to being less profitable, excessive quantities, misused or inappropriate materials can produce unwanted effects ”, adds the professor from the University of Seville.
This work has been directed by Massimo Prosdocimi (University of Padova, Italy) in collaboration with the Med_soil Research Group of the University of Seville, Paolo Tarolli (University of Padova, Italy), Saskia Keesstra (University of Wageningen, Holland), Ágata Novara ( University of Palermo, Italy) and Artemi Cerdà (University of Valencia).
Massimo Prosdocimia, Antonio Jordán, Paolo Tarolli, Saskia Keesstra, Agata Novara, Artemi Cerdà. "The immediate effectiveness of barley straw mulch in reducing soil erodibility and surface runoff generation in Mediterranean vineyards". Science of The Total Environment 547, 15 March 2016, Pages 323–330. doi: 10.1016 / j.scitotenv.2015.12.076