Effectiveness of the GAEC standard of cross compliance Management of set aside on soil erosion control

摘要

The GAEC standard Management of set aside is applied to arable lands subjected to set aside and kept non-cultivated throughout the year. The standard is also applied to other set aside areas eligible for direct payments. For the implementation of this Standard, the farmer must assure the presence of natural or artificial green cover on the surface throughout the year and adopt consistent agronomic practices as mowing, or other equivalent, in order to maintain the normal state of soil fertility, protect wildlife, prevent the formation of a potential inoculum of fires, especially during drought and prevent the spread of weeds. Up to the CAP Health Check the legislation on the set aside required the farmer to plough the soil by mid-May. Therefore, the natural vegetation cover could neither establish nor express its value against erosion throughout the year. Since mid 2004, cross compliance has banned ploughing of set aside surfaces. This novelty is very important in relation to the effectiveness of the standard in erosion control. In Italy there are only few studies carried out in the field that have measured the effect of set aside on soil erosion. The few existing experiments regarded the effect of set aside managed in accordance with the CAP dictates prior to the CAP Health Check . The results of case studies show very contrasting results regarding soil erosion on set aside plots managed through the annual ploughing in the period in which this rule remained in force. This finding can be explained by considering that most of soil erosion in the Mediterranean environment is determined by extreme events; so, set aside resulted ineffective in protecting the soil, when very erosive events occurred on bare soil (soil in seed bed condition after ploughing and harrowing) or when the plant cover of soil was still scarce. In these conditions soil erosion rate resulted similar to that observed in the intensive cropping systems. On the contrary, for events occurred when the natural vegetation was sufficiently developed, the beneficial effect of set aside in limiting erosion was similar to that exerted by total grass cover. In general, it can be argued that on plough set aside, an average period of 2 months is needed for the establishment of natural cover sufficient enough to ensure a significant protection of soil from erosion. The results show that in Italy set aside before the CAP Health Check might have determined a decrease of soil erosion by 50% (on average). Since 2005, set aside under cross compliance regime appears to have had a greater beneficial effect than before in reducing erosion, as total grass cover was able to decrease soil loss by 98% compared to intensive farming systems.