Controlling soil water erosion and phosphorus losses from arable land in England and wales

Soil water erosion and P losses were monitored annually in 13 erosion susce ptible arable catchments (ca. 80 fields) in England and Wales between 1989 and 1994. Erosion was recorded in 38% of the 385 fields monitored, with ca. 80% of the erosion events occurring on land cropped to winter cereals. Thr ee main factors were associated with the erosion events: poor crop cover (< 15%), presence of valley floor features that concentrated surface runoff, a nd compacted tramlines/wheelings. The rainfall events causing erosion were generally greater than 15 mm/day (90% of cases), with maximum intensities > 4 mm/h (94% of cases). Mean annual soil losses were 17 Mg/ha (median 0.48 M g/ha). Annual edge-of-field P losses via soil (rill and gully) erosion from arable land were estimated at ca. 2300 Mg, equivalent to approximately 18% of estimated P losses from agricultural land in England and Wales. A numbe r of erosion control techniques also were tested. The use of minimum (or no ninversion) tillage techniques that leave straw on the soil surface were ef fective in reducing erosion, although there were some practical problems wi th crop establishment. Avoiding fine rolled seedbeds minimized slaking and capping at the soil surface, helping to maintain water infiltration rates a nd reduce runoff. Where winter cereals were grown, early drilling encourage d crop cover development during the autumn period, protecting the soil from the erosive impact of rainfall. To avoid wheeling compaction, tramlines we re best set up after winter cereal crops had emerged and any trafficking de layed or avoided in the autumn.