HEATHLAND AND ACID GRASSLAND CREATION ON ARABLE SOILS AT MINSMERE - IDENTIFICATION OF POTENTIAL PROBLEMS AND A TEST OF CROPPING TO IMPOVERISH SOILS

The RSPB is attempting to establish heathland and acid grassland on 15 8 ha of arable land at Minsmere, ultimately to benefit two species of rare breeding birds, the stone curlew Burhinus oedicnemus and the wood lark Lullula arborea. An initial study of the arable soils was carried out to assess their suitability for the establishment of Calluna heat hland and acid grassland. Selected chemical properties of the arable s oils were compared to (1) existing heathland and (2) some old-field su ccessions on former arable land, both adjacent to the arable fields to assess the magnitude of the change required. Three soil factors were identified as potential constraints; the arable soils had a much great er soil pH and higher concentrations of exchangeable calcium and extra ctable phosphorus than heathland soils, almost certainly from previous lime and fertilizer additions. These factors will almost certainly ha ve to be reduced in order to establish heath or acid grassland communi ties on the arable soils at Minsmere. In the initial stages the RSPB f ollowed the prescription adopted by MAFF for the re-establishment of h eathland on arable soils within the Breckland Environmentally Sensitiv e Area. This involved an arable cropping regime designed to reduce 'so il fertility'. At Minsmere, linseed, spring and winter barley, and cer eal rye were planted, and inorganic nitrogen and potassium fertilizers applied. The aim was to improve crop yield, increase nutrient uptake and hence remove more nutrients from the system. The crops were harves table in most years, although yields were lower than those found under normal farm management. The cropping removed more nutrients from the system than measured inputs, but there have been no appreciable reduct ions in soil pH or available nutrients. There was a slight indication that the exchangeable calcium concentrations may be declining after se ven years, brit no reduction in soil pH was found. Accordingly, croppi ng must be viewed as a medium to long-term option (> 7 :years) for imp overishing the arable soils at Minsmere. (C) 1998 Elsevier Science Ltd . All rights reserved.