SHEEP MANURE IMPROVES THE NUTRIENT RETENTION CAPACITY OF APPLE ORCHARD SOILS

The tree fruit industry has been rapidly developed in the last decade in China. Most of the new orchards were established in mountainous areas, and the orchard soils are usually shallow, sandy and infertile. The soil nutrient and water supply, in most case, cannot satisfy the demand of trees, and therefore tree growth and development is hindered (Shu 1998). Coarse soil structure also results in serious leaching loss of applied chemical fertilizers and irrigation water, which not only increases the production cost, but also causes environmental problems. Improving soil fertility including soil nutrient retention capacity are challenges for the orchard management.
It has been found that application of organic amendments can improve physical and chemical properties of soil and increase soil nutrient and water-holding ability and crop production (Martens and Frankenberger 1992, Turner et al 1994, Dong et al 1997, Zebarth et al 1999, Moskal et al 2001, Whalen et al 2002, Yamada 2002). Soil organic amendments reduced soil bulk density, promoted the formation of organic-inorganic colloid, stabilized soil aggregates and increased bioactivity. There are various soil organic amendments available for the local growers such as animal manures, municipal biosolids, crop straws and industrial wastes. The objective of this study was to determine effects of sheep manure on soil fertility with an emphasis on soil nutrient retention capacity.