果草系统土壤理化特征

本研究比较了樱桃（Cerasus pseudocerasus）园生三叶草（Trifolium repens)、间种苹果（Malus domestica)苗及清耕3种管理模式对土壤理化性质的影响，结果表明，生三叶草能显著提高0~20 cm土层硝态氮、铵态氮含量，分别为清耕的1.73、1.93倍；速效钾、有机质含量比清耕分别提高了35.08%、52.38%。而间种苹果苗对表层土壤硝态氮、铵态氮、有机质含量无显著影响，仅速效钾含量比清耕提高了48.61%。但生三叶草处理使20~40 cm土层土壤含水量降低25.27%，出现与果树争水的矛盾，因此在天水地区樱桃园的管理中建议生草时间最长为3年，之后便实行清耕覆盖保墒。

Soil fertility of cherry orchard interplanting with grasses systems

The influence of three different management patterns (planting white clover, interplanting apple seedlings and bare land) on soil physical and chemical characteristics was determined in the experiment. The results showed that planting white clover significantly increased the nitrate nitrogen and ammonium nitrogen concentrations of 0-20 cm soil layer, and was 1.73 and 1.93 times of the bare land (CK), respectively. Available potassium and organic matters were also increased by 35.08% and 52.38%. Interplanting apple seedlings had no significant influence on concentrations of nitrate nitrogen and ammonium nitrogen in topsoil, while it made available potassium concentration increase by 48.61% compared to CK. However, the soil water content under planting white clover treatment decreased 25.27%, and the competition for water between grass and trees appeared. Thus, we suggested that the span of growing grass in cherry orchards in Tianshui area should be less than 3 years and then the soil should be cultivated and mulched for water retention.