草地早熟禾草坪土壤水分动态与根系生长分布

Soil moisture dynamic and root growth of Kentucky bluegrass turf

对草地早熟禾草坪土壤水分动态和根系生长发育状况进行研究,结果发现不同土壤层次水分变化有所不同,0～15cm变化最大,15～30cm次之,30cm以下土层水分变化不大;草地早熟禾的根系生长呈现双峰曲线模式,5月中旬和8月中下旬总根量处于峰值;其主体根系主要分布在0～30cm土层内,占总根量的85%以上;根重密度随土层深度呈指数衰减关系,0～30cm土层下降幅度较大,30cm以下土层根重密度相差不大;在0～30cm土层内不同层次根量占总根量的比例在不同时期亦有差异,春秋季节10～20cm和20～30cm土层内根量比例较大,说明此时期主体根系分布在较深的土层;综合分析认为草地早熟禾草坪主要利用土壤浅层水分,在降雨较少的春秋季节,根系较深,适宜深层灌溉,在降雨频繁的夏季,根系较浅,适宜浅层灌溉。

With expanding turf areas and increased costs for developing water resources in urban, it has become very important to research irrigation requirements. Water moves into turfgrass roots from soil. The irrigation rate should be not equal in each season because the depth of root system decided the intensity for using soil water. The experiment on soil moisture dynamic and root system growth of Kentucky bluegrass turf was conducted. The results showed that: (a) Acuteness of soil water content change was different from soil layer to layer. It was greatly in 0～15cm, less so in 15～30cm, and light below 30cm.In June and the middle of July to August in 2002 and in May to the middle of August and September in 2003,in which precipitation focused relatively, volumetric soil water content of 0～15cm was 20%～35%,of 15～30cm was 25%～35%,of 30～45cm was 30%～35%,of 45～60cm was 25%～30%,of 60～90cm was 17%～22%,and of 90～120cm was 20%～25%.Compared to rainy season, it of 0～15cm could decrease to 15% and of 15～30cm could decrease to 23%,but of 30～120cm changed not too hardly in drought period. It of 60～120cm was located basically in field capacity. But when intense precipitation and irrigation taken place, it would increase quickly and then decrease fastly, which illustrated seepage loss existed.(b) Root system growth showed a bimodal growth pattern which was similar to the growth pattern of type cool-season turfgrass. Maximum occurred at the middle of May and August, and minimum occurred at June and July;(c) About 85% of root lived at 0～30cm soil layer. Root density showed index movement. The root proportion in 10～20cm and 20～30cm soil layer was greatly in May and the middle of August to the middle of September, which showed that the major root zone was relatively deep in this period. On the summed-up results, Kentucky bluegrass turf use mainly water in top-layer soil. Because of the deeper root and less rainfall in spring and autumn, it is suitable to irrigate turf deeply. Oppositely, it is suitable to irrigate turf shallowly in summer.