Abstract: To find a suitable ridge-mulching material and yield-increasing mechanism for sainfoin production with a ridge-furrow rainwater harvesting system in the semi-arid Loess Plateau,a field experiment with a randomized block design was conducted during sainfoin growing season in 2017. The experiment was designed to investigate the effects of different ridge mulching materials and furrow to ridge ratios on roots characteristics (dry matter,length,surface area,volume of roots) and nodule characteristics (number and weight of root nodules). Traditional flat planting (TFP) was used as a control. The results indicated that sainfoin roots and nodules were mainly distributed at 0 to 20 cm depth of the soil layer,and the values of roots and nodules characteristics increased as ridge width increased,but decreased as soil depth increased. Root and nodule characteristics of sainfoin plants found at the border of the furrows were distinctly higher than those found at the center furrows. Compared with TFP,MCS (ridges with manually compacted soil),MSB (ridges with manually compacted soil with maize straw biochar),and CDB (ridges with manually compacted soil with cow dung biochar) increased in root dry matter production as follow 18%,113% and 56%,respectively. Similarly,there was an increase in root nodule numbers (180%,860% and 313%) as well as root nodule weight (86%,489% and 198%). In contrast,there was a decrease in sainfoin root length treated with MCS (37%),MSB (33%),and CDB (27%),respectively. Similarly,there was a decrease in root surface area (53%,27% and 44%) and root volume (54%,14%,and 34%) on sainfoin treated with MCS,MSB,and CDB,respectively. The study revealed that the suitable soil water moisture in the furrow profile resulted in an increase of root dry matter,root number and root nodule weight,whereas the suitable drought stress resulted in an increase of root length,root surface area,and root volume of sainfoin plants.

Key words: Biochar-soil crust, Ridge-furrow rainwater harvesting, Root, Nodule, Sainfoin

摘要： 本试验为寻求垄沟集雨种植适宜覆盖材料，探究生物炭土壤结皮增产机理，以传统平作为对照，研究了不同垄覆盖材料和不同沟垄比对红豆草（Onobrychis viciifolia Scop）根系特征值（根干重、根长、根表面积、根体积）和根瘤特征值（根瘤数量和重量）的影响。结果表明，红豆草根系和根瘤集中分布于表层（0~20 cm）土壤，红豆草根系特征值和根瘤特征值随垄宽度增加而增加，随土壤深度增加而减少，沟边的根系和根瘤特征值明显大于沟中。与对照相比，土垄、玉米秸秆炭垄和牛粪炭垄的红豆草总根干重分别增加18%，113%和56%，总根瘤数分别增加180%，860%和313%，总根瘤重分别增加86%，489%和198%；但红豆草总根长分别减少37%，33%和27%，总根表面积分别减少53%，27%和44%，总根体积分别减少54%，14%和34%。适宜土壤湿度促进红豆草根干重、根瘤数量和根瘤重量提高；适宜土壤水分胁迫有利于红豆草根长、根表面积和根体积增加。

关键词: 生物炭土壤结皮, 垄沟集雨, 根系, 根瘤, 红豆草