[Effects of land use types on deep soil water content in the loess hilly area of the north Shaanxi Province, China]. / 黄土丘陵区不同土地利用模式对深层土壤含水量的影响.

This study explored the differences of soil water content at 0-20 m soil depth at three locations, including economical plantation in Mizhi, reforestation area in Shenmu, and wind break and sand fixation forest district of Yuyang, and for clarifying the impacts of different land use types on deep soil water distribution and storage characterization, as well as its eco-environmental effect on the loess hilly area. The results showed that in the soil profile of 0-20 m, land use patterns had a significant impact on soil moisture distribution. There were significant differences of soil water sto-rage for the economical plantation, pruning Ziziphus jujuba plantation ＞ Z. jujuba plantation with 587.9 mm difference. There was no significant difference in soil water storage between Caragana korshinskii plantation and degraded artificial vegetation or between pine forests and natural grass field, degraded artificial grassland ＞ C. korshinskii plantation with 98.8 mm difference at Shenmu, and natural grassland ＞ Pinus sylvestris var. mongolica plantation with 7.5 mm difference at Yuyang. The pruning Z. jujuba tree reduced soil water consumption and was beneficial to sustainable use of soil water due to the decreased crown width and thus reduced transpiration. There were no obvious differences of soil water content between C. korshinskii plantation and degraded artificial grassland due to the historical alfalfa planting which was characterized by high water consumption due to its deep root distribution and large biomass. In contrast, P. sylvestris var. mongolica plantation and na-tural grassland had similar and low averaged soil water contents with 3.4% and 3.6%, respectively, mainly due to the sandy soil texture and weak soil water holding capacity. In addition, with increa-sing soil depth, soil water content increased in this area, indicating the effect of plants on water moisture of deep soil was very limited. Except for the underlying control of soil texture on soil water content in the soil profile, different vegetation played a key role in the dynamics of soil water content due to the difference of root zones. It was very important to choose the suitable type of vegetation regarding the protection and sustainable use of deep soil water.

[Indoor simulation on dew formation on plant leaves].

Dew forming on plant leaves through water condensation plays a significant ecological role in arid and semi-arid areas as an ignorable fraction of water resources. In this study, an artificial intelligent climate chamber and an automatic temperature-control system for leaves were implemented to regulate the ambient temperature, the leaf surface temperature and the leaf inclination for dew formation. The impact of leaf inclination, ambient temperature and dew point-leaf temperature depression on the rate and quantity of dew accumulation on leaf surface were analyzed. The results indicated that the accumulation rate and the maximum volume of dew on leaves decreased with increasing the leaf inclination while increased with the increment of dew point-leaf temperature depression, ambient temperature and relative humidity. Under the horizontal configuration, dew accumulated linearly on leaf surface over time until the maximum volume (0.80 mm) was reached. However, dew would fall down after reaching the maximum volume when the leaf inclination existed (45 degrees or 90 degrees), significantly slowing down the accumulative rate, and the zigzag pattern for the dynamic of dew accumulation appeared.

Comparison of drip, pipe and surge spring root irrigation for Jujube (Ziziphus jujuba Mill.) fruit quality in the Loess plateau of China.

Loess Plateau is a typical rain-fed farming region, facing the threat of drought. Irrigation method is among the most important factors affecting jujube quality. This study investigated the response of Ziziphus jujuba Mill. cv. Lizao quality to three different irrigation methods (drip-, pipe- and surge spring root irrigation) combining two water levels (20 m(3)/hm(2) and 120 m(3)/hm(2)). The effects of the trials were evaluated by taking into account the physical-chemical characteristics of jujubes and the antioxidant activity. Concomitant to this, the concentration of some taste-related (viz. glucose, fructose, TSS and malic acid) and health-related compounds/parameters (viz. catechin and epicatechin) were generally much greater in jujube fruit treated with drip irrigation (120 m(3)/hm(2)). Different irrigation treatments had no significant effects on antioxidant capacity, total phenolics and proanthocyanidins (except for pipe irrigation 20 m(3)/hm(2)). The best compromise between quality and irrigation of jujube fruit was achieved with drip irrigation (120 m(3)/hm(2)).

[Water impounding characteristics of bamboo-shaped rainwater harvesting ditch in the hilly loess region].

Bamboo-shaped rainwater harvesting ditch (BRHD) is a new water harvesting and application technology being promoted in the hilly loess region of North Shannxi Province. This paper measured the soil moisture condition and water storage capacity of BRHDs filled with straw, branch or gravel through field and simulated rainfall experiments to evaluate the water holding and absorption capacity of different BRHD fillers. From May to October, the water storage of BRHDs showed a decrease trend at first and then increased in field experiment. The water storage depths within 30-200 cm profile of branch ditch (BD), gravel ditch (GD) and straw ditch (SD) were 186.76, 177.23 and 169.26 mm in May, respectively, and increased by 14.24, 20.28 and 21.23 mm in October, respectively. In contrast, the water storage depth of the level bench was reduced by 6.52 mm in October from 185.76 mm in May. The soil water restoration depth was different between BRHDs with different fillers and the level bench within 30-200 cm profile in October. The SD and BD had the deepest restoration depth (140 cm), followed by GD (110 cm), and the level bench was the minimum (80 cm). Through rainfall simulation experiment, the amount of water intercepted by BRHD was in the order of SD (99.5 L) > GD (91 L) > BD (71.5 L). The water-holding rate of straw and branch showed logarithmic function with soaking time, while the water-absorption rate followed a power function. Moreover, there was a negative logarithm correlation between water-holding rate and water-absorption rate. Straw showed a better water holding and absorption capacity than branch. Gravel had a weak water holding and absorption capacity which was almost not changed during soaking, while it displayed a negative liner correlation between water holding rate and absorption rate. The three kinds of BRHDs could be applied in the hilly loess region, and that filled with straw would exhibit the best capacity of water interception and holding.