强降雨事件对不同演化阶段白刺灌丛沙堆土壤水分的影响

强降雨事件对干旱区植被土壤水分空间变异有着很大的影响。通过测定民勤县一次强降雨(47.6 mm)事件前后不同演化阶段白刺灌丛沙堆的土壤水分,分析了它对不同演化阶段白刺灌丛沙堆土壤水分及其贮量的影响。结果表明,(1)不同演化阶段灌丛沙堆土壤水分在1 m土层内垂直方向上的变化趋势一致。雏形阶段土壤水分垂直方向上变异最大且变化不稳定,稳定阶段土壤水分垂直方向上变异最小。(2)不同演化阶段白刺灌丛沙堆土壤水分补给深度存在很大差异。发育阶段和活化阶段土壤水分补给最大深度为50 cm,雏形阶段和稳定阶段土壤水分补给最大深度为30 cm。(3)不同演化阶段土壤水分补给总量差异较大。发育阶段补给总量最大,占总降雨量的74.66%～90.06%;稳定阶段补给总量最小,占总降雨量的12.27%～12.86%。

生物炭输入对砾石土水肥保蓄及酿酒葡萄产量、品质的影响

为了探讨有机无机配施条件下,生物炭输入对砾石土水分养分保蓄及酿酒葡萄产量品质的调节作用,在贺兰山东麓开展了2年定位试验,分析了不同用量生物炭输入条件下土壤理化性质及作物生物学响应。结果表明:有机无机配施条件下,随着生物炭施用量的增加,>0.25 mm粒径水稳性团聚体含量显著升高,<0.25 mm粒径水稳性团聚体含量显著降低,土壤结构明显改善;生物炭施用量6000 kg/hm~2以上,可显著提高土壤0~80 cm土体贮水量超过30%,显著提高土壤有机质、碱解氮和速效钾含量;并且显著促进酿酒葡萄叶片的光合作用,优化了果穗长,进而提高了葡萄产量,改善了葡萄品质,基于理论产量模拟最佳生物炭输入量为7260 kg/hm~2。因此,贺兰山东麓砾石土酿酒葡萄园,在有机无机配施条件下,补施生物炭7260 kg/hm~2可快速构建土体,保蓄土壤水分养分,有利于推进酿酒葡萄产业健康可持续发展。

PAM对砾石土水肥保蓄及酿酒葡萄产量与品质的影响

【目的】探讨在有机肥基础上配施不同用量聚丙烯酰胺(PAM)对砾石土土壤改良与水肥保蓄的影响,为PAM应用于酿酒葡萄园土壤改良与产质提升提供理论与技术支撑。【方法】对常规施肥(化肥总量N、P2O5、K2O质量比为26∶10∶12)、单施有机肥6000 kg/hm^2、有机肥6000 kg/hm^2+PAM 300 kg/hm^2、有机肥6000 kg/hm^2+PAM600 kg/hm^2、有机肥6000 kg/hm^2+PAM 900 kg/hm^2、有机肥6000 kg/hm^2+PAM 1200 kg/hm^2等6个施肥模式下砾石土水稳性团聚体、含水率、土壤化学性质及酿酒葡萄产量和品质进行了比较分析。【结果】有机肥配施PAM可显著提高砾石土>2 mm水稳性团聚体量,显著降低<0.25 mm水稳性团聚体量,显著增加土体20~60 cm层次土壤含水率,不同处理以PAM 1200 kg/hm^2配施土壤贮水量最高;PAM施用量超过600 kg/hm^2时,可显著促进葡萄果穗长,进而显著提高葡萄产量,同比常规施肥产量增幅44.08%,模拟显示最高理论产量PAM最佳施用量为1161.23kg/hm^2;PAM施用量为900 kg/hm^2时具有显著提高葡萄可溶性固形物、还原糖量及总酚量,提升土壤有机质,保蓄土壤氮钾养分的作用。【结论】贺兰山东麓砾石土酿酒葡萄园PAM与有机肥最佳配施用量为900 kg/hm^2。

闽北4种林分特征及其林下可燃物载量研究

为更好地进行森林经营与防火管护,以闽北蒲城县4种林分特征及其林下可燃物载量为研究对象,通过采集马尾松林、毛竹林、杉木林、硬阔叶林的样地林分特征与林下可燃物负荷量和水分贮量数据,建立树高曲线,分析林下可燃物载量差异,以及地表死可燃物载量与各影响因子的相关性。结果表明,4种类型的林分特征量较接近,可用于分析林下可燃物载量差异;灌木层、草本层、腐殖质层、枯落物层4种林下结构的可燃物负荷量存在差异,且符合森林生态系统群落可燃物负荷量分布规律;4种林下结构的可燃物水分贮量与乔木树种之间关系不紧密。

Changing the Moisture Content of the Spartina and Miscanthus and Willow Shoots during Storage in Natural Conditions

The aim of this study was to determine the characteristics of the distribution of energy plant moisture content along the height of their shoots and the dynamics of moisture during storage in natural conditions. The shoots of Spartina, Miscanthus and willow were used in the study. Entire shoots were cut into sections of 10 cm and for each set in monthly cycles for six months moisture content was evaluated. After a month＇s storage of freshly cut shoots the biggest decrease of content moisture in the shoots of Spartina and Miscanthus was recorded, by 31% and 22%, respectively, and the lowest in willow shoots （12%）. After sixth months of shoots storage the lowest moisture content （10%-12%） was reached in miscanthus. The most uneven moisture content along the height of shoots Spartina was characterized because on one third of the height from the bottom, the moisture content of shoots was 20%, and the top had moisture content in the range 5%-10%. Willow shoots were characterized by the smallest drop in moisture, and the final moisture content was about 23%, with the top part of moisture content of 10%-20%. The dynamics of moisture change during the six months of storage of grass shoots （Miscanthus and Spartina） in natural conditions under roofing was described by one power function regression, and willow by another one. Empirical models can be used to predict changes in moisture content of these plants in experiment conditions, since the coefficients of determination were 94.66% and 89.18%, respectively.

A Physicoempirical Model for Soil Water Simulation in Crop Root Zone

To predict soil water variation in the crop root zone, a general exponential recession （GER） model was developed to depict the recession process of soil water storage. Incorporating the GER model into the mass balance model for soil water, a GER-based physicoempirical （PE-GER） model was proposed for simulating soil water variation in the crop root zone. The PE-GER model was calibrated and validated with experimental data of winter wheat in North China. Simulation results agreed well with the field experiment results, as well as were consistent with the simulation results from a more thoroughly developed soil water balance model which required more detailed parameters and inputs. Compared with a previously developed simple exponential recession （SER） based physicoempirical （PF^SER） model, PE-GER was more suitable f0r application in a broad range of soil texture, from light soil to heavy soil. Practical application of PE-GER showed that PE-GER could provide a convenient way to simulate and predict the variation of soil water storage in the crop root zone, especially in case of insufficient data for conceptual or hydrodynamic models.