黄土低山丘陵及坨甸草原区风蚀规律的研究

本文通过对黄土低山丘陵及坨甸草原区248个风蚀图斑资料的分析,运用线性模型理论,对此地区的风蚀规律进行了研究。获得了下垫面各因素与风蚀量关系的数学模型。找出了影响风蚀的主导因素,并系统阐述了植被覆盖度和土地利用类型对风蚀量大小的影响,且与水蚀规律进行了比较分析。     

陇中黄土高原半干旱区9个燕麦品种籽粒产量及其营养价值研究

本研究对9个燕麦(Avena sativa)品种的主要农艺性状、种子产量和籽粒营养品质进行了比较,以期筛选出适宜在陇中黄土高原半干旱区生产利用的燕麦品种。结果表明：供试燕麦品种均属于中熟型,在当地均能成熟;9个燕麦农艺性状、种子产量及籽粒营养品质之间存在显著差异(P<0.05),‘迪燕1号’的株高和穗长最高,分别为150.00cm和30.50cm,但种子产量最低,为1734.20kg·hm^-2,穗粒数和穗粒重均以‘魏都莜5号’最高,分别为128.4粒和2.84g,‘晋燕17号’的种子产量和淀粉含量最高,分别为2500.00kg·hm^-2和53.68%,但粗蛋白含量最低,仅为15.95%,‘张莜8号’的千粒重最高,为28.20g,粗蛋白含量以‘张莜9号’最高,达18.75%,‘坝莜18号’的β-葡聚糖和粗脂肪含量最高,分别为4.37%和6.35%。应用灰色关联度理论方法对9个燕麦品种的主要农艺性状、种子产量与籽粒营养品质指标进行综合分析得出,‘晋燕17号’‘魏都莜5号’‘迪燕1号’综合性状较好,适宜在陇中黄土高原半干旱区种植及推广。     

耕作措施对温带半干旱地区土壤温室气体(CO2、CH4、N2O)通量的影响

通过设置在甘肃省定西市李家堡镇的不同耕作措施试验, 利用CO₂分析仪、静态箱-气相色谱法对双序列轮作次序下春小麦地、豌豆地生育期内CO₂、CH₄和N₂O通量进行了测定。试验结果表明: 4种耕作措施下春小麦地和豌豆地在生育期内均表现为CO₂源、N₂O源和CH₄汇的功能。传统耕作不覆盖、免耕不覆盖、免耕秸秆覆盖和传统耕作结合秸秆还田下, 春小麦生育期内平均土壤CO₂通量(μmol·m^-2·s^-1)分别为0.203 6、0.221 2、0.241 8、0.224 9, CH₄通量(mg·m^-2·h^-1)分别为-0.041 6、-0.078 0、-0.081 8、-0.053 7, N₂O通量(mg·m^-2·h^-1)分别为0.089 1、0.069 2、0.046 1、0.065 6; 豌豆生育期内平均土壤CO₂通量(μmol·m^-2·s^-1)分别为0.273 6、0.261 6、0.218 1、0.236 0, CH₄通量(mg·m^-2·h^-1)分别为-0.055 0、-0.073 7、-0.066 2、-0.054 5, N₂O通量(mg·m^-2·h^-1)分别为0.123 4、0.084 7、0.080 6、0.035 0。少免耕及小麦秸秆覆盖有利于减少土壤CO₂排放通量, 免耕不覆盖、免耕秸秆覆盖及传统耕作结合秸秆还田均能不同程度地增加CH₄吸收通量、减少N₂O排放通量。综合来看, 免耕不覆盖、免耕秸秆覆盖和传统耕作结合秸秆还田3种保护性耕作措施有助于减少土壤温室气体的排放量。春小麦地CO₂通量随着土壤温度、土壤含水量的逐渐升高而增大; CH₄吸收通量随着土壤含水量的逐渐升高而增大, 而随着土壤温度的逐渐升高而减小。豌豆地CO₂通量的变化与土壤含水量存在极显著正相关关系; 而春小麦地N₂O通量则与平均土壤温度呈显著正相关, 豌豆地则为极显著正相关。     

半干旱黄土高原生物结皮处理下集水造林的初步研究(英文)

集水措施是干旱半干旱地区解决因降雨少且季节间分配不均带来的水资源短缺的主要措施之一,有关微集水区防渗处理材料及其防渗效果的研究也已广泛开展。本文通过5 年(1992-1996)的野外试验对半干旱黄土高原微集水系统生物结皮覆盖对造林的影响进行了研究。结果表明,结皮接种3 年后,集水区表面大部分为结皮所覆盖,其集水功能已经部分地表现出来。在春季3 个典型时段内浅层土壤含水量与对照相比显著提高(0.05 水平),1m 土层内春季月均含水量均比对照提高了0.9%–6.04%。同时在研究期末(1996 年)结皮处理的样地内树木个体的树高(H)、胸径(DBH)和地径(DGL)均较对照有显著提高(0.05 水平),提高幅度分别为22.38%、17.34%和20.49%。作为一种生物防渗材料,生物结皮具有无污染、自我繁殖、使用期长和投入小等特点,因此很可以作为西部大开发中植被恢复的主要集水材料,进一步的工作应放在干旱环境下当地适宜结皮种类的选择及其快速繁殖技术上。     

Soil water response to precipitation in different microtopographies on the semi-arid Loess Plateau,China

Soil water is an important factor restricting afforestation on the semi-arid Loess Plateau.The microtopography of the loess slope has changed the distribution pattern of soil water on the slope.To improve water utilization efficiency and optimize afforestation configuration patterns,the relationship between soil water and precipitation at micro-topographic scale must be studied.We used time series analysis to study the temporal variation of soil water and its response to precipitation in four kinds of micro-topographies and undisturbed slope on loess slopes.Micro-topographies significantly influenced soil water distribution and dynamics on the slopes.Soil water stored in the platform,sinkhole,and ephemeral gully influenced subsequent soil water for 4 weeks,whereas soil water stored in the scarp and undisturbed slope could influence soil water for 2 weeks.It took 12 weeks,10 weeks,18 weeks,6 weeks,and 12 weeks for precipitation to reach the deeper soil layer in the platform,sinkhole,scarp,ephemeral gully,and undisturbed slope,respectively.These soil water characteristics in different micro-topographies are vital factors that should be taken into consideration when undertaking afforestation on the Loess Plateau.     

Institutional performance and participatory paradigms: Comparing two groups of watersheds in semi-arid region of India

Watershed development programmes carried out in different agroclimatic conditions in India resulted in beneficial impact in terms of productivity enhancement and natural resources conservation, but less attention paid to institutional and participatory aspects. This paper explored the performance of various institutions regarding execution of watershed development programmes in semi-arid region of India. Recorded observations from documents maintained at watershed level and information collected through primary survey as well as focus group discussion with different types of stakeholders were used for analysis. The results indicated lacunae in participatory aspects during programme implementation process like monitoring activities, management of common property resources and equity. Gap in linkages and differential level of performance of various watershed level functionaries indicates the necessity for corrections in the structures and linkages pattern for sustainability of the infrastructure and institutions. The study also showed unequal priorities by the implementing agencies towards institutions, land and water resources development, production enhancement activities and fodder resources development as well as rationalities of technical, economic, financial, political and social aspects among the watersheds.     

Soil salinity and sodicity effects of wastewater irrigation in South East Australia

Although ‘sewage farming’ or wastewater irrigation started in Australia in the latter parts of the 19th century, it was in the late 1960s that a considerable interest was revived in arid and semi-arid parts of the world due to scarcity of alternative water sources and the urgency to increase local food production. The practice has manifold benefits in the form of water conservation, nutrient recycling, surface and ground water pollution prevention. But for arid and semi-arid regions like many parts of Australia, while wastewater irrigation can be an attractive solution to irrigation water problems, it might not be the ideal solution for the common soil types encountered in these regions. Due to characteristic low rainfall, high evaporation and low leaching, these soils tend to have higher salt accumulations. This paper examines the soil salinity and sodicity effects of wastewater irrigation in soil types typical to South Eastern Australia and takes the soils of Western Treatment Plant (WTP) as a case study to highlight these issues.     

半干旱区玉米行距调整增密对群体冠层结构及产量的影响

为增加玉米种植密度,构建不同的群体冠层结构,以玉米不同行距配置为基础,研究乳熟期玉米群体的光能利用情况,分析不同行距配置对冠层结构及产量、产量构成因素的影响。结果表明,玉米产量与群体消光系数达到显著相关,且为负相关。在吉林省半干旱区玉米宽窄行行距70-30 cm和宽窄行行距80-30 cm配置下玉米群体对光能资源的利用达到最佳,且有效提高玉米群体产量,增产分别达到8.06%和22.82%。     

Deficit irrigations during soybean reproductive stages and CROPGRO-soybean simulations under semi-arid climatic conditions

This study was carried out to determine the effect of water stress on five different generative stages of soybeans and to evaluate the CROPGRO-soybean model under semi-arid climatic conditions. The study was conducted at the Faculty of Agricultural Engineering, Harran University research field in 2003 and 2004 growing seasons. Plants received full irrigation during vegetative stages, after which it was cut off at different reproductive stages (treatments): R_1-2, beginning of flowering and full bloom; R₃, beginning of pod; R₄, full pod; R₅, beginning of seed; and R₆, full seed. The control treatment was full irrigation throughout. Observed yields ranged from 1955 (R₆) to 3684 kg ha⁻¹ (control) in 2003, and from 1867 (R₆) to 3952 kg ha⁻¹ (control) in 2004, respectively. Generally, in both of the years any water stress imposed on soybeans in three different generative stages (R₃, R₅, and R₆) resulted in substantial yield reduction compared with full irrigation; yield reduction was greatest at the R₆ stage. Biomass and 1000 seed weight also showed significant difference. Overall, CROPGRO-soybean simulated parameters from all treatments were higher compared with observed ones. Although simulated yield results were close to measured ones, they could not track observed yield patterns. Generally, the CROPGRO-soybean simulation model failed to satisfactorily mimic observed soybean yield, biomass, and 1000 seed weight and therefore it is suggested not to be used for similar scenarios and climatic conditions.     

北方半干旱区的PDSI和SPI比较研究

以北方半干旱地区老哈河流域为研究区域,利用流域内及其周边15个气象站1957～2008年的长序列日观测资料,计算逐月的帕默尔干旱指标(Palmer Drought Severity Index,PDSI)和不同时间尺度(1、3、6及12月)的标准化降水指标(Standard Precipitation Index,SPI)。结果表明,52年间分别有6段主要的湿润期和干旱期,持续时间都在1年以上,说明老哈河流域旱涝持续性较强。将不同时间尺度的SPI与PDSI进行对比发现,随着时间尺度的增大,SPI对干旱持续性的表现能力增强,12个月时间尺度的SPI与PDSI一致性较好。