循环曝气灌溉条件下小白菜生长及水分与养分利用

研究循环曝气灌溉对不同土壤作物水分及养分利用影响的规律可为循环曝气灌溉技术在不同土壤中的应用提供理论指导。以河南省3种典型土壤(郑州黏土、洛阳粉壤土和驻马店砂壤土)为供试对象,小白菜为供试作物,设置常规地下滴灌为对照组(CK)、循环曝气灌溉为试验组(CAI)开展盆栽试验,研究了循环曝气灌溉对作物生长生理指标及水分与养分利用的影响。结果表明,与CK相比,CAI可促进根系生长,其中郑州黏土和洛阳粉壤土CAI根系活力分别显著增大46.36%和16.79%(P0.05),根干质量分别显著增大35.33%和26.22%(P0.05)。CAI处理净光合速率较CK有显著提高(P0.05),其中郑州黏土、洛阳粉壤土、驻马店砂壤土依次增大了17.69%、12.41%和21.43%。循环曝气处理有效提高了作物氮、磷、钾的吸收效率,其中,郑州黏土和洛阳粉壤土氮素吸收量较CK分别显著提高23.68%和27.72%(P0.05);3种土壤CAI作物磷、钾吸收效率均有显著提高(P0.05),其中郑州黏土分别增加了27.54%和62.81%,洛阳粉壤土增加了25.20%和63.26%,驻马店砂壤土增加了26.86%和23.97%。循环曝气灌溉能显著提高小白菜产量和水分利用效率,其中,郑州黏土和洛阳粉壤土小白菜地上部鲜质量较CK分别提高了58.42%和62.03%,水分利用效率分别提高了27.86%和16.47%。综合比较小白菜生长指标、产量、水分利用及养分吸收效率,郑州黏土循环曝气灌溉处理具有最为显著的改善作用。     

Can hydrochar and pyrochar affect nitrogen uptake and biomass allocation in poplars?

Positive effects of pyrochar on soil nutrient availability and plant growth are widely reported in literature. However, few studies have reported effects of hydrochars on plant nutrition. A pot trial was conducted over a period of 2 years to investigate the effect of a pyrochar (AGT) and a hydrochar (HTC) on poplar (Populus × generosa , clone AF8) growth, biomass allocation and nitrogen (N) uptake with special emphasis on the quantification (using an isotopic mass balance approach) of char‐derived nitrogen (CDN) absorbed by plants. We found that both pyrochar and hydrochar positively affected above‐ground biomass productivity in the first year, and biomass and nitrogen (N) allocation over the 2 years by reducing the allocation of resources to fine roots. By the end of the experiment, even though the total N uptake was not affected by char, the CDN was more than 24% of the total N absorbed by HTC‐treated plants compared to a negligible amount absorbed by AGT‐treated ones. Finally, char did not affect nitrogen use efficiency (NUE) in the first year of growth, but by the end of the experiment, NUE was higher in the above‐ground biomass of HTC‐treated than in AGT‐ and control poplars.     

Three decades following afforestation are sufficient to yield δ13C depth profiles

Vertical gradients in stable carbon isotope ratios (δ¹³C) in soil profiles can serve to approximate decomposition of organic matter under field conditions. This study tested the time (0, 30, and ≥ 150 y) required for the development of vertical δ¹³C profiles in topsoil by comparing arable, afforested and continuously forested sites, and showed that three decades following afforestation of former cropland are sufficient to develop distinct δ¹³C depth profiles.     

泾惠渠灌区畦长对夏玉米耗水特性和产量影响

泾惠渠灌区中畦田规格参差不齐,灌区由于畦田过长而造成的灌溉水量浪费屡见不鲜,不仅没有形成高产而且极大的造成了水资源的浪费。通过大田与小区试验相结合,以当地农民习惯的灌溉方式为对照,设置3个灌溉畦长处理(80、120、240 m),每个处理设置3次重复,改水为80%。研究了灌溉畦长对夏玉米在生育期内的耗水特性和产量的影响,土壤水分分布与产量及其构成因素的关系等问题,选择出兼顾节水高产可行的最优畦长。研究结果表明:在生育期灌水后,80和120 m处理畦长内畦首、畦中和畦尾的土壤相对含水率较为均匀无显著差异,240 m处理畦长畦首、畦中和畦尾的土壤相对含水率产生显著性差异;80和120 m处理夏玉米在畦首、畦中和畦尾灌水均匀度较为平均且无显著差异,240 m畦长处理差异较为显著,且80 m畦长处理产量分布最为平均、平均水分利用效率最高产量为1.021 839万kg/hm2,水分利用效率为25.12 kg/(hm2·mm)。综合夏玉米产量及其分布、水分利用效率等因素,在泾惠渠灌区80 m的灌溉畦长是兼顾节水高产的最适宜畦长,该结论以期为泾惠渠灌区大田作物高产节水提供一定理论依据。     

基于元胞自动机模型的土地利用情景模拟与驱动力分析

土地利用格局的形成过程比其最终形成的结果更为重要。本文以哈尔滨市双城区为例，利用不同时期的土地利用数据，在土地利用变化关键驱动因素分析的基础上，选取了对土地利用变化影响较大的距离变量、邻近土地利用类型数量、单元自然属性、社会经济因素等4方面14个驱动力因子，建立了基于元胞自动机(CA)与人工神经网络(ANN)相结合的土地利用空间格局模拟模型。在此基础上，对研究区自然禀赋、社会经济快速发展、基本农田保护及土地利用规划等不同情景驱动机制下的土地利用空间格局进行了时空模拟，以此解析土地利用变化过程与驱动力因素的响应关系。模拟结果显示：自然禀赋情景下，各地类变化趋势与现在保持一致；在社会经济快速发展情景下，建设用地面积增加明显，主要由旱地和其他用地转入；在基本农田保护情景下，耕地面积比较稳定，各地类变化趋势较为缓和；在土地利用规划情景下，各地类变化较为合理，兼顾耕地保护和经济发展。研究结果显示，该方法对哈尔滨市双城区土地利用格局变化的驱动机制具有较好的解释作用。     

宁夏中部干旱区滴灌条件下枸杞耗水规律研究

通过开展枸杞覆膜与不覆膜滴灌田间试验,研究了覆膜和灌溉定额对枸杞产量的影响以及枸杞耗水规律。结果表明,(1)除F6(灌溉定额2 160 m3/hm2)、F7(灌溉定额2 430 m3/hm2)处理外,覆膜处理产量均高于不覆膜处理。随灌溉定额增大,覆膜和不覆膜枸杞产量均先增大后减小。当灌溉定额为1 620 m3/hm2时,覆膜和不覆膜枸杞产量均最高,覆膜枸杞产量最高为10 400.7 kg/hm2,不覆膜枸杞产量最高为9 923.40 kg/hm2。(2)不覆膜比覆膜处理全生育期耗水量平均值高19.02 mm。覆膜与不覆膜枸杞各生育期耗水量及耗水模系数随生育期延长均先增大后减小,均呈"果熟期落叶期开花初期春梢生长期"的变化趋势。(3)覆膜枸杞各处理水分利用效率平均为2.99 kg/m3,不覆膜枸杞各处理水分利用效率平均为2.76 kg/m3,覆膜高于不覆膜。除F6(灌溉定额2 160 m3/hm2)、F7(灌溉定额2 430 m3/hm2)处理外,膜下滴灌枸杞各处理的水分利用效率(WUE)均高于不覆膜。枸杞膜下滴灌技术有利于保持土壤水分,减少棵间蒸发,有效节约水资源,适宜在宁夏中部干旱区广泛推广。     

Impact of newly introduced perennial bioenergy crops on soil quality parameters at three different locations in W‐Germany

The land areas used for bioenergy crop cultivation are increasing across Europe. For several years now, various perennial crops have been cultivated, including Miscanthus , switchgrass and reed canary grass, and the newly introduced cup plant, giant knotweed, tall wheatgrass, virginia mallow, and wild plant mixtures. We investigated the impact that many of these perennial bioenergy crops (PECs) have on the soil organic C and N pools, microbial properties, and earthworm activity at three different study sites in W‐Germany with varying soil conditions after an experimental period of five years. Silage maize (Zea maize ) in rotation with green rye (Cecale cereale ) or Triticale was used for comparison (= annual energy crops; AEC). The overall intention of this study was to gain insights into the future trends of soil quality with changes in land‐use towards bioenergy production. Our results emphasized that in general, soil quality was improved through the cultivation of perennials. For example, after five years of investigation, the mean soil organic carbon contents increased, on average, by 1–2% at two of the three study sites, the soil microbial biomass increased from 13% (virginia mallow) to 27% (tall wheatgrass) (p < 0.05) compared to AEC treatment and the mean earthworm activity (cast production) was significantly improved in PECs compared to AEC. These trends were mainly found in silty to loamy soils, but the results were slightly different in sandy soils and dry climate conditions. We suggest that this might be traced back to unfavourable growing conditions for perennial crops during the first years of establishment. To our knowledge, this is the first comprehensive field investigation of the impact of these newly introduced perennial crops on soil quality indicators that considers various site‐ and soil‐specific growth conditions.     

基于"节水增粮行动"取用水合理性分析及补偿措施建议

通过对凌海市节水增粮建设规模、取用水方案及取水合理性分析,其水资源开发利用通过采取管灌、膜下滴灌等工程,可以提高项目区水土资源利用效率,从而达到合理开发利用水资源的目的.本文并对取水的影响与补偿措施提出合理化建议.该项目的实施有利于提高农业综合生产力,保障粮食增产增收.     

丘陵山地区耕地水约束状态研究——以黎香溪流域为例

建立一种土壤水循环机理与地形特征结合的层次评价模型,以长江一级支流——黎香溪流域为研究区,以土壤的蓄水量、土壤地形湿度、蒸散发量和灌溉用水条件作为评价因子,采用层次分析法对流域耕地水约束状态进行综合分析,将水约束状态分为轻度、一般、较重、重度、极重5个等级。通过对300个样本的抽样调查,分析结果总体正确率为78%。灌溉条件的影响力随着约束等级的降低而增加,正确率随着约束等级的降低而降低,从极重到轻度正确率分别为85.00%、81.67%、78.33%、75.00%和68.33%。流域内耕地受用水较重及以上程度约束占总面积的55%。模型对流域内部耕地用水状态的相对差异模拟精度较高,灌溉水平的差异是误差的主要来源。     

Efficiency of Land Utilizationand Urbanization Progress of China

Urbanization is a process that is undergoing all over the world, which will speed up in the forthcoming years, especially in China as the boom of economy. On average, urbanization level is not only depended on the speed, but theefficiency, particularly efficiency of using land resource which affects urbanization directly. This paper provided status quo of land resource utilization efficiency, indictors, methods and factors, and illustrated the reference of well land utilization, aiming at fostering urbanization in China.