Effects of 'Agri-SC' soil conditioner on soil structure and erodibility: some further observations

Abstract. In field and laboratory experiments the conditioner‘Agri-SC’has shown improvements in the structure of loamy sand soils in east Shropshire, UK. It resulted in statistically significant decreases in soil bulk density values and increases in soil porosity and aggregate stability. Further experiments are in progress on both loamy sand and silt loam soils.     

Yield Stability of Winter Wheat (Triticum sp.) Cultivars and Lines

The purpose of this study was to compare responsiveness to environment as well as the stability of newly developed promising lines with traditional commercial cultivars. Subject research was conducted in Ankara between 1983-1989 on common and durum wheat cultivars and lines. Regression coefficient (b) was used as the criterion of genotypes' responsiveness to environment whereas deviation from regression (S²d) and coefficient of determination (r²) were used as stability parameters. Each experiment year was regarded as an environment and yield average of each year was used as the environmental index.
In consequence of the research, it was determined that new varieties with high yield, adaptable to diverse environments could be developed by means of hybridizations between parents having different genetic characteristics which were provided from diverse ecological regions.     

长期不同施氮量下黑土团聚体稳定性及有机碳含量的变化

为测定不同氮肥施用量对黑土团聚体组成及稳定性、有机碳含量及团聚体有机碳分布的影响,阐明黑土有机碳稳定性对不同施氮水平的响应机制,本研究在吉林省梨树县不同施氮水平长期定位试验田进行取样,以施氮水平不同设置5个处理,分别为T1(0)、T2(160 kg·hm^-2)、T3(240 kg·hm^-2)、T4(280 kg·hm^-2)、T5(320 kg·hm^-2),分析长期不同施氮量下水稳性团聚体组成、团聚体结构特征、土壤总有机碳含量及团聚体有机碳分布的变化,探究酸化黑土有机碳含量影响特征。结果表明：随氮肥施用水平的升高,土壤碱解氮(AN)和全氮(TN)含量先增后减,T3处理含量最高,AN和TN分别比T1处理高24.90%、10.28%;土壤速效磷(AP)的含量呈下降趋势。随氮肥用量的提高,土壤团聚体呈现大粒径团聚体向小粒径团聚体转变的趋势,>2 mm粒径团聚体下降14.55%。土壤有机碳总量随施氮水平的提高呈先增后减的趋势,施氮量为280 kg·hm^-2有机碳含量最高;>2...     

电涡流缓速器对车辆制动稳定性的影响分析

修正车辆理想制动力分配曲线使之适用于装用电涡流缓速器的车辆,对装用电涡流缓速器的车辆制动稳定性进行了定性分析,并且提出了增加前后制动器制动力的分配系数来提高装用缓速器后的车辆制动稳定性的技术措施.对给定参数的车辆的定量分析表明,提出的技术措施能扩大车辆同步附着系数的范围,降低车辆后轮先抱死的可能性,提高车辆的制动稳定性.     

Analysis of a site x year experiment with timothy polycross progeny

Summary Results from a cooperative breeding programme with timothy for the northern areas of Scandinavia are presented. The main aim of the programme was to identify genotypes for synthetic populations that are high yielding, adapted over the whole area and stable over years. A polycross comprising 12 genotypes from each of five sites within the region was formed. The subsequent 60 half-sib families and four reference varieties were then compared under sward conditions at the same sites. The trials lasted for three years and results for total dry matter yields are presented.Significant differences in yield between lines were found. There were also significant two and three factor interactions between lines, sites and years. A new two-step procedure is presented to select the genotypes to make up a synthetic variety. Firstly, a superiority measure (Q-value) is used to select a group of genotypes that are high yielding and stable over sites and years. Secondly, the GxE part of the Q-value is split into two terms. One measures adaptation to predictable environmental conditions. The other one measures stability to unpredictable changes in the environment. A plot of these two measures provides a tool for discarding unstable or poorly adapted genotypes. The statistical properties of the selection parameters are discussed.     

中国六省土地沙漠化敏感性时空格局与趋势分析

以我国新疆维吾尔自治区、青海省、内蒙古自治区、甘肃省、宁夏回族自治区和陕西省六省区为研究区,分析了1990年、2000年、2005年、2010年4个时期的土地沙漠化敏感性空间格局分布和时间动态变化特征,探讨变化成因并采用CA-Markov耦合模型对土地沙漠化敏感性格局变化趋势进行预测。结果表明:中国六省四期土地沙漠化敏感性格局相似,各级敏感区按分布面积大小排序为:轻度敏感区域 > 中度敏感区域 > 高度敏感区域 > 不敏感区域 > 极敏感区域。极敏感区域主要分布在土壤质地为流动沙地的沙漠区域,不敏感区域主要分布在高山、湖泊附近;人口增多、人为活动强度增加的区域敏感性程度增高;建立治沙工程的区域敏感性降低。对2020年土地沙漠化敏感性格局预测结果显示,相比2010年,极敏感区域在原有的基础上向外围扩张了7 120.04 km²,增幅为4.63%。本文通过分析中国六省土地沙漠化敏感性时空格局与趋势,为中国土地沙漠化防治分区策略制定和划分沙漠化扩展屏障区提供科学依据。     

干拌法橡胶粉改性沥青混合料高温稳定性的时间敏感性分析

利用干拌法制作橡胶粉改性沥青混合料,将搅拌好的沥青混合热料在搅拌锅中进行闷料处理,温度恒温在165℃,分别闷至0 min、15 min、30 min、45 min、60 min,用每个时间段的沥青混合料制成试验用的试件进行高温稳定性分析,结果表明,在闷料开始阶段,橡胶粉改性沥青混合料的稳定度随闷料时间的增加逐渐提高,当闷料时间为15 min左右时,混合料的稳定性达到最大值,随后,稳定性逐渐下降。     

在体外模拟瘤胃发酵条件下N-乙酰-DL-蛋氨酸稳定性的研究

通过两个试验,研究在体外模拟瘤胃发酵条件下N-乙酰-DL-蛋氨酸的降解率。试验1:N-乙酰-DL-蛋氨酸在pH值6.5、温度为39℃的缓冲液中孵育9h,其降解率为3.3%。试验2:运用瘤胃体外发酵技术研究N-乙酰-DL-蛋氨酸不同添加量对pH值、氨态氮、微生物蛋白动态变化的影响。结果表明,添加0.4、0.6gN-乙酰-DL-蛋氨酸发酵3～6h,均能够显著降低体系的pH值;添加0.6gN-乙酰-DL-蛋氨酸发酵12h能够显著提高氨态氮的浓度;N-乙酰-DL-蛋氨酸在发酵过程中不影响微生物蛋白产量。以上结果显示,N-乙酰-DL-蛋氨酸在体外模拟瘤胃发酵的条件下可以稳定存在。     

Bats adjust temporal parameters of echolocation pulses but not those of communication calls in response to traffic noise

Many studies based on acute short‐term noise exposure have demonstrated that animals can adjust their vocalizations in response to ambient noise. However, the effects of chronic noise over a relatively long time scale of multiple days remain largely unclear. Bats rely mainly on acoustic signals for perception of environmental and social communication. Nearly all previous studies on noise‐induced vocal adjustments have focused on echolocation pulse sounds. Relatively little is known regarding the effects of noise on social communication calls. Here, we examined the dynamic changes in the temporal parameters of echolocation and communication vocalizations of Vespertilio sinensis when exposed to traffic noise over multiple days. We found that the bats started to modify their echolocation vocalizations on the fourth day of noise exposure, with an increase of 42–91% in the total number of pulse sequences per day. Under noisy conditions, the number of pulses within a pulse sequence decreased by an average of 17.2%, resulting in a significantly slower number of pulses/sequence (P < 0.001). However, there was little change in the duration of a pulse sequence. These parameters were not significantly adjusted in most communication vocalizations under the noise condition (all P > 0.05), except that the duration decreased and the number of syllables/sequences increased in 1 type of communicative vocalization (P < 0.05). This study suggests that bats routinely adjust temporal parameters of echolocation but rarely of communication vocalizations in response to noise condition.