模拟鸟巢式体育场结构对场内草坪生长环境的影响

通过模拟鸟巢式体育场的框架结构来研究其对场内环境因子的影响,分别于2006、2007年夏、冬季连续测定了模拟鸟巢式体育场内不同区域的光照强度、直射光照时间、温度及相对湿度等草坪生长环境指标。结果表明：模拟鸟巢式体育场内的光照强度与直射光照时间显著低于场外对照,夏、冬2季场内的平均光照强度分别为场外对照的23．98％～68．07％和8．00％-60．47％;平均直射光照时间分别只有场外对照的12．08％和3．34％。模拟鸟巢式体育场内的温度和相对湿度则显著高于场外对照,夏季场内外气温的最大差异分别为7．8℃和7．5℃,冬季场内外气温的最大差异只有2．4℃;夏季场内外相对湿度的最大差异分别为6．0％和7．0％,冬季场内外相对湿度的最大差异高达13．0％。文中还讨论了上述草坪生长环境因子的变化可能给场内运动草坪养护管理所带来的困难。     

模拟酸雨对菜园土壤施用猪粪后重金属释放的影响

    采用平衡培养方法,研究模拟酸雨对菜园土壤施用富含重金属猪粪后重金属释放的影响结果表明,pH 36的模拟酸雨培养10 d可导致菜园土壤明显酸化,土壤溶液中Cu、Zn、Cd、Pb等重金属浓度和累积释放量显著高于pH 56的对照溶液,其中Zn和Cd的差异尤为明显,As的情况则相反尽管施用富含重金属的猪粪能缓解土壤的酸化,但菜园土壤培养液中重金属浓度显著高于对照,尤其是Zn和Cd可见,在酸雨沉降频繁的地区大量施用富含重金属的畜禽粪便,将会增加重金属对蔬菜和生态环境污染的风险     

Effect of supplementation with grain, hay or straw on the performance of weaner Merino sheep grazing old man (Atriplex nummularia) or river (Atriplex amnicola) saltbush

Old man saltbush ( Atriplex nummularia ) and river saltbush ( A. amnicola ) are widely used in commercial grazing systems on saline land in south-western Australia. Three hypotheses were tested during a 3-year study aimed at understanding the performance of weaner Merino sheep grazing saltbush-based pastures. The first hypothesis, that young Merino sheep grazing river saltbush would be better able to maintain live weight, body condition and would grow more wool than sheep grazing old man saltbush, was not supported by the data. Across the 3 years of the study, sheep grazing old man saltbush lost significantly less live weight and grew more wool (proportionately 0·06) than sheep grazing river saltbush. Differences in animal performance were considered to be associated with differences between the plant species in in vitro digestibility, concentrations of fibre, sulphur and crude protein in the herbage and the architecture of the Atriplex plants. The second and third hypotheses concerned supplementation strategies for sheep grazing saltbush. Three supplements were offered, namely barley grain, cereal straw or cereal hay, at a rate that approximated to one-third of the daily metabolizable energy requirements for maintenance of live weight. The performance of the sheep was higher when the grain supplement was offered but there was no effect of feeding roughage supplements compared to no supplementation. The findings suggested that the practice of feeding saltbush with adjacent crop stubbles is unlikely to be beneficial once any fallen grain has been consumed.     

Effect of altering the grazing interval on growth and utilization of grass herbage and performance of dairy cows under rotational grazing

The effects of short grazing intervals in the early part of the grazing season on the growth and utilization of grass herbage, and the performance of grazing dairy cows, in a rotational grazing system were examined. Seventy-six cows were allocated to two grazing treatments: a normal rotation treatment (20-d rotations for the first 60 d) and a short rotation treatment (12-, 8-, 8-, 8-, 12- and 12-day rotations). Thereafter, both treatments had the same grazing interval and over the season as a whole both treatments received the same amount of nitrogen fertilizer and were stocked at the same rate. The short rotation treatment significantly reduced pre- and post-grazing sward heights and pre-grazing herbage mass in May and June. Total herbage production was significantly lower on the short than the normal rotation treatment as a result of a significant reduction in the growth rate of herbage in May and June. The short rotation treatment had a significantly lower milk output per cow. Grazing shorter swards, as a result of shorter rotations, significantly reduced herbage intake, reflecting reductions in intake per bite, grazing time and total bites per day. Treatment had no significant effect on herbage quality or pre- and post-grazing sward height in August and September, despite the increased grazing severity in May and June with the short rotations. The severity of rotation length in this instance had a detrimental impact on animal performance, whereas a more modest reduction in grazing interval may control herbage production, without reducing animal performance.     

Effect of frequency of application of inorganic nitrogen fertilizer within a rotational paddock-grazing system on the performance of dairy cows and inputs of labour

As herd sizes and labour costs increase, and the availability of skilled labour decreases, efficient use of available labour becomes more important in dairy cow systems. Two experiments were conducted to examine the effect of reducing the frequency of application of inorganic nitrogen (N) fertilizer on inputs of labour and performance of dairy cows. Experiments 1 (duration of 169 d) and 2 (duration of 179 d) involved fifty-eight and forty multiparous Holstein–Friesian dairy cows, respectively, in mid-lactation. In each experiment, in the 'infrequent' treatment fertilizer was applied to all paddocks on a single occasion at the start of each grazing cycle, while in treatment 'frequent', fertilizer was applied on three occasions each week, within 2 or 3 d of each paddock having been grazed. The experimental treatments were started from 30 March and 29 March in Experiments 1 and 2 respectively. Total N application rates were approximately 360 and 250 kg N ha⁻¹ in Experiments 1 and 2 respectively. Concentrate feed (4·0 kg per cow) was offered daily in both experiments. With the 'infrequent' treatment, highest concentrations of crude protein and nitrate in herbage were observed in swards grazed approximately 10 d after N fertilizer was applied. Treatment had no significant effect on milk yield, milk fat and protein concentrations, and final live weight and body condition score of cows in either experiment. Milk urea and plasma urea concentrations were not significantly affected by treatment. Calculated application times of fertilizer for a herd of 100 dairy cows were 107 and 83 min week⁻¹ for the 'frequent' and 'infrequent' treatments respectively.     

春季禁牧对内蒙古草原植被的影响

2002年春季进行禁牧与自由放牧的对比研究。结果表明,春季禁牧对草原植被的群落特征具有十分显著的影响;在禁牧区,植被产草量、盖度、高度和密度等与自由放牧区之间差异显著(P<0.05)。春季禁牧有利于草原植被的可持续利用。同时,禁牧期的长短对草原植被也有一定的影响,但是不显著。     

土地利用规划管理信息系统的设计研究

针对土地利用规划工作的需要,土地管理必须走信息化的道路,必须充分利用日益完善的地理信息系统技术,以提高管理的效率。设计的土地利用规划管理信息系统,可以大大地提高榆林地区土地管理工作的现代化和科学化决策水平,改善土地利用中存在的问题,其社会效益和经济效益十分显著,具有广阔的市场推广应用前景。     

黄土区野外模拟降雨条件下坡面径流—产沙试验研究

降雨及径流所引起的水力侵蚀产沙问题,是当今世界上最大的环境问题之一。通过野外模拟降雨试验,研究不同雨强下不同下垫面降雨侵蚀产流、产沙、入渗等的相关规律。研究结果表明:雨强90mm/h时,原生地径流量最大,达到28.4L/min,林草地径流量最小,在4.1～7.6L/min之间波动,雨强120mm/h时规律保持一致,原生地达到36.05L/min,林草地为6.85～10.88L/min;产沙量规律为荒地最大,林草地最小,荒地在两种雨强下产沙量分别为45.77～252.94g和52.76～162.48g,林草地分别为2.82～6.99g和7.33～40.24g;入渗规律为林草地最大,原生地最小,其中小雨强时林草地入渗率为1.18mm/min左右,原生地为0.09mm/min左右,大雨强时林草地为1.42mm/min左右,原生地为0.12mm/min左右。这些规律之间均有很好的相关性,产沙量与径流量大时其入渗率就小。说明地表有植被覆盖时可以增大入渗率,减小径流,产沙量。雨强不同时其规律保持一致。该研究对于深入理解流域产流产沙过程具有十分重要意义,可为相关的模型研究提供可靠的试验支持,也可为今后水土保持与生态建设提供重要科学依据。     

太行山区侧柏林地人工降雨下的入渗特性

对降雨入渗的研究是揭示华北地区水源地来水量变化研究的基础。运用人工模拟降雨,在2个2m2的径流小区(编号为P1、P2,坡度分别为19.6°,11.7°)上研究了太行山区侧柏林地的入渗特性,分析了雨强、土壤前期含水量和坡度对入渗的影响。结果表明:(1)入渗过程经历了供水控制阶段和剖面控制阶段,在供水控制阶段,降雨全部入渗,雨强越大,初始入渗率越大;在剖面控制阶段,表观入渗率逐渐降低并直至稳定,而P2小区的首场降雨中表观入渗率却呈现出"先降低后升高"的特点且供水控制阶段时间更短;(2)雨强越大,初始入渗率越大。在P1小区,表观稳定入渗率随雨强增大而增大,这一现象并没有在P2小区出现;(3)土壤前期含水量越大,供水控制阶段的时间越短;对比场次降雨下的土壤负压势变化表明湿润锋运动速度随土壤前期含水量的增加而增快;(4)坡度较大的P1小区(19.6°),其平均表观稳定入渗率较大(0.57mm/min),P2小区(11.7°)的平均表观稳定入渗率较小(0.35mm/min)。     

镧对西葫芦幼苗模拟酸雨胁迫的缓解效应

以西葫芦为材料, 研究了模拟酸雨胁迫下适量镧（La）对幼苗生长及叶绿素、可溶性蛋白和脯氨酸含量的影响。结果显示, 镧处理对酸雨胁迫有一定的缓解作用. 在pH 3.5和3.0 时,幼苗鲜重均显著高于模拟酸雨组,并恢复到对照的94.7%和78.6%;但在其他胁迫强度下, 镧处理的缓解效应不显著。叶绿素和可溶性蛋白的含量变化与幼苗鲜重类似,在pH 3.0时镧处理的缓解效应最显著;pH 3.5时镧处理的可溶性蛋白含量超过对照。脯氨酸含量呈现持续上升趋势,且镧处理可增加脯氨酸的积累,但只有pH 3.5和3.0 时显著高于模拟酸雨组。表明镧处理只对中强模拟酸雨胁迫有显著的缓解效应。