铬天青S－溴化十六烷基三甲铵－乙醇高灵敏分光光度法测定植物和土壤水中铝

本文探讨了铝与铬天青Ｓ的最佳显色反应条件。当ｐＨ为６．５，在溴化十六烷基三甲铵（ＣＴＭＡＢ）和乙醇的存在下，铝与铬天青Ｓ形成绿色配合物，最大吸收峰位于６３５ｕｍ，表观摩尔吸光系数为１．６５×１０５Ｌ／ｍｏｌ·ｃｍ，铝含量在０～０．２４μｇ／ｍＬ范围内符合比耳定律。在本实验条件下，该方法具有良好的选择性，应用于植物和土壤水中铝的测定，结果满意。     

植物对水分胁迫的分子响应及其遗传改良研究进展

植物对水分胁迫适应性的生理机理已相继在水稻、小麦、玉米、高梁等作物中得以报道。然而，有关这些性状的遗传控制及其在与逆境下作物生产的关系却了解甚少，由此阻碍了抗性遗传改良的进展。随着基因定位、基因组图谱、基因转移等分子生物学技术的发展，对植物抗逆性状进行分子剖析成为可能。本文综述了主要禾谷类作物对水分胁迫的抗性生理及遗传研究上的最新进展，讨论了植物抗性遗传改良的发展前景。     

铵、钾同时存在时, 土壤对铵的优先吸附

The water stability of aggregates in various size classes separated from 18 samples of red soils under different managements, and the mechanisms responsible for the formation of water-stable soil aggregates were studied. The results showed that the water stability of soil aggregates declined with increasing size, especially for the low organic matter soils. Organic matter plays a key role in the formation of water-stable soil aggregates. The larger the soil aggregate size, the greater the impact of organic matter on the water stability of soil aggregates. Removal of organic matter markedly disintegrated the large water-stable aggregates (> 2.0 mm) and increased the small ones (< 0.25-0.5mm) to some extent, whereas removal of free iron(aluminium) oxides considerably destroyed aggregates of all sizes, especially the < 0.25-0.5 mm classes. The contents of organic matter in water-stable aggregates increased with aggregate sizes. It is concluded from this study that small water-stable aggregates (< 0.25-0.5 mm) were chiefly cemented by Fe and Al oxides whilst the large ones (> 2.0 mm) were mainly glued up by organic matter. Both free oxides and organic matter contribute to the formation and water stability of aggregates in red soils.     

榆林沟流域坝系建设调查

榆林沟流域坝系建设调查郭玉梅，张庆伟（黄委会绥德水土保持科学试验站，陕西绥德县７１８０００）寇俊峰，武哲（黄委会黄河上中游管理局）榆林沟流域是无定河中游左岸的一条支流，流域面积６５．８ｋｍ２，其中沟谷地占５１．１３％，沟间地占４８．８７％，主沟道长１...     

黄河流域水土保持梯田建设

黄河流域水土保持梯田建设高荣乐（黄委会黄河上中游管理局，西安７１００４３）一、梯田建设的发展历程黄河流域坡地修成梯田的历史悠久，有明确记述及可考证的是在明清两代。古代农民在坡地耕作中沿等高线留地界使坡面逐步形成阶梯状，这是黄河流域梯田最早形成的方式。...     

植被盖度对水土保持功效影响的研究综述

就近年来国内有关植被盖度对降雨能量、降雨截留、土壤入渗、初损降雨量、径流量以及泥沙量的影响做了综述;分析了理研究中不足之处,并就今后研究中应注意的问题提出了作者的观点和看法。     

调整农业结构与水土保持

农村土地利用结构是否合理, 对水土流失严重区小流域水土保持综合治理效果及农村经济发展影响很大。湖南省衡东县水保站通过在不同坡度、耕作措施、植被状况下设立降雨-径流-土壤流失观测试验小区进行观测试验的基础上, 调整土地利用结构, 使之逐步趋于合理, 再结合水土保持生物、工程措施, 使该流域水土流失综合治理效益显著。     

治理荒漠 保持水土 加快生态农业建设步伐

<正>榆林地区位于陕西省北部,毛乌素沙漠南缘.全区12个县(市),总人口321万,农业人口283万,总土地面积4.36万km~2.榆林地区以长城为界分为两大地貌单元,北部为风沙草滩区,占42%;南部为黄土丘陵沟壑区,占58%,属干旱半干旱大陆性季风气候,年平均降水量399mm.区情特点是:经济相对落后,是国家重点扶持的贫困地区;资源极为丰富,是国家重点开发、可持续利用的能源重化工基地;生态环境脆弱,是全国水土保持、防沙治沙的重点地区.     

Practice to avoid contamination of drainflow and runoff from slurry spreading in spring

Abstract. Use of either three or six occasions to spread similar total amounts of slurry was investigated over the late winter/early spring period in two years, on plots with underdrainage. Slurry was spread on four 7 m by 25 m plots which were instrumented to allow collection of drainflow and runoff. The 'mobile water' pore space allowed transport of a small proportion of applied slurry through the 0.75 m soil profile. Evidence of a polluted 'mobile water' pulse occurred after periods of up to 48 hours following spreading, suggesting subsurface rather than overland flow. Timing of the pulse depended on whether subsequent rainfall accelerated the flow The contaminated flow persisted for 6–12 hours. The worst contamination of 39 mg/l NH₄⁺ -N occurred under 'bypass flow' conditions, when 52 mm of rain fell during the 48 hours after a 5.2 mm application. Two contributory factors appeared important. The first was the long duration of the high intensity storm and the second was an extended period of severe frost believed to have created fissures associated with frost heave. Making several applications of slurry in amounts less than 35 m³/ha is preferable to fewer larger applications during spring, for cereals on medium to heavy soils. This recognises the likelihood of there being underdrainage on arable land and the optimal use of well-drained, partially frozen ground to avoid compaction by slurry tankers.     

半干旱黄土区沙棘的水分生理生态与形态解剖学特性研究

1986～1997年在半干旱黄土区的陕西吴旗、安塞县和宁夏固原县,对沙棘进行了蒸腾、净初级生产量、土壤水分等生理生态和形态解剖学特性研究。试验结果表明:沙棘每生产lg地上干物质,总耗水量为711～829g,其中蒸腾耗水量为551～654g,该地区荒山植被生产lg地上干物质蒸腾耗水量为343～709g,总耗水量却达2540～4501g。水分利用效率为1.21～1.53g/（m²·mm）,是荒山植被的3.1～6.4倍。沙棘水分利用效率较高,水分生产潜力较大。观察沙棘叶、根具有耐大气干旱、耐高温和水湿的形态解剖学特性,说明沙棘有较强的生态适应性。因而在半干旱黄土区的荒山、荒沟,营造沙棘林,能有效利用水土资源,这是快速治理荒山,提高土地生产力的有效途径之一。