福建土壤对酸沉降的相对敏感性评价与区划

选择母岩、土壤类型、土地利用和降雨量 4个生态因子 ,应用半定量化方法对其进行类目划分和权重 ,综合评价了福建省土壤对酸沉降的相对敏感性 ,并应用地理信息系统进行了区划 .由于福建省风化缓慢的硅质岩所占的比例较大 ,土壤大多呈酸性至微酸性反应 ,降水丰富 ,加之针叶林面积大 ,所以全省有 60 %以上面积的土壤显示出较大的敏感性等级 (5～ 7级 )     

Residue management for reducing evaporation in relation to soil type and evaporativity1

Abstract. Usual residue-management options are to remove the residue, use it as mulch with or without undercutting or to incorporate it into the soil. While the role of surface mulch in evaporation has been widely studied, the information on the effect on evaporation of mulch with undercutting or residue incorporated into soil, particularly in relation to soil type and evaporativity (E_o) is lacking. We studied the effect of wheat straw used in various ways on the course of evaporation loss from soil columns with three soils at Ludhiana, India and one soil at Bushland, Texas, USA, under two E_o's Energy-limited evaporation rates under mulch (E_om) followed the soil-specific relation E_om/E_o= a e^(bRes+cEo), where Res is residue rate t/ha and a, b and c are constants; E_o, is expressed in mm/d. In an effort to model the total evaporation (CE) during the energy-limited stage ‘U’ was obtained from appropriate CE versus time curves and (CE-U) was regressed over (t - ti)^0.5 to obtain the slope ‘α’ (Ritchie 1972) for the soil-limited evaporation stage. The observed ‘U’ was independent of mulch rate and E_o but was strongly affected by soil type, Values of ‘α’ decreased with increase in mulch rate and decrease in E_o and coarseness of soil. The otherwise short lived benefit of evaporation reduction with mulch per se, which peaked after a few days was maintained when residue was mixed with soil at the stage when evaporation reduction reached a maximum; this benefit continued for several weeks. Cumulative evaporation values computed from ‘U’ and ‘α’ agreed closely with the observed values under straw mulch for loamy sand and clay loam soils and for ‘undercut’ and ‘residue mixed’ treatments on all soils regardless of E_o, and for all situations under small E_o. However, for sandy loam and silt loam soils under E_o of 10 mm/d, the modified square root of the time function of Jalota et al. (1988) gave a better fit.     

重迎茬亚麻生长发育障碍机制的研究

重迎茬亚麻减产是由多种因素综合作用的结果,亚麻重迎茬可使病害加重是最主要因素,重茬年限越久发病越严重;重迎茬造成了土壤营养元素的单一消耗,随着重迎茬年限的增加,土壤中速效氮、速效磷、速效钾等含量降低。     

松嫩平原羊草草地水淹干扰恢复过程的群落动态

根据随机取样的测定数据，经过幂函数和多元回归分析及相关检验，揭示了草地水淹干扰对羊草 寸草苔、羊草 杂类草群范数量性状的变化规律。水淹干扰对草地植被的物种组成及其比例有明显的影响。水淹后基本恢复到正常草地的种类数量和生产量配置大约需要6—7年。随着生境水分减少和土壤变干，羊草种群的数量和生物量均以幂函数形式增加，而寸草苔和杂类草的数量和生物量则呈先增后降的变化过程。     

铅对草坪植物生物量与叶绿素水平的影响

通过盆载模拟试验研究了铅对植物生物量、叶片叶缘素含量变化的影响，以及植物中毒后的症状。结果表明，铅对植物根系生长发育影响极大，可使根冠细胞有丝分裂减少、根量减少。铅进入叶肉组织后导致叶片失绿，严重时使叶片枯黄死亡。试验早期植物中毒症状表现为根冠膨大变黑，严重时根系腐烂。当营养液中Pb浓度达5.0mol／m^3时，试验后期引起植物死亡且不易恢复。     

覆盖免耕在休闲期的节水和生育期的调温效应

对免耕覆盖、秸秆还田和常规耕作在休闲期的节水效果研究表明:在夏季休闲期,免耕覆盖比常规耕作多贮水30.62mm,比秸秆还田多23.91mm;在冬季储水灌溉期间,可将储水定额从2100m3/hm2减少到600和975m3/hm2。对春小麦生育期土壤表层,5、10、15、20和25cm处温度变化观测发现:免耕覆盖土壤温度在气温较低的8:00可以提高土壤表层温度,在气温较高的14:00可以减缓土壤温度的升高,而在19:00气温降低时可以减缓土壤温度的降低,使土壤温度一直保持在一个稳定的状态,这有利于调节农田小气候,创造作物良好的生长环境。     

尕海地区弃耕地土壤可溶性盐分测定

１９９０～１９９３年在柴达盆地尕海地区弃耕地进行土壤可溶性盐分测定，测定结果，该地区土壤盐分组成为氯化物－硫酸盐和硫酸盐－氯化物，大部分地区耕层盐分含量小于１０ｇ．ｋｇ＾－１，少部分盐荒地表层含盐量高达７０ｇ．ｋｇ＾－１，牧草生长季节中，土壤盐分含量最低期在６月份。     

碧峰峡森林土壤性状研究

碧峰峡不仅是旅游景点,还是多学科研究的天然“实验室”,地处雅安亚热带区,原始森林植被保护完好,土壤垂直分布明显,地质现象复杂,也是大熊猫、金丝猴出没之地。经研究结果：土壤呈酸性,自然肥力高．经相关分析结果：土壤有机质含量和ＣＥＣ等有关理化特性的相关性,较物理性粘粒与ＣＥＣ间更加显著。     

梯田基线设计与简易放线法

梯田基线设计,多采用经验法,等高等宽不好兼顾,“大弯就势,小弯取直”往往只能定性,不能量化,由此设计出的梯田埂线,难以得出最佳梯田断面。如根据地形图等高线走向趋势,选择代表地面走向的等高线,通过概化分析,以数学函数式表达等高线,使其横贯坡面切割等高线为最少,以此作为梯田地埂基线,由其函数对应值,在实地进行坐标放线,即可做到等高布设、等宽兼顾和“大弯就势,小弯取直”定量化,既满足机械作业对曲率半径的要求,也避免了施工时的大切大垫。