Nutrient Release from Weathering of Purplish Rocks in the Sichuan Basin,China

Purplish soils having high fertility with mineral nutrients inherited from the parent rock are widely distributed in the hills along the Yangtze River,especially in the Sichuan Basin.Pot and field weathering experiments were conducted to mimic rock weathering and nutrient release processes in order to better understand soil fertility and nutrient compensation. Three types of purplish rock formations formed in the Jurassic period,Shaximiao(J_2s),Suining(J_3s),and Penglaizhen (J_3p),as well as one type formed in the Cretaceous period,the Chengqiangyan group(K_1c),were used in this study. Results showed that the soil formation rate was in the range from 11.2 to 19.6 mm every year,and rock weathering was in the order of J_3s>J_3p>J_2s>K_1c.Because more rock surface was exposed to sunlight and rainfall in field conditions,pot weathering was slower than field weathering.Nutrient release rates increased with rock weathering and was in the order similar to that of rock weathering:J_3p>J_3s>J_2s>K_1c.Potassium release was the most important in all rocks;after 2 years of weathering,19.4% to 46.9% of K was released from the initial parent rocks,which suggested that K release from weathering could meet most of the crop K requirement in purplish soils.Thus,rapid release of nutrients from weathering of purplish rocks was key to nutrient replenishment and fertility of purplish soils.

紫色母岩养分的风化与释放

通过田间实验与盆钵模拟, 研究侏罗系蓬莱镇组(J3p)、遂宁组(J3s)、沙溪庙组(J2s) 和白垩系城墙岩群(K1c)紫色母岩的风化和养分释放过程。结果表明,紫色母岩的成土模数为15800～25500t/km 2.a, 其风化顺序为: J3s> J3p> J2s> K1c;风化条件对风化进程影响较大, 模拟风化过程中, 扰动取样更快, 而田间比盆钵模拟风化快2～4 倍。紫色母岩养分释放与风化同步。盆钵模拟风化实验结果表明,1m3J3p 和K1c紫色母岩风化一年,分别有52.78、121.31、3948.4和31.13、71.81、2016.9gN、P、K释放出来。紫色母岩养分风化释放是紫色土养分补偿的重要过程,也是紫色土肥力的主要特点。

紫色土母质的分布及其地质环境——紫色土再研究

紫色土的分布决定于其母质——紫色岩石的分布。紫色岩石是红层的主要部分。红层的形成有一定的水热条件限制,当今地表红层的分布状况却与当地的现实水热条件不完全相符。因此,只有从地质历史演进的角度看待今日红层岩石的分布规律。通过讨论红层分布的历史原因,认为紫色岩石的分布是全球性的,紫色土亦然。

应用生物方法研究紫色母岩风化物供钾能力

利用盆栽试验研究紫色母岩风化物供钾能力。结果表明:紫色母岩母质肥力较高,籽粒苋的耗钾过程中,紫色母岩风化物各钾素形态逐渐降低,不施钾处理比施钾处理降低更快。籽粒苋吸钾量与其生物量有一定的相关性,不施钾处理r2=0 9584 ,回归方程为y=3 24+16 866x。施钾处理r2=0 9604 ,回归方程为y=2 36+17 43x。籽粒苋钾素活化率顺序与其速效钾含量高低顺序一致。因此,可以用植物对土壤钾素的活化率和籽粒苋吸钾总量来评价紫色土的供钾能力。

泥岩岩质边坡破坏过程的模型试验研究

为揭示泥岩岩质边坡在环境荷载以及由于边坡倾角改变引起的失稳过程,采用二维边坡模型,对不同坡脚、结构面填充条件下的岩质边坡破坏过程进行了详细的试验研究。通过模拟人工降雨条件下的岩质边坡破坏揭示了干湿循环的渐进性物理风化过程;对有无干湿循环、填充物以及不同结构面倾向的泥岩岩质边坡的破坏进行对比研究,揭示泥岩边坡破坏的影响因素。利用工业相机采用非接触手段采集边坡破坏的发生、发展过程,对破坏形态进行归纳总结。结果表明:泥岩岩质边坡破坏与边坡倾角、坡脚、结构面填充物及外部环境有密切关系;反倾边坡破坏易从坡顶关健体破坏并迅速扩展,从而导致整体垮塌;泥岩岩质边坡坡面处应力集中最严重,破坏从坡面开始并迅速往坡内发展,导致边坡的整体失稳。最后结合实验结果,给出了具体的工程建议。