农业耕层土壤生态环境保护及改良措施研究

由于人们对耕地的高强度开发和不合理的利用,加上不利自然条件的破坏,致使坡结构遭受了严重的损害,很多地区的农业耕层土壤受到了不同程度的破坏,甚至有的损害不可逆转。因此,为保证农业生产的可持续发展,本文对农业耕层土壤生态环境保护及改良措施进行分析研究,以增强耕层土壤肥力,以达到保护及改良农业耕层土壤生态环境的目的。

耕层土壤剥离再利用覆土时空优化研究

科学确定有覆土需求的地块,是耕层土壤剥离与再利用工程的先决条件.本文在ArcGIS技术支持下,以重庆市江津区为例,采用信息熵法构建了规划期内山地丘陵区耕地耕作层覆土需求优先度的评价指标体系,根据覆土优先度综合分值划定近期覆土区、中期覆土区、远期覆土区.结果表明:1)基期(2013年)至规划期(2020年),非农建设用地转化为耕地的现象覆盖了研究区大部分区域,覆土区总面积为648.27hm^2;2)基于自然条件、社会条件和用地条件,采用熵权法对上述指标进行权重计算,得出2013-2020年江津区覆土优先度综合分值Q,Q≥0.49的覆土区域划为近期覆土区,0.35≤Q<0.49的覆土区域划为中期覆土区,Q<0.35的覆土区域则划为远期覆土区;3)近期覆土区覆土迫切性较高,具有较强的社会可行性,应优先安排耕层土壤覆土工程;中期覆土区优先度次于近期覆土区,为后备覆土区域;远期覆土区缺乏一定的经济基础,总体来说该区域覆土迫切度较低,覆土社会可行性不高.因此,覆土改良不仅要考虑土壤质量等自然条件,还应考虑社会条件和用地条件,而确定合理的覆土时序和覆土区域则关系着耕层土壤剥离与再利用工程的投资、工期和效果.

铝土矿赤泥的开发利用

赤泥耕层土是一种大量消纳赤泥,同时又将其转化为二次资源的赤泥产品。该技术以农作物废弃物为改性剂,通过改性剂在赤泥中发酵腐化的产物改性赤泥成适宜植物生长的土壤。该技术应用不受赤泥组分、结构差异等因素限制,具有广泛适用性,尤其是有价金属元素含量低、又不适宜于制作建材的赤泥以及堆场防渗、防溃(堤)能力弱,需迅速消减的赤泥库的赤泥土可优先选用该技术处理。

Characteristics and Evaluation of Soil Fertility in Sugarcane-producing Areas in Guangxi

[Objective] Soil fertility in Guangxi sugarcane-growing areas was evaluated to provide theoretical reference for sugarcane scientific planting and fertilization and further optimize evaluation system for soil fertility in Guangxi sugarcane-growing ar- eas. [Method] Nutrients of soil samples in 3 006 plots were measured, and fertility characters were evaluated based on the improved Nemerow composite index method. [Result] Soil in Guangxi sugarcane-growing area was sticky and acidic with an average pH value of 4.94. Available B was insufficient with an average content of 0.24 mg/kg. Exchangeable Mg was low with an average content of 62.34 mg/kg. Organic matter content was moderate. The contents of alkali N, rapidly available P, rapidly available K, available Cu, available Zn, available Mn and available Ca were moderate. However, unlike the soil in high-yield areas, there was unbalanced nutri- tion distribution. According to Nemerow integrated index method, soil fertility in sug- arcane-growing areas was grade lU, namely low fertility. The integrated fertility index was 0.56. Individual fertility indexes including rapid available Cu, rapidly available Zn, exchangeable Mg, available Mn, rapidly available manganese Mn and alkali N were at poor level. Other indexes were at medium or high level. [Conclusion] It could be concluded that soil fertility in Guangxi sugarcane-growing area was gener- ally low, The above-mentioned evaluation method could help to build a quantified and scientific soil fertility evaluation system and reduce the impacts of subjective factors during evaluation process.

Characteristics of Channeling Flow in Cultivated Horizon of Saline Rice Soil

By applying bromide ion as tracer, the channeling flow has been quantitatively described in saline rice soil and alkaline soil of Da＇an City, Jilin Province of China. Breakthrough curves of bromide ion in the saline rice soils after 1-year cultivation and 5-year cultivation and alkaline soil have been attained. Results show that the rice cultivation practice can improve the alkaline soil structure, however, it can accelerate the development of channeling flow pathway. Therefore, the channeling flow pathway has been developed widely in saline rice soil, but rarely in the alkaline soil. Three models of convection-dispersion equation （CDE）, transfer functional model （TFM） and Back-Progation Network （BP Network） were used to simulate the transportation process of bromide ion. The peaks of probability density function of saline rice soil are higher with left skewed feature compared with that of the alkaline soil. It shows that the TIM and CDE can simulate the transportation process of the bromide ion in saline rice soil after 5-year cultivation, however, some deviation exists when it was used to simulate transportation process of bromide ion in saline rice soil after 1-year cultivation and alkaline soil; BP network can effectively simulate transportation process of bromide ion in both saline rice soil and alkaline soil.