控释肥对农田氮磷流失的影响研究(英文)

[目的]研究控释肥对农田氮磷流失的影响。[方法]通过选取巢湖流域水田作物水稻和旱地作物玉米进行大田试验,分别研究了施用普通复合肥、控释复合肥和减量20%控释复合肥对农田氮磷径流流失与淋溶流失的影响。[结果]水稻和玉米氮磷的径流与淋溶流失主要发生在施肥初期,其中径流流失量均占总流失量的98%以上,而淋溶流失部分所占比例均不到2%,说明水稻和玉米营养盐的流失主要通过径流流失。相对于普通复合肥处理组,减量20%控释复合肥处理组水稻田氮磷的总流失量分别降低了60%和63%,玉米地分别降低了27.8%和34%,表明施用控释复合肥能维持作物生长后期较高的土壤养分,提高氮磷的利用效率,有效地减少雨季水稻和玉米的氮磷流失,降低农业面源污染。[结论]该研究结果表明控释肥对农田作物养分流失具有减缓作用,为控释肥的大面积推广及减轻农业面源污染等提供了科学依据和技术支撑。     

皂苷对污染土娄土中重金属Cu、Pb的淋洗动力学特征

为探明生物表面活性剂皂苷(Saponin)对污染土娄土中重金属Cu、Pb的修复机制,采用批次试验方法,分析污染土娄土中不同形态Cu、Pb的质量分数,初步研究皂苷对污染土娄土中Cu、Pb的淋洗动力学特征。结果表明:(1)污染土娄土中Cu主要以有机结合态、碳酸盐结合态、硫化物残渣态的形式存在,Pb主要以碳酸盐结合态、硫化物残渣态的形式存在;(2)皂苷对Cu、Pb的淋洗过程分为快慢2个阶段,0~240min为皂苷淋洗Cu、Pb的快反应阶段,240~1 440min为皂苷淋洗Cu、Pb的慢反应阶段,在240min左右时淋洗基本达到平衡。随着淋洗时间的延长,皂苷对Cu、Pb的淋洗速率逐步降低;(3)淋洗平衡时,皂苷对单一和复合污染土娄土中Cu的淋洗量分别为39.94mg·kg-1和34.09mg·kg-1,对Pb的淋洗量分别为32.54 mg·kg-1和33.43mg·kg-1。质量浓度为10g·L-1皂苷可以去除土娄土中交换态、吸附态和部分有机态结合的Cu、Pb;(4)5种动力学方程描述皂苷淋洗土娄土中重金属的优劣顺序为:准二级方程Elovich方程双常数方程抛物线方程准一级动力学方程。     

Heavy-Metal Bioavailability and Chelate Mobilization Efficiency in an Assisted Phytoextraction Process by Sesbania sesban (L.) Merr

Chelate-induced phytoextraction is an innovative technique for cleaning metal- contaminated soil. The present study evaluates the degree of metal mobilization in soil and enhancement of phytoextraction of cadmium (Cd), lead (Pb), and zinc (Zn) by Sesbania sesban (L.) Merr. from artificially contaminated soil by application of ethylenediaminetetraacetic acid (EDTA). After 30 days of plant growth, the pots were divided into three sets (0.0, 2.5, and 5.0 mmol EDTA per kg soil). Experimental results indicated that levels of diethylenetriaminepentaacetic acid (DTPA)–extractable metals and metals in the leachate decreased as the EDTA dose increased. Plant growth parameters and total chlorophyll contents in the plants with EDTA applied were less than those of control. However, EDTA application significantly reduced metal accumulation in root and increased metal accumulation in the shoot of plants; similar results were obtained for the bioconcentration factor and translocation factor. The application of 5 mmol EDTA kg^?1 to metal-spiked soil may be an efficient alternative for the chemically enhanced phytoextraction by S. sesban.     

大气CO2浓度升高对稻田土壤Ca、Mg迁移的中长期效应

为了进一步认识稻田土壤中Ca、Mg元素生物地球化学循环对大气CO2浓度升高的响应,本实验利用中国稻麦轮作FACE(free air carbon-dioxide enrichment)试验平台,通过观测稻季不同生育期不同深度(30、60和90 cm)土壤溶液中的Ca2+、Mg2+ 浓度,研究大气CO2浓度升高对土壤Ca、Mg淋移的中长时期(第9年)影响。研究结果表明,随着土壤深度的增加,土壤溶液中的Ca2+浓度呈降低趋势,Mg2+浓度呈增加趋势;随着生育期的推进,呈现先增加后减小的趋势,并在抽穗期达到最大值。大气CO2浓度升高略微降低30、60 cm处土壤溶液的Ca2+ 浓度,增加90 cm处Ca2+ 浓度(6.7%)。稻田不同深度土壤溶液中Mg2+ 浓度对大气CO2浓度升高的响应有所不同,且在60 cm处有较强的正响应(12.1%)。研究明确高浓度CO2有加剧Ca2+、Mg2+ 向下淋溶损失的趋势,耕层土壤有机物料输入增多、 浓度增加、pH下降等是主要原因。大气CO2浓度升高对农田生态系统土壤Ca、Mg元素循环的长期影响值得进一步关注。     

氮肥用量对旱地冬小麦产量及夏闲期土壤硝态氮变化的影响

在陕西渭北旱塬,利用长期定位试验研究了长期不同氮肥用量（0、80、160、240、320 kg hm-2）对旱地冬小麦产量形成,氮素利用,土壤硝态氮残留、夏闲期淋溶和矿化的影响。结果表明：随用量增加,施氮提高旱地小麦产量的效应下降,而土壤硝态氮残留迅速增加。作物生长当季的硝态氮残留主要分布在0～60 cm土层,施氮超过160 kg hm-2时,达56.8～211.7 kg hm-2,来源于当季施用氮肥的残留占64%～90%。夏闲期土壤硝态氮发生淋失的土层深度和硝态氮淋失量均与施氮量呈显著的抛物线关系（r = 0.988 9和0.994 0）,施氮量超过160 kg hm-2时,每增加100 kg hm-2的氮肥投入,硝态氮淋失深度和淋失量增加量分别高于27 cm和80.4 kg hm-2。平均每10 mm的夏闲期降水可使离开原土层发生淋溶的硝态氮向下移动2～4 mm。施氮量对硝态氮淋失的深度没有显著影响。夏闲期土壤氮素矿化量、来源于当季施入土壤肥料氮被生物固定后的再矿化量分别为51.8～160.9 kg hm-2和31.6～109.2 kg hm-2。基于本研究,建议渭北旱塬冬小麦施氮量控制在146～163 kg hm-2,以保证旱地小麦高产,防止过量肥料氮残留,减少淋溶风险。     

Challenging targets for future agriculture

This article points out the kinds of problems agriculture is facing, outlines and structures agricultural quality components and defined aims for them, discusses the shortcomings of organic farming, proposes some important research areas and presents an outlook. The quality components are a type of checklist of those factors that we should be aware of concerning protection of the environment, production of healthy food and the practice of good ethics. These components can be integrated into the general aims of sustainable agriculture. Many European and other countries focus on organic farming as a solution, but this approach is dangerous because it does not necessarily lead to a better environment or better food products. Concerning future agricultural research, the following issues are highly important: precision agriculture, low leaching cropping systems, management of soil biological processes and maximum recirculation. Finally, the article discusses some issues of future agriculture such as intensity, nutrient imbalances caused by regional farm specialisation, and the development of an agricultural quality assessment system.     

矿区地下水中Fe(Ⅱ)转化因素的影响

通过浸溶试验,研究p H、有机质、铵态氮及氧化还原条件对矿区地下水中Fe(Ⅱ)转化的影响,并且通过正交试验确定各变量对铁元素溶出影响的主次顺序以及最佳溶出条件、最佳抑制条件。通过极差分析,发现p H对溶液中Fe(Ⅱ)浓度的影响最大,腐殖酸含量、氯化铵浓度次之;Fe(Ⅱ)最佳溶出条件为:p H 3,腐殖酸含量1.5 g/L,氯化铵浓度0。在此试验条件下,Fe(Ⅱ)的溶出浓度达到4.061 mg/L。Fe(Ⅱ)最佳抑制条件为:p H 7,腐殖酸含量0.5 g/L,氯化铵浓度50 mg/L。在此条件下,Fe(Ⅱ)的溶出浓度仅为0.193 mg/L。该研究通过掌握矿区地下水中各环境因素对Fe(Ⅱ)浓度的影响,对控制地下水中的铁污染有一定的指导意义,并且能够缓解饮用水短缺的问题。     

Tillage effects on soil strength and solute transport

To study the effect of different soil tillage practices and the consequences of soil deformation on the functioning of the pore system, we performed unsaturated leaching experiments (by applying a suction of −10 kPa) on undisturbed soil columns from the Ap-horizon of a luvisol derived from glacial till (agricultural site at Hohenschulen, North Germany). We compared two different tillage practices (conventionally tilled to 30 cm depth, and conservational chiselled to a depth of 8 cm-Horsch system) with respect to soil strength, pore connectivity and their effect on the fate of surface-applied fertilisers. The soil strength was measured by determining the precompression stress value (PCV). The conventionally tilled topsoil had a PCV of 21 kPa at a pore water potential of −6 kPa, while the conservation treatment resulted in a slightly higher PCV of 28 kPa, suggesting a slowly increasing soil strength induced by the formation of aggregates under reduced tillage practice.

The leaching experiments were modelled using the convection dispersion equation (CDE) and a modified version of the mobile–immobile approach (MIM), which included three water fractions: mobile, immobile and totally immobile water. From the CDE mobile water fractions (θ_m) ranging from 47 to 67% were found, and θ_m was slightly higher in the ploughed seedbed compared to the conservation-tilled one. This could be due to higher aggregation in the latter one. Dispersivities were relatively large, ranging from 44 to 360 mm, but no difference was found for the treatments. The MIM could simulate the drop in concentration when leaching was interrupted, but overall did not improve the simulation, despite the larger number of fitting parameters.

Compacting the soil with loads of 70 kPa prior to the leaching experiment did not affect solute transport in the conservational tilled soil. In the conventional-tilled soil, however, the dispersivity decreased and the mobile water content increased compared to the non-compacted soil, suggesting that the former one is less prone to deformation by mechanical loads.     

几种低分子量有机酸淋溶对土壤pH和交换性铝的影响

采用原状土柱进行模拟淋溶实验,比较研究了模拟酸雨和几种低分子量有机酸对红壤pH和交换性Al的影响。结果表明,与去离子水CK相比,pH3.5和pH4.5模拟酸雨淋洗后0~10cm土层pH分别降低了0.27、0.44和0.08、0.18个单位,土壤交换性Al含量分别增加了4.43%和2.38%;而10~50cm土层pH没有显著变化。柠檬酸、苹果酸和草酸淋洗后0~10cm土层pH比模拟酸雨淋洗后高0~0.3个单位,土壤交换性Al含量则要低0.08~0.75cmol/kg。与模拟酸雨相比,100μmol/L柠檬酸、苹果酸和草酸淋洗后10~50cm土层pH降低幅度基本上<0.1个单位,交换性Al含量增加了6.99%~12.82%;而10mmol/L柠檬酸、苹果酸和草酸淋洗后10~50cm土层pH降低幅度达0.02~0.83个单位,交换性Al含量增加了22.45%~34.66%。这意味着低分子量有机酸或许比酸雨在加速土壤酸化方面有更大的威胁。     

Deficit irrigation under water stress and salinity conditions: The MOPECO-Salt Model

In both arid and semi-arid areas the use of saline water for irrigation is a common practice, even though it may cause a drop in crop yield and progressive soil salinization. In order to determine the most suitable irrigation strategy for higher yield, profitability, and soil salinity management of certain crops, the MOPECO-Salt Model has been developed. This model was first validated in the Eastern Mancha Agricultural System in Albacete (Spain) through a test carried out on onion crop in April-September 2009, where the simulated yield was 2% lower than the observed one. The model was then tested at Tal Amara Research Station in the Central Bekaa Valley Agricultural System (Lebanon) using data from a 5-year experiment on the effects of deficit irrigation on two cultivars of potato (Spunta: July-October 2001, and June-September 2002; and Agria: March-August 2004, 2005, and 2007). Furthermore, these results were compared with those obtained through AquaCrop, which does not currently assess crop response to salinity. Differences between observed and simulated yields were lower than 3% for MOPECO-Salt and up to 12% for AquaCrop. According to findings from simulations, the irrigation strategies without leaching fraction employed in both areas are remediable since the off-season rainfall is sufficient to wash out soluble salts supplied with irrigation water. Results showed that as much as 14.4% water could be saved when this strategy was adopted for onion crops.