基于SALTMOD模型的灌溉水矿化度对土壤盐分的影响

以河套灌区沙壕渠灌域为例,运用SALTMOD模型探讨了区域尺度灌溉水矿化度对根层土壤盐分的影响。结果表明,根层土壤盐分随灌溉水矿化度的增大而增加,加大排水沟深度和提高渠道衬砌水平可缓解高矿化度灌溉水对土壤积盐的影响;采用地下微咸水和黄河水混合灌溉可有效控制盐渍化的发展,混合比在1∶1范围内时,根层土壤处于脱盐状态,最高脱盐率为23%,脱盐率高于引用黄河水灌溉的脱盐率(4%)。因此,适度利用地下微咸水灌溉,可有效的控制地下水位,节约淡水资源。     

再生水灌溉对玉米产量、品质及重金属影响的试验研究

以龙口市和高密市污水处理厂的再生水为灌溉水源,进行玉米再生水灌溉试验,研究了不同灌水定额对玉米产量、品质、含重金属量的影响。研究表明,再生水灌溉条件下,玉米品质及产量有不同程度的提高,籽粒含重金属量与清水灌溉并无差异,重金属在植株体内的累积表现为:根>茎>籽粒,籽粒含重金属量符合《粮食卫生标准》(GB2715—2005)和《食品中污染物限量》(GB2762—2005)的要求。     

Deficit irrigation based on drought tolerance and root signalling in potatoes and tomatoes

Agriculture is a big consumer of fresh water in competition with other sectors of the society. Within the EU-project SAFIR new water-saving irrigation strategies were developed based on pot, semi-field and field experiments with potatoes (Solanum tuberosum L.), fresh tomatoes (Lycopersicon esculentum Mill.) and processing tomatoes as model plants. From the pot and semi-field experiments an ABA production model was developed for potatoes to optimize the ABA signalling; this was obtained by modelling the optimal level of soil drying for ABA production before re-irrigation in a crop growth model. The field irrigation guidelines were developed under temperate (Denmark), Mediterranean (Greece, Italy) and continental (Serbia, China) climatic conditions during summer. The field investigations on processing tomatoes were undertaken only in the Po valley (North Italy) on fine, textured soil. The investigations from several studies showed that gradual soil drying imposed by deficit irrigation (DI) or partial root zone drying irrigation (PRD) induced hydraulic and chemical signals from the root system resulting in partial stomatal closure, an increase in photosynthetic water use efficiency, and a slight reduction in top vegetative growth. Further PRD increased N-mineralization significantly beyond that from DI, causing a stay-green effect late in the growing season. In field potato and tomato experiments the water-saving irrigation strategies DI and PRD were able to save about 20-30% of the water used in fully irrigated plants. PRD increased marketable yield in potatoes significantly by 15% due to improved tuber size distribution. PRD increased antioxidant content significantly by approximately 10% in both potatoes and fresh tomatoes. Under a high temperature regime, full irrigation (FI) should be undertaken, as was clear from field observations in tomatoes. For tomatoes full irrigation should be undertaken for cooling effects when the night/day average temperature >26.5 °C or when air temperature >40 °C to avoid flower-dropping. The temperature threshold for potatoes is not clear. From three-year field drip irrigation experiments we found that under the establishment phase, both potatoes and tomatoes should be fully irrigated; however, during the later phases deficit irrigation might be applied as outlined below without causing significant yield reduction:

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Potatoes

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After the end of tuber initiation, DI or PRD is applied at 70% of FI. During the last 14 days of the growth period, DI or PRD is applied at 50% of FI.

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Fresh tomatoes

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From the moment the 1st truce is developed, DI is applied at 85-80% of FI for two weeks. In the middle period, DI or PRD is applied at 70% of FI. During the last 14 days of the growth period, DI or PRD is applied at 50% of FI.

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Processing tomatoes

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From transplanting to fruit setting at 4th-5th cluster, the PRD and DI threshold for re-irrigation is when the plant-available soil water content (ASWC) equals 0.7 (soil water potential, Ψ_soil = −90 kPa). During the late fruit development/ripening stage, 10% of red fruits, the threshold for re-irrigation for DI is when ASWC = 0.5 (Ψ_soil = −185 kPa) and for PRD when ASWC (dry side) = 0.4 (Ψ_{soil, dry side} = −270 kPa).

The findings during the SAFIR project might be used as a framework for implementing water-saving deficit irrigation under different local soil and climatic conditions.     

不同滴灌条件下土壤水分分布与运移规律

通过对相同规格的滴灌带在不同土壤含水量、不同滴灌方式和不同灌水量条件下灌水,研究水分在土壤中的下渗分布规律。结果表明,单管滴灌条件下,水分在不同含水量土壤中湿润体均呈坛状;双管滴灌条件下,水分在不同含水量土壤中湿润体依灌水量大小而异,灌水量较小时呈并放双碗状,随灌水量增大,湿润体逐渐呈坛状。不同滴灌方式下灌水,满足植物根系需要的灌水量不同,单双管滴灌灌水量分别为300 m3/hm2和450 m3/hm2时即可满足植物根系对水分的需求。单双滴在相同灌水量条件下,土壤表层湿润半径大小变化因土壤含水量不同而不同,土壤垂直湿润深度随灌水量增大而增加;在相同灌水量条件下,滴灌方式和初始土壤含水量对土壤水分湿润圈大小有很大影响。     

基于WPI的水安全评价体系研究

针对水安全评价问题,介绍了水贫穷指数(WPI)。根据我国实际情况对水贫穷指数中的水安全评价指标进行深入研究,并在此基础上提出适合我国流域的水安全评价指标。以石羊河流域为例的应用证明了该指数能够清晰地反映威胁流域水安全的因素的具体特征,通过水安全分级的方法可以确定各特定区域的水安全级别,为制定水安全预警机制提供依据。     

基于GIS的绿色农产品基地适宜性评价

建立和完善绿色农产品基地适宜性评价方法,提高评价结果的实用性和准确性,是实现农产品安全的根本保障。研究依据基地认证者、规划者、生产者3种评价主体实际需求,分别引入污染潜在风险指标和经济状况指标,建立面向不同评价主体需求的多种主导因子评价指标体系,并借助GIS的空间分析方法进行定量评价,最后以北京大兴区为例进行了案例分析研究。结果表明,基地与工矿企业距离、与居民地距离等潜在污染风险对基地适宜性限制大,且不同评价主体下建立不同指标体系使评价更具针对性,利用GIS功能可提高效率,评价结果可视化程度好,具有很强的     

基于模糊神经系统与GIS的区域土壤侵蚀快速评价

土壤侵蚀调查与评价是水土保持工作的重要组成部分。该文对区域土壤侵蚀评价进行了尝试性研究,提出一种基于模糊神经系统和GIS技术的快速评价方法。研究中利用模糊神经系统技术从地面监测调查数据中提取土壤侵蚀强度的评价规则,建立能够全面、客观地反映特定区域范围内土壤侵蚀自然特征及规律的评价标准,在此基础之上结合GIS技术以实现对整个地区的快速评价。采用该方法进行湖北省土壤侵蚀普查,结果表明全省侵蚀面积约占国土总面积的30.1%。其中,鄂西南、鄂西北高山区土壤侵蚀情况最严重,鄂东南、鄂东北低山丘陵区次之,鄂北岗地中度侵蚀面积较大,而江汉平原基本无明显侵蚀。经验证评价结果与实际情况具有较好的一致性。     

土壤盐分与灌溉水质对滴灌棉花出苗率的影响

试验研究了灌溉水质与土壤初始含盐率对滴灌棉花出苗率的影响.试验结果表明,土壤不舍盐时,灌溉水质d对内行棉花出苗率影响不显著,对外行棉花出苗率影响显著;自来水处理的内行与外行棉花出苗率均大于微成水处理;在4种微咸水中,EC小的水质对应的出苗率高,EC值相同时,SAR值小的内行出苗率高,SAR值大的外行出苗率高.当土壤舍盐...     

干旱区降雨过程对土壤水分与温度变化影响研究

通过定点监测并结合统计方法分析了干湿交替时节一次降雨过程前后不同土地利用方式下土壤水分与土壤温度的动态变化特征.结果表明,降雨过程对土壤水分和土壤温度在时间动态变化和深度变化过程有着重要影响;降雨影响周期中土壤含水率在一定深度范围内有一次明显的升高过程,从降雨前到降雨后呈现低→高→低的变化趋势,其变异程度随着深度的增加...     

灌区用水效率与效益评价——以天津市里自沽灌区为例

以天津市宝坻区里自沽大型灌区的基本资料为基础.选取灌溉水利用系数、渠系水利用系数、田间水利用系数、灌溉水生产效率、耕地有效灌溉率、节水灌溉工程面积率6个指标,构建了模糊综合评价模型,对影响灌区用水综合效益的因素进行了分析.结果表明,2004-2008年,里自沽大型灌区综合评价指数分别为3.299、3.423、3.624、3.679、3.687整体上呈现明显的上升趋势,其用水效率状况处于较好阶段.利用模糊综合评价法,对灌区用水效率与效益进行了评价.结果表明,工程状况与管理水平对于灌区用水系数的影响较显著.必须加大灌区节水改造以及灌区管理体制改革力度,进一步提高农业灌溉水的利用效率和效益,促进水资源的可持续发展.