咸淡轮灌和生物炭对滨海盐渍土水盐运移特征的影响

为利用滨海地区微咸水改良盐渍土,进行了不同咸淡水轮灌(淡淡、淡咸、咸淡、咸咸)和施用生物炭(0、15、30 t/hm2)的室内入渗试验,探讨了咸淡轮灌和生物炭施用下滨海盐渍土水盐运移过程.结果表明:滨海盐渍土水分运动主要受初始入渗水质的影响,先咸后淡的轮灌方式更有利于土壤水分入渗,入渗速率增加了8.2％～46.9％,并...     

咸-淡水交替漫灌淋洗改良滨海盐土效果

为探讨咸-淡水交替淋洗改良滨海盐土效果和节水潜力,通过土柱模拟试验,对咸-淡水交替淋洗下土壤溶液电导率变化、淋出液矿化度变化、淋洗用水量等进行了研究。结果表明,咸-淡水交替淋洗模式咸水(矿化度5.35 g L_-1)淋洗阶段,当100 cm深土体底部开始有淋出液时,距土表40 cm深处土壤溶液电导率下降已非常明显,而距土表80 cm、100 cm深处土壤由于盐分的聚积而电导率较高;咸水持续淋洗下40 cm深处土壤电导率始终缓慢下降,而80 cm、100 cm深处土壤电导率变化历经较快、快速、缓慢下降三个过程。咸-淡水交替淋洗模式淡水淋洗阶段,前期不同深度处土壤溶液电导率基本保持稳定;随着淋洗水量的增加,由土表向下不同深度位置土壤溶液电导率先后经过快速下降和缓慢下降两个过程。咸-淡水交替淋洗模式咸水淋洗阶段,淋出液矿化度变化经过快速、较快、缓慢下降三个过程,直至下降到7.32 g L_-1。淡水替换咸水继续淋洗下,前期淋出液矿化度保持稳定,当淡水淋洗水量增加到7 L(27.49 cm水层)时淋出液矿化度开始下降。咸-淡水交替淋洗模式咸水、淡水淋洗阶段结束后100 cm深土体土壤平均含盐量从初始的23.92 g Kg_-1下降到5.92 g Kg_-1和1.46 g Kg_-1,咸、淡水淋洗水量分别为21.45 L和14.85 L,与对照淡水淋洗模式比较咸-淡水交替淋洗模式淡水节约率为25.38%。咸-淡水交替淋洗模式改良滨海盐土效果较好,且节水潜力较高,但相应需要更长的淋洗改良时间。     

村规民约对牧民减畜决策行为的影响

牧民的减畜行为在草原退化过程中起着关键的作用。村规民约作为一种基层自治方式,在一定程度上,对实现草原环境治理的制度化和法制化具有积极作用。因此,本研究通过探讨村规民约对牧民减畜决策行为的影响,以期从非正式制度视角,提出控制牧民超载过牧行为的政策建议。本研究在对村规民约对牧民草原保护决策行为影响机制进行分析的基础上,以内蒙古和新疆193户牧民的实地调研数据为依据,运用Double-Hurdle模型,实证分析村规民约对牧民草原生态保护决策行为的影响。研究发现,以书面形式制定,且近5年内容未发生变化的村规民约,可显著提高牧民的减畜意愿;宗教信仰对牧民的减畜意愿有显著的制约作用;汉语水平越好的牧民,其减畜意愿越高。本研究认为村规民约对其生产生活影响程度越高的牧民,其减畜比例越高;牧民的受教育水平和家庭收入水平与其减畜比例均显著负相关。因此,重视村规民约制定形式的规范性和内容的稳定性,提高牧民对村规民约的遵守程度和认可程度,定期开展牧民汉语培训工作,提高牧民的汉语水平等方式对引导牧民做出有利于保护草原生态的决策行为有积极作用。     

磷肥用量对滨海盐土油菜光合性状和干物质生产的影响

为研究盐分土壤条件下磷肥对油菜光合性状和干物质生产的影响效应,以甘蓝型常规油菜品种‘宁油20号’为供试品种,设置不同磷肥用量处理,测定不同生育期叶面积、叶片净光合速率以及干物重。结果表明,0~120 kg/hm²磷肥用量范围内,随着磷肥用量的增加,苗期和初花期叶面积指数、干物质积累量逐渐增加,成熟期籽粒产量及干物质积累量也逐渐增加。不施磷肥和30 kg/hm²磷肥用量处理籽粒含油率较低,在磷肥用量达到60 kg/hm²时再增加磷肥用量籽粒含油率无显著变化。苗期叶片净光合速率随磷肥用量的变化趋势与干物重变化一致,当磷肥用量达到60 kg/hm²时进一步增加磷肥用量,初花期叶片净光合速率无显著变化。     

Effects of traditional salt placement and strategically placed mineral mix supplements on cattle distribution in the Western Italian Alps

Effects of traditional salt placement (TS) and strategically placed mineral mix supplements (MMS) on cattle distribution were compared in the Italian Alps. Salt was placed within flat and herbaceous sites following the traditional method of farmers, whereas MMS blocks were placed on steep and shrub‐encroached sites within three large pastures (44 ha on average). Each TS and MMS site was paired with a control site, and eleven cows were tracked with GPS collars. Within 10 and 50 m of TS and MMS, treatment sites were used more than control sites (P < 0·05). No differences were detected (P > 0·05) in the number of visits by cows within 10 and 50 m of TS and MMS placements. No differences were detected in time spent within 10 m of TS and MMS placements, but cows spent more time (P < 0·05) within 50 m of TS. With either TS or MMS, cattle preferred areas with gentler terrain, higher forage pastoral value and closer to water (P < 0·001). When MMS was available cattle also preferred areas near MMS (P < 0·001). Shrub and herbaceous cover decreased near MMS placements (P < 0·05) from cattle grazing and trampling. Placement of MMS is a promising tool to enhance cattle distribution and potentially reduce shrub encroachment in rugged mountain pastures.     

高粱体细胞抗盐系的筛选

用高粱体细胞梯度筛选法筛选了在3％NaCl培养其中能存活的体细胞系，并获得了再生植株，利用芽期和苗期抗盐鉴定和产比结果表明，高粱体细胞抗盐新品系T011有较强的抗盐能力和高配合力。     

黄土丘陵区不同管理方式下草地优势种群的生态位

以吴起县杨青川流域草地为研究对象,对封育(Enclosure)、放牧(Grazing)、施肥(Fertilization)、刈割(Clipping)、灭鼠(Deratization)5种管理方式的草地群落进行调查,并运用Levins生态位宽度和Pianka生态位重叠指数对5种管理方式下主要植物种群生态位特征进行分析。结果表明,达乌里胡枝子(Lespedeza davurica)、铁杆蒿(Artemisia sacrorum)、赖草(Leymus secalinus)、猪毛蒿(Artemisia scoparia)和硬质早熟禾(Poa sphondylodes)的种群总生态位宽度较大,封育放牧施肥刈割灭鼠管理模式下,生态位宽度最大的分别是达乌里胡枝子、赖草、紫花地丁(Viola philippica)、达乌里胡枝子和猪毛蒿,生态位宽度值大于4的物种数分别为6、6、3、4和3种。不同管理方式下各种对间的重叠指数平均值由大到小依次封育放牧施肥刈割灭鼠。施肥管理中,种群间生态位宽度与生态位重叠之间存在线性关系,其它管理方式中种群生态位宽度与生态位重叠之间不存在线性关系。生态位分析表明,封育和放牧管理下种群间对资源的需求趋于相同,彼此间通过竞争共存,有利于群落演替,草地生态系统逐渐得到恢复,施肥、刈割、灭鼠管理使群落物种竞争排序发生变化,破坏了草地生态系统原有的竞争机制,导致群落向简单群落演替。从牧草发展角度出发,封育、施肥和刈割有利于优质牧草生长。     

Field Crop Production in Areas with Saline Soils and Shallow Saline Groundwater in the San Joaquin Valley of California

SUMMARY

Salinity in soil and water is irrevocably associated with irrigated agriculture throughout the world and as a result requires that salt management becomes an integral part of the production system. With careful water management, it is possible to sustain irrigated agriculture in areas with saline soil and saline groundwater with and without subsurface drainage. The results from two field projects conducted in an area with saline soils and saline groundwater demonstrated the type of irrigation systems and management needed to sustain production of moderately salt tolerant and tolerant crops. During the first study at Murrieta farms, yields of cotton and sugar beet were maintained using both saline and non-saline water for irrigation when pre-plant irrigation and rainfall were adequate to maintain soil salinity at a tolerable level. Wheat production was reduced in areas that used saline water for irrigation. Use of saline water containing toxic elements such as boron for irrigation poses a threat to the sustainability of the system. The second study evaluated the management of furrow and subsurface drip irrigation in the presence of shallow saline groundwater. Careful management of the furrow system during pre-plant irrigation and the first irrigation of the growing season was required to prevent waterlogging. It was possible to manage the subsurface drip system to induce significant crop water use from shallow groundwater. Rainfall and pre-plant irrigation were adequate at this site to manage soil salinity.     

豆科、禾本科5种牧草异行混播草地当年建植效果研究

[目的]通过不同混播比例、不同种植方式建植混播草地的研究,探索自然降水在500mm以上的雨养地区,建植优质、高产、稳定与中长利用年限混播人工草地的技术途径.[方法]试验设红三叶(Trifolium pratens)、红豆草(Onobrychis viciaefolia)与鸭茅(Dactylis glomerata)、无芒雀麦(Broumis inermis)、猫尾草(Phlemu pratense)5种牧草混播,混播比例为4∶6、6∶4、5∶5三种处理,各处理又以1∶1行、2∶2行、3∶3行异行种植;在豆科牧草花期与禾本科牧草抽穗期,刈割测定草地群落各种群组分的密度、高度与产草量,对比分析各处理的草地经济性状表现.[结果]在不同种植方式的处理中,1∶1行的异行种植方式,各项经济性状指标均优于其它种植方式;在不同混播比例处理中,以4∶6混播比例的草群产量最高,在1∶1行处理中,平均产干草1209.1g/m2;其它处理也多在800g/m2以上.[结论]试验区草地在建植当年就表现出良好的长势与较高的生产性能,尤其是豆科牧草的产量在草群中大幅度增加,可极大地提升草地的质量.     

伊利石对碱性盐化土壤中镉形态的影响

[目的]研究不同伊利石添加量对碱性盐化土壤中重金属镉形态的影响及达到吸附稳定的时间。[方法]采用Tessier连续提取法。[结果]在pH为7.93的土壤溶液中,黏土矿物伊利石的添加使得土壤中重金属镉的有效态逐渐减少,其有效态减少总量从2.047mg/kg增加到3.103 mg/kg,铁锰氧化态和碳酸盐态均有不同程度的升高,有机结合态变化不明显,在吸附行为发生14 d左右基本达到平衡,最后出现少量的离子"释放"。[结论]伊利石对碱性盐化土壤中镉形态有较显著的影响。