免耕对黑土蚯蚓数量和土壤密度的影响

以自2001年秋在吉林省德惠市中层黑土上进行的耕作定位试验小区为研究对象,对比免耕和常规耕作对东北黑土蚯蚓数量和土壤密度的影响.试验设计为裂区随机区组设计(免耕和常规秋翻两个处理),4个区组,种植作物为玉米和大豆.在玉米6叶期和8月末或9月初两次测定蚯蚓数量,土壤密度秋收后测定.采用SAS软件对2004～2006年的蚯蚓数量和土壤密度进行方差分析.试验结果表明,耕作方式、作物类型和采样时间对蚯蚓数量的影响较大,均达显著差异(P《0.05).免耕处理的蚯蚓数量是秋翻处理蚯蚓数量的2.4倍,种植大豆的蚯蚓数量是种植玉米蚯蚓数量的1.6倍,第1次的蚯蚓数量是第2次蚯蚓数量的1.9倍.耕作方式和作物类型对土壤密度没有显著影响.虽然免耕处理使5cm～10cm的土壤密度略有增加,但免耕的土壤密度与秋翻的土壤密度相比,并无显著差异.因此,同常规秋翻相比,免耕明显增加土壤中的蚯蚓数量,而且不会引起土壤的板结.     

短期免耕对黑土孔隙度的影响

对短期玉米免耕和秋翻处理对耕层黑土孔隙度的影响进行了分析。结果表明,耕作处理对土壤孔隙度影响较大,毛管孔隙和贮存孔隙在整个剖面内免耕均小于秋翻,但秋翻处理下的中小孔隙占有很大比例。两个处理之间的大孔隙数量相差很小,多在3%～8%之间。秋翻总孔隙度表现出表层和底层差异很大,而免耕孔隙分布相对均匀,且上下孔隙连通性较好。     

免耕探墒对土壤环境因素和旱地玉米产量的影响

对不同耕作方式下旱地玉米种植的试验结果显示,免耕探墒播种条件下2cm～7cm深处土壤容重较旋耕增加了4．31％,没有达到显著水平;免耕探墒播种降低了地温,提高了0era-20cm深处土壤的水分含量;免耕探墒播种产量为6591．82kg／hm2,较旋耕降低553．36kg／hm2,减产效果没有达到显著水平。由此说明,免耕探墒播种是旱地农业生产中有效的抗旱播种方法。     

Diversity and life-history traits of wild bees (Insecta: Hymenoptera) in intensive agricultural landscapes in the Rolling Pampa,Argentina

The decline of bees is a major concern due to their vital role in pollinating many crops and wild plants. Some regions in South America, and especially the Pampas, are amongst those parts of the world where stressors of bee populations have been little studied. The Pampas has been intensively transformed for agriculture, being presently one of the most productive areas of agricultural commodities in the world. Here, we aim to provide first insights on the taxonomic and functional composition of bee assemblages in the Rolling Pampa, the most intensively managed part of the Pampas. Soybean (herbicide-tolerant genetically modified varieties) is the predominant crop in this region. Bees were sampled with coloured pan traps. Sampling points were located on field margins in either the cropped or the semi-natural grassland area of a farmland site devoted to annual cropping. A total of 2384 individuals were caught, representing 33 taxa [mainly (morpho)species]. The subgenus Lasioglossum (Dialictus) largely dominated captures (78% of the total abundance) and was relatively abundant in the entire study area, suggesting that some species are likely to reach their ecological requirements in cropped areas. No-till fields and field margins may provide large areas for these below-ground nesting species, while their polylectic food preferences allow them to collect pollen on a wide range of plant species, among them possibly soybean. On the contrary, the richness and the abundance of other taxa were higher in the semi-natural area than in the cropped area. Among them, above-ground nesting or oil-collecting species, which have more specialised nesting and floral requirements, were highly associated with the semi-natural area. Our findings highlight the large dominance of L. (Dialictus) species in this highly intensively managed landscape, and the urgent need of preserving semi-natural habitats to maintain species-rich and functionally diverse bee communities in the Pampas.     

短期免耕对东北黑土硝态氮淋失的影响

以吉林省德惠市中层黑土上耕作定位试验小区为研究对象,探讨了免耕和秋翻两种耕作方式对土壤NO3--N在土体中分布的影响。6a的田间定位试验表明,免耕玉米小区NO3-N含量呈自上而下递减的趋势,表层和亚表层NO3--N含量均高于底层。秋翻玉米小区除2004年外,其他年份也表现出这种趋势。在试验的后两年,由于玉米根系和土壤动物的作用,免耕处理开始形成连贯的大孔隙,大豆小区免耕处理NO3-N有向土壤底土层富集的现象,免耕对土壤NO3--N淋失的影响已经开始显现。图3,表1,参19。     

长期少免耕对稻麦产量与土壤肥力的影响

在沿江砂壤土上进行了长达１２ａ的稻麦复种连作长期少免耕定位试验，结果表明：少耕的、麦产量与常耕基本持平，免耕小麦稳定增产，平均增产５．３％，免耕水稻平均减产２．２％，长期少免耕产量没有明显的时间趋势变化，在经历约５ａ的少免耕后，土壤有机质基本处于稳定状态，全耕层有机质含量耕法间无明显差异，但在层交由有所不同，少、免耕表现出表层富集，富集系数后７ａ平均分别为１．１１４０和１．１６０８，不同耕法间０－     

穴居、悬棺葬、免耕与生态适应

对贵州紫云麻山地区的穴居现象、特殊的葬式和残留的免耕农作进行了详细分析,认为这些看似独立的文化特性其实都是对当地喀斯特地形的适应,并与苗族文化中的其他特征相互渗透融合,有效地回避了喀斯特生态系统的脆弱环节,因此,对于重新思考石漠化地区的治理目标具有参考价值,有利于为其他的类似生态脆弱地区的发展提供借鉴与启发。     

小麦免耕栽培技术研究

为探讨小麦免耕栽培技术,采用三个因素三个水平正交设计L9(34),研究种植方式、覆盖物和施肥量对小麦产量的影响.结果表明:处理之间小麦产量差异极显著,但处理与对照产量的差异均不显著.种植方式之间产量差异极显著,预留行种植8行的产量极显著高于另外2种种植6行的产量;农家肥盖种的产量显著高于另外两种盖种的产量;施肥量之间产...