稻田肥水管理对氮肥效益的影响

本文在阐明水稻氮需求、氮效应、稻田氮肥施用技术,及水分管理对氮肥效应的影响的基础上,提出了水稻氮肥施用应在适宜氮肥施用量的范围内,采取控前攻中施肥法,与水分管理结合,以水带肥,提高稻田氮肥效益。     

Volcanic ash additions control soil carbon accumulation in brown forest soils in Japan

Abstract

The objective of the present study was to clarify the influence of volcanic ash addition on soil carbon stocks and the carbon accumulation process in brown forest soils (BFS) in Japan. The degree of volcanic ash addition to the soil was estimated according to the acid ammonium oxalate extractable aluminum (Al_ox) and lithic fragment contents, and their vertical distribution patterns. The BFS was classified in order of increasing volcanic ash influence on the soil into the following types: high Al_ox content with no gravel (H-Al_ox-NGv), high Al_ox with a high gravel content (H-Al_ox-Gv), moderate Al_ox (M-Al_ox), and low Al_ox (L-Al_ox), and then analyzed for carbon content, carbon amount, carbon stock, Al_ox amount and pyrophosphate extractable aluminum (Al_py) amount. The correlation between the carbon and Al_py amounts and the relationship between the Al_py and Al_ox amounts in the BFS samples indicated that the amount of carbon is determined by Al—humus complex formation, which is defined by the active Al generated from additional volcanic ash in BFS soil samples of BFS. Therefore, soils with thicker horizons and greater amounts of Al_ox had higher carbon levels in deeper horizons. For this reason, soil carbon stocks at depths of 0–30 cm and 0–100 cm, and in the effective soil depth of BFS, were larger and followed the order H-Al_ox-NGv = H-Al_ox-Gv > M-Al_ox > L-Al_ox. Furthermore, successive accumulations of volcanic ash on the soil surface promoted soil carbon accumulation as a result of the development of the surface horizon in H-Al_ox-NGv BFS. Our results suggest that volcanic ash additions control the soil carbon accumulation of forest soil in Japan.     

贵州坡耕地三种种植模式的水土保持效果对比研究

通过研究紫花苜蓿—玉米间作、作物分带轮作和玉米单作3种种植模式下地表覆盖度和表层土壤含水量月变化,年均土壤和养分流失量以及产量等,比较不同模式的水土保持效果。结果表明:紫花苜蓿—玉米间作与分带轮作模式可保持坡耕地全年覆盖,并在整个雨季保持较高的覆盖度。紫花苜蓿根系发达,增加了0—20cm耕层土壤中的根量,增强了土壤的渗透能力,保护了生物多样性,可减少地表径流39.3%,减少土壤侵蚀59.3%;分带轮作可减少地表径流10.4%,减少土壤侵蚀21.3%;两种模式都提高了雨季前和雨季耕层土壤中的水分,减少了水土流失引起的有机质流失29.9%～52.4%,全N流失26.7%～54.9,全钾流失27.3%～70.9%,缓效钾流失21.4%～58.9%,提高玉米产量33.0%～35.9%;紫花苜蓿—玉米间作还可收获紫花苜蓿干草13 664kg/hm2,复合产量是农民习惯的4.1倍;分带轮作可收获大豆、红薯、油菜等,复合产量为12 492kg/hm2,是农民习惯的2.7倍。     

基于P一S一R模型的城市生态安全模糊物元评价——以吉林省四平市为例

利用P—S—R模型构建指标体系,采用熵权法求取权重,基于吉林省四平市模糊物元模分析方法,利用1991年、2001年和2007年的3期TM遥感影像,结合野外调查数据及社会经济数据等,分析处理提取生态安全评价指标,对四平市的生态安全进行评价。结果表明:（1）四平市1991—2007年城市生态安全状况是不稳定的,经历了由“不安全”向“临界安全”转化的过程;（2）影响四平市城市生态安全的因素并不协调统一,其中,城市化率、人均GDP、万元GDP能耗、恩格尔系数等指标为安全状态,而人均道路面积、建设区紧凑度、每万人拥有公共交通车辆、建设区绿化覆盖率等指标为不安全状态;（3）四平市在今后的发展中,要继续提高环境保护意识,转变经济增长方式,加大科技投入,优化产业结构,增加人均公共绿地面积和公共交通车辆,提高土地利用率,从而实现经济效益、环境效益和社会效益的协调统一。     

“川农号”系列小麦产量和抗病性相关分析

[目的]描述四川小麦育种的概括和今后四川小麦育种走向,并为小麦育种和栽培提供一定的帮助。[方法]选定1999～2007年由四川农业大学任正隆课题组选育的17个优质小麦品种进行相关的产量和抗病性分析。[结果]＂川农号＂系列小麦大多属于早中熟春性品种,产量介于5 000～5 500 kg/hm2,增产幅度较为明显,高抗条锈病,中感白粉病,其有效穗和穗粒数变异系数是11.11%和11.47%,在保持原有产量结构的基础上,增加有效穗和穗粒数是今后提高四川小麦产量的有效途径。[结论]证明了四川地区培育高产优质小麦的可行性。     

小兴安岭两种林型的土壤有机碳研究

为阐明小兴安岭两种原始红松林土壤有机碳变化特征及其影响机制,采样分析了云冷杉红松林与椴树红松林土壤总有机碳、易氧化碳、微生物生物量碳及土壤理化性质。结果表明:两种林型土壤总有机碳、易氧化碳、微生物生物量碳含量垂直分布特征一致,均自上向下逐渐减少;土壤总有机碳与易氧化碳含量表现为:云冷杉红松林 < 椴树红松林,同海拔高度变化（云冷杉红松林 < 椴树红松林）一致（仅10—20 cm土层,云冷杉红松林的两个因子高于椴树红松林,但差异不显著）,两种林型土壤微生物量碳含量的差异在不同土壤层次有所不同,但差异均不显著;两种林型间土壤活性碳占总有机碳比率的差异在不同土层无一致的规律性;两种活性碳、总有机碳与土壤全氮、C/N之间为显著（p < 0.05）或极显著（p < 0.01）正相关,与土壤容重呈极显著负相关（p < 0.01）。     

Evaluation of moisture content distribution in wood by soft X-ray imaging

A technique for nondestructive evaluation of moisture content distribution in Japanese cedar (sugi) during drying using a newly developed soft X-ray digital microscope was investigated. Radial, tangential, and cross-sectional samples measuring 100 × 100 × 10 mm were cut from green sugi wood. Each sample was dried in several steps in an oven and upon completion of each step, the mass was recorded and a soft X-ray image was taken. The relationship between moisture content and the average grayscale value of the soft X-ray image at each step was linear. In addition, the linear regressions overlapped each other regardless of the sample sections. These results showed that soft X-ray images could accurately estimate the moisture content. Applying this relationship to a small section of each sample, the moisture content distribution was estimated from the image differential between the soft X-ray pictures obtained from the sample in question and the same sample in the oven-dried condition. Moisture content profi les for 10-mm-wide parts at the centers of the samples were also obtained. The shapes of the profiles supported the evaluation method used in this study. Part of this work was presented at the 57th Annual Meeting of the Japan Wood Research Society, Hiroshima, August 2007     

Quantification of visual inducement of knots by eye-tracking

Knots have been considered an undesirable visual feature of lumber. To clarify the essence of this visual undesirability, eye-tracking data from 20 subjects, who freely observed 55 images of wood wall panels, were recorded and distribution maps of eye-fixation pauses were composed. These maps were compared with the arrangement of knots on each knotty wall panel image and the visual inducement of knots was evaluated using a new numerical index of pausing probability. The present study is the first to objectively quantify the visual inducement of knots. In addition, the subjective noticeability of knots and ten visual impressions of each wood panel image were investigated by a sensory evaluation. There was a very clear linear relationship between the visual inducement of knots and the subjective noticeability of knots. A correlation analysis suggested that many visual impressions of wood wall panels were influenced by a complementary effect between the subjective noticeability of knots and the visual inducement of knots. The visual impact of knots was masked to some extent by special visual stimuli such as deep red grooves on the wood wall panels. This study was presented at the 56th and 57th Annual Meetings of the Japan Wood Research Society, Akita and Hiroshima, August 2006 and August 2007, respectively     

施氮量对玉米植株硝态氮含量及产量的影响

[目的]探讨施氮量对玉米不同时期硝态氮含量及产量的影响。[方法]通过田间小区试验研究了施氮量01、503、004、50 kg/hm2对玉米植株硝态氮(NO3--N)含量及产量的影响。[结果]随玉米生育期的延长玉米各部位中NO3--N含量总体上呈下降趋势;在苗期、拔节期和灌浆期,不施氮处理的玉米植株硝态氮含量均低于各施氮处理,且这3个时期玉米各叶位的硝态氮含量与施氮量的相关性差异较大;第3叶位和6叶位的NO3--N含量在不同生育期的表现为:苗期3位叶高于6位叶,拔节期和灌浆期6位叶高于3位叶;3个时期的植株体内硝态氮含量,叶鞘均明显高于叶肉,且均在施氮量大于300 kg/hm2时氮含量增长减缓。[结论]施用氮肥可显著提高玉米籽粒和秸秆产量,合理施氮量应控制在300 kg/hm2左右。     

超干处理对蓝桉种子发芽及生理生化特性的影响

采用热空气恒温（50℃）干燥法对蓝桉种子进行超干处理,将蓝桉种子含水量由自然干燥的9．8％分别降至9％、8％、7％、6％、5％、4％、3％、2％、1％,研究超干燥处理对蓝桉种子发芽及生理生化特性的影响。结果表明:蓝桉种子耐脱水性较强,脱水至5％时,未发现种子活力明显下降,细胞膜能保持较好完整性,电导率最低,α—淀粉酶和脱氢酶活性高,各发芽能力指标在9个超干处理中最好。对各测定指标综合分析表明,蓝桉种子超干处理是完全可行的,最适含水率为5％,为蓝桉种子超干燥处理和贮藏提供了依据。