Analysis of Adverse Selection in the Credit Market and the Impact of Mortgage Means

From the impact of mortgage loan on the degreeof investment risk and the expected profit of bank,the authors draw the conclusion that the risk of mortgage loan is larger than the risk of credit loan when the gage is not enough by comparing mortgage loan with credit loan. And they also analyse the relation of the gage, loan rate, and adverse selection. The gage and loan rate are presented which can be use as themeans of examining information for the bank.     

以水稻为主的种植系统对土壤有机质状况的影响

A long-term simulation experiment was carried out to study the effect of rice-based cropping system, green manure and ground-water level on soil organic matter. Soil organic matter content increased when upland soil was puddled and cropped under submerged conditions. Among all treatments, soil organic matter contents in the treatments of rice-rice-flooded fallow in winter (WF) were the highest, those in the treatments of rice-rice-astragalus (WG) came the second, and those in the treatments of rice-rice-rape (WR) were the lowest. At the same rate of green manure application, the degrees of organo-mineral complexing in soils of treatments WG and WR were higher than those of treatment WF. After 9-year rice cultivation, the state of combination of humus in heavy fraction varied with treatments. The relative content of loosely bonded humus decreased in the order of WR > WG > WF, and it correlated significantly with Se availability.     

石灰性土壤无机磷的形态分布及其有效性

本文应用蒋柏藩和顾益初(1989)提出的石灰性土壤无机磷的分级方法,对我国北方主要的石灰性土类进行了无机磷形态分级的研究,并对其有效性作出了初步评价。供试的甘肃、陕西和河南的16种土壤的无机磷形态的分布情况为:Ca₂-P平均占无机磷总量的1.34%,Ca-P占9.91%,Al-P占4.27%,Fe-P占4.40%,O-P占10.9%,Ca₁₀-P占69.1%。生物试验的结果表明:Ca₂-P型的磷酸盐是最有效的,也是作物磷素营养的主要来源;Ca₈-P、Al-P和Fe-P可以作为缓效磷源;Ca₁₀-P和O-P只是一种潜在磷源。本研究为石灰性土壤无机磷的研究和磷肥的合理施用提供了理论依据。     

波尔多液营养保护剂对石灰性土壤铜、铁有效性及花生产量的影响研究

选用山东省花生主产区的代表性石灰性土壤，通过土培试验的方法，研究了波尔多液营养保护剂BNPP和美国铜基杀菌剂Koeide两种可湿性粉剂对石灰性土壤pH值和铜、铁有效性及其对花生产量的影响。结果表明，与CK（喷清水）相比，喷施BNPP后，土壤pH值有所降低，而土壤有效铁、铜含量都有所提高。同时喷施BNPP后土壤有效铜含量要低于Kocide处理。另外．BNPP处理花生叶绿紊、活性铁、全铁含量以及生物量都有显著提高，产量比CK提高了1．25～1．53倍。波尔多液营养保护剂效果要优于美国Kocide产品。     

微生物活性指标: 重金属污染下的土壤质量敏感指标

Physicochemical properties, total and DTPA (diethylenetriaminepentaacetic acid)-extractable Cu, Zn, Pb and Cd contents, microbial biomass carbon (C) content and the organic C mineralization rate of the soils in a long-term trace metal-contaminated paddy region of Guangdong, China were determined to assess the sensitivity of microbial indices to moderately metal-contaminated paddy soils. The mean contents of total Cu, Zn, Pb and Cd were 251, 250, 171, and 2.4 mg kg^-1 respectively. DTPA-extractablc metals were correlated positively and significantly with total metals, CEC, and organic C (except for DTPA-extractable Cd), while they were negatively and highly significantly correlated with pH, total Fe and Mn. Metal stress resulted in relatively low ratios of microbial biomass C to organic C and in remarkable inhibition of the microbial metabolic quotient and C minera]ization rate, which eventually led to increases in soil organic C and C/N. Moreover, microbial respiratory activity showed a stronger correlation to DTPA-extractable metals than to total metal content. Likewise, in the acid paddy soils some "linked" microbial activity indices, such as metabolic quotient and ratios of basal respiration to organic C, especially during initial incubation, were found to be more sensitive indicators of soil trace metal contamination than microbial biomass C or basal respiration alone.     

土壤非交换性钾释放动力学特征及其生物

采用生物耗竭法和0.2mol L-1的NaTPB化学浸提法,利用不同动力学方程对我国8种主要土壤非交换性钾的释钾特性及其生物有效性进行定量评估。结果表明,供试土壤非交换性钾释放分为快速释放和稳定释放两个阶段,一级动力学方程、Elovich 方程、双常数曲线方程和抛物线扩散方程均能描述土壤非交换性钾的释放过程。根据双常数方程中的参数（a）所表征的土壤非交换性钾释放速率常数,供试8种土壤的释钾能力按取土地区存在着自西向东、自北向南渐减的趋势。盆栽试验中,在累积释钾量高且释放速率快的土壤上,黑麦草累积生物量、累积吸钾量和相对含钾量较高,表现出强的供钾能力;与此相反,累积释放量低且释放速率慢的土壤上,黑麦草各项指标偏低,供钾能力较弱。以黑麦草钾素丰缺临界值34.00 mg kg-1 DW-1和土壤非交换性钾释放速率396.32 mg kg-1 h-1作为评价指标,供试8种土壤中,仅取自新疆石河子、陕西常武和黑龙江哈尔滨地区的土壤在短期不施用钾肥的情况下能保证黑麦草丰产且不出现缺钾症状。因此,为了维持土壤钾素平衡和保证作物高产稳产,在我国西北、东北地区耕地土壤中应加强秸秆的循环利用,而在华中和华东地区则需增施钾肥和有机肥。     

Wolves in the Casentinesi Forests: insights for wolf conservation in Italy from a protected area with a rich wild prey community

The Casentinesi Forests, in the northern Apennines, harbour a rich community of wild ungulates, with the wolf representing the largest predator in the area. Between 1993 and 2000, wolf pack distribution in the area was monitored and estimates of pack size were obtained by wolf-howling surveys, snow-tracking, and occasional observations. Three to five packs were detected yearly, with sizes averaging 4.2 ± 0.9 wolves (maximum 7). The overall density in the area was 4.7 wolves per 100 km² with an average distance between adjacent packs of 11.1 km. The high wolf density in the Casentinesi Forests is mostly related to abundance and size of wild prey. In this, like in other areas at low latitudes, wolf density depends mainly on the number of packs, as pack size is rather small and recruitment limited by early dispersal and high mortality. Three homesites used in several years by resident packs were discovered. Homesite fidelity and pack reproductive success were higher in fully protected rather than harvested areas. Establishing a network of protected areas with high ungulate diversity and abundance is proposed as the main factor for allowing a full recovery of the wolf population in Italy.     

The status of atmospheric concentrations of ammonia in an intensive dairy farming area in central Japan

(pp. 41–46)
Silicon availability in 36 commercial nursery bed soils was evaluated by four methods the phosphate buffer (pH 6.2, 40 mmol L⁻¹), incubation, supernatant and acetate buffer (pH 4.0, 1 mol L⁻¹) Methods. The influence of silicon availability in the nursery bed soils on the silicon uptake of rice Oryza sativa L. cv. Hitomebore seedlings and the effect of silicon fertilizer application were examined in a glass house in 2002.
The results revealed that the best correlation between silicon content in rice seedlings and available silicon in soils was obtained with the phosphate buffer-solution method ( r  = 0.86). More precise evaluation of available silicon was achieved by grouping soils based on these phosphate absorption coefficients (PAC). The correlation coefficients between silicon content in rice seedlings and available silicon in soils were 0.92 and 0.72 for volcanic soils (PAC > 1500) and non volcanic soils (PAC < 1500), respectively.
We concluded that the phosphate buffer method is the most easily adjusted method for estimation of silicon availability in nursery bed soils, and silicon fertilizers should be applied when silicon availability in non-volcanic nursery bed soils goes below 200 mg kg⁻¹, whereas the level is less than 350 mg kg⁻¹ in volcanic soils.     

Genotypic variation for phosphorus uptake dinitrogen fixation in cowpea on low‐phosphorus soils of southern Cameroon

In cowpea, efficient N₂‐fixing genotypes are being selected to promote sustainable cropping systems in southern Cameroon (SC). However, N₂ fixation and growth of these genotypes are largely hampered by low levels of soil plant‐available P. To evaluate the genotypic variation in N₂ fixation and P uptake among cowpea (Vigna unguiculata L.) genotypes, field experiments were conducted over two years on two acid soils low in available P. The experiments were laid out in a split‐block design with four replications on typic (TK) and rhodic (RK) Kandiudult soils with seven cowpea genotypes. Phosphorus (P) fertilizers were applied on the main plots with 0 kg P, 30 kg P ha^–1 as triple superphosphate (TSP) and 90 kg P ha^–1 as Togo phosphate rock (PR). Nodule dry matter (DM), shoot DM, grain yield, and P uptake of cowpea significantly varied with site, P application, and genotype (p < 0.05). The N₂ fixation of the cowpea genotypes ranged from 29 to 51 kg N ha^–1 on both TK and RK soils and was significantly increased with P application. Significant genotypic variations in N₂ fixation were observed with superior ability of the genotypes IT89KD‐391 and IT90K‐59 to fix N₂. The harvest index (HI) did not significantly differ between soils and P application levels (p > 0.05). Four genotypes were selected to investigate root mechanisms responsible for efficient P acquisition in pot experiments. The results suggest that a better root infection by arbuscular mycorrhizal fungi (AMF) in genotype IT90K‐59 and root morphological and physiological characteristics in IT89KD‐391 were the most important factors for increasing P uptake.