Composition of organic C fractions in soils of different texture affected by sugarcane monoculture

ABSTRACT

Sugarcane is a strategic commodity in Indonesia. It is usually raised in a monoculture system. There is a lack of information about the effects of extended sugarcane monoculture on the soil carbon fraction. The aim of this study was to determine the relative changes in the soil organic C fractions in response to the duration of sugarcane monoculture on Entisols, Inceptisols, and Vertisols. The measured variables were the percentages of sand, silt, and clay, organic matter (OM), total nitrogen (TN), pH (H₂O), cation exchange capacity (CEC), NH₄ ⁺, NO₃ ^-, labile carbon fraction (soil carbon mineralization (C-Min), soil microbial carbon (C-Mic), and carbon particulate organic matter (C-POM)), and stable carbon fraction (humic and fulvic acids). Soil type with sugarcane monoculture period had significant influences on the percentages of clay, sand, silt, CEC, and pH (H₂O). Soil type and sugarcane monoculture period had no apparent significant effect on C-Min or C-POM but did significantly influence C-Mic. The humic and fulvic acid levels in all three soil types were affected by the duration of sugarcane monoculture. To establish the impact of long-term sugarcane monoculture on the physicochemical properties of soils with various textures, it is more appropriate to measure the soil stable carbon fractions such as humic and fulvic acid rather than the soil labile carbon fractions such as C-Min, C-POM, or C-Mic.     

Glutathione content of in vivo and in vitro matured canine oocytes collected from different reproductive stages

Glutathione (GSH) concentrations of oocytes are considered as an important marker of the cytoplasmic maturation. The present study was designed to compare GSH concentrations of in vivo and in vitro matured canine oocytes. In vivo matured oocytes were collected 72 hr after ovulation by flushing fallopian tubes after laparotomy. Ovaries were collected from bitches with different reproductive stages, and collected oocytes were divided into 2 groups according to the size viz. < 120 microm and > 120 microm in diameter and cultured for 72 hr in Tissue Culture Medium-199 supplemented with 10% FBS, 2.2 mg/ml sodium bicarbonate, 2.0 microg/ml estrogen, 0.5 microg/ml FSH, 0.03 IU/ml hCG, and 1% penicillin-streptomycin solution in the presence or absence of 50 microM beta-mercaptoethanol. GSH concentrations were determined by the dithionitrobenzoic acid-glutathione disulfide (DTNB-GSSG) reductase recycling assay. GSH concentrations of immature canine oocytes were 2.9 and 3.8, 3.5 and 6.8, and 3.1 and 6.5 pM/oocyte for < 120 microm and > 120 microm in diameter oocyte groups at anestrous, follicular and luteal stage, respectively (P<0.05). In vivo matured oocytes had significantly higher GSH concentrations compared with in vitro matured oocytes. The GSH content was 19.2 pM/oocyte for in vivo matured oocytes, while 4.1 to 8.1 and 5.7 to 13.2 pM/oocyte for in vitro matured oocytes cultured in the absence or presence of beta-mercaptoethanol, respectively (P<0.05). Presence of beta-mercaptoethanol increased GSH synthesis in canine oocytes cultured in vitro, and oocytes collected from follicular and luteal stage was superior to anestrus oocytes.     

Island differences in population size structure and catch per unit effort and their conservation implications for Komodo dragons

Species inhabiting archipelagos are often characterised by high levels of interpopulation divergence (e.g. size related traits). This divergence may, in turn, influence their life-history. To facilitate better management and conservation of the Komodo dragon (Varanus komodoensis), an island endemic, we identified demographic differences between two island populations in Komodo National Park, Indonesia. Comparison of data collected from dragon populations inhabiting Rinca Island and the much smaller Gili Motang Island indicated that between 1994 and 2004, the Komodo dragon population on Gili Motang significantly decreased its: (1) mean body mass, (2) body condition and (3) relative abundance. These results suggest that the numerically small Gili Motang population was oscillating downwards; in contrast, the Rinca Island population had been relatively stable. More importantly these results emphasize the necessity for managers of this priority conservation species to understand further the inherent functional differences among dragon populations to develop island specific management units. Current management practices (e.g. monitoring) instigated by Komodo National Park management ignore small island dragon populations and thus run the risk of being unable to detect adverse effects for populations that are potentially most prone to decline.     

Kinetic Parameters of Gross N Mineralization of Peat Soils as Related to the Composition of Soil Organic Matter

Peat land has been considered as an alternative type of land for agricultural development especially in the tropics. In the present study, the N-supplying capacity, one of the most important soil properties in terms of crop production, of peat soils was examined. Ten peat soil samples were collected from Indonesia, Malaysia, and Japan. Gross N mineralization in the soil samples was estimated using a zero-order model, and kinetic parameters of mineralization were determined using a simple type model. Soil organic matter composition was investigated using ¹³C CPMAS NMR. Mineralization potential ( N ₀), apparent activation energy ( E _a), and mineralization rate constant ( k ) ranged between 571–2,445 mg kg⁻¹, 281–8,181 J mol⁻¹, and 0.009–0.020 d⁻¹, respectively. Although none of the parameters showed a significant correlation with the soil C/N ratio, a negative correlation was observed between the k value and the ratio of the proportion of alkyl C in total C to that of O -alkyl C estimated by ¹³C CPMAS NMR. The latter suggested that the k values were higher in the peat soils relatively rich in readily decomposable organic matter including carbohydrates.     

内蒙古半荒漠区鼠害区划及防治策略研究

本文自1988～1993年历时5年的时间在内蒙古半荒漠区约11万km2（涉及行政上12个旗、县、郊区）的调查区域内共设量259个样方，以夹日法调查为主，并辅以线路调查法、地箭法、踪迹法等方法，共布放有效夹日131109个，捕获啮齿动物36种，加之80年代以来作者在该地区的工作，共采集啮齿动物标本5000余号，基本查清了该地区啮齿射物的种类，分布、密度及其危害情况，根据调查结果对该地区害鼠对农业、牧业、林业危害的特点及其成因迸行了分析，结果发现当地阴山北麓的旱作农田是受害鼠危害较重的地区；而半荒漠草原中严重退化的荒漠草原鼠害极为严重；林地则为人工林地及育苗圃内遭受鼠害较重。根据其危害特点将该地区害鼠区划为6十大的危害区的11个害鼠害区类型。     

Nutrient availability and response of sago palm (Metroxylon sago Rottb.) to controlled release N fertilizer on coastal lowland peat in the tropics

Sago palms (Metroxylon sagu Rottb.) growing on peat soils were found to grow more slowly and to show a lower production than palms growing on mineral soils. This difference was related to the physical and chemical constraints of peat soils, which include low bulk density, high acidity, and low N, P, K, Ca, Zn, and Cu levels. In coastal lowland peat soils, the distance from the sea has been found to be an important determinant of soil elemental composition. We predicted that a sufficient supply of N at the rosette stage would improve sago palm growth and that the availability of N in soil to which controlled release N fertilizer was applied might be higher than that in soil treated with soluble fertilizer. To investigate the changes in the nutrient composition of peat soils at various distances from the sea and the effect on sago palm growth, we studied sago palm areas in Indonesia and Malaysia. To observe the influence of N on the growth performance, we also conducted a fertilizer experiment on coastal lowland peat soil in Indonesia. Distance from the sea had no significant effect on the cation concentration in the soil solution (with the exception of Mg) or on the levels of soil-exchangeable cations. No significant differences were observed between the concentrations of exchangeable cations in surface peat soils and those in mature leaves. However, the concentrations of K, Na, and Ca in mature leaves increased significantly with their concentrations in the soil solution. This finding implies that the concentrations of cations in sago palm leaves depend directly on the concentrations of cations in the soil solution. No significant effect of N fertilizers on plant height and leaf formation was observed. N fertilizers applied twice a year did not affect appreciably the foliar concentration of N determined in December 1998 (5 months after the initial application) and December 1999. In June 2000, we detected a significantly higher concentration of N (p < 0.01) in young leaves of the palms treated with LP-100 or urea than in control leaves. However, no significant difference was detected between the LP-100 and urea treatments in the concentration of N in both mature and young leaves. This finding indicated that the concentration of N in sago palm leaves increased with the level of soil-applied N, regardless of whether N was applied as controlled release fertilizer or in the soluble form. We anticipate that a significant difference in the effects of these N fertilizers may occur during the next rainy season, when there should be a considerable loss of soluble N.     

Well-defined multispecies probiotic and enzyme combination outperforms traditional fermented probiotic applications in an intensive Pacific white shrimp,Litopenaeus vannamei (Boone, 1931), culture system

A series of treatments were designed to evaluate the efficacy of feeding commercial multispecies probiotics feeding with enzymes and fermentation process on the growth parameters and culture environment of Pacific white shrimp, Litopenaeus vannamei (Boone, 1931), in an intensive culture system. Commercial multispecies probiotics and enzymes (PEs) were continuously applied in three different doses, namely (i) 0.2, (ii) 0.4, and (iii) 0.6 mg L⁻¹ and designated as 0.2, 0.4, and 0.6 PE during the first 30 days of intensive culture of Pacific white shrimp, L. vannamei (Boone, 1931). The probiotics were continually applied every alternate day, while the enzymes were added every sixth day throughout the trial period. The PE dose for all treated tanks was increased by 0.2 ppm after 30 days of culture and another 0.2 ppm after day 60. Meanwhile, fermentation technique, which has become the common method applied in Indonesia in the control treatment, was added on the same day with the PE group with increasing dosage, following the same trend with the 0.6 PE group. Results showed that the group receiving 0.6 PE showed higher final biomass, higher mean weight, and protein retention efficiency as well as a lower feed conversion ratio compared with the control treatment. Abundance of Vibrio spp. remained below 10³ cfu mL⁻¹ throughout the trial. Water quality indicators TAN, NO₂ N and NO₃ N peaked in weeks 3–5 and then declined after that until the end of the culture period in all tanks. This decline was significantly faster in PE-treated tanks. Multispecies PEs have potential applications in controlling Vibrio spp., maintaining proper water quality condition, and enhancing the growth of shrimp in intensive culture system.     

逐步判别分析在呼市地区长爪沙鼠年龄鉴定中的应用

长爪沙鼠是我区的主要鼠类之一,为探讨该鼠种在农林牧业系统中的作用,并有效地控制其危害,提高防治鼠害的技术水平和效果,研究该种群的年龄组成及鉴定所属年龄组是非常必要的。本文利用逐步判别分析法对3个年龄组中的72个个体作了分析,结果表明判别准确率达90.28％。在13个特征中选出了来自头骨外形的5个最显著的特征。在今后的实际工作中,为了鉴定所属年龄组,只需简单地测量这5个指标而不需要测量体重、体长以及观察毛色等特征。