饲用玉米根际促生菌资源筛选及其特性研究

为获得玉米根际促生菌(PGPR)菌株并明确其功能特性;以玉米根系及根际土壤为材料,利用选择性培养基分离筛选溶磷菌与固氮菌,测定所选菌株溶磷能力和固氮酶活性,并测定其产IAA的能力,从中筛选综合性能优良的菌株,在此基础上,运用生理生化鉴定和16SrDNA分子生物学鉴定相结合的方法鉴定优良菌株的种属。结果表明:玉米根际有大量PGPR菌,分布特征表现出根表(RP)根表土(RS)远根土(NRS)根内(HP)的数量分布规律,呈根际效应。最终获得262株PGPR菌,其中固氮菌48株,溶解无机磷细菌108株,溶解有机磷细菌106株,有分泌IAA能力的菌株15株。筛选出综合性能优良、有进一步开发应用潜力的菌株7株。经鉴定其中3株为Pseudomonas fluorescens;2株为Bacillus subtilis;Klebsiella oxytoca和Bacillus megaterium各1株。     

饲用乳酸菌固态发酵棉籽粕产有机酸的研究

本文研究了6株不同饲用乳酸茵固态发酵棉籽粕产有机酸情况。结果表明：德氏乳杆菌产酸量最高,可达18．56g／kg。为了增加产酸量,利用响应面分析法对德氏乳杆菌固态发酵棉籽粕培养基进行了优化,建立了二次回归方程：Y1=25．07—1．0325＊X1—0．47625＊X2—1．28875＊X5—1．8;5125＊X1＊X1＋0．67＊X1十X2＋O．17＊X1＊X5—1．59575．X2＊X2-0．6775．X2＊X3—1．06;575＊X5＊X3,并确定了最佳培养基配方为：棉粕916．44g／kg,麸皮83．56g／kg,糖蜜27．91g／kg,水480．24g／kg。在此条件下,使德氏乳杆菌固态发酵棉籽粕产有机酸含量达到25．64g／kg,比优化前提高了39．65％。     

草坪坪床对土壤的要求

通过对土壤理化性质及其生物组成的分析 ,对草坪坪床土壤提出了要求 ,并且提出了改良措施     

控制性隔沟交替灌溉条件下土壤蒸发的预测研究

棵间土壤蒸发是控制性交替灌溉条件下农田土壤耗水的重要组成部分,为了了解沈阳地区潮棕壤土条件下大豆田不同控制性交替灌溉制度下的土壤蒸发变化规律,对土壤蒸发进行预报,采用Micro-lysimeters(MLS)对不同灌溉处理下的土壤蒸发量进行了测定,并建立了以气象因子、土壤含水率和叶面积指数为自变量的土壤蒸发的预报模型.结果表明,在本试验的条件下,各处理的相对土壤蒸发率(E/ET0)与表层土壤含水率(θ)的关系均呈指数函数形式,决定系数在0.71以上.各处理的E/ET0与LAI之间亦呈很好的指数函数关系,决定系数均在0.78以上.     

Influence of organic amendments on dissipation kinetics of two different pesticides in soil: a case study

A study was undertaken to investigate the remedial effect of some soil amendments (farmyard manure (FYM), press mud compost (PMC), cereal straw (CS) at 5 t ha^?1 and fresh cow dung slurry (FCD) @ 0.5 t ha^?1) on dissipation kinetics of imidacloprid and sulfosulfuron under laboratory conditions. Incorporation of CS or FCD was found to be most effective in degrading both the pesticides at faster rates. Dissipation of both the pesticides could be well accounted by two component (1 + 1) first order kinetics. The computed values of parameters revealed that use of organic amendments increased the dissipated fraction of imidacloprid and sulfosulfuron. Incorporation of CS or FCD in soil maintained relatively higher dissipation rate constants for both faster and slower dissipation processes of pesticides in comparison to control. Hence, eco-friendly practices of CS or FCD incorporation as soil amendment in soil can play a vital role in preventing soil and water pollution.     

井冈山及周边地区有机农业的发展

有机农业是新世纪世界农业发展的重要方向之一,也是中国新时期农业发展的重要模式之一。井冈山及周边地区（包括井冈山市和莲花县、永新县、泰和县、遂川县、炎陵县、茶陵县）具有得天独厚的自然条件和生态环境优势,适宜发展有机农业。在对井冈山及周边地区发展有机农业的优势进行分析的基础上,以遂川县有机茶为例,重点分析了发展有机农业取得的实际成效;接着,指出了井冈山及周边地区发展有机农业存在的主要问题;最后,提出了该地区新世纪新时期发展有机农业的对策和措施。全文对山区有机农业的发展具有一定的指导意义和参考价值。     

改良型双污泥工艺处理低C/N城市污水

[目的]优化双污泥工艺存在的缺陷。[方法]采用改良型双污泥工艺处理人工配制模拟生活污水,测定处理前后水质并进行比较。[结果]系统出水COD〈40 mg/L、TN〈15 mg/L、氨氮〈3 mg/L、TP〈0.5 mg/L,均达到了《城镇污水处理厂污染物排放标准》（GB18918-2002）的一级A标准。[结论]改良型双污泥工艺不仅可以解决硝化细菌与除磷菌之间的泥龄矛盾问题,而且较适合处理低C/N条件下的城市污水。     

茅山苍术与苍术素相关的RAPD标记研究

[目的]探索鉴别苍术素高含量株与低含量株的方法,为筛选高含量苍术素株苗提供理论依据。[方法]对茅山100个苍术单株进行苍术素含量测定分析,从中选取3个高含量株和3个低含量单株,将其总DNA用于茅苍术-苍术素相关性RAPD研究。[结果]在所筛选的132个随机引物中,引物B16(5-′TTTGCCCGGA-3′)和F15(5-′CCAGTACTCC-3′)可以对苍术素高含量株与低含量株进行鉴别。用这2条引物分别对3个高含量单株和3个低含量单株进行扩增,结果表明,高含量株系的特异性条带只在高含量单株中存在,低含量株系的特异性条带只在低含量单株存在。[结论]该研究成功找到了与苍术素高含量株或低含量株相关的分子标记。     

Soil organic matter and related physical properties in a Mediterranean wheat-based rotation trial

Under semi-arid Mediterranean conditions, limited moisture is the main constraint to rainfed cropping with wheat (Triticum aestivum), barley (Hordeum vulgare), and food and forage legumes. With increasing land-use pressure, moisture-conserving fallowing is being replaced by continuous cropping, which is considered an unsustainable practice. Thus, a long-term trial with durum wheat (T. turgidum var. durum) was established in 1983 at Tel Hadya, Aleppo, Syria (mean annual rainfall 330 mm) to assess alternative rotation options to fallow and continuous cropping. Nitrogen (N) and grazing/residue management were secondary factors. Soil aggregation, infiltration, hydraulic conductivity, and total soil organic matter and component fractions (fulvic and humic acids and polysaccharides) were determined at the end of 12 years. Some rotations, e.g., medic (Medicago sativa) and vetch (Vicia faba), significantly increased soil organic matter (12.5–13.8 g kg⁻¹ versus 10.9–11 g kg⁻¹ for continuous wheat and wheat/fallow). All measurements, or indices, indicated parallel trends with increasing organic matter, e.g., coefficients of macro-structure, micro-aggregation, and water-stable aggregates, and decreasing dispersion. Similarly, legume rotations had higher infiltration rates (16.2–21.8 cm h⁻¹ versus 13.9–14.4 cm h⁻¹ with continuous wheat and wheat/fallow) and hydraulic conductivity rates (8.7–12.4 cm h⁻¹ versus 6.2–7.4 cm h⁻¹ with continuous wheat and wheat/fallow). We conclude that cereal/legume rotations, in addition to being biologically and economically attractive, also enhance soil quality and thus promote soil use sustainability in fragile semi-arid areas as in the Mediterranean zone.     

Long-term organic phosphorus mineralization in Spodosols under forests and its relation to carbon and nitrogen mineralization

In forest soils where a large fraction of total phosphorus (P) is in organic forms, soil micro-organisms play a major role in the P cycle and plant availability since they mediate organic P transformations. However, the correct assessment of organic P mineralization is usually a challenging task because mineralized P is rapidly sorbed and most mineralization fluxes are very weak. The objectives of the present work were to quantify in five forest Spodosols at soil depths of 0-15 cm net mineralization of total organic P and the resulting increase in plant available inorganic P and to verify whether net or gross P mineralization could be estimated using the C or N mineralization rates. Net mineralization of total organic P was derived from the net changes in microbial P and gross mineralization of P in dead soil organic matter. We studied very low P-sorbing soils enabling us to use lower extractants to assess the change in total inorganic P as a result of gross mineralization of P in dead soil organic matter. In addition, to enable detection of gross mineralization of P in dead soil organic matter, a long-term incubation (517 days) experiment was carried out. At the beginning of the experiment, total P contents of the soils were very low (19-51 μg g⁻¹) and were essentially present as organic P (17-44 μg g⁻¹, 85-91%) or microbial P (6-14 μg g⁻¹; 24-39%). Conversely, the initial contents of inorganic P were low (2-7 μg g⁻¹; 9-15%). The net changes in the pool size of microbial P during the 517 days of incubation (4-8 μg g⁻¹) and the amounts of P resulting from gross mineralization of dead soil organic matter (0.001-0.018 μg g⁻¹ day⁻¹; 0.4-9.5 μg g⁻¹ for the entire incubation period) were considerable compared to the initial amounts of organic P and also when compared to the initial diffusive iP fraction (<0.3 μg g⁻¹). Diffusive iP corresponds to the phosphate ions that can be transferred from the solid constituents to the soil solution under a gradient of concentration. Net mineralization of organic P induced an important increase in iP in soil solution (0.6-10 μg g⁻¹; 600-5000% increase) and lower increases in diffusive iP fractions (0.3-5 μg g⁻¹; 300-2000% increase), soil solid constituents having an extremely low reactivity relative to iP. Therefore, soil micro-organisms and organic P transformations play a major role in the bioavailability of P in these forest soils. In our study, the dead soil organic matter was defined as a recalcitrant organic fraction. Probably because gross mineralization of P from this recalcitrant organic fraction was mainly driven by the micro-organisms’ needs for energy, the rates of gross mineralization of C, N and P in the recalcitrant organic fraction were similar. Indirect estimation of gross mineralization of P in dead soil organic matter using the gross C mineralization rate seems thus an alternative method for the studied soils. However, additional studies are needed to verify this alternative method in other soils. No relationships were found between microbial P release and microbial C and N releases.