Quantitative assessment of hydrolase production and persistence in soil

The aim of this work was to calculate indices of hydrolase production (Pr) and persistence (Pe) through simple arithmetical calculations. Changes in acid and alkaline phosphomonoesterase, phosphodiesterase, urease, protease, and β-glucosidase activities were monitored under controlled conditions in seven soils with a wide range of properties, in which microbial growth was stimulated by adding glucose and nitrogen. Glucose mineralization was monitored by CO₂–C evolution, and microbial growth was quantified by determining the soil adenosine triphosphate (ATP) content. Hydrolase Pr and Pe indices were numerically quantified by the following relationships: Pr = H / t _H and Pe = (r / H)Δt, respectively, where H indicates the peak value of each measured hydrolase activity, t _H is the time of the peak value, r indicates the residual activity value, and Δt is the time interval t _r − t _H, where t _r is the time of the residual activity value. Addition of glucose and N-stimulated soil respiration increased ATP content and stimulated the production of the measured hydrolase activities in all soils; the measured variable reached a maximum value and then decreased, returning to the value of the control soil. Apart from β-glucosidase activity, whose activity was not stimulated by glucose and N addition, the other measured hydrolase activities showed a trend that allowed us to calculate the Pr and Pe indices using the above-mentioned equations. Acid phosphomonoesterase and protease Pr values were significantly higher in soils under forest or set aside management; the alkaline phosphomonoesterase and phosphodiesterase Pr values were generally higher in the neutral and alkaline soils, and the urease Pr values showed no obvious relationships with soil pH or management. Concerning the persistence of enzyme activities, Pe values of the acid phosphomonoesterase activity were significantly higher in the acidic soils, and those of urease activity were higher in acidic soils and the Bordeaux neutral soil. No relationships were observed between Pe values of alkaline phosphomonoesterase, phosphodiesterase, or protease activities and soil pH or management. The different responses of hydrolases were discussed in relation to soil properties, microbial growth, and regulation at the enzyme molecular level.     

麦秸覆盖对盐渍土肥力及作物产量的影响

在田间条件下采用定位试验,研究了麦秸覆盖还田措施改良盐化潮土的作用和效果。结果表明:麦秸覆盖还田增加了土壤有机质和 N、P、K 等养分,降低了土壤 pH 值,改善了土壤的物理性状,促进了土壤脱盐;麦秸覆盖还田减少了地面水分的蒸发,有效保持土壤水分,从而抑制了盐分向地表的积聚;麦秸覆盖还田为玉米的正常生长发育创造了良好的土壤肥力基础,使玉米比对照增产 1470 kg/hm2,增产率为 16.20%。     

我国农牧系统素转化循环的宏观特征与生态农业

本文应用作物、畜禽、土壤三个养分库的简化氮循环模型、建立反映我国农业氮素转化循环宏观特征及其变化的定量图解模型，提示了我国农业发展历程中日益加强的无机化倾向和低效率问题。从50年代初到80年代末，我国农牧系统在作物生物氮生产总量提高1.3倍、食物氮供应总量提高1倍、食物氮中动物性氮比重提高３倍的同时，农田生产性输入总量及化肥氮施用量分别增长了7倍和186倍，有机氮输入量经重由占总输入氮量的97%下降到25%，农田总投入氮和化肥氮肥的主产品氮生产效率分别从1.12和3.63下降到0.34和0.46。满足人口13-15亿时适当改善的食物氮需求，需增产饲料氮1-2倍，增施化肥氮1倍以上，并将出现严重的生态环境后果。论文讨论了为解决我国农业氮素转化循环问题可能采取的生态农业对策。     

No-tillage drilling of Italian ryegrass (Lolium multiflorum L.): Crop residue effects, yields and economic benefits

Variable practical results have been observed for no-till (NT) drilling of grasslands in Galicia, northwest Spain. One of the possible explanations to this erratic behaviour could be the influence of different types of stubble on drill performance and grassland emergence. Because the rotation of silage corn (Zea mays L.) with grassland is the most popular rotation in the Galician dairy farms at present, NT drilling of Italian ryegrass on corn stubble and ryegrass stubble was evaluated. Results were compared with NT drilling after shredded stubble and with conventional drilling (with tillage) for 5 years. Annual ryegrass establishment, biomass production, and forage production were measured each year. Treatments considered were: (1) NT on shredded ryegrass stubble; (2) NT on ryegrass stubble; (3) NT on corn stubble; (4) NT on shredded corn stubble; (5) conventional tillage (CT). Better plant stands and more forage production were obtained on the CT and NT-shredded treatments. Allelopathic effects were not observed, and the differences in plant stands among treatments could be caused by the physical effects of stubble and not by its physiological effects. The shredding operation improved plant stands and forage production of Italian ryegrass, which were not influenced by the type of stubble. Years with abundant rainfall negatively affected crop development, which was more evident in NT treatments. NT methods had advantages in terms of timeliness and low economic costs, as compared to CT.     

白藜芦醇的生理功能及其在猪生产中的应用研究进展

白藜芦醇是一种天然的植物多酚,在大豆、葡萄、虎杖等植物中广泛存在,具有抗氧化、抗炎、抑菌等生物学活性。本文总结了白藜芦醇的来源、提取工艺及合成途径,并综述了其生理功能相关的分子机理,以期为白藜芦醇在养猪生产中的合理利用提供参考与研究思路。     

饲用谷子在环渤海盐碱旱地的生产性能及饲用品质评价

为揭示环渤海盐碱旱地不同饲用谷子（Setaria italica）的生产潜力,本研究通过2年的栽培试验,比较了23个饲用谷子的产量性状、农艺性状、营养成分指标,并采用标准差系数赋予权重法及粗饲料分级指数（Grading index,GI）对不同饲用谷子进行了综合评价分析。结果表明,不同饲用谷子品种间的各性状指标均存在显著差异。‘武安莠谷杂交-1-1’、‘HG001’、‘印90-39’、‘古川粟’、‘邯郸莠谷-11’、‘印度0907’干草产量能达到11 000 kg·hm^-2及以上;‘承03-992’、‘饲草4号-4’、‘衡谷15号’、‘豫谷18号’、‘大同37号’、‘邯郸莠谷-11’、‘K3201’粗饲料分级指数在12.45以上,饲用品质优良;结合抗倒性综合评价,以‘邯郸莠谷-11’、‘衡谷15号’、‘印度0906’、‘太选2号’较好。因此,在环渤海盐碱旱地种植饲用谷子具有可行性,可优先推广‘邯郸莠谷-11’、‘衡谷15号’、‘印度0906’和‘太选2号’。     

肉免专门化新品系的利用与推广

肉兔专门化新品系（ 以下简称Ａ 系兔）是经四川省畜牧科学研究院连续九年、六个世代的选育，供作母系亲本利用的中型肉兔专门化品系。多年来在农村饲养条件下推广利用结果表明：Ａ 系兔在农村养兔户的平均胎产仔数８－１ ±１－２ 只，年平均产仔７－１ ±０－８４ 胎，年产仔数达５７－５ 只的高水平。与引进的齐卡兔配套生产的商品兔，农村条件下产仔数达８－４３ ±１－９６ 只，９０ 日龄重达２－４５ ±０－３８ｋｇ，明显高于省内“七·五”期间比利时兔×本地兔或加利福尼亚兔×本地兔，以及“八·五”期间齐卡兔改良本地兔的生产效果。Ａ 系兔现已在全国１８ 个省及四川省内１２０ 余个县推广利用。     

中国棉花生产优势省域分析

中国棉区分布广阔,各地宜棉程度差别很大。在前人研究的基础上,利用1989—2003年的全国及各省区的生产统计资料,以规模优势指数、单产优势指数、集中度优势指数、综合优势指数、棉粮单产比指数、棉粮面积比指数对各省区近阶段产棉优势分布及部分省区优势变化进行了分析。分析结果表明:中国有新疆、河南、山东、河北、湖北、江苏、安徽,这7个稳定的棉花生产优势省区,天津可能成为新兴的棉花优势省区,总体而言,中国棉花生产优势在东部有所波动,略有减小的状态下,植棉重心向西北部偏移。     

EM技术对蒙古黄芪产量效应的应用研究

研究了EM技术对蒙古黄芪产量效应的影响。结果表明,EM堆肥增产效应显著。     

买方市场条件下蔬菜产销的问题及对策

在分析买方市场条件下蔬菜产销面临的问题的基础之上 ,根据买方市场的特征 ,结合蔬菜产销的特点 ,提出了新的市场环境条件下蔬菜产销发展的基本对策