垄膜沟播与秸秆还田对内蒙古黄土高原玉米农田土壤水分、酶活性及产量的影响

为明确全覆膜垄膜沟播种植和秸秆还田措施下玉米农田土壤保水改土效果及增产效应,在内蒙古黄土高原旱作区对比分析了全覆膜垄膜沟播结合秸秆还田（S+M）、秸秆还田（S）、全覆膜垄膜沟播（M）、秸秆不还田不覆膜（CK）4种不同耕作方式下土壤水分、酶活性变化规律及玉米产量形成特性。结果表明：全覆膜垄膜沟播种植和秸秆还田均能提高玉米各生育阶段0—100 cm土层土壤含水量,尤以0—20 cm土层土壤含水量差异最为显著,且全覆膜垄膜沟播种植提升效果优于秸秆还田,两者耦合后土壤含水量表现为最大;垄膜沟播和秸秆还田均可显著提高土壤过氧化氢酶、脲酶、蔗糖酶和碱性磷酸酶活性,且随玉米生育期推移,土壤酶活性呈先增加后降低趋势,在大喇叭口期达到峰值;同时,垄膜沟播和秸秆还田均能提高玉米干物质量和产量,由高到低次序为S+M＞M＞S＞CK,与CK相比,S、M、S+M处理玉米产量分别提高11.84%、37.83%、45.13%,全覆膜垄膜沟播结合秸秆还田明显优于其他处理,可作为内蒙古黄土高原旱作区玉米节水增效增产栽培模式。     

生物炭施用下土壤微生物量碳氮的动态变化

为了研究生物炭施用量对整个玉米生育期内土壤微生物量及玉米产量的影响,采用田间定位试验,生物炭施用量设置0（BC0）、10（BC1）、20（BC2）和30（BC3） t·hm^-2共4个处理,测定不同处理下土壤微生物量碳、氮及其动态变化和收获后玉米的籽粒产量。结果表明,玉米生育期内各土层土壤微生物量碳随生物炭施用量的增加而增加;与BC0相比,施用生物炭对播种前土壤微生物量碳的影响最为显著,其中,BC3处理在0—10、10—20和20—30 cm土层的微生物量碳较对照分别增加103.2%、91.8%和158.5%。土壤微生物量氮和微生物量碳氮比的变化则与玉米生育期有关。从整个生育期来看,土壤微生物量碳、氮含量在播种前最低,在拔节期达到峰值,之后缓慢降低并保持相对稳定。在播种前,BC3处理土壤微生物商增幅最大,较BC0增加了59.5%,其他生育期土壤微生物商无显著变化。玉米籽粒产量随生物炭施用量的增加而增加,BC2和BC3分别较BC0显著增产11.2%和14.1%。因此,在土壤中施用生物炭可在一定程度上增加土壤微生物量,提高土壤肥力,增加作物产量,为该地区生物炭的合理施用提供理论依据。     

绿肥翻压与氮肥减施对水稻产量、品质及土壤肥力的影响

为探明绿肥山黧豆种植翻压下减量施用化学氮肥的潜力,通过3年田间定位试验,设置冬闲+100% N肥（常规施肥,CK）、山黧豆+60% N肥（GM+N60）、山黧豆+70% N肥（GM+N70）、山黧豆+80% N肥（GM+N80）、山黧豆+不施肥（GM）和冬闲+不施肥（NF）共6个处理,研究不同处理对水稻产量、品质及土壤肥力的影响。结果表明,与CK相比,山黧豆与氮肥减量配施能提高水稻产量,GM+N70和GM+N80处理显著提高水稻产量,分别增产13.84%和7.25%;且能提高稻米糙米率、精米率、整精米率和蛋白质含量,降低垩白度及垩白粒率和直链淀粉含量。其中,GM+N70处理的整精米率最高,为78.02%,垩白粒率最低,为18.11%;GM+N80处理的直链淀粉含量最低,为14.26%。山黧豆与氮肥减量配施能明显提高土壤有机质、全氮、碱解氮和速效钾含量,对土壤有效磷含量无显著影响。综上,种植翻压山黧豆与氮肥减量20%~30%配施有利于提高水稻产量、品质及土壤肥力,为构建四川稻区山黧豆种植翻压还田后科学施用氮肥提供理论依据。     

Use of geographical information systems as a tool for predicting fish yield in tropical reservoirs: case study on Sri Lankan reservoirs

Use of geographical information systems (GIS) in inland fisheries has hitherto been essentially restricted to site evaluation for aquaculture development and assessment of limnological changes in time and space in individual water bodies. The present GIS study was conducted on the land-use pattern of the catchments of nine reservoirs in Sri Lanka, for which detailed fishery data, viz. yield, fishing intensity, landing size of major constituent species, together with selected limnological data such as conductivity and chlorophyll- a , were available. Potential statistical relationships (linear, curvilinear, exponential and second-order polynomial) of fish yield ( FY , in kg ha⁻¹ yr⁻¹) to different land-use patterns, such as forest cover ( FC , in km²) and shrub-land ( SL , in km²), either singly, or in combination, and/or the ratio of each land type to reservoir area ( RA in km²) and reservoir capacity ( RC in km³), were explored. Highly significant relationships were evident between FY to the ratio of SL and/or FC + SL to RA and/or RC . Similarly, the above land-use types to RA and RC ratios were significantly related to limnological features of the reservoirs. The relationships of FY to various parameters obtained in this study were much better correlated than those relationships of FY to limnological and biological parameters used in yield prediction in tropical and temperate lacustrine waters previously.     

通过小型探鱼无人船探测大型围网养殖区大黄鱼的分布特性

为了明确大黄鱼在大型围网养殖区内的分布规律,本实验通过集成、构建具备大黄鱼探测以及水温、盐度、光照、pH、溶解氧等海洋环境探测功能的小型探鱼无人船,并在浙江省舟山市桃花岛大黄鱼围网养殖基地内开展了6次现场监测试验。实验结果表明,①在水平分布方面,大黄鱼主要分布在大型围网养殖区内礁石丰富且水流相对较缓的区域;②在垂直分布方面,大黄鱼主要分布在加权相对深度0.6~0.9的养殖海区中下层;③围网养殖海区内温度、盐度、pH、溶解氧等海洋环境条件整体变化较小（p>0.05）,大黄鱼往往分布在光照强度分别为5921±2702lx、50799±50988x、5990±542lx、3494±695lx、6836±4761lx、15395±5531lx相对较弱的区域。本实验首次通过小型探鱼无人船系统地研究了围网养殖区内大黄鱼的分布特性及相应的海洋环境对其分布的影响,结果为大黄鱼围网养殖区的操作平台选址、投喂管理、起网设计等提供了依据。     

Managing fisheries is managing people: what has been learned?

Understanding the behaviour of fishermen is a key ingredient to successful fisheries management. The aggregate behaviour of fishing fleets can be predicted and managed with appropriate incentives. To determine appropriate incentives, we should look to successes to learn what works and what does not. In different fisheries incentive systems have been found to reduce the race‐for‐fish and make fisheries profitable, to stimulate stock rebuilding, to reduce bycatch, and to provide for reductions in illegal fishing. Yet, success can be evaluated in many dimensions, but is, in fact, rarely done – per cent overfished seems to be the dominant measure of performance. I evaluate the yield lost due to overfishing in several ecosystems and contrast the situation of North Atlantic cod where considerable yield is lost, to fisheries in New Zealand and the west coast of the USA where lost yield due to overfishing is very small. Much more systematic evaluation of the other aspects of fisheries performance is greatly needed. From examples explored in this paper I conclude that prevention of overfishing can be achieved with strong central governments enforcing conservative catch regulations, but economic success appears to require an appropriate incentive structure.     

考虑应力敏感性影响的三项式产能方程

低渗透气藏存在较强的应力敏感性,大量岩石实验数据回归研究表明,幂函数渗透率应力敏感性经验方程相关性相对较好,而前人利用该关系式来研究低渗透气藏气井产能的报道较少。在这样的背景下,利用幂函数应力敏感性经验公式,综合考虑渗透率应力敏感效应、启动压力梯度、紊流效应和表皮系数,建立了一个新的适用于低渗透异常高压气井的三项式产能方程。不同参数组合情况下的气井流入动态曲线对比研究结果表明,应力敏感性、启动压力梯度和紊流效应对低渗透气藏气井产能的影响较大,在产能评价研究时必须予以考虑。     

基于灰色关联下的广西粮食主要生产影响因素评价

通过对1995—2010年主要年份广西主要粮食（稻谷、玉米、大豆、薯类）产量与相关生产因素的灰色关联度动态分析,提出广西主要粮食生产的可持续发展途径,为农业可持续发展提供参考。运用灰色系统理论中的关联度分析法对1995—2010年其中6个主要年份与粮食生产有关的7个影响因素进行量化动态分析。结果表明：粮食产量与相关生产因素的关联度为播种面积〉城镇居民家庭人均购买粮食数量〉化肥施用量〉乡村从业人员〉农田有效灌溉面积〉单位面积产量〉农田总用电量。     

Temporal associations between low body condition,lameness and milk yield in a UK dairy herd

Previous work has hypothesised that cows in low body condition become lame. We tested this in a prospective longitudinal study. Body condition score (BCS), causes of lameness and milk yield were collected from a 600-cow herd over 44-months. Mixed effect binomial models and a continuous outcome model were used to investigate the associations between lameness, BCS and milk yield. In total, 14,320 risk periods were obtained from 1137 cows. There were 1510 lameness treatments: the most common causes of lameness were sole ulcer (SU) (39%), sole haemorrhage (SH) (13%), digital dermatitis (DD) (10%) and white line disease (WLD) (8%). These varied by year and year quarter. Body condition was scored at 60-day intervals. BCS ranged from 1 to 5 with a mean of 2.5, scores were higher in very early lactation but varied widely throughout lactation; approximately 45% of scores were <2.5. The key finding was that BCS < 2.5 was associated with an increased risk of treatment for lameness in the following 0–2 months and >2–4 months for all causes of lameness and also specifically for SU/WLD lameness. BCS < 2.5 was associated with an increased risk of treatment for SH in the following 0–2 months but not >2–4 months. There was no such association with DD. All lameness, SU/WLD, SH and DD were significantly more likely to occur in cows that had been lame previously, but the effect of BCS was present even when all repeat cases of lameness were excluded from the analysis. Milk yield was significantly higher and fell in the month before treatment in cows lame with SU/WLD but it was not significantly higher for cows that were treated for DD compared with non-lame cows. These findings support the hypothesis that low BCS contributes to the development of horn related claw lameness but not infectious claw diseases in dairy cows. One link between low BCS and lameness is a thin digital cushion which has been proposed as a trigger for claw horn disease. Cows with BCS 2 produced more milk than cows with BCS 2.5, however, this was only approximately 100 kg difference in yield over a 305-day lactation. Given the increased risk of lameness in cows with BCS 2, the direct costs of lameness and the small variability in milk yield by BCS, preventing cows from falling to BCS < 2.5 would improve cow welfare and be economically beneficial.     

不同叶面肥对桑叶产量的影响

在桑园管理措施一致的前提下,用5种常用叶面肥对桑叶产量的影响进行了比对,结果表明,667 m2产叶量依次为：0.3-0.5%的磷酸二氢钾[KH2PO4]＞0.5-0.7%的尿素[CO（NH2）2]水溶液＞0.3-0.5%的硫酸铵[（NH4）2SO4]＞0.4-0.6%的硫酸钾[K2SO4]＞0.5-0.8%的过磷酸钙[Ca（H2PO4）2]。据此认为,桑园施用叶面肥应首选0.3-0.5%的磷酸二氢钾[KH2PO4]和0.5-0.7%的尿素[CO（NH2）2]水溶液。考虑到生产成本及工作之便,生产上推荐使用0.5-0.7%的尿素[CO（NH2）2]水溶液。