杂交油菜施用粉煤灰磁化肥的效应

通过对杂交油菜施用粉煤灰磁化复合肥的试验研究，初步探明了粉煤灰磁化复合肥较同等N，P，K的复混肥，未磁化粉煤灰复合肥及当地群众习惯施肥法有显著的增产效果，试验表明，粉煤灰磁化肥在油菜上一般用量为757．58kg/hm^2左右。粉煤灰磁化肥比对照增产21．9％，比当地农民习惯施肥措施增产10．5％，比等量N，P，K混膈肥增产9．9％，增产180kg/hm^2，比未磁化粉煤灰复混肥增产4．5％，最高产量施用粉煤灰磁化肥为1026．9kg/hm^2，油菜产量为2084．85kg/hm^2；最佳产量施用粉煤灰磁化肥为757．58kg/hm^2，油菜产量为2041．79kg/hm^2。     

旱地长期定位施肥对冬麦水分利用的影响研究

本文在长期定位施肥试验基础上研究了黄土高原旱地不同施肥条件下冬小麦对水分的利用。结果表明：旱地不同施肥连续15年种植冬小麦后对土壤剖面含水量影响显著，施N或NP配合处理与CK和单施P处理剖面含水量差异均达显著或极显著水平，冬小麦对土壤储水的利用深度超过200cm，最大施肥处理N180kg/hm^2P2O2180kg/hm^2小麦收获后0－400cm剖面储水量比CK少173.89mm，高N肥投入产量与生育年降水量显著相关，旱地土壤深层储水利用有很大的抗旱增产潜力。     

基于“3414”模型研究宁夏盐池县玉米氮磷钾施肥效应

2008年在盐池县具有代表性的土壤类型上进行了玉米＂3414＂试验,结果表明：地力贡献率为54.84%,说明土壤属于中等肥力。N、P、K对玉米产量影响大小顺序为N〉P〉K,增产效果居首位的为氮肥,施用纯N 240 kg/hm2的增产效应达到2 751.45 kg/hm2;P肥的增产幅度次之,施用纯P 120 kg/hm2的增产效应达到1 023.45 kg/hm;施用纯K 75kg/hm2的增产效应为236.7 kg/hm2。在不同肥料的交互作用中,N×P的交互作用对产量影响最大,N×P〉N×K〉P×K。施氮（N）量为360 kg/hm2,施磷量（P）为107.81 kg/hm2,施钾量（K）为4.30 kg/hm2时,玉米产量最高为7 652.23 kg/hm2。玉米产量与N、P、K肥料效应回归模型为三元二次多项式回归模型,经显著性检验达到极显著水平,可以为玉米生产施肥提供借鉴。     

不同氮磷施肥量对天鹰椒产量与性状的影响

采用二次饱和D-最优设计法研究了N、P化肥施用量对天鹰椒产量及其相关性状的影响结果表明，P肥增加椒数的作用大于N肥；N、P肥对单株椒重的作用基本相同；N肥对株高的增高作用大于P肥；随P肥施用量的增加而分枝下降，且随N肥施用量的增加而分枝增多，随N、P肥施用量的增加，产量均呈抛物线趋势，先增高后下降；根据肥料效应方程求出干椒4767kg/hm^2的目标产量，其适宜施用量为N281.11kg/hn^2、P2O582.11kg/hm^2。     

甘肃河西灌区啤酒酒大麦施钾效应研究

通过3年多点田间试验，探讨了钾肥对啤酒大麦的增产效应及适宜施肥量。结果表明，影响啤酒大麦产量的限制因子为N＞P＞K。通过建立肥料效应方程。确定了河西灌区啤酒大麦适宜的施肥量为纯N180－210kg/hm^2,P2O5120-150kg/hm^2,K2O70-90kg/hm^2。河西灌区土壤虽富钾，但钾肥仍表现出一定的增产效果。     

日光温室滴灌条件下黄瓜氮、磷、有机肥肥效与施肥模式研究

采用N、P、有机肥三因素五水平最优设计,在陕北黄土高原进行了日光温室黄瓜N、P和有机肥肥效与施肥模式的田间试验。得到了日光温室黄瓜N、P和有机肥的肥效反应模式,以及N、P和有机肥单因素对日光温室黄瓜产量的影响。结果表明N、P、有机肥对日光温室黄瓜产量增加的影响是有机肥 N P,施用有机肥是日光温室黄瓜增产的主要措施。当施P2O5量小于750 kg/km2、施氮量小于1150 kg/hm2时,N、P肥有增产效果,用量大于此施肥量时N、P肥效降低。根据反应模式提出在黄瓜目标产量在83000~88000 kg/hm2之间,95%置信区间的N、P、有机肥最佳施肥用量为N 807.5～1309.3、P2O5 576.6～991.6 kg/hm2;有机肥41.3～148.9 t/hm2。N∶P2O5为1∶0.714～0.757。日光温室黄瓜种植应以有机肥为主,氮磷肥配合施用。     

不同降水年型下温度升高对旱地春小麦产量的影响

为探究不同降水年型下温度升高对黄土丘陵区旱地春小麦产量的影响效应,本研究以甘肃省定西市安定区1979—2018年历史气象数据为基础,运用APSIM模型对不同降水年型下日最高、最低温度在0～2℃范围内耦合变化时旱地春小麦的产量进行模拟,并采用二次多项式回归、单因素分析和通径分析研究了不同降水年型下温度升高对旱地春小麦产量的影响机制。结果表明:在试验设计范围内,不同降水年型下旱地春小麦产量与日最低温度、日最高温度呈开口向上的二次抛物线变化且无阈值出现。日最高温度不变、日最低温度升高对产量呈正效应,其增产效果表现为干旱年平水年湿润年,日最低温度每增加0.5℃,最大增产幅度为3.99%;日最低温度不变、日最高温度升高对产量呈负效应,其减产效果表现为干旱年湿润年平水年,日最高温度每增加0.5℃,最大减产幅度为9.18%。不同降水年型下温度升高导致了旱地春小麦减产,日最高、最低温度升高对产量存在负交互关系,日最高温度升高带来的减产效应远大于日最低温度升高带来的增产效应。     

增施绿肥与降低氮肥对小麦产量和土壤肥力的影响

在甘肃河西绿洲灌区,通过田间试验研究了增施绿肥7500kg/hm^2后减施无机N肥施用量对小麦产量、经济性状、土壤肥力和土壤微生物数量的影响。结果表明,绿肥＋70%N处理比当地农民习惯施肥模式（FFP）增产829～1525kg/hm^2,增产率为10.7%～22.9%,且土壤碱解N、速效P、速效K和有机质含量均较高,能...     

降水对春小麦产量贡献率的研究

利用黑龙江省国营农场 40余年资料 ,用多元正态回归方法建立了春小麦产量与土壤有机质含量、降水量、气温间关系的计算机模型 ,研究结果表明该地年降水量对春小麦产量最大贡献率为 2 4kg/hm2 ·mm ,拔节～开花期 (约 50d)降水量 <80mm时对春小麦产量最大贡献率为 45kg/hm2 ·mm ,灌浆期 (约 2 0d)降水量 <10mm时对春小麦产量最大贡献率为 3 6kg/hm2 ·mm。     

宁南山区不同降水年型与地形的施肥模式研究

采用回归饱和最优设计 ,对宁南山区 3种不同立地农田生态系统影响春小麦产量的氮肥和磷肥用量进行了长期定位研究 ,并建立了春小麦施肥效益函数模型。通过对函数模型分析 ,确定了最大产量效应和最佳经济效应的施肥组合方案 ,明确了模型因素效应顺序和高产施肥的关系。     

Acidic precipitation and forest vegetation

Effects of acidic precipitation on forest vegetation may be classified as being either direct or indirect. Among the most important direct effects are damage to protective cuticular layers, interference with normal functioning of guard cells, poisoning of plant cells after diffusion of acidic substances through stomata or cuticle and interference with reproductive processes. Indirect effects include accelerated leaching of substances from foliar organs, increased susceptibility to drought and other environmental stress factors, and alteration of symbiotic associations and host-parasite interactions. The potential importance of nutrient take up through foliage and the need to understand atmosphere-plant-soil interactions are stressed.     

基于随机降水的冬小麦灌溉制度制定

为了确定合理的冬小麦灌溉制度,该文在分析广利灌区30 a降水分布规律的基础上,应用蒙特卡罗方法对其进行模拟出长系列（500 a）的旬降水,结合试验所得到的冬小麦耗水的基本参数,制定出了每个模拟年份冬小麦最优灌溉制度,并对灌水规律进行统计分析,得到不同灌溉定额条件下,各生育期灌水定额的的概率分布以及不同灌水定额的高产概率。结果表明：以30 mm为灌水定额的变化步长情况下,灌溉定额为60 mm时,越冬和拔节期各应该灌30 mm,高产概率为1%;灌溉定额为120 mm时,越冬和返青期灌30 mm,拔节期灌60 mm,高产概率为12%;灌溉定额为 180 mm时,越冬和灌浆期灌30 mm,返青和拔节期灌60 mm,高产概率为62.8%;灌溉定额为240 mm时,拔节期和抽穗期灌60 mm,其他生育期灌30 mm,高产概率为98.8%。该文丰富了灌溉制度的研究方法,为冬小麦的科学灌水提供了有力的技术支持。     

Effects of acidic precipitation and acidity on soil microbial processes

Effects of soil acidity on microbial decomposition of organic matter and transformation of N in an acid forest soil were investigated. In the oak-leaf-amended pH-adjusted acid soils, CO₂ production in 14-and 150-day preincubated samples decreased by about 6 and 37%, respectively. In the control (unamended) acidified soils, reductions in CO₂ production of 14% in 14-day preincubated samples and of 52% in 150-day samples were observed. Ammonia formation in the pH-adjusted acid soil was about 50% less than in the naturally acid soil. Increased rates of ammonification and nitrification were observed in the pH-adjusted neutral soil. Little autotrophic and heterotrophic nitrifying activity was detected in naturally acid and acidified forest soils. The rate of denitrification was rather slow in acid soils, and at greater acidities N₂O was the predominant end product. The abundance of N-fixing free-living bacteria was very low in acidic and acidified forest soils, and N gains by asymbiotic bacterial fixation in an acid forest ecosystem may be insignificant. These results suggest that further acidification of acid forest soils by addition of H₂SO₄ or by acid precipitation may lead to significant reductions in the leaf litter decomposition, ammonification, nitrification, and denitrification and thus reduce nutrient recycling in the forest ecosystem.     

Fallow method influences on soil water and precipitation storage efficiency

Summer fallowing is practiced in the Great Plains of the U.S.A. in order to store soil water, control weeds, make nutrients available and stabilize crop yields. Soil water storage and precipitation storage efficiencies on chemical and stubble-mulch fallow plots were compared for three 14-month fallow periods for a winter-wheat-fallow rotation (Triticum aestivum L.) and three 21-month fallow periods for spring-wheat-fallow rotation in the northern Great Plains to determine during which seasonal segment the fallow method might influence soil water storage. The experiment was conducted on a glacial till Williams loam (fine-loamy mixed, Typic Argiboroll) from July 1981 to April 1985. Soil water contents to a depth of 1.70 m were measured, using the neutron scatter technique, for seasonal segments during the fallow period. Soil water storage was similar from harvest to spring on chemical and stubble-mulch fallow plots. The over-winter to spring segment resulted in the most consistent precipitation storage efficiencies (33.3–71.1%). Soil water storage differences as a result of a fallow method are most likely to occur during summer fallow for 14-month winter-wheat-fallow rotations and during the second overwinter for 21-month spring-wheat-fallow rotations. Soil water storage for the entire fallow period was greater on chemical fallow than on stubble-mulch fallow in two out of three 14-month winter-wheat fallow periods and in one out of three 21-month spring-wheat fallow periods.     

Polyphenol/peptide binding and precipitation

Polyphenols are largely responsible for the astringency and "mouthfeel" of tea and wine by their interactions with basic salivary proline-rich proteins. Astringency arises from precipitation of polyphenol/peptide complexes, which is an important protective mechanism in animals that consume polyphenols. This paper presents biophysical studies of the interactions between chemically defined polyphenols and peptides. It is shown that intermolecular binding is dominated by stacking of polyphenolic rings onto planar hydrophobic surfaces and is strengthened by multiple cooperative binding of polyphenolic rings. Affinities weaken at higher temperatures and are unaffected by pH between pH 3.8 and 6.0. Measurements of self-diffusion rates for peptides with increasing concentrations of polyphenol demonstrate that peptides become increasingly coated with polyphenol. When the coating is sufficiently extensive to provide cooperative polyphenol bridges, the peptide dimerizes and precipitates. Light scattering measurements and electron microscopy indicate that the insoluble particles fall into two discrete size classes of ca. 80 and 500 nm diameter. The larger particles are favored at higher temperature and pH, suggesting that the particles are in a colloidal state, with the smaller particles being stabilized by charge repulsion between particles, and that precipitation of the complexes may be a phase separation process.     

Effects of acidity in precipitation on terrestrial vegetation

Over the last several decades rain in the Northeastern United States has become more acidic presumably as a result of anthropogenic inputs of SO_x and NO_x to the atmosphere and their conversion to H₂SO₄ and HNO₃. Present experimental results suggest that acidic precipitation would initially affect organisms on leaf surfaces and epidermal cells of leaves of higher plants. More internal cell layers would be affected with increasing duration or frequency of exposure. Differences in responses of plant foliage among plant species to acidic precipitation appear to be due to the degree of leaf wetting and differences in responses of leaf cells to low pH rain. Moreover, within the same plant, particular structures or cell types may be more sensitive than others. If the United States is to utilize coal reserves for electric power generation that might increase rainfall acidity in the future, an assessment of the impact that acidic rain might have on terrestrial vegetation is necessary. In one experiment, field-grown soybeans were exposed to short duration rainfalls of either pH 4.0, 3.1, 2.7, or 2.3 to provide inputs of 50, 397, 998, or 2506 μeq of H⁺, respectively, above ambient levels throughout the growing season. Control plots received only ambient rainfalls. These additional H⁺ decreased seed yield, 2.6, 6.5, 11.4, and 9.5%, respectively. A treatment response function determined between H⁺ treatments and seed yield wasy=21.06?1.01 logx had a correlation coefficient of ?0.90. Researchers must design additional experiments with adequate experimental controls to assess the impact that acidic rain, at the present pH levels of 3.0 to 4.0 or at anticipated worst-case levels, that could occur if the acidity of rain should increase. Only a holistic view of the impacts that acid precipitation may have on vegetation will enable optimal energy and environmental policy decisions to be made.     

CLIGEN降水要素在黄土塬区的适应性评估

 CLIGEN是目前较全面产生降水要素(降水量、历时、达到最大降水强度的时间与降水总历时的比率、最大降水强度与平均降水强度的比率)的天气发生器,其生成降水要素的质量直接影响水文和农业响应模型的输出结果。利用黄土高原长武1957—2001年的日气象观测数据、王东沟流域1988—2001年的降水要素数据和CLIGEN生成的100年日气象数据,对CLIGEN模型产生日、月、年降水量的均值和方差、概率分布、降水极端值和降水历时、强度进行评估。结果表明:CLIGEN对日、月和年降水量均值的模拟效果较好,相对误差都不大于1.0%;对标准差的模拟结果偏低,相对误差的绝对值小于6.6%;没有模拟出日降水量的概率分布,但是较好地模拟出了月和年降水量的概率分布;对日、月和年最大降水量的模拟误差较大,表明CLIGEN对极值的模拟精度有待提高。CLIGEN很好地模拟出连续降水的频率,但是连续干旱天数在20d以内的累积频率的平均相对误差为8.9%;CLIGEN产生的最大降水强度与平均降水强度的比率高于实测数据;相对于实测数据,CLIGEN模拟的降水历时和降水量具有相同的趋势,对小降水量或短历时的模拟结果偏高,对大降水量或长历时的模拟结果偏低。     

Impacts of acid precipitation on coniferous forest ecosystems

This paper summarizes the results from current studies in Norway. One main approach is the application of artificial acid ‘rain’ and of lime to field plots and lysimeters. Application during two growth seasons of 50 mm mo^?1 of ‘rain water’ of pH 3 to a podzol soil increased the acidity of the humus and decreased the base saturation. The reduction in base saturation was mainly due to leaching of Ca and Mg. Laboratory experiments revealed that decomposition of pine needles was not affected by any acid ‘rain’ treatment of the field plots. Liming slightly retarded the decomposition. No nitrification occurred in unlimed soils (pH 4.4-4.1). Liming increased nitrification. The soil enchytraeid (Ohgochaeta) fauna was not much affected by the acidification. Germination of spruce seeds in acidified mineral soil was negatively affected when soil pH was 4.0 or lower. Seedling establishment was even more sensitive to increasing soil acidity. Analysis of throughfall and stemflow water in southernmost Norway reveals that the total deposition of H₂SO₄ beneath spruce and pine is approximately two times the deposition in open terrain. A large part of this increase is probably due to dry deposition. Increased acidity of the rain seems to increase the leaching of cations from the tree crowns. Tree-ring analysis of spruce (Picea abies (L.) Karst.) and pine (Pinus sylvestris L.) has been based on comparisons between regions differently stressed by acid precipitation and also between sites presumed to differ in sensitivity to acidification. No effect that can be related to acid precipitation has yet been detected on diameter growth.