Forest Fertilization Research in Finland: A Literature Review

This paper summarizes results from fertilization research carried out in Scots pine ( Pinus sylvestris L.) and Norway spruce [ Picea abies (L.) Karst.] stands growing on mineral soil in Finland. The use of needle and soil analyses to indicate nutrient status and the need for fertilization are discussed along with the possibilities of increasing tree growth in various site types and stages of stand development. Doses, types of fertilizer, application time, growth increase, wood quality and the profitability of fertilization are also discussed. The stand response in terms of soil acidity, biological activity, soil fauna and resistance of trees to nutrient addition are all reviewed. The effects of fertilization on understorey vegetation, mushrooms and berries, and leaching loss of nutrients are also included.     

影响金耳多糖提取率因素的正交试验

金耳子实体干品复水后呈韧胶质状，主要成分之一－－金耳多糖，溶解于水中形成较大粘度的胶体溶液，对其提取分离造成很大的困难。本文以其理化性质为基础，提出了影响提取率的几个因素，通过正交试验，得到了较为理想的结果。     

Within-field variability of mineral nitrogen in grassland

 The within-field variability of soil mineral nitrogen (N_min) in a grazed grassland of 8000 m² was examined. NO₃ ^–-N concentrations were characterized by a high spatial variability. This can be explained by the uneven deposition of animal excreta. All NH₄ ⁺-N as well as NO₃ ^–-N values were lognormally distributed, before and after the grazing season. At the end of the grazing season the largest part of the variability of NO₃ ^–-N was found for NO₃ ^–-N concentrations measured within a distance of a few metres. A high variability for NO₃ ^–-N over very short distances was also indicated by a large nugget variance. During the grazing season, observed mean N_min values increased from 22 to 132 kg N ha^–1. Regions with clearly higher NO₃ ^–-N concentrations could be identified. These zones matched with the drinking place and the entrance of the pasture, places which were more frequently visited than others. High residual N levels in autumn led to relatively high losses of N, mostly by leaching, during the subsequent drainage period. Knowing the variability of N_min, the number of samples needed to estimate the average N_min in a field could be calculated for different probabilities and various degrees of precision. From the spatial distribution of the N_min concentrations and the restrictions imposed by the new European decree, adapted fertilizer strategies can be proposed at least for places where systematically higher N_min concentrations can be expected. Received: 14 December 1999     

An update on the Koc concept in regard to regional scale management

The normalization of soil sorption data to the soil organic matter content (SOM) produces a sorption constant, K_oc, which is pesticide specific and independent of soil properties. Despite certain inherent problems with this constant, it has proven valuable in providing a tool for ranking pesticide leaching potential and for evaluating sorption properties where actual data is lacking. It cannot, however, provide reliable prediction of pesticide fate on the regional or catchment scale. The variability in K_oc and SOM values and their effect on leaching indices is briefly reviewed. Several new and modern techniques such as GIS and GPS provide us with the means to map, and store in databases, the variability of SOM within fields and to implement site-specific pesticide application (Precision Agriculture) where the amount applied will be a function of the SOM. This mapping can then be used in regional scale management systems.     

多年生黑麦草草地矿质氮淋溶与径流流失的关系

以人工放水模拟冲刷试验,研究多年生黑麦草草地土壤矿质氮素淋溶和径流流失的关系。当硝态和铵态氮肥用量分别达到5000kgN/km²,冲刷强度为1mm/min,冲刷时间为50min时,观测氮素径流流失,于48h后检测土壤矿质氮动态。结果表明,坡度为25°、20°、15°、10°和5°土壤,铵态氮径流流失量分别为97.3、87.9、79.0、57.1和50.4kg/km²,分别占施氮量的1.9%、1.8%、1.%、1.1%和1.0%。铵态氮淋溶深度仅达到60cm,其淋溶量占施氮量的55.3%～8.1%,且随着坡度的增大淋溶量逐渐减少。硝态氮随着径流的流失量分别为575.4、330.3、282.6、140.1和91.0kg/km2,分别占施氮量的11.5%、6.6%、5.7%、2.8%和1.8%。硝态氮淋溶与土壤水分入渗同步,随着坡度的降低淋溶深度则逐渐增加,硝态氮主要在0～0cm土层累积,其累积量介于209～3433kg/km2之间,占施肥量的41.9%～8.7%,而在0～105cm土层累积量则介于723～2521kg/km²之间,占施氮量的14.5%～50.3%。     

辽河平原区玉米旱田氮磷流失特征研究

采用田间试验方法,2016～2017年原位监测不同试验处理下地表径流与地下淋溶水分和氮磷流失过程.结果表明,径流和淋溶流失均集中发生于6～8月,且流失水量与降雨密切相关.氮磷在径流和淋溶水中均以可溶态为主(径流水中磷除外),且淋溶水氮浓度高于径流,径流水磷浓度高于淋溶.氮流失负荷在两年监测中均表现为淋溶高于径流,磷流失...     

缓释肥料棒氮钾缓释特性研究

采用室内间歇式土柱淋溶试验,研究了缓释肥料棒氮钾在土壤中的淋出率,以期明确缓释肥料棒对氮钾的缓释效果。结果表明,缓释肥料棒可明显减缓氮钾淋出,减少氮、钾淋出量,对氮、钾具有缓释作用,且随着聚丙烯酰胺用量增加,缓释肥料棒氮、钾累积淋出率逐渐减小。当42 d淋溶时,聚丙酰胺用量为2%、4%、6%的缓释肥料棒氮素累积淋出率分别较普通肥料减少了10.91%、16.85%、21.93%,且处理间差异显著;钾素累积淋出率较普通肥料分别减少了26.28%、29.16%、32.61%。而且一级动力学方程对缓释肥料棒的氮、钾累积淋出率曲线拟合效果最佳,可用于表征氮、钾素累积淋出率与时间的关系。     

Evaluating an environmental indicator: Case study of MERLIN, a method for assessing the risk of nitrate leaching

The need to achieve acceptable levels of nitrate in drinking water has led to the development of simulation models and indicators for assessing the environmental performance of agricultural practices. These indicators are necessarily based on simplifications in order to meet the practical constraints of feasibility, but they should nevertheless meet scientific standards, especially as regards their validation. The overall objective of this paper is to evaluate the MERLIN indicator and sub-indicators, an assessment method developed by French agricultural advisors. This tool estimates and classes the risks of water pollution by nitrates, integrating farmer practices both during crop cultivation and in between two successive crops, as well as soil sensitivity to leaching. The evaluation was performed according to the methodological framework proposed by Bockstaller and Girardin [Bockstaller, C., Girardin, P., 2003. How to validate environmental indicators? Agric. Syst. 76, 639–653]: design, output and end-use validation. Design validation involved submission of the method to experts and checking the sub-indicators against literature. Output validation was carried out by comparing real values to indicator outputs. End-use validation was based on information gathered by users. In particular we compared output data from the original method with that of users that had adapted the method to their situation, in order to assess the consequences of these changes. The first step confirmed that the assumptions of MERLIN and its sub-indicators are scientifically sound. However, the weighting of the different sub-indicators raised questions. The second output validation step gave acceptable results for the EQUIF sub-indicator but the MERLIN test highlighted the need for additional experimental data before validation. This approach also showed that improvements in the precision of parameters do not necessarily increase the accuracy of the classification. The last step confirmed that the indicator is considered useful by decision-makers but also reveals that in some cases users adapt parameter values to their situation. This has lead to the production of a user guide which defines the method more clearly to avoid numerous adaptations by users.     

Effects of seed maturity,seed storage and pre-germination treatments on seed germination of cleome (Cleome gynandra L.)

The influence of seed maturity, seed storage and germination pre-treatments on seed germination of cleome (Cleome gynandra L.) were investigated. Seed maturation studies showed that capsules harvested at 18 days after anthesis possessed the highest dry weight with 19.2% moisture and 1% germination. Development of fresh-ungerminated seed was observed with increasing maturity of fruit, suggesting that cleome exhibited forms of seed dormancy. Storing mature seed at 15 °C and at room temperature for 5 months showed that seed dormancy was broken after 3 months under both storage regimes. When mature seeds were subjected to different treatments including various levels of GA₃, KNO₃, leaching, pre-chilling, soaking and pre-heating at different temperatures, it was found that pre-heating at 40 °C for period of 1–5 days was the most effective method in breaking dormancy in cleome.     

黑土区农田氮磷淋溶消减措施

黑土是我国重要的土壤资源,承载了全国50%以上的玉米产量。但过量的化肥施入和不合理的农业管理造成黑土土壤氮磷大量残留,氮磷淋溶风险增强。相关研究表明,尽管黑土区旱地农田氮磷淋溶损失相对较低,肥料残留效应仍致使其潜在淋溶风险增强。因此,本研究综合分析了环境因子和农业管理措施对黑土区农田氮磷淋溶特征的影响规律,明确了黑土氮磷淋溶消减措施,并针对玉米农田和蔬菜地提出消减策略。具体结果如下:施肥和降水是影响黑土农田氮磷淋溶的重要因素,灌溉是影响蔬菜地氮磷淋溶的关键农田管理措施;按需施肥、有机无机配施、避免雨热同期追肥、节水灌溉、免耕秸秆覆盖、不同作物轮作和添加生物炭等均是适合于当地气候和土壤条件的氮磷淋溶阻控措施。建议玉米农田采用一次性基肥施入,有机肥占比50%～70%,采用免耕秸秆覆盖技术;蔬菜地在常规施肥和灌溉频次下分别降低20%的施肥量和灌溉量,推荐蔬菜秋季收获后秸秆粉碎深埋等管理措施。本研究明确了黑土区农田氮磷淋溶消减策略,有助于实现黑土区农业绿色可持续发展和绿色生态环境的构建。