林地施肥

大多数国家林区土壤肥力下降,林木生长量减少。其原因:①土壤中氮多数不能被林木吸收,氮碳比率高,②在高山多雨林区因雨水冲刷,氮流失严重,土壤贫瘠;③森林采伐后林地气候因子发生变化,特别是湿度变小,土壤微生物活动受到抑制,枯枝落叶分解慢,土壤养分缺少而不能满足林木正常生长的需要,为此要提高林地土壤肥力,施肥是补充林地养分主要技术措施。同时施肥对提高林地生产力,加快林木生长,扩大根系幅度,缩短林木采     

林木施肥与桉树短轮伐期用材林施肥研究进展

林木施肥,是人们有意识地根据林木对营养元素的需求以及土壤的供给能力,将某种有机或无机的营养物质施入土壤或者喷洒在植物体上,对其进行营养补充,以满足林木健康生长的需求,维持土壤养分平衡,达到优质、高产、低成本的营林目的。介绍林木施肥、桉树专用肥、桉树平衡施肥的概况及施肥研究趋势。     

施肥对沙地樟子松生理活动的影响

在贫瘠的沙地上,针叶人工纯林,随树龄的增长,土壤肥力下降,林木生长量逐渐减少,其原因除林木自身消耗外,还由于:(1)沙荒地区土壤粘性低,透水性强,持水性差,降雨量集中,雨水淋溶后造成土壤养分贫瘠;(2)针叶人工纯林中相对湿度较小,土壤微生物活动受到限制,枯枝落叶分解缓慢,土壤养分不足,不能满足林木正常生长的需求。为此,提高林地土壤肥力是促进林木生长的关键,而施肥则是补充林地土壤养分的主要技术措施之一,借以改善土壤理化性状,提高林分生产力。     

林木生长与营养动态模型研究——立地养分效应配方施肥模型

与常规林木施肥试验方法不同,林木立地养分效应配方施肥模型是通过立地与养分效应参数及相关系数测定来确定林地施肥的必要性、林木生长与养分吸收的动、静态关系、土壤养分容量与强度曲线和目标效益方程.基于这一组曲线与方程来确定最佳目标增产量、达标所需的有效养分增量、相应的施肥量与配方、以及最佳施肥时期与方法.施肥模型的特点是理论性强,试验处理简单,实践中易于操作,适用性广,不受区域和林木生长阶段的限制,应用中具有较高的精确度和推广价值.     

人工林精准施肥研究进展

施肥是实现人工林速生丰产的重要手段,合理施肥可以维持土壤养分平衡,提高土壤质量,促进林木生长,同时减少环境负效应。人工林精准施肥是以农业精准施肥为基础形成的营林应用技术体系,主要包括林地管理单元精准划分、林地营养精准诊断、精准施肥及施肥效应精准检验。精准施肥技术在农业上取得了很大进展,但应用到人工林上还有很大的局限性。文中结合农林业施肥研究现状,分析实现人工林精准施肥所需解决的关键问题,提出人工林精准施肥的发展方向。     

施肥对林木生长效应的理论研究

笔者从林木生长、林分产量、木材质量三方面总结了施肥对林木生长效应的影响,从光合速率、叶绿素含量、养分含量、抗逆性等几方面阐述了施肥对林木活力的影响。同时指出施肥对林木效应理论基础研究的重要性,在定性研究的基础上开展定量研究,探求和制订最佳施肥方案,以指导林木施肥。     

从生物固氮到树木自然施肥

经营森林和农作物不同,林木和生长主要靠自身功能吸取自然养分,供其生长,不可能大面积经常性施肥。近几年来,森林培育工作者,为了缩短林木生长周期,提高单位面积收获量,研究如何利用森林树种间的互利、互助作用和植物间共生关系,探讨利用生物固氮,自然施肥,促进林木生长。     

施肥对森林土壤中代换性Ca和代换性Mg的影响

一、前言对壮令林施肥,能提高树叶中养分的浓度,使林木生长良好,因为枯枝落叶掉回地后,能改善表土的物理、化学性,应考虑到这一间接效果,并从养分的还原来计算土壤的施肥量。但是林地施肥对土壤各种性质的影响,人们却很少直接进行研究。     

Ⅰ-214杨施肥效应系统研究通过鉴定

由中国林科院林研所主持,与山东省茌平县苗圃、中国林科院木材所等单位共同承担的意大利214杨林地施肥效应系统研究已通过了技术鉴定。该项研究成果包括林地施肥的林木生长效应;施肥对木材理化性质影响;林地施肥土壤养分的消长变化及经济效益分析。     

杉木施肥与针叶养分动态的初步研究

矿质元素是直接影响林业生长、发育的营养物质.为了探明它在林木体内的代谢过程及其与生长关系,Bowersox、Hetherington等研究者曾对不同树龄、品种和立地条件进行广泛的研究,结果找出了土壤、林木养分含量和生长之间的相互关系,有的还导出了定量的数学表达式,为诊断林木对某种营养物质的需求程度、临界值、施肥期、施肥量等,并通过采取合理的经营措施,进一步提高林木的产量起到了一定作用.但还有许多理论和技术问题尚未完全解决.因此,近几年来,我们在杉木幼林中进行了不同施肥处理试验,定期测定针叶养分含量和生长量,以寻求它们之间的内在关系,为促进杉木的速生丰产提供必要的科学依据.     

Nitrogen retranslocation, allocation, and utilization in bare root Larix olgensis seedlings

We quantified biomass accumulation and nitrogen (N) retranslocation, allocation, and utilization of Changbai larch (Larix olgensis) seedlings subjected to four fertilization treatments (24, 59, 81, 117 kg·ha-1 N) with an unfertilized control during summer and autumn 2009. Ammonium phosphate (18-46-0) was the fertilizer used in all treatments. On both sampling dates, the needles had greater biomass and N content than new (2009) stems and old (2008) stems, and coarse, medium and fine roots (diameters of >5, 2-5 mm, and 0-2 mm, respectively). Higher N concentration was observed in old stems and coarse roots than that in new stems and medium roots. In mid-summer, fine roots had higher N concentration than coarse roots. The treatment with 24 kg·ha-1 N had the greatest biomass and N content in needles and old stems, and highest net N retranslocation (NRA) and amount of N derived from soil. On September 21, no N translocation was observed, while the treatment with 24 kg·ha-1 N had the highest N utilization efficiency and fertilizer efficiency. Vector analysis revealed that all four fertilization treatments induced N excess relative to the control. The treatments with 59, 81, 117 kg·ha-1 N induce N excess compared with treatments at 24 kg·ha-1 N. We conclude that the traditional local fertilizer application rates exceeded N requirements and N uptake ability for Changbai larch seedlings. The application rate of 24 kg·ha-1 N is recommended.     

Organic amendment and inorganic fertilization affect soil properties and quality of Larix olgensis bareroot stock

Bareroot Changbai larch (Larix olgensis Henry.) seedlings were reared with inorganic fertilizer (nitrogen (N):phosphorus (P) = 1:1, W/W) applied at a rate of 100 (F100) or 200 kg N ha⁻¹ (F200) with (+) or without (−) chicken manure as a soil amendment (O) in north-eastern China. An unfertilized control treatment was included. Inorganic and organic fertilizer treatments tended to increase soil ammonium, nitrate, available P, total P, organic carbon content and electrical conductivity, and biomass and N concentration in seedlings. Organic amendment improved first order lateral root number, tap root length, fine root morphology (length, surface area, volume) in seedlings, while the F100 treatment increased N accumulation in needles and stems compared to the F200 treatment, on average. Most fertilizer treatments tended to increase P content in combined stems and roots, but F200 − O and F100 + O treatments diluted P in needles. Organic amendment combined with inorganic fertilizer at a rate of 100 kg N and P ha⁻¹ is recommended to improve seedling growth and N reserves in woody tissues.     

Phosphorus uptake and maize response to organic and inorganic fertilizer inputs in Rubona,Southern Province of Rwanda

Green manure of multipurpose trees is known to be a good source of nutrients to crop. However, most agroforestry species do not have adequate phosphorus (P) in their leaves. Supplementing green manure with moderate dose of P is a beneficial strategy to improve food security in Rwanda. This study examines the effects of Calliandra calothyrsus Meissner, Tithonia diversifolia Hensley A.Gray and Tephrosia vogelii Hook.f. green manure applied independently or in combination with triple super phosphate (TSP) and lime on maize yield and P uptake in the Oxic Tropudalf of Rubona, Rwanda. The treatments were the control, lime at 2.5 t ha⁻¹, TSP at 25 and 50 kg P ha⁻¹, leaf of C. calothyrsus, T. diversifolia, and T. vogelii each at 25 and 50 kg P ha⁻¹, respectively. Leaf shrubs biomass, TSP and lime were applied for four consecutive seasons (2001–2004). The results showed that the combination of green manure with TSP at a rate of 50 kg P ha⁻¹ significantly increased maize yield from 24 to 508% when compared to the control and T. divesifolia combined with TSP was leading (508%). Equally, the same treatments as indicated above showed higher P uptake (15.6–18. 6 kg P ha⁻¹) than the control (5 kg P ha⁻¹) and 65% of maize yields variation was explained by total P uptake. The plant residues quality such as C:N ratio, total plant N, and P significantly influenced the variability of maize grain yields.     

Nitrogen budget of a rehabilitated forest on a degraded granitic hill

Rehabilitated forests established about 100 years ago on denuded lands in a hilly granitic area are widespread in the Kyoto–Osaka area, the second largest megalopolis in Japan. From 2001 to 2003, we monitored the annual nitrogen (N) budget of a rehabilitated forest watershed dominated by Quercus serrata and Ilex pedunculosa. The ion concentrations of bulk rain in the watershed were similar to those of other watersheds in Japan. The annual bulk rain input of N ranged from 5.1 to 6.3 kg N ha⁻¹ year⁻¹, and the N deposition from throughfall and stem-flow ranged from 7.5 to 8.2 kg N ha⁻¹ year⁻¹. Estimated annual outputs of N from the stream ranged from 3.3 to 10.6 kg N ha⁻¹ year⁻¹. These results indicate that the amount of N deposition in this area is less than that in urban Tokyo (>10 kg N ha⁻¹ year⁻¹), but the N output of the watershed is comparable with that of the Tokyo area. We discuss the characteristics of N dynamics in rehabilitated forests, focusing on the biogeochemical processes of this watershed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.     

Does exceeding the critical loads for nitrogen alter nitrate leaching,the nutrient status of trees and their crown condition at Swiss Long-term Forest Ecosystem Research (LWF) sites?

Nitrogen (N) deposition exceeds the critical loads for this element in most parts of Switzerland apart from the Alps. At 17 sites (8 broadleaved stands, 8 coniferous stands, and 1 mixed stand) of the Swiss Long-term Forest Ecosystem Research network, we are investigating whether N deposition is associated with the N status of the forest ecosystems. N deposition, assessed from throughfall measurements, was related to the following indicators: (1) nitrate leaching below the rooting zone (measured on a subset of 9 sites); (2) the N nutrition of the forest stand based on foliar analyses (16 sites); and (3) crown defoliation, a non specific indicator of tree vitality (all 17 sites). Nitrate leaching ranging from about 2 to 16 kg N ha⁻¹ a⁻¹ was observed at sites subjected to moderate to high total N deposition (>10 kg ha⁻¹ a⁻¹). The C/N ratio of the soil organic layer, or, when it was not present, of the upper 5 cm of the mineral soil, together with the pool of organic carbon in the soil, played a critical role, as previous studies have also found. In addition, the humus type may need to be considered as well. For instance, little nitrate leaching (<2 kg N ha⁻¹ a⁻¹) was recorded at the Novaggio site, which is subjected to high total N deposition (>30 kg ha⁻¹ a⁻¹) but characterized by a C/N ratio of 24, large organic C stocks, and a moder humus type. Foliar N concentrations correlated with N deposition in both broadleaved and coniferous stands. In half of the coniferous stands, foliar N concentrations were in the deficiency range. Crown defoliation tended to be negatively correlated with N concentrations in the needles. In the majority of the broadleaved stands, foliar N concentrations were in the optimum nutritional range or, on one beech plot with high total N deposition (>25 kg ha⁻¹ a⁻¹), above the optimum values. There was no correlation between the crown defoliation of broadleaved trees and foliar concentrations.     

Water balance and maize yield following improved sesbania fallow in eastern Zambia

Sesbania [Sesbania sesban (L.) Merr.] fallows are being promoted as a means for replenishing soil fertility in N-depleted soils of small-scale, resource-poor farmers in southern Africa. Knowledge of soil water distribution in the soil profile and water balance under proposed systems is important for knowing the long-term implications of the systems at plot, field and watershed levels. Soil water balance was quantified for maize (Zea mays L.) following 2-year sesbania fallow and in continuous maize with and without fertilizer during 1998–1999 and 1999–2000 at Chipata in eastern Zambia. Sesbania fallow increased grain yield and dry matter production of subsequent maize per unit amount of water used. Average maize grain yields following sesbania fallow, and in continuous maize with and without fertilizer were 3, 6 and 1 Mg ha⁻¹ with corresponding water use efficiencies of 4.3, 8.8 and 1.7 kg mm⁻¹ ha⁻¹, respectively. Sesbania fallow increased the soil-water storage in the soil profile and drainage below the maximum crop root zone compared with the conventionally tilled non-fertilized maize. However, sesbania fallow did not significantly affect the seasonal crop water use, mainly because rainfall during both the years of the study was above the normal seasonal water requirements of maize (400 to 600 mm). Besides improving grain yields of maize in rotation, sesbania fallows have the potential to recharge the subsoil water through increased subsurface drainage and increase nitrate leaching below the crop root zone in excess rainfall seasons. This revised version was published online in June 2006 with corrections to the Cover Date.     

Nitrogen-fixation dynamics in a cut-and-carry silvopastoral system in the subhumid conditions of Guadeloupe, French Antilles

This paper summarizes several studies on N recycling in a tropical silvopastoral system for assessing the ability of the system to increase soil fertility and insure sustainability. We analyzed the N₂ fixation pattern of the woody legume component (Gliricidia sepium), estimated the recycling rate of the fixed N in the soil, and measured N outputs in tree pruning and cut grass (Dichanthium aristatum). With this information, we estimated the N balance of the silvopastoral system at the plot scale. The studies were conducted in an 11-year-old silvopastoral plot established by planting G. sepium cuttings at 0.3 m × 2 m spacing in natural grassland. The plot was managed as a cut-and-carry system where all the tree pruning residues (every 2-4 months) and cut grass (every 40-50 days) were removed and animals were excluded. No N fertilizer was applied. Dinitrogen fixation, as estimated by the ¹⁵N natural abundance method, ranged from 60-90% of the total N in aboveground tree biomass depending on season. On average, 76% of the N exports from the plot in tree pruning (194 kg [N] ha^–1 yr^–1) originated from N₂ fixation. Grass production averaged 13 Mg ha^–1 yr^–1 and N export in cut grass was 195 kg [N] ha^–1 yr^–1. The total N fixed by G. sepium, as estimated from the tree and grass N exports and the increase in soil N content, was about 555 kg [N] ha^–1 yr^–1. Carbon sequestration averaged 1.9 Mg [C] ha^–1 yr^–1 and soil organic N in the 0-0.2 m layer increased at a rate of 166 kg [N] ha^–1 yr^–1, corresponding to 30% of N₂ fixation by the tree. Nitrogen released in nodule turnover (10 kg [N] ha^–1 yr^–1) and litter decomposition (40 kg [N] ha^–1 yr^–1) contributed slightly to this increase, and most of the recycled N came from the turnover or the activity of other below-ground tree biomass than nodules. This revised version was published online in June 2006 with corrections to the Cover Date.     

Specific gravity responses of slash and loblolly pine following mid-rotation fertilization

Wood quality attributes were examined in six stands of slash pine (Pinus elliottii Engelm. var. elliottii) and loblolly pine (P. taeda L.) in the lower Coastal Plain of Georgia and Florida. Several plots comprised each stand, and each plot was divided so that it received three fertilizer treatments: a control treatment with herbaceous weed control at planting and brush control at mid-rotation only (control); 45 kg ha⁻¹ N + 56 kg ha⁻¹ P + herbaceous weed control at planting and 224 kg ha⁻¹ N + 45 kg ha⁻¹ P + brush control at mid-rotation (fertilizer with N at planting); and 56 kg ha⁻¹ P + herbaceous weed control at planting and 224 kg ha⁻¹ N + 45 kg ha⁻¹ P + brush control at mid-rotation (fertilizer without N at planting). Ring width, ring earlywood specific gravity (SG), ring latewood SG, whole ring SG, and ring percent latewood were measured on each of seven trees. Of these measurements, this study focused mainly on the properties related to SG. Examination of the rings showed that latewood SG was significantly lower in trees treated with fertilizers with and without N at planting in the two to three years following fertilization, but that latewood SG gradually returned to a level similar to the control. Fertilizer without N at planting may also have had a brief negative effect on earlywood SG following mid-rotation fertilization, but it was not as clear or lasting as the effect on latewood SG. Additionally, although slash and loblolly pine appear to differ in the developmental patterns of these SG properties, there were no significant differences in how these patterns interacted with treatment. This study demonstrated that fertilization treatments have similar short-term effects on the SG of slash and loblolly pines, particularly in latewood, but the trees will return to a SG pattern consistent with unfertilized trees within two or three years.     

缓释肥N/P养分配比及加载量对3种珍贵树种大规格容器苗生长的影响

[目的]研究缓释肥N/P养分配比及加载量对南方红豆杉、浙江楠和浙江樟苗木生长发育的影响,以科学指导大规格容器苗的高效培育。[方法]试验采用析因设计,研究N/P养分配比(1.75∶1、2.25∶1、2.75∶1和3.25∶1)及其加载量(1.5 kg·m~(-3)、2.5 kg·m~(-3)、3.5 kg·m~(-3)和4.5 kg·m~(-3))对3种珍贵树种2年生容器苗生长、株高生长节律、干物质积累及叶片SPAD值等影响。[结果]缓释肥N/P养分配比及加载量对3个树种容器苗生长及SPAD值影响不一。南方红豆杉、浙江楠和浙江樟干物质积累及根冠比在不同N/P养分配比间差异不大,浙江樟苗木生长受N/P养分配比影响较小,随着N/P养分配比增加,明显促进了浙江楠容器苗生长,却抑制了南方红豆杉的生长。缓释肥加载量对3个树种2年生容器苗生长和干物质积累的影响均达到极显著水平,随着缓释肥加载量增加可明显地促进3种树种株高、地径生长及干物质积累,增加了浙江楠地上干物质积累及南方红豆杉地下干物质积累,而对浙江樟根冠比影响未达统计学显著水平,但均显示加载量在3.5 kg·m~(-3)时达到最大值。N/P养分配比及与加载量的互作对3个树种苗木生长和干物质积累影响不明显,说明N/P养分配比对3个树种容器苗生长和质量的影响不因加载量的改变而变化或变化不大,反之亦然。随着缓释肥N/P养分配比的增加,可明显地延长南方红豆杉苗木株高的线性生长期,提高浙江楠株高的线性生长量,但对浙江樟株高的线性生长影响不明显。3种树种苗木叶片SPAD值差异很大,N/P养分配比及加载量并未改变3种树种叶片SPAD值动态变化规律,但随着N/P养分配比提高使南方红豆杉和浙江樟叶片SPAD值的起伏强度增大,3个树种SPAD值动态变化均随加载量增加而增大。[结论]南方红豆杉大规格容器苗培育较适宜的N/P养分配比为A1(1.75∶1)或A2(2.25∶1),而浙江楠和浙江樟为A3(2.75∶1),加载较高量的缓释肥F3(3.5 kg·m~(-3))可明显促进3种树种大规格容器苗的生长及SPAD值的提高,但加载量超过一定限度后,反而影响苗木的生长发育。