Effects of freeze-thaw on soil nitrogen and phosphorus availability at the Keerqin Sandy Lands, China

A laboratory simulated freeze-thaw was conducted to determine the effects of freeze-thaw on soil nutrient availability in temperate semi-arid regions. Soil samples were collected from sandy soils （0-20 cm） of three typical ecosystems （grassland, Mongolian pine plantation and poplar plantation） in southeastern Keerqin Sandy Lands of China and subjected to freeze-thaw treatment （-12℃ for 10 days, then r 20℃ for 10 days） or incubated at constant temperature （20℃ for 20 days）. Concentrations of the soil NO3^--N, NH4^＋-N, NaHCO3 extractable inorganic P （LPi） and microbial biomass P （MBP） were determined on three occasions： at the start of the incubation, immediate post-thawing and at the 10th day post-thawing. The results showed that soil net nitrification and N mineralization rates at three sites were negatively affected by freeze-thaw treatment, and decreased by 50%-85% as compared to the control, of which the greatest decline occurred in the soil collected from poplar plantation. In contrast, the concentration of soil NH4^＋-N, NaHCO3 extractable inorganic P （LPi） and microbial biomass P were insignificantly influenced by freeze-thaw except that LPi and NH4^＋-N showed a slight increase immediate post-thawing. The effects of freeze-thaw on soil N transformation were related to soil biological processes and the relatively constant available P was ascribed to severe soil aridity.     

Variation of soil enzyme activity and microbial biomass in poplar plantations of different genotypes and stem spacings

To improve the productivity of poplar plantations, a field experiment of split-plot design with four tree spacings and three poplar clones was established, and four soil enzyme activities and microbial biomass were monitored in the trial.Soil enzyme activities, in most cases,were significantly higher in topsoil(0–10 cm) than in lower horizons(10–20 cm).Soil cellulase, catalase and protease activities during the growing season were higher than during the non-growing season, while invertase activity followed the opposite trend.Soil invertase, cellulase and catalase activities varied by poplar clone but soil protease activity did not.Cellulase and protease activities in the plantation at 5×5 m spacing were significantly higher than in the other spacings.The highest catalase activity was recorded at 6×6 m spacing.At the same planting density, invertase activity was greater in square spacings than in rectangular spacings.Soil microbial biomass was also significantly affected by seedling spacing and poplar clone.The mean soil MBC was significantly lower in topsoil than in the lower horizon, while MBN showed the opposite pattern.Significantly positive correlations were observed among soil cellulase, protease and catalase activities(p0.01), whereas soil invertase activity was negatively and significantly correlated with cellulase, protease and catalase activities(p0.01).Soil microbial biomass and enzyme activities were not correlated except for a significantly negative correlation between soil MBC and catalase activities.Variations in soil enzyme activity and microbial biomass in different poplar plantations suggest that genotype and planting spacing should be considered when modeling soil nutrient dynamics and managing for long-term site productivity.     

长白山高山冻原生态系统植被生物量分布和养分生物循环研究(英文)

A study was conducted to test the correlation between biomass and elevation and the differences in concentration and storks of nutrients among five vegetation types (Felsenmeer alpine tundra vegetation-FA, Lithic alpine tundra vegetation-LA, Typical alpine tundra vegetation-TA, Meadow alpine tundra vegetation MA, and Swamp alpine tundra vegetation-SA) on alpine tundra of Changbai Mountains,Jilin Province, China in growing seasons of 2003, 2004 and 2005. The biomass of 43 mono-species and soil nutrients in alpine tundra ecosystem were also investigated. Dominant species from Ericaceae (such as Rhododendron chrysanthum and Vaccinium jliginosum var.alpinum) were taken to analyze organ biomass distribution. Result showed that the biomass and elevation had a significant correlation (Biomass=-237.3 In(Elevation) 494.36; R2=0.8092; P＜0.05). No significant differences were found in phosphorus and sulphur concentrations of roots, stems and leaves among the five vegetation types. There were significant differences in nitrogen and phosphorus stocks of roots, stems and leaves and in sulphur stock of stems and leaves among TA, MA, and SA vegetation types (p＜0.05). The nutrient stock of five vegetations was averagely 72.46 kg·hm-2, of which N, P, S were 48.55, 10.33 and 13.61 kg·hm-2, respectively. Soil N and S concentrations in meadow alpine tundra soil type was significantly higher than those in other four soil types (Cold desert alpine tundra soil, Lithic alpine tundra soil, Peat alpine tundra soil, and Gray alpine tundra soil). Phosphorous concentration in SA type was higher (p＜0.05) than in other types. Soil nutrient stock (0-20cm) was averagely 39.59 t·hm-2, of which N, P, S were 23.74, 5.86, 9.99 t·hm-2, respectively.     

Growth and nutrient dynamics of Betula alnoides seedlings under exponential fertilization

Betula alnoides is a fast-growing hardwood species grown in large plantations in Southeast Asia and South China.Nitrogen requirements for producing robus seedlings,growth and nutrient dynamics were investigated using exponential fertilization treatments.Root collar diameter,height,dry mass and nutrient contents of seedlings increased exponentially in all fertilization treatments as time progressed.Moreover,with water soluble fertilizer(Plant Products plus microelements N–P_2O_5–K_2O:20–20–20),300 mg N seedling~(-1)was adequate.Vector analysis revealed that P was the most responsive nutrient element followed by N and K.Dilutions of N and K were evident in the plants without N addition,which induced initial P sufficiency and then luxury consumption probably due to the antagonistic interaction between N and P.However deficiencies of N,P and K were mostly observed in al exponential regimes during the experiment because seedling growth rate exceeded nutrient uptake rate,inferring that further study on improving the nutrient uptake efficiency is needed.Analysis of relationships among nutrient supply,dry mass,N content and N concentration demonstrated that 100–400 mg N seedling~(-1)induced sufficiency to luxury consumption of nitrogen without significant change in dry mass,and 400 mg N seedling~(-1)is recommended to apply for nutrient loading of seedlings before outplanting.The findings will help improve seedling quality and enhance the production of robust seedlings for plantation forestry of this species.     

Influence of main site factors on Fraxinus mandshurica（Oleaceae） plantation

The investigation was carried out on 10-year-old plantation of Fraxinus mandshurica in Mao‘er Mountain Experimental Station of Northeast Forest University.tree height(H),diameter at breast height(D1.3) and the increment of tree height in 5 years (H5),the thickness of humus layer,as well as the soil moisture were measured for the plantation and the growth indexes(H,D1.3,H5) for different site conditions were analyzed.The results showedthat main site factors influencing the growth of Fraxinus mandshurica were soil moisture,gradient and location of siope in order.The growth of Fraxinus mandshurica was better on the middle-or up-slope site than on the down-slope site.Soil moisture and late frost caused by terrain are the main reasons that limit the growth of Fraxinus mandshurica plantation.     

Comparing growth and fine root distribution in monocultures and mixed plantations of hybrid poplar and spruce

Disease prevention, biodiversity, productivity improvement and ecological considerations are all factors that contribute to increasing interest in mixed plantations. The objective of this study was to evaluate early growth and productivity of two hybrid poplar clones, P. balsamifera x trichocarpa (PBT) and P. maximowiczii x balsamifera (PMB), one improved family of Norway spruce (Picea glauca (PA)) and one improved family of white spruce (Picea abies (PG)) growing under different spacings in monocultures and mixed plots. The plantations were established in 2003 in Abitibi-Témiscamingue, Quebec, Canada, in a split plot design with spacing as the whole plot factor (1 × 1 m, 3 × 3 m and 5 × 5 m) and mixture treatments as subplot factor (pure: PBT, PMB, PA and PG, and 1:1 mixture PBT:PA, PBT:PG, PMB:PA and PMB:PG). Results showed a beneficial effect of the hybrid poplar-spruce mixture on diameter growth for hybrid poplar clones, but not for the 5 × 5 m spacing because of the relatively young age of the plantations. Diameter growth of the spruces decreased in mixed plantings in the 1 × 1 m, while their height growth increased, resulting in similar aboveground biomass per tree across treatments. Because of the large size differences between spruces and poplars, aboveground biomass in the mixed plantings was generally less than that in pure poplar plots. Leaf nitrogen concentration for the two spruce families and hybrid poplar clone PMB was greater in mixed plots than in monocultures, while leaf nitrogen concentration of clone PBT was similar among mixture treatments. Because of its faster growth rate and greater soil resources demands, clone PMB was the only one showing an increase in leaf N with increased spacing between trees. Fine roots density was greater for both hybrid poplars than spruces. The vertical distribution of fine roots was insensitive to mixture treatment.     

Bio-amelioration of alkali soils through agroforestry systems in central Indo-Gangetic plains of India

A long-term field study was initiated during 1995 at Central Soil Salinity Research Institute, Regional Research Station, Lucknow(26°47′58′′ N and 80°46′24′′ E) to analyze the effect of agroforestry systems on amelioration of alkali soils. Three agroforestry systems(pastoral, silvipastoral and silvicultural) were compared with the control where no agroforestry system was introduced. Tree-based silvicultural and silvipastoral systems were characterized by tree species Prosopis juliflora and Acacia nilotica along with grass species Leptochloa fusca, Panicum maximum, Trifolium alexandrium and Chloris gayana. Growth of ten-year-old Prosopis juliflora and Acacia nilotica planted in combination with grasses was significantly higher over the silviculture system with the same species. Tree biomass yields of P. juliflora(77.20 t?ha-1) and A. nilotica(63.20 t?ha-1) planted under silvipastoral system were significantly higher than the sole plantation of(64.50 t?ha-1 and 52.75 t?ha-1). Fodder yield under the pastoral system was significantly higher than the silvipastoral system during initial years but it was at par with that of silvipastoral systems after eight years of plantation. The microbial biomass carbon in the soils of silvipastoral systems was significantly higher than in soils under sole plantation of trees and control systems. The Prosopis-based silvipastoral system proved more effective in reducing soil pH, displacing Na+ from the exchange complex, increasing organic carbon and available N, P and K. Improvement in soil physical properties such as bulk density, porosity, soil moisture and infiltration rate was higher in the Prosopis-based silvipastoral system than in the silviculture system or control. On the basis of biomass production and improvement in soil health due to tree + grass systems, silvipastoral agroforestry system could be adopted for sustainable reclamation of highly alkali soils.     

Study on the Effect of Fertilization on Eucalyptus globulus Plantation in Yunnan

10 fertilization tests of different match and ratio of N，P，K were conducted on young Eucalyptus globulus plantation in limestone red soil in Baoshan City for 5 years. The results of tests indicated that fertilization obviously promoted the growth of young E. globulus plantation. At 1.5 years after afforestation，the growth response was at the highest point，the height and DBH of the tree were promoted by 33.69％，48.39％ for the 9 manuring treatments. At 5 years after afforestation，the growth response were promoted by 16.45％，10.71％ for the 9 manuring treatments. Phosphoric fertilizer is the main factor in promoting the growth of E. globulus plantation.Applying 430 g calcium magnesium phosphate as base fertilizer for each tree，can make the best growth response. The growth responses of N，K fertilizer is not obvious. Organic fertilizer can promot the growth of the trees. Among the 10 treatments，the 3 treatments of No.6 （65 g carbamide，430 g calcium magnesium phosphate），No.9 （130 g carbamide，430 g calcium magnesium phosphate ，54 g KCl），No.10 （treatmet No.9 added with 5 kg organic fertilizer） gained remarkable growth effect. The treatments with best economic benefit are No.6 and No.9.     

Growth and mineral nutrient analysis of teak (Tectona grandis) grown on acidic soils in south China

Teak(Tectona grandis L.f.) is widely planted in the world due to its high market demand, economic, ecological and social value. Its plantations have mostly been established and expanded into sites that are acidic to severely acidic in southern China. But, there are no available and specific evidence-based nutrient management techniques. To better recognize and understand the relationship between teak tree growth and nutrient content in the foliage and soil and establish nutrient norms are critical to optimally manage these young plantations. We studied the foliar nutrient and soil chemistry in 19 representative teak plantations aged 5–8 years. Regression analysis indicated that the mean annual increment of teak volume was linearly and positively correlated with foliar N, Ca, Fe and B concentrations, with soil base saturation percentage,available P and Zn concentrations, and negatively correlated with soil Al concentration. Only if the Ca and Mg contents in soil were enhanced, could the increase in soil base saturation percentage benefit teak growth. A revised classification of low-and high-yielding stands was established by using a sorting method of principal components over 6 foliar macro and 8 micro elements in a Diagnosis and Recommendation Integrated System(DRIS). Specific DRIS norms for teak plantations in acid soils were derived.The nutrient balance of N, P, K Ca, Mg, Zn, B with Fe or Al, Ca with Mg, and Fe with Al provided a key to promote the growth of teak in acid soils. Meanwhile, soil Zn was also found as a primary trace element that affected teak growth in this study.     

Effects of thinning on microsites and natural regeneration in a Larix olgensis plantation in mountainous regions of eastern Liaoning Province, China

In order to understand the effects of thinning on microsite conditions and natural regeneration in the larch plantation, thinning experiment was conducted in a 40-year-old Larix olgensis plantation in Qingyuan County in eastern Liaoning Province, China in 2003-2004 Five thinning treatments （0%, 10.2%, 19.8%, 29.7% and 40.3% thinned） were designed on the same site. After thinning, canopy openness and the microsite conditions such as photosynthetic photon flux density （PPFD）, soil moisture content, and soil temperature were measured in one growing season. Meanwhile, the investigation of natural regeneration was conducted at the end of the growing season. The results showed that the canopy openness increased with the increase of thinning intensities. PPFD and soil temperature and soil moisture content in different soil layers were positively relative with canopy openness after thinning. The richness of regenerating tree species did not significantly increase （p=0.30） after one growing season since thinning, but the regeneration density and frequency of tree species increased significantly （p〈0.05）. In addition, the number of regenerating tree species increased, and the increment was correlated with the characteristics of iudividual tree species. The increasing percentage of regenerating seedlings of the shade-intolerant tree species was more than that of shade-tolerant tree species. Among the investigated regeneration species, the biggest response of seedling emergency to the canopy openness was Phellodendron amurense. This paper confirmed the following conclusions： after thinning, the variety of regenerating tree species was correlative with the characteristics of regenerating tree species, and the distribution of unthinned trees and the site conditions in the investigated larch plantation were the additional factors influencing, the regeneration.     

油橄榄低效林土壤培肥技术研究

【目的】为给油橄榄的科学施肥提供参考依据。【方法】以油橄榄品种阿贝基娜为试材,通过对低效园与高产园土壤养分的调查、油橄榄叶片中各营养元素的检测,找出了影响油橄榄生长发育的关键营养元素;再选择生长势弱且挂果较少的样树,对其施用有机肥加浓度分别为0.3%、0.4%、0.5%和0.6%的高效水溶肥进行施肥试验,以常规施肥处理为对照,比较分析了不同施肥处理对油橄榄树势、叶片和果实生长发育的影响情况。【结果】养分调查中,低效园与高产园的效益差别受到土壤营养状况的影响,高产园区油橄榄叶片中N、P、K、Ca、Zn、Fe的含量均高于低效园的;其中,N含量未达到国外标准,P、K含量符合国外标准,而Ca、Zn、Fe含量均高于国外标准。施肥试验中,与常规施肥处理相比,施用有机肥加浓度分别为0.3%、0.5%、0.6%的高效水溶肥,均促进了油橄榄的树高生长;施用有机肥加浓度分别为0.4%、0.5%、0.6%的高效水溶肥,均能增加油橄榄叶片长度和百叶质量;施用有机肥加浓度分别为0.3%、0.4%、0.5%和0.6%的高效水溶肥,均能显著提高油橄榄坐果率,总体效果随水溶肥浓度的增加而呈先增后减的变化趋势,其中,施用有机肥加0.5%的高效水溶肥的总体效果最佳。【结论】Ca、Zn、Fe这3种微量元素均非金堂地区油橄榄生长及产量增加的关键营养元素,而N、P、K这3种大量元素特别是N元素才是限制油橄榄生长发育的关键营养元素。施用有机肥加水溶肥有利于油橄榄树体、叶片、果实的生长,其中施用有机肥加0.5%的高效水溶肥的总体效果最佳。     

沙地杨树刺槐人工混交林的改良土壤功能及养分互补关系

杨树刺槐混交林是我国北方地区沿河及滨海沙地上成功的固氮树种和非固氮树种人工混交林。本文在简单介绍混交林生长情况的基础上,主要对林地土壤养分改良及其种间Ｎ、Ｐ养分互补关系进行了阐述。指出杨树刺槐混交林生产力提高主要是因为林地土壤养分（特别是Ｎ素养分）的极大改善及树种间Ｎ、Ｐ养分的互补。混交林土壤Ｎ素养分水平提高的根本原因是林地土壤微生物活性高,加快了含Ｎ较高枯落物分解速度,增强了土壤氨化及硝化强度。而杨树刺槐种间的Ｎ、Ｐ养分互补则主要表现在混交林中杨树可将吸收入体内的Ｐ素通过根系接触转移给相邻的刺槐,而刺槐则可将固定的Ｎ素通过根系接触转移给杨树,而且Ｎ、Ｐ转移的强度很大。这种奇妙的树种间养分互补机制对杨树刺槐混交林幼林期生产力提高是有重大意义的。     

杨树刺槐混交林细根养分动态研究

对两树种细根在北京市潮白河沿河沙地加拿大杨 (2 7a生 )刺槐 (2 2a生 )混交林中的分解情况进行了研究 ,从细根养分循环角度探索了两树种混交协调生长的机理。结果表明 :(1)加拿大杨和刺槐林木细根的分解特点不同 ,杨树细根在分解前期的N、Ca、Mg元素浓度逐渐升高 ,P、K元素浓度则逐渐降低。刺槐细根分解过程中N、P、K元素浓度逐渐降低 ,杨树刺槐混交林细根混合分解中各元素含量变化介于两树种细根单独分解之间 ;(2 )细根的N、K、Mg年归还量以刺槐纯根最大 ,两树种混根次之 ,杨树纯根最小 ;(3)混交林中N素归还量的增加有利于改善杨树的N素状况 ,杨树细根的P素归还量大于刺槐细根 ,有利于改善刺槐的P素营养 ,混交林杨树与刺槐在细根N、P养分方面形成协调互补的关系     

Effects of an exotic conifer (Pinus radiata) plantation on forest nutrient cycling in southeastern Australia

The distribution and movement of N, P, K, Na, Mg, and Ca were studied in southeastern Australia in a 37—year-old Pinus radiata plantation and in a nearby Eucalyptus obliqua — Eucalyptus dives forest of the same age and of the same type as that which had been replaced by the P. radiata plantation. The soil beneath the P. radiata plantation contained significantly less total N and exchangeable K, Mg, and Ca than that beneath the eucalypt forest. No large accumulation of nutrients was found in either the litter or the trees in the P. radiata plantation relative to that in the eucalypt forest. However, there was a slightly greater accumulation of N and K in the P. radiata biomass than in the eucalypt biomass. The annual soil nutrient balance obtained by subtracting outputs (mineral soil leachate + biomass incorporation) from inputs (precipitation + mineral weathering) indicated a more favourable balance for each nutrient in the soil beneath the eucalypts than in the soil beneath the pines. Calculations suggested that these balances could only partially account for the differences in soil nutrient quantities between eucalypt and pine ecosystems. It was hypothesized that these differences are also partially explainable in terms of the nutrient losses accompanying two fires which had occurred in the pine plantation area. Nitrogen balances in this study were incomplete because several potentially important fluxes were not measured.     

施P肥和外生菌根菌接种对蓝桉林产量和养分积累的影响

主要研究施P肥和接种外生菌根菌对蓝桉生长、生物量和养分积累的影响。在云南楚雄的试验表明：接种外生菌根菌只能在幼林期促进树木生长，3a后这种促进作用不显著。施P肥能在幼林期促进蓝桉树高和胸径的生长，但4．5a后这种促进作用也变得不显著。由于施P肥提高了蓝桉的保存率，所以也显著地提高了蓝桉林的生物量。低P处理时，树木保存率低，较大的生长空间促进了树木的后期生长，可能会导致施P肥对后期单株蓝桉树高和胸径生长作用不显著。施P肥还增加了树木N、P和K的养分积累量，提高了上述养分的利用效率。施P肥同时还明显增加了林下植被和林下凋落物P的积累量，但不能明显增加N和K的养分积累量。树木叶片和土壤分析结果进一步说明施P肥对蓝桉幼林作用明显。试验表现出接种外生菌根菌只能在低P情况下促进树木生长，不能在高P情况下促进树木生长的基本趋势。     

不同施钾水平对油茶树体生长和林地养分含量的影响

为了确定油茶幼林钾肥最适施用量,从而为油茶的科学施肥提供理论依据,以‘赣无’系列的5年生油茶林分为试验对象,设置了5个钾素水平处理(K0、K1、K2、K3、K4),1个施用复合肥的对照处理(CKFHF)和1个不施肥的处理对照(CK0),就不同施肥处理对油茶树体生长、叶片养分积累和土壤养分含量的影响情况进行了试验、测定与分析。结果表明:施肥均能显著提高油茶树体各生长指标的增幅和叶片及土壤中各种养分的含量;随着施钾水平的提高,油茶树体各生长指标的增幅和叶片中各种养分的含量均随之增加,K3处理的达到最大值,复合肥处理的肥效小于K2处理;随着施钾水平的提高,油茶林地土壤中速效钾和有机质的含量均显著性增加,而土壤中碱解氮和有效磷的含量则随着施钾水平的提高均先减小后增加,K4处理的降到最小值;对油茶叶片中的钾含量、土壤中的速效钾含量与施钾量进行拟合,得出其响应曲线,并确定了对油茶幼树施用钾肥的最适用量范围为317.72~322.25 g/株。     

Relationships between soil and foliar nutrients in young densely planted mini-plots of Pinus radiata and Cupressus lusitanica

The long-term nature of forest crop rotations makes it difficult to determine impacts of forestry on soil nutrients that might be depleted by forest growth. We used small scale, highly stocked plots to compress the length of the rotation and rapidly induce nutrient depletion. In the study, two species (Pinus radiata D. Don and Cupressus lusitanica Miller) are compared under two disturbance regimes (soil undisturbed and compacted), and two fertiliser treatments (nil and plus fertiliser), applied in factorial combination at 33 sites, covering the range of climatic and edaphic variation found in plantation forests across New Zealand. To assess our ability to rapidly highlight important soil properties, foliar nutrient concentrations were determined 20 months after planting. It was hypothesised that the densely planted plots, even at a young age, would create sufficient pressure on nutrient resources to allow development of relationships between properties used as indicies of soil nutrient availability and foliar nutrient concentrations. For both species significant relationships between foliar nutrients and 0–10 cm layer soil properties from unfertilised plots were evident for N (total and mineralisable N) and P (total, acid extractable, organic, Bray-2 and Olsen P). With the exception of Ca in C. lusitanica, foliar K, Ca and Mg were correlated with their respective soil exchangeable cation measures. The results thus confirm the utility of the experimental approach and the relevance of the measured soil properties for forest productivity.

In unfertilised plots foliar N and P concentrations in P. radiata exceeded those in C. lusitanica, the differences being eliminated by fertiliser application. Foliar N/P ratios in P. radiata also exceeded those in C. lusitanica. In contrast to N and P, foliar K, Ca and Mg concentrations were all higher in C. lusitanica, the difference being particularly marked for Ca and Mg. P. radiata contained substantially higher concentrations of the metals Zn, Mn and Al than C. lusitanica, whereas the latter contained higher B concentrations. Possible reasons for differences between species in foliar nutrient concentrations are discussed.     

Reclaiming sodic soils for wheat production by Prosopis juliflora (Swartz) DC afforestation in India

A green house pot trial was conducted to assess the impact of Prosopis afforestation on the productivity and fertility of degraded sodic soils in Haryana, India. Wheat (Triticum aestivum, L; cultivar HD 2329) plants were grown from seed on top soils collected from a chronosequence of 0, 5, 7, and 30-year-old Prosopis juliflora plantations established on highly sodic soils and a non-sodic reference soil collected from a local farm. The afforestation improved physical and chemical properties of surface soils by decreasing pH, electrical conductivity and exchangeable Na levels, and increasing infiltration capacity, organic C, total N, available P, and exchangeable Ca, Mg, and, K levels. The amelioration effect of the trees on top soil increased with duration of tree occupancy. Soil nutrient status under the 30-year-old plantation was higher than that of the non-sodic farm soil. The reduced soil sodicity and improved fertility contributed to higher germination, survival, growth, and grain yield of wheat plants grown on the Prosopis chronosequence soils, even surpassing the yield attained on the farm soil in the case of 30-year-old plantation soil. Sodium accumulation in the crop declined while N, P, K, Ca, and Mg uptake increased with soil plantation age reflecting the changing nutrient status of the rooting zone due to afforestation. Results confirmed that successful tree plantation may restore the productivity and fertility of highly degraded sodic soils.     

辽宁地区日本栗养分用量与分配研究

为科学地指导栗树施肥,该文研究了嫁接6~8年生大峰和辽栗10号各器官的年生物量及其分配比例,测定了2个品种各器官的养分含量,计算单株所需养分用量及其相应施肥量。结果表明:嫁接6~8年生栗树的单株平均生物量为:10.64、19.97、29.75 kg,生物量年均递增率达76.59%,同立地、年龄,不同品种间生物量差异很大;在干枝、根、叶、果肉、刺苞、1年生枝、果壳、雄花中的分配依次降低。嫁接7~8年生栗树单株年间养分(N、P2O5、K2O、Ca、Mg)平均吸收量分别为175.87、34.55、68.21、170.88、31.13 g。盛果初期,栗树分配于生殖生长的养分量逐年加大,各器官中,N、P2O5用量最多的是叶片,K2O用量最多的是果肉;树体内各营养元素吸收量占总量的排序NCaKPMg。根据试验分析:每生产100 kg鲜栗果,树体需要施N 3.06 kg、P5O21.50 kg、K2O 1.48 kg,N:P5O2:K2O=2:1:1。这一指标可作为辽宁地区日本栗的科学施肥依据。     

A study on the relation between soil and needle content of nutrient elements in the Korean pine plantation

Through the content analysis of nutrient elements in the soil and in the needle at the different site classes and periods of growth ofP. koraiensis, and in a single growing season, some conclusions can be drawn below: Most of the soil nutrient elements were higher at the good sites than at the poor ones in an annual average concentration of them, i.e., site class 1 > site class 2> site class 3. And forP. koraiensis tree at every site class, the nutrient elements in their needles did the same. However, each of the elements in the soil or in the need was seldom at the same level of concentration on the good or on the poor site during different periods of growth. There are no an inevitable relationship between the contents of the soil nutrient elements and the needle’s. And whether these elements are high or low within a tree body may depend on the physiogical requirement of the tree, but not on their contents in the environment. Some nutrient elements required forP. koraiensis varied with growth periods during a whole growing season. N, P and K, for example, were greatly needed only at the fast growth period, while Ca at the initial growth period; and on the contrary, Ca was needed less at the fast growth period. In intensive forest management, therefore, fertilizers with N, P and K should much be applied at the fast growth period, while fertilizer with Ca at the initial growth period to meet requirements of growth ofP. koraiensis trees.