Changes in fine root production and longevity in relation to water and nutrient availability in a Norway spruce stand in northern Sweden

The PEACH computer simulation model of reproductive and vegetative growth of peach trees (Grossman and DeJong 1994) was adapted to estimate seasonal nitrogen (N) dynamics in organs of mature peach (Prunus persica (L.) Batsch cv. O'Henry) trees grown with high and low soil N availability. Seasonal N accumulation patterns of fruits, leaves, stems, branches, trunk and roots of mature, cropping peach trees were modeled by combining model predictions of organ dry mass accumulation from the PEACH model with measured seasonal organ N concentrations of trees that had been fertilized with either zero or 200 kg N ha(-1) in April. The results provided a comparison of the N use of perennial and annual organs during the growing season for trees growing under both low and high N availability. Nitrogen fertilization increased tree N content by increasing organ dry masses and N concentrations during the fruit growing season. Dry mass of current-year vegetative growth was most affected by N fertilization. Whole-tree N content of fertilized trees was almost twice that of non-fertilized trees. Although N use was higher in fertilized trees, calculated seasonal N accumulation patterns were similar for trees in both treatments. Annual organs exhibited greater responses to N fertilization than perennial organs. Estimated mean daily N use per tree remained nearly constant from 40 days after anthesis to harvest. The calculations indicated that fertilized trees accumulated about 1 g N tree(-1) day(-1), twice that accumulated by non-fertilized trees. Daily N use by the fertilized orchard was calculated to be approximately 1 kg N ha(-1), whereas it was approximately 0.5 kg N ha(-1) for the non-fertilized trees. During the first 25-30 days of the growing season, all N use by growing tissues was apparently supplied by storage organs. Nitrogen release from storage organs for current growth continued until about 75 days after anthesis in both N treatments.     

Land-use effects on phosphorus fractions in Indo-Gangetic alluvial soils

Phosphorus (P) in soil exists both in organic and inorganic forms and their relative abundance could determine P supplying capacity of soil. Differential input of exogenous and plant-mediated phosphorus and carbon in soil under different land-uses could influence P availability and fertilizer P management. While the effect of land-use on soil organic carbon (SOC) is fairly well-documented, its effect on soil P fractions is relatively less known. We investigated the effect of different land-uses including rice–wheat, maize–wheat, cotton–wheat cropping systems and poplar-based agroforestry systems on soil P fractions and organic carbon accrual in soils. Total P concentration was the highest under agroforestry (569 mg P kg^?1) and the lowest under maize–wheat (449 mg P kg^?1) cropping systems. On the contrary, soils under rice–wheat had significantly higher available P concentration than the agroforestry systems, probably because of higher fertilizer P application in rice–wheat and prevailing wetland conditions during rice growth. In soils under sole cropping systems viz. rice–wheat, maize–wheat and cotton–wheat, inorganic P was the dominant fraction and accounted for 92.2–94.6% of total P. However, the soils under agroforestry had smaller proportion (73%) of total P existing as inorganic P. Among soil P fractions, water soluble inorganic P (0.13–0.26%) represented the smallest proportion inorganic P in soils under different land-uses. Agroforestry showed significantly (p < 0.05) higher concentrations of SOC than the other land-uses. Soil organic C was significantly correlated with soil P fractions. It was concluded that poplar-based agroforestry systems besides leading to C accrual in soil result in build-up of organic P and the P supplying capacity of soil.     

Phosphorus availability under annual cropping, alley cropping, and multistrata agroforestry systems

The hypothesis that agroforestry systems conserve P in forms that are more crop-available than those found in annual cropping systems was tested on two tropical sites: an Ultisol in Yurimagas, Peru, and a volcanically derived Inceptisol in Turrialba, Costa Rica. In both sites, the Hedley P fractions were compared in annual cropping, alley cropping, multistrata agroforestry and old forest systems. On the Ultisol, the effect of P fertilization on the soil P fractions was also examined. Under non-fertilized conditions, the multistrata and forest systems maintained more and a greater proportion of P in plant-available resin form than the annual or alley cropping systems. Greater resin P was associated with greater amounts and percentages of P in bicarbonate fractions and less P in residual fractions. The latter may be caused by greater and more temporally constant organic matter additions, less mineralization of labile soil organic matter fractions due to lower soil temperatures, and the long-term mobilization of residual P due to P immobilization in the biomass of the multistrata or forest systems. With P fertilization, resin P was related to inorganic P fractions. However, resin P increased even more when inorganic P fertilizers were combined with organic residue additions. This revised version was published online in June 2006 with corrections to the Cover Date.     

土壤肥力对余甘子产量的影响

福建省惠安县是余甘子的主产地,然而余甘子单产不稳不高。通过对不同产量的余甘子土壤肥力进行分析,并结合余甘子果实营养成分进行比较,结果表明:要提高余甘子产量,必须提高土壤有机质含量,以改良土壤理化性状,提高土壤肥力。要获得35 955 kg/hm2以上的产量水平,土壤中A层的全氮、全磷、全钾的含量应分别高于0.097%、0.126%、4.13%,B层中全氮、全磷、全钾的含量应分别高于0.038%、0.074%、4.24%。提高土壤中磷素含量(特别是速效磷的含量)对于余甘子的高产优质至关重要。在惠安丰产余甘子园的氮、磷、钾肥施用量平均为N247.5 kg/hm2,P2O5为298.5 kg/hm2,K2O为387 kg/hm2,N、P2O5、K2O比例1∶1.21∶1.56。这个施肥量及元素比例与果实营养含量比例较接近,不仅满足了树体连续高产的养分需求,又防止滥施肥料之弊病。     

Accumulation of residual soil microbial carbon in Chinese fir plantation soils after nitrogen and phosphorus additions

Nitrogen(N) and phosphorus(P) additions can affect soil microbial carbon(C) accumulation.However,the mechanisms that drive the changes in residual microbial C that occur after N and P additions have not been well-defined for Chinese fir plantations in subtropical China.We set up six different treatments, viz.a control(CK), two N treatments(N_1: 50 kg ha~(-1) a~(-1); N2:100 kg ha~(-1) a~(-1)), one P treatment(P: 50 kg ha~(-1) a~(-1)),and two combined N and P treatments(N_1P:50 kg ha~(-1) a~(-1) of N+50 kg ha~(-1) a~(-1) of P; N_2P:100 kg ha~(-1) a~(-1) of N+50 kg ha~(-1) a~(-1) of P).We then investigated the influences of N and P additions on residual microbial C.The results showed that soil pH and microbial biomass decreased after N additions, while microbial biomass increased after P additions.Soil organic carbon(SOC) and residual microbial C contents increased in the N and P treatments but not in the control.Residual microbial C accumulation varied according to treatment and declined in the order: N_2PN_1PN2N_1PCK.Residual microbial C contents were positively correlated with available N, P, and SOC contents, but were negatively correlated with soil p H.The ratio of residual fungal C to residual bacterial C increased under P additions, but declined under combined N+P additions.The ratio of residual microbial C to SOC increased from 11 to 14%under the N_1P and N_2P treatments, respectively.Our results suggest that the concentrations of residual microbial C and the stability of SOC would increase under combined applications of N and P fertilizers in subtropical Chinese fir plantation soils.     

Inorganic and organic soil phosphorus and sulfur pools in an Amazonian multistrata agroforestry system

In the central Amazon basin, the effects of secondary vegetation and primary forest on inorganic and organic P and S pools were compared with those of different fruit and timber tree species in a multistrata agroforestry system. The soils (Xanthic Ferralsols) were low in readily available P and S. Fertilizer applications increased the less accessible nutrient pools more than the plant available pools. For example, dilute-acid extractable P increased substantially (from 2 to 76 mg P kg⁻¹), whereas Mehlich P (plant available) increased less (from 3 to 19 mg P kg⁻¹). In contrast, the recalcitrant soil P pools, such as the residual P, did not increase on the short term, but only after more than six years following application. The proportion of less available ester-sulfate S was significantly higher in fertilized sites than in unfertilized sites, in contrast to soluble inorganic sulfate S or carbon-bonded S. The marked increase of successively available soil P and S pools through fertilization was advantageous with respect to the long-term effect of nutrient applications. Soil nutrient availability was not only related to the amount of nutrients applied but was also influenced by tree species. Nutrient return by litterfall and litter quality played an important role in soil P and S dynamics. Incorporation of applied nutrients into successively available organic nutrient pools will decrease potential P fixation and S losses by leaching and increase long-term nutrient availability. Therefore, tree species with rapid above-ground nutrient cycling and high quality litter (such as annato [Bixa orellana] and peach palm [Bactris gasipaes]) should constitute the majority of crops in multistrata agroforestry systems on infertile soils to ensure adequate medium to long term availability of P and S. This revised version was published online in June 2006 with corrections to the Cover Date.     

Seasonal variations in phosphorus fractions in semiarid sandy soils under different vegetation types

We investigated the seasonal patterns of soil phosphorus (P) fractions under five vegetation types – Ulmus macrocarpa savanna, grassland, Pinus sylvestris var. mongolica plantation, Pinus tabulaeformis plantation, and Populus simonii plantation – in the southeastern Keerqin Sandy Lands of China. The measured P fractions (0–20 cm depth) included: soil total P (TP), total organic and inorganic P (TPo and TPi), bicarbonate extractable organic and inorganic P (BPo and BPi), microbial biomass P (MBP), and in situ resin-adsorbed P (resin-P). Soil TP and TPo concentrations in the savanna and grassland were significantly lower in summer than in spring and autumn. However, they were relatively stable in three forest plantations. Soil labile P fractions showed a significant seasonal pattern under all vegetation types with the peak in summer, except soil MBP that was constant in the savanna and grassland and BPo that decreased over time in the savanna. This pattern of labile P fractions was attributed to a combination of seasonal climatic changes, low P availability, as well as the biological controls of soil P transformation in the study area. Litter decomposition played a key role in soil P availability. The monthly resin-P released from litter decomposition in summer was 2.6–7.4 times greater than in other seasons, and was 1.7–3.4 times of that in the 10 cm depth soil. Concentrations of soil P fractions were obviously affected by vegetation type. The savanna had the highest total P and MBP concentrations and the P. tabulaeformis plantation had the highest BPi and resin-P among all vegetation types. Among forest plantations, P. simonii plantation had the highest total P and MBP. These results suggest that U. macrocarpa savanna is the best system conserving soil nutrient (particularly P) stocks and microbial activity, followed by the grassland and P. simonii plantation, while the pine plantations are the worst.     

Impacts of competition and nitrogen addition on plant stoichiometry and non-structural carbohydrates in two larch species

Previous research has shown that competition between plants can have differential effects on leaf stoichiometry and non-structural carbohydrate(NSC) in different environments.However,little attention has been given to understanding these effects on non-photosynthetic organs,particularly of deciduous tree species.Here we assess the impact of competition on below and aboveground biomass,stoichiometry,nutrient composition and NSC in pure and mixed forests of two Larch species,Larix kaempferi and L.olgensis under nitrogen(N) addition.Nitrogen enrichment did not result in stronger intraspecific competition for both species and L.olgensis benefited from the presence of L.kaempferi under different N levels.Stems kept relatively stable C/N compared to roots and branches in response to competition,while N addition imposed stronger impacts on N/P of different organs rather than competition.In contrast to stable C concentrations,starch and soluble sugar concentrations were more easily impacted by competition and the addition of nitrogen.Competition forced L.kaempferi and L.olgensis to allocate more carbon into storage by increasing their starch concentration and starch/soluble sugar of stems under competition.However,no significant differences in stoichiometry and NSC concentration between intra-and interspecific competition were found.NSC and nutrient pools of L.kaempferi stems,branches and coarse roots consistently declined due to competition regardless of N addition.Coarse and fine roots of L.kaempferi accumulated more N when in competition with L.olgensis than with a conspecific neighbor under N addition.Our results show that NSC was more sensitive to competition relative to stoichiometric traits(N and P) of non-photosynthetic organs.     

Effects of fertilisation on phosphorus pools in the volcanic soil of a managed tropical forest

Acacia koa forests benefit from phosphorus fertilisation, but it is unknown if fertilisation is a short or long term effect on P availability. Past research suggests that P cycling in soils with high P sorption capacity, such as Andisols, was through organic pathways. We studied leaf P and soil P fractions in a tropical forest Andisol for 3 years after fertilisation with triple super phosphate. Leaf P concentration and labile P remained high after fertilisation. Fertilisation had increased all the inorganic P fractions over the length of the study, while organic P fractions had not. The results suggested that the organic P fractions had a reduced role as a source of labile P after fertilisation. The size and dynamics of the sodium hydroxide- and hydrochloric acid-extractable P pools would suggest that either pool could be major sources of labile P. Because of the high level of poorly crystalline minerals in Andisols (allophone and imogolite), it would be expected that applied P would quickly lead to strong P sorption onto mineral surfaces and thus a rapid decline in P availability. We propose that the high organic matter present in these soils had masked some of the Al and Fe sorption sites, which allowed the sorption and desorption when large amounts of addition P were applied.     

毛竹配方施肥研究初报

作者在浙江安吉县和福建沙县设置60块标准地研究毛竹林最适配方施肥。采用正交设计排列田间试验。第一年的结果表明:毛竹施肥三要素的重要性顺序为N>P>K;N起主要作用。每亩最适三要素用量为N6.9公斤,P_2O_54.2公斤,K_2O2.7公斤;其三要素比例为: N:P_2O_5:K_2O=1:O.6:0.4     

Fertilizers in agroforestry systems

This review encompasses results of fertilization experiments on several agroforestry systems—alley cropping, perennial shade systems, home gardens—in which fertilizer use is a likely management alternative. Fertilizer response was found to be most common in alley cropping, variable in perennial shade systems, and rarely reported in home gardens. Level of nutrient removal in harvested products is probably the overriding factor in determining fertilizer response; greater accumulation of organic residues, slower growth under shade, and longer periods of nutrient uptake probably also contribute to the relatively smaller fertilizer response of the perennial shade systems and home gardens. Considerable knowledge gaps exist regarding the breakdown of organic residues, and interactions between mineral and organic amendments. Systems based on annual crops (e.g., alley cropping) are likely to be less nutrient-efficient and sustainable than systems based on perennial crops, due to reduced fixation and transfer of N to the crops, the tendency of the trees to compete for and sequester nutrients, relatively high P requirements of the crops, and the high labor cost of tree management. The possible benefits of fertilization of specific components in home gardens, and relative advantages of including low-value tree legumes, high-value shade trees, and fertilization in shaded perennial systems are only beginning to receive research attention.     

连香树人工幼林群落营养元素含量、积累分配和循环

研究了 1 0年生连香树人工群落 8种营养元素的含量、积累分配和循环。主要结论是 :( 1 )连香树营养器官中各种元素的平均含量顺序为Ca>N >Al>K >Mg>P >Fe >Mn。 ( 2 )元素量在各营养器官的分配顺序为根 >叶 >去皮干 >皮 >枝 ,各元素含量顺序为Ca>N >K >Al>Mg>P >Fe >Mn。 ( 3)连香树群落 8种元素的吸收量、存留量和归还量分别是 72 9 82kg·hm- 2 a- 1 、2 0 6 72kg·hm- 2 a- 1 和 52 3 1 0kg·hm- 2 a- 1 。 ( 4) 51 2 %的归还总K量靠降水淋溶归还 ,其余元素总归还量的 55 7%～ 96 5%靠凋落物归还。Fe、Al归还量的 4 1 3%和 4 4 3%通过死根归还。 ( 5) 8种元素的利用系数、归还比和周转期分别为 0 2 3～ 0 54、0 57～ 0 82和 2 2 6～7 63。文中改进了降水淋溶归还的算法 ,提出了群落归还系数、积累系数和吸收系数 ,讨论了落叶树种元素生物循环的算法     

麻竹山地林配方施肥及生长调节剂对竹笋产量影响

对福建南靖国有林场山地麻竹笋用林采用五因素二次回归正交试验设计进行配方施肥研究。结果表明:氮、磷、钾、有机肥对竹笋产量影响的回归方程显著,氮、磷对麻竹出笋数量回归方程的影响显著,氮、磷(P2O5)、钾、花生饼的最佳施肥量分别为0·2195、0·8258、0·1906、2·3055t·hm-2;竹笋最高产量的氮、磷(P2O5)、钾、花生饼施肥量分别为0·2186、0·8262、0·1899、2·3064t·hm-2。     

施肥对苦竹笋养分及营养成分的影响研究

采用单因素变量设计,研究含相同量氮、磷、钾的有机肥、复合肥、无机肥等不同肥料种类对苦竹笋养分含量及营养成分的影响。研究结果表明,施肥能显著地或极显著地提高苦竹笋中氮、磷、钾含量。不施肥处理竹笋中还原糖、可溶性总糖、蔗糖含量均高于施肥处理,且差异达到极显著水平;蛋白质、粗纤维、粗脂肪含量则为施肥处理高于不施肥处理,差异达到极显著水平。在3种肥料中,与复合肥和无机肥相比,有机肥处理苦竹笋中还原糖、可溶性总糖、蔗糖、粗蛋白、粗纤维、粗脂肪等营养成分含量均为最高,除可溶性总糖差异显著外,其他指标均达到极显著差异。     

不同类型土壤对柑生长结果的影响

于2002年和2003年测定了湖南西部红砂土、红泥土和紫色土9年生枳砧柑园土壤物理性状、化学性状以及柑的生长结果情况.结果表明:3种土壤有机质含量不足,红砂土和红泥土速效氮、磷偏低,紫色土速效氮、磷含量不足;紫色土、红砂土速效钾适量,红泥土速效钾缺乏;紫色土有效钙、镁含量充足,红砂土与红泥土二者有效钙、镁缺乏;除红砂土和红泥土有效铁、有效锰含量充足外,其他所测微量元素缺乏,因而柑产量不高,果实达不到优质果标准;3种土壤类型中,红砂土整体营养水平较高、土质疏松,因而红砂土柑产量和品质都优于紫色土和红泥土.     

影响锥栗对栗瘿蜂抗性表达的土壤因子研究

影响锥栗抗虫性的土壤因子有：全P含量、20～60cm层土壤的速效K含量、20～40cm层土壤的通气透水性指标（特别是非毛管孔隙度）和40～60cm层土壤的pH值、有机质含量。全P含量越高，锥栗越抗虫，反之，则越易感虫。20～60cm层土壤的速效K含量对锥栗的抗虫性有显著的影响，速效K含量越高，锥栗的抗虫性越强。20～40cm层土壤的通气透水性良好．有助于锥栗抵御栗瘿蜂的危害。非毛管孔隙度小于6％，则锥栗生长受影响，易受栗瘿蜂危害。40～60cm层土壤的pH值和有机质含量对栗瘿蜂危害锥栗亦产生影响。在pH值4．5～5．0范围内，pH值小能提高锥栗的抗虫性。     

Multiscale analysis of the contents of palmatine in the Nature populations of Phellodendron amurense in Northeast China

Palmatine is a valuable ingredient in Chinese medicine that is produced by Phellodendron amurense Rupr.The contents of palmatine content in root bark, trunk bark,perennial branch bark, annual branches, and leaves of the trees with different ages and geographies in Northeast China were measured by high-performance liquid chromatography.The contents of palmatine in the barks of root, trunk, and perennial branch were significantly higher than those in annual branches and leaves. The contents of palmatine in trunk bark and root bark from Lesser Khingan Mountains increased with age, which is significantly opposite to other three vegetation types. The contents of palmatine in perennial branch bark, annual bark and leaves had no significant regularity. Moreover, the contents of palmatine in samples of root bark, trunk bark, perennial branch bark and annual bark varied significantly with latitude. The nature populations of P. amurense growing at low latitude contained significantly more palmatine than those growing at high latitude. These results provide a scientific basis for the reasonable cultivation and efficient utilization of P. amurense.     

绿竹笋营养成分及笋期叶养分的施肥效应

研究施有机肥、复合肥、无机肥对绿竹笋营养成分及笋期叶片N、P、K含量的影响。结果表明 :3种肥料处理对绿竹笋N、P、K含量、粗蛋白质、粗纤维、蛋白质水解氨基酸含量有明显的促进作用 ,竹笋N和蛋白质含量以无机肥处理最高 ,P含量、氨基酸总量、必需氨基酸总量以复合肥处理最高 ,K含量、粗纤维、半需氨基酸总量以有机肥处理最高 ,但还原糖、总可溶性糖、蔗糖、淀粉含量不施肥处理明显高于施肥处理。 3种肥料处理对绿竹叶片N、P、K含量的影响在不同发笋时期表现出一定的差异性 ,发笋初期N、P、K含量施肥处理明显高于不施肥处理 ,以无机肥处理最高 ;盛期叶片N、P含量以有机肥处理最高 ,K含量以无机肥处理最高 ;末期N含量以有机肥处理最高 ,P含量以不施肥处理最高 ,K含量以无机肥处理最高 ,表现出不同肥料施肥效应的差异性。     

Relationships between foliar phosphorus fractions of Pinus sylvestris var. mongolica and soil available phosphorus

In order to find out the best foliar diagnostic index of phosphorus (P) nutrition in Mongolian pine (Pinus sylvestris var. mongolica) in the southeastern Keerqin Sandy Lands, the concentrations of total nitrogen (N), inorganic P, organic P and total P in needles of different ages and soil available P were examined. The results show that in the study area, soil available P was rather low (0.12–0.63 mg/kg) and was significantly correlated with inorganic P (cPi) and total P (cPt) concentrations in current year needles of Mongolian pine. The significant correlation between soil available P and needle cPt derived from the significant correlation between cPi and cPt. Compared with cPt, cPi did reflect the level of soil P supply more accurately and more directly. __________ Translated from Chinese Journal of Applied Ecology, 2008, 19(3): 494–498 [译自: 应用生态学报]     

Phosphorus cycling and soil P fractions in Douglas-fir and red alder stands

Nitrogen-fixing species can dramatically increase soil acidity and organic matter content, and potentially alter biogeochemical P dynamics. We compared ecosystem P cycling in adjacent stands of N₂-fixing red alder (Alnus rubra Bong.) and non-fixing Douglas-fir (Pseudotsuga menziesii Franco) in order to determine whether P-cycling rates within stands were related to soil P forms as measured by sequential P fractionation. Above-ground annual P uptake was 61% greater in the red alder stand, although soil available P, as measured by Bray (NH₄F–HCl) extraction, was only 10% of that found in the Douglas-fir stand. Total ecosystem P in the alder stand was only 69% of that found in the Douglas-fir stand, and could indicate a pre-establishment difference between stands. However, the percentage of total soil P released by Bray or NaOH extraction was also lower in the alder stand, which suggests that differences in total P alone did not control the patterns observed in P fractions. Concentrations of inorganic P sorbed to Fe and Al minerals and contained in Fe minerals and apatite were greater under Douglas-fir, while organic P was slightly greater under red alder. While fluxes of P in litterfall, uptake and resorption were 94, 60 and 292% higher in the alder stand, soil extractable fractions meant to represent available P were lower under alder. Static measures of available P do not appear to adequately reflect P supply, and the development of techniques to assess P turnover is needed to better understand cycling and plant availability of P.