Effect of long-term fertilization on the biomass production and nutrient status of Scots pine stands

The effect of repeated fertilization on soil properties, nutrient status of the stand and the biomass production of the above-ground components of the trees are examined in the study on the basis of material from three fertilization experiments. Two of the experiments were established in sapling stands, and the third in a pole-stage stand. The stands had received repeated doses of fertilizer totalling N 597–776 kg ha^–1 and P 69–80 kg ha^–1 over a 26 to 30-year study period in accordance with a factorial experimental design.Nitrogen fertilization increased the amount of organic matter in the humus layer of two of the experiments by 25–35%, and the amount of total nitrogen by about 50%. The C/N ratio of the humus layer in all three experiments decreased as a result of nitrogen fertilization by 11–18%. No decrease in soil pH was detected.At the end of the experimental period, i.e. 5–6 years after the most recent fertilization, the nitrogen concentration of the current needles on the nitrogen-fertilized plots was clearly lower than that of the older needle age classes. Fertilization did not have any marked effect on the concentrations of other macronutrients in the needles.Of the above-ground components, stemwood production was affected the most by nitrogen fertilization. The range of the relative growth response was 22–36%. The effect on branch biomass was 25% on the least fertile site, but there was no effect on the most fertile site. The effect of nitrogen fertilization on the needle biomass component was least, from –8 to 18%, owing to the 5 to 6-year time lag between the preceding fertilization and biomass sampling. A negative response was found on the least fertile site, where six years had elapsed since the most recent fertilization. However, on this site the proportion of over one-year-old needles was greater on the nitrogen-fertilized plots (24%) than on the others (19%). Phosphorus fertilization had only a slight effect on stemwood production.In general, nitrogen fertilization decreased the crown biomass per unit volume of stemwood.     

Fertilization of sugar maple showing dieback symptoms in the Quebec Appalachians,Canada

A research project on foliar and soil chemistry in declining sugar maple (Acer Saccharum, Marsh) stands was carried out in the Beauce-Mégantic region of southern Quebec. Foliar nutrient concentrations in declining stands were low in P, K, and in some cases, Ca and Mg. Fertilizers and liming materials containing Ca, Mg, and K were applied in 1987. Foliar and soil nutrient levels of base cations were increased as a result of treatment and visual evaluation of tree health indicated an improvement. Data are also presented on the number of samples required to obtain a statistically significant change in foliar and soil chemistry in response to fertilization.     

Base cations and micronutrients in forest soils along three clear-cut chronosequences in the northeastern United States

Determining effects of clear-cutting on base cations and micronutrients is essential for ensuring the sustainability of forestry for biofuels and wood products. The objective of this study was to quantify long-term changes in forest floor and mineral soil base cations (Ca, Mg, and K) and micronutrient (Mn, Zn, and Cu) concentrations and pools following clear-cutting in forests aged 1–120 years. We studied forest soils along three clear-cut chronosequences located in the Adirondack Ecological Center in Newcomb, NY, Bartlett Experimental Forest in Bartlett, NH, and Harvard Forest in Petersham, MA. We utilized a strong-acid extraction to quantify base cations and micronutrient concentrations and pools, which may better assess nutrients over the chronosequences than the conventional exchangeable extraction. Generalized linear mixed-effect models (GLMMs) show forest floor and mineral soil Ca, Mg, Mn, and Cu concentrations and pools decreased with increasing forest age across the three study areas. Potassium and Zn concentrations and pools were not significantly different with stand age and neither did soil C and N pools and pH using GLMMs. We calculated that 32–67% of the Ca pool decrease can be attributed to uptake by regenerating vegetation but only 0.02–9% of Mg, Mn, and Cu after harvest. Thus, leaching was likely to the dominant loss process for Mg, Mn, and Cu following clear-cutting. Our results suggest nutrient pools decreased for over a century following clear-cutting, but it is unclear if this will impact plant growth.     

Nutritional management ofPinus radiata at Gurnang State Forest,New South Wales

A survey of foliage and soil nutrients and productivity in post first-thinned stands (15 years +) ofP. radiata showed high variability on uniform soil parent material. Site index was significantly related to stand age and soil P. Nutritional monitoring plots in pre-crown closure stands showed P and B deficiency in the foliage and declining concentrations with age. High accumulations of Al and Mn in the foliage in both surveys were unrelated to stand age or site index. A 14-year-old once-thinned stand responded to N and P but not to K, Mg, Ca, B, Cu or Zn. The requirement for P in foliage appears to increase with age, though assessing the critical level is difficult. Nutritional monitoring, supported by fertilizer trials, appears essential to assess nutritional needs and to maintain productivity.     

Forest fertilization research and practice in the Pacific Northwest

Forest managers in the Pacific Northwest (PNW) use fertilization as a means to increase timber yields in managed stands. Information on the biological basis for nutrient amendments and stand growth responses to fertilization is required to effectively use fertilization as a silvicultural tool, and research programs in mineral cycling and forest nutrition have been underway in the region for about four decades.Most PNW Douglas-fir forest sites are nitrogen deficient. Mineral cycling research has shown high C/N ratios and low nitrification rates for soils in the region.Research and development projects in the Pacific Northwest have produced an information base that is used to select sites and stands for fertilization and to forecast growth after treatment. Much of the basis for operational fertilization programs in western Oregon and Washington comes from cooperative research programs; current activities for these programs are directed toward improving site-specific response information.Forest fertilization in the Pacific Northwest has become a silvicultural practice of major significance over the past two decades. Forest industry and government organizations managing forest lands in western Oregon and Washington apply nitrogen fertilizer to Douglas-fir stands over a range of soil and stand types (operational fertilization of other species is minor). About 50,000 to 55,000 ha are fertilized each year, and future programs will likely be of similar magnitude. Most current plans for management regimes including fertilization call for multiple applications.     

Effects of mulch and mineral fertilizer on crop, weevil and soil quality parameters in highland banana

The decline of cooking banana production in parts of East Africa hasbeen associated with a loss of soil fertility and increased pest pressure.Previous work indicated that the use of mineral fertilizers at recommendedratesis not financially viable on plantations where pest pressure is high. Theobjectives of this study were to determine the effects of half the recommendedrates of mineral fertilizers and organic mulch on banana yield, soil and foliarnutrient status, soil water and pest damage in the central region of Uganda.Thestudy was conducted in a four-year old banana plantation infested with weevils.Treatments consisted of mineral fertilizer alone, mulch alone, a combination ofmulch with fertilizer, and a control (no mulch from outside the plot, ormineralfertilizer applied). Fruit yield was generally low (mean of 7.4 Mgha^–1 yr^–1) and increases above thecontrol ranged from 1.1 to 2.0 Mg ha^–1 yr^–1. Banana yield was significantly higher in the solemulch treatment than in the control. However, there were no significantdifferences in yield among the treatments that received external inputs. Thus,there was no demonstrable yield advantage of combining mineral fertilizer withmulch. At the end of the trial, soil K concentrations in the two treatmentsthatwere mulched, were almost twice those of the control, but this difference wasnotstatistically significant. Concentrations of Ca and Mg did not differ withtreatment. Soil available P significantly increased when mineral fertilizer andorganic mulch were combined. Treatments that received organic mulch were lowerin foliar concentrations of N and Mg, and higher in K. Soil water content wasgreater in the surface soil layer in the treatments that received mulch,presumably due to less surface run-off and evaporation, since there was nochangein surface soil porosity. The effect of organic and inorganic amendments had noimpact on weevil damage, which remained above 5% at the end of the trial. Weconclude that where weevil damage is over 5% of the cross section near thecollar, banana production may not be economically increased through use ofeither mineral fertilizer and/or organic mulch.     

Relations between damage symptoms and nutritional status of Norway spruce stands (Picea abies Karst.) in southwestern Germany

Since the mid-1970s new types of forest damage are observed in the Federal Republic of Germany. Typical damage symptoms in coniferous tree species are needle yellowing, reddening and premature loss of older foliage. Needle analysis carried out in damaged Norway spruce stands indicated that these phenomena, most of all needle yellowing, are influenced by the nutritional status of the trees. For the investigated sites Mg but also other elements, particularly P, S, K, Ca and Zn may play a causal role. As N is the most abundant element in the plant its form of uptake is important for a balanced nutrition. On the contrary to NO₃-N high NH₄-N uptake reduces the uptake of cations, particularly Mg and Ca, eventually inducing foliar discoloration symptoms on specific sites. Fertilizer experiments indicated that Mg fertilization is an appropriate tool to mitigate forest damages associated with Mg deficiency for a sustained time period. The application of N in the form of NH₄-N may impede Mg uptake. This mechanism may cause severe damage in forest areas receiving continuously high NH₄-N deposition.     

Microcosmic study of soil microarthropod and earthworm interaction in litter decomposition and nutrient turnover

A microcosm experiment was set up under laboratory conditions and verified under field conditions with the objective of investigating the interaction of soil microarthropods and earthworms in litter decomposition, nutrient release, and uptake by maize crop. The treatments included: soil alone (control), soil with leaf litter (Senna siamea leaves), soil with leaf litter and soil microarthropods, soil with leaf litter and earthworms (Hyperiodrilus africanus), and soil with litter and both of the soil faunal groups. After an 8-week incubation period, the amounts of litter decomposed and N, P, K, Ca, and Mg released followed the order: with microarthropods and earthworms > with earthworms > with microarthropods > no faunal addition. The presence of microarthropods and earthworms also increased the net level of mineral N in the incubated soil. The additive roles of soil microarthropods and earthworms were observed on decomposition and nutrient release. Such faunal interactions resulted in an increased N uptake by maize in the incubated soil. Despite their lower biomass, soil microarthropods contributed significantly to nutrient turnover in the presence of earthworms. This study emphasizes the need to quantify and devise ways of controlling and regulating the abundance and activities of soil fauna for effective nutrient cycling and, consequently, for better crop yields in low-input tropical agricultural ecosystems.     

Concentrations of calcium,magnesium, sodium and potassium in human milk and infant formulas

Concentrations of calcium, magnesium, sodium and potassium were determined in 55 samples of mature human milk from Canary women and 5 samples of powdered infant formula. According to the literature our data fell within the normal intervals described for each kind of milk. The mean concentration of Ca, Mg, Na y K of powdered infant formula was higher than those concentrations found in the human milks. Significant differences among the concentrations of Ca, Mg and Na for the milks of the considered mothers were observed. Only the Ca intakes for infants fed with human milk were lower than those requirements recommended by the Food and Nutrition Board (1989). However, the infants fed with powdered infant formula had an adequate intake of all the studied metals. A progressive decrease of the Na, K and Ca concentrations with the lactation stage was observed. Maternal age, parity and sex of the newborns did not affect the metal concentrations significantly.     

The effects of fertilizing on the foliar nutrient concentrations inEucalyptus grandis

The foliar concentrations of macro- and micro-nutrients were studied in four N P K-lime fertilizer experiments withEucalyptus grandis, in the Natal Midlands and Zululand, South Africa. The sampling method and the chemical analysis of the foliar nutrient concentrations are described. Nutrient levels are similar to results found elsewhere and they differ little from those for other eucalypt species. There are many significant changes in foliar nutrient concentrations as a result of fertilizing. The relationship between soil and foliar N and P concentrations are clear as well as the importance of well-balanced N/P and Ca/Mg ratios. The Zn-P and Zn-Mg relationships make it apparent that Zn-enriched fertilizers should be used forE. grandis.     

Stratification of soil phosphorus,pH, and macro-cations under intensively cropped grass ley

The large amounts of nutrients applied to and removed from soil by intensive grass production may cause quick changes in the nutrient pools available to plants and exposed to leaching and runoff losses. Stratification of applied nutrients is especially important for phosphorus (P), which moves slowly in soil. To study the vertical distribution of extractable nutrients and soil pH in different types of ley soil, P fertilisers were incorporated or placed prior to sowing or broadcast annually at ten sites for 3 years. Then the soils were sampled in several layers 2.5 or 5 cm deep and analysed for pH and the concentrations of phosphorus, potassium (K), calcium (Ca), and magnesium (Mg) extractable with acid ammonium acetate. In mineral soils, broadcast P mainly remained within the uppermost 2.5 cm of soil, in which the concentrations of extractable P more than doubled during the study period. When commonly used NK and NPK fertilisers were applied, the uppermost 5 cm of soil was acidified by about 0.5 pH units and its Ca value decreased by about 25%. Broadcast K enriched a thin surface layer even if the K balance was negative. Estimation of the concentration of dissolved phosphate in runoff suggested that the high P losses that are possible at excessive levels of soil test P can be diminished by perennial grasses supplied with abundant water and other nutrients. Surface-applied P appeared to increase the losses, but even a shallow placement seemed to prevent them efficiently if all fertiliser granules become covered with soil.     

腐植酸对设施土壤的养分、盐分及番茄产量和品质的影响研究

试验选择具有10年棚龄的北方大棚,在不同施肥条件下,分别对土壤养分、盐分及番茄产量和品质等进行了研究,具体对因处理不同而引起的土壤养分与水溶性盐分含量、盐基离子组成的变化以及番茄的维生素C（Vc）含量和含糖量等进行了分析。结果表明,腐植酸含有多种物质,它的施用可以提高土壤有机质含量,并且能增加土壤速效态P、K的含量,降低土壤电导率。施用复混肥的土壤电导率增加37％,而施用腐植酸可以使土壤电导率降低10．4％。土壤盐基离子含量的增加,主要是由水溶性NH4^＋、K^＋、Ca^2＋、Mg^2＋含量的增加引起的。腐植酸由于含有各种官能团,可以有效抑制土壤中水溶性K^＋、Ca^2＋、Mg^2＋等盐基离子的增加,进而降低土壤的电导率。腐植酸对番茄的产量和品质也都有显著的影响,能使番茄增产36．5％,并明显提高番茄的VC含量和含糖量。     

Mulch N recycling in green manure leys under Scandinavian conditions

Nitrogen (N) recycling to the regrowth of mulched red clover (Trifolium pratense L.) and mulched mixed red clover/perennial ryegrass (Lolium perenne L.) leys was determined in field experiments during three consecutive years using ¹⁵N-labelled shoot material. Nitrogen recycling was greater in the pure clover stands than in the mixed stands in the beginning of the growing season, but increased successively in the mixed stands so that it was similar (14–15.5%) in both stands at the end of the season. This recycling of N from the mulch led to increased biomass accumulation but did not alter stand composition in the mixed stands. Mulch-derived N was incorporated into the soil organic N in both pure clover and mixed stands which thus contributed to building up soil fertility. An approximately similar proportion of N remained unaccounted for in mulched pure clover and mixed stand leys and presumably represented gaseous losses. To exploit the benefits of green manure leys in the humid temperate zone while minimising the negative environmental impact, these should be harvested rather than mulched.     

Mineral nutrition of slash pine in subtropical Australia. II. foliar nutrient response to fertilization

In the previous paper, we reported the stand growth of slash pine (Pinus elliottii) during the first 11.5 years of plantation in response to (1) initial fertilization at plantation establishment with P rates of 11, 22, 45 and 90 kg P ha^–1 which were either banded or broadcast in the presence or absence of basal fertilizers containing 50 kg N ha^–1, 50 kg K ha^–1 and 5 kg Cu ha^–1 and (2) application of additional 40 kg P ha^–1 at age 10 years. Here we present the responses in foliar nutrient concentrations of slash pine in the first 11.5 years to the initial fertilization and the additional P applied at age 10 years.Foliar N and K concentrations in the first 9.6 years of plantation decreased with the initial P rate. Application of the basal fertilizers improved foliar Cu concentration. Foliar Ca and Mg concentrations increased linearly with the initial P rate. The initial fertilization did not affect foliar Mn concentration in the first 9.6 years. Foliar P concentration increased quadratically with the initial P rate, which accounted for 77–86% of the variation in foliar P concentration. Most of the explained variation in foliar nutrient concentrations was attributable to the plantation age except for foliar P concentration. In the case of foliar P concentration, 53% was explained by the initial P rate, 31% by the plantation age and 2% by the positive interaction between the initial P rate and the plantation age. Foliar P concentration of slash pine at age 11.5 years increased quadratically with the initial P rate and linearly with the additional 40 kg P ha^–1 applied at age 10 years, accounting for 81% of the variation in the foliar P concentration. Foliar nutrient analysis indicated that P was the major limiting nutrient affecting the stand growth of slash pine in the first 11.5 years.     

Role of allelopathy as a possible factor associated with the rising dominance ofBunias orientalis L. (Brassicaceae) in some native plant assemblages

Leaf extracts ofBunias orientalis were shown to inhibit seed germination of a variety of cultivar plant species and of species cooccurring withB. orientalis in the field. Root exudate solutions and leaf litter leachates ofB. orientalis were tested for their allelopathic activity using seedling growth assays. Additionally, in comparative seedling growth assays soil cores removed from denseB. orientalis stands were tested bimonthly for elevated allelopathic effects. The impact of root exudates on seedling growth was generally weak and varied between species. Similar results were obtained for the effect ofB. orientalis leaf litter leachates on seedlings grown in sand culture relative to the effect of leaf litter leachates of a plant species mixture. When soil as a growth substrate was used, no consistent differences in seedling growth were obtained between the two litter leachate treatments. In the soil core experiment seedlings grown in soil cores collected from a denseB. orientalis stand unexpectedly showed better performance than seedlings grown in soil cores collected from a nearby mixed plant stand withoutB. orientalis, at least in early spring and late autumn. Predominating nutrient effects are, therefore, assumed to conceal a potentially increased allelopathic effect of soil beneath denseB. orientalis stands. It is concluded that other factors than allelopathy must be investigated to explain the rapid establishment of dense stands of this alien plant species.     

Soil condition,nutrition and growth performance of Norway spruce (Picea abies [L.] Karst.) in fast-growing plantations

By ploughing in the humus layer and soil vegetation, simultaneous CaP application and subsequent N fertilization it is possible to ameliorate acid loess loam soils. Under favourable climatic conditions a high growth performance of Picea abies (L.) Karst. can be attained after such ameliorations.Under these fast-growing pure spruce stands a new humus layer develops. Already during the first 15 years of growth of such plantations considerable quantities of nutrient elements accumulate in the humus layer. After application of CaPN (and CaPNK respectively) the Al level in spruce needles decreases, while the Al content in the humus layer increases. In spite of amelioration this newly developing humus layer is rather acid.     

Nutrient concentration in soil water extracts and soybean nutrition in response to lime and gypsum applications to an acid Oxisol under no-till system

No-till system (NTS) occupies 20 million hectares with grain crops in Brazil. However, calcium deficiency and aluminum toxicity can limit crop yields in many soils, and liming, associated to gypsum application, is an option for improving soil management. The objective of this study was to evaluate the effects of lime and gypsum application on the composition of soil water extracts of a clayey Rhodic Hapludox, cultivated with soybean under NTS. The experiment had a randomized complete block design with split-plots. The plots consisted of lime treatments (either a single rate of 4.5 t ha⁻¹ or three annual rates of 1.5 t ha⁻¹) surface-applied or incorporated at 0.2 m depth. The subplots received surface applications of gypsum (3, 6 and 9 t ha⁻¹). Liming increased total calcium and magnesium concentrations and the magnesium free Form activity (aMg²⁺) in the water extracts. The effect of liming on Mg was observed at deeper layers of the soil profile. Gypsum increased total concentration and free forms activities at calcium (aCa²⁺) and sulfate, but decreased to magnesium in the 0.05–0.2 m soil layer. Part of Mg lost from these upper layers probably contributed to increased Mg in the subsoil (0.4–0.8 m). Free forms activities at the aluminum, calcium, magnesium and sulfate were lower than the total concentrations, mainly for aluminum. Ca and Mg concentrations in soybean leaf tissue were positively correlated to the aCa²⁺ and aMg²⁺ in the soil water extract. Soybean grain yield was negatively correlated to both Mn total concentration and activity (free form) in the soil water extract, but it was positively correlated to sulfate (total concentration and free form activity) in the subsoil layer and to the Ca total concentration in the upper layer (0–0.05 m). It is concluded that lime and gypsum ameliorate soybean grain yield under NTS.     

Are Partial Nutrient Balances Suitable to Evaluate Nutrient Sustainability of Land use Systems? Results from a Case Study in Central Sulawesi,Indonesia

Nutrient input–output balances are often used as indicators for the sustainability of land use systems. In a case study on plot scale in Central Sulawesi, Indonesia, we measured nutrient input–output balances of natural rainforest and two unfertilized land use systems (maize, and coffee/cacao agroforestry). These are the two major land use systems on converted rainforest sites in this part of Sulawesi. We wanted to test if (a) plant nutrient balances are negative, (b) which pathway is most important for losses of plant nutrients, and (c) if partial plant nutrient balances are suitable to evaluate sustainability of the land use systems. We measured nutrient inputs by precipitation and nutrient outputs by harvest export and leaching. We selected two locations, the first was situated on a fertile Cambisol developed on alluvial sediment soil, and the second on a less fertile Cambisol developed on weathered phyllite substrate. Nutrient losses through leaching were higher on sites with higher soil fertility. Nutrient balances in natural forest on fertile soils were negative for N, Ca, K and Mg. Inputs of P by precipitation and outputs by leaching were below detection limit. On less fertile soils, leaching of N and K in natural forest was lower than inputs by precipitation. As net nutrient losses were highest in agroforestry, followed by maize and natural forest stands, forest conversion into agricultural land will result in increased nutrient losses. Main output pathway of N, P and K was harvest, whereas main output pathway for Ca and Mg was through leaching. The annual losses of nutrients we measured were higher than in comparable studies on nutrient poor soils; however losses were only small fractions of available nutrient stocks. Our results showed negative partial nutrient balances in both agricultural systems. Nutrient balances in this study were more influenced by native soil fertility than by land use. Because we found indirect evidence that some nutrient pathways, which were not measured, may have significantly changed the overall balance (biological N fixation, weathering), we conclude that partial nutrient balances are no good indicators for sustainability of land use systems.     

Influence of application of sewage sludges, and sludge and manure composts on plant Ca and Mg concentration and soil extractability in field experiments

Application of organic waste influences crop uptake of Ca and Mg and soil extractability, depending on the nature of the crop and the waste. Four organic wastes: (i) digested sewage sludge (DSS), (ii) irradiated sludge (DISS), (iii) composted sludge (DICSS), and (iv) composted livestock manure (CLM) were applied for two years at rates of 10, 20, 30, and 40 Mg solid ha^-1 year^-1. Fertilizers N and K were applied to the control treatment (CT), as well as to the waste treatments to supplement crop growth across all treatments, so that these nutrients were not treatment variables. Calcium and Mg concentrations in the tissue of lettuce, bean pods and petunias in 1990 and two cuts of lettuce in 1991, and the CH₃COONH₄-extractable soil Ca and Mg were determined. Concentration of Ca and Mg in bean pods did not change to the waste application. Calcium concentration in bean pods was less than half of that in other crops. Magnesium concentration in bean pods and petunias was same, but was much lower than in lettuce. Application of DSS, in general, increased Ca concentration in the crops more than did other wastes. The extractable soil Ca was positively correlated with Ca applied with DISS (r=0.453, P<0.05). Although only a limited amount of Ca was supplied with CLM at the rate of 10 Mg solid ha^-1(40 kg Ca ha^-1), Ca concentration in petunias increased significantly, then, decreased with increased Ca application (r=0.453, P<0.05). A similar pattern with CLM was found in the extractable soil Ca. The waste application from all the sources had no influence on crop Mg concentration in 1990, possibly due to low Mg concentration in the wastes. While continuously applied DSS and DISS in 1991 linearly increased Mg concentration in both cuts of lettuce (r=0.867, P<0.01; r=0.670, P<0.01 and r=0.671, P<0.01; r=0.665, P<0.01 for first cut and second cut of lettuce with DSS and DISS application respectively), application of CLM decreased Mg concentration in first cut lettuce. The patterns of extractable soil Mg were opposite to crop Mg concentration, as the extractable soil Mg linearly increased with CLM, and decreased with the high rate of DSS application. The ability of wastes to supply N was an important factor influencing crop cations (K, Ca and Mg) uptake.     

再论“人口&#183;粮食&#183;环境&#183;肥料”

依据我国经济高速增长、社会进步及饮食结构变化,讨论了我们人口与粮食的关系,饮食结构对国家粮食安全以及畜禽业发展与施肥对环境的影响.介绍了我国农田生态系统N、P2O5、K2O、S、Ca和Mg的养分平衡.在S、Ca、Mg养分平衡中,过磷酸钙、钙镁磷肥起到了重要作用.在小麦基肥和玉米追肥中,碳铵、硝铵均优于尿素.探讨了缓释、控释肥用于超级玉米、超级水稻种植的可能性.