High Nutrient Use Research Articles

Watershed-scale assessment of oil palm cultivation impact on water quality and nutrient fluxes: a case study in Sumatra (Indonesia).

High fertilizer input is necessary to sustain high yields in oil palm agroecosystems, but it may endanger neighboring aquatic ecosystems when excess nutrients are transported to waterways. In this study, the hydrochemical dynamics of groundwater and streams under baseflow conditions were evaluated with bi-monthly measurements for 1year on 16 watersheds. Hydrochemical measurements were related to the spatial distribution of soil and fertilization practices across a landscape of 100km(2), dominated by oil palm cultivation, in Central Sumatra, Indonesia. The low nutrient concentrations recorded in streams throughout the landscape indicated that the mature oil palm plantations in this study did not contribute to eutrophication of aquatic ecosystems. This was ascribed to high nutrient uptake by oil palm, a rational fertilizer program, and dilution of nutrient concentrations due to heavy rainfall in the study area. Soil type controlled dissolved inorganic N and total P fluxes, with greater losses of N and P from loamy-sand uplands than loamy lowlands. Organic fertilization helped to reduce nutrient fluxes compared to mineral fertilizers. However, when K inputs exceeded the oil palm requirement threshold, high K export occurred during periods when groundwater had a short residence time. For higher nutrient use efficiency in the long term, the field-scale fertilizer management should be complemented with a landscape-scale strategy of fertilizer applications that accounts for soil variability.

English

Banana is an important source of food and income for millions of people in sub-Saharan Africa and Uganda in particular. This makes it one of the most important food crops in the country. However, production is limited by both biotic and abiotic constraints. Among the biotic constraints, is the decline in soil fertility. In addressing some of these biotic and abiotic constraints, banana breeding programmes are developing and releasing new banana varieties with limited information of their efficiency to capture soil nutrients. This study was to establish the physiological nutrient use efficiency of three new banana varieties namely FHIA17, M9 and M2 at harvesting time. The study was carried out in 8 (eight) districts of Uganda. Soil and tissue samples were collected from already established banana plantations for analysis of N, P, K, Ca and Mg. Tissue samples were collected by destructive sampling. Means of nutrients within district were separated using the Least Significant Difference (LSD) test at 5% level of significance (SAS, 2008). The nutritional status of bananas and the concentrations in various organs were, with respect to N, P, K, Ca and Mg, levels subjected to ANOVA. The relationship between plant content of the five nutrients and their concentration in the soil was determined by coefficient of correlation (r). The results showed no major significant nutrient use efficiencies between cultivars with FHIA 17 having the highest nutrient use efficiency. There were a few positive correlations between soil and plant nutrients. Key words: Nutrient concentrations, Banana cultivars, destructive sampling, nutrient interactions.

Enhancement of nitrogen release properties of urea–kaolinite fertilizer with chitosan binder

The use of controlled release fertilizer (CRF) has become a new trend to minimize environmental pollution. In this study, urea–kaolinite containing 20 wt% urea after one hour dry grinding was mixed with different concentrations of chitosan as a binder to prepare nitrogen-based CRF. Fourier transform infrared spectroscopy confirmed the hydrogen bonding between urea and kaolinite. Covalent interaction between urea–kaolinite and chitosan make the granules stronger. The nitrogen release was measured in 5 days interval using a diacetylmonoxime calorimetric method at a wavelength of 527 nm. The results illustrated that by increasing the chitosan concentration from 3 to 7.5%, nitrogen release decreased from 41.23 to 25.25% after one day and from 77.31 to 59.27% after 30 days incubation in water. Compressive stress at break tests confirmed that granules with chitosan 6% had the highest resistance and were chosen for ammonia volatilization tests. Ammonia volatilization was carried out using the forced-draft technique for a period of 10 weeks. The results showed that the total amount of ammonia loss for conventional urea fertilizer and urea–kaolinite–chitosan granules was 68.63 and 56.75%, respectively. This controlled release product could be applied in agricultural crop production purpose due to its controlled solubility in the soil, high nutrient use efficiency and potential economic benefits.

Forest and fynbos are alternative states on the same nutrient poor geological substrate

We ask two questions concerning the creation and maintenance of boundaries between forest and fynbos biomes in the southern Cape, South Africa: 1) is the presence of forest vegetation constrained to nutrient-rich soils? and 2) do plant traits (specific leaf area, leaf area, leaf dry matter content, leaf nutrients) reflect underlying soil nutrient status? At seven paired sites where forest and fynbos occur adjacent to each other with identical geology and position in the landscape, we tested whether forest soils had a different nutrient status to that of fynbos soils. At three of these sites we measured a suite of plant traits and tested whether these traits were correlated with soil characteristics. The paired site comparisons found that forest soils had a higher nutrient status and higher soil C:N ratios than the fynbos soils. Nonetheless, when compared across sites many forest soils had a nutrient status that was equivalent or lower than some fynbos soils. In addition, the forest soils at our study sites are still relatively nutrient-poor when compared to those of other temperate ecosystems. Although fynbos vegetation had traits that confer higher nutrient use efficiency than forest, both forest and fynbos species seem to have traits that confer conservative resource strategies (e.g., low leaf N and high leaf dry matter content). We suggest that both fynbos and afrotemperate forest are dominated by communities that are adapted to nutrient-poor conditions, and that the increase in nutrient status observed in forest soils is driven by niche construction.

Characterization of nitrogen, phosphorus, and potassium mass balances of dairy farms in New York State

A whole-farm nutrient mass balance (NMB) is a useful measure of the nutrient status of a dairy farm. Research is needed to define and determine a feasible NMB range for dairy farm systems in New York State (NY). The objectives of this study were to (1) document the distribution of N, P, and K mass balances of 102 NY dairy farms (including 75 small, 15 medium, and 12 large farms); (2) establish initial NMB benchmarks based on what 75% of the farms achieved; (3) determine the maximum animal density that allows an example NY dairy farm to balance cow P excretions and crop P removal without exporting crops or manure; and (4) identify opportunities to improve NMB over time. Nutrient mass balances of the 102 farms ranged from −39 to 237kg of N/ha for N without including N2 fixation (N1), from −14 to 259kg of N/ha when N2 fixation was included (N2), from −7 to 51kg of P/ha, and from −46 to 148kg of K/ha. Seventy-five percent of the farms were operating at NMB less than 118kg of N/ha for N1, 146kg of N/ha for N2, 13kg of P/ha, and 41kg of K/ha (75% benchmarks). Farms with the highest nutrient use efficiencies (lowest NMB per unit of milk produced) operated with less than 8.8kg of N/Mg of milk for N1, 11.8kg of N/Mg of milk for N2, 1.1kg of P/Mg of milk, and 3.0kg of K/Mg of milk. The biggest contributor to the NMB was the amount of imported nutrients, primarily feed purchases. The example farm assessment (assuming no export of crops or manure) suggested that, when 70% of the feed is produced on the farm and P in feed rations does not exceed 4g of P/kg of DM, cow P excretion and crop P removal were balanced at a maximum animal density of 2.4 animal units (AU)/ha (~0.97 AU/acre). Dairy farms operating with animal densities <2.4 AU/ha typically had NMB below the 75% benchmark, whereas most dairies with more than 2.4 AU/ha needed to export manure or crops to meet the 75% benchmark. Opportunities to reduce NMB on many farms, independent of size and without changes in animal density, are possible by more tightly managing fertilizer and feed imports, increasing the percentage of farm-produced nutrients, implementing precision feeding, and exporting crops or manure.

RECENT TRENDS IN SALINITY CONTROL FOR SOILLESS GROWING SYSTEMS MANAGEMENT

The consequences of closed hydroponic systems, the impact of salinity build-up on crop yield and product quality are reviewed. Soilless cultivation, especially in closed-loop systems offers a great option for water saving in greenhouses. Capture and recycling of the drainage will considerably improve the water use efficiency in horticultural crops and restrict water pollution by nutrients and pesticides. However, accumulation of undesired ions in the root environment constrains the potential of complete recycling. This is due to the presence of undesired ions in irrigation water, which is the case in many regions, especially in the Mediterranean countries. For fruit vegetables, high salinity of the nutrient solution in the root environment will induce inhibition of growth and production at one hand, but it may increase fruit quality on the other hand and thus offers possibilities for product quality control. Therefore the maximum acceptable salt accumulation will depend on the expected yield and quality responses at one hand, and the desire for the highest water and nutrient use efficien-cies on the other. To enable growers of regions with low quality water to adopt recycling of the excess irrigation water, efficient solutions have to be found to control, manage and minimize salt accumulation. Taking into account that the effects of salinity – apart from the water quality itself – strongly depend on (i) crop character-istics, (ii) greenhouse climate, (iii) irrigation and drainage management method and (iv) fertilization level, the above issues are analysed and the relevant literature is discussed. Alternative methods to overcome the problem of salt accumulation and increase water and fertilisers use efficiency, such as desalination of poor quality irriga¬tion water are also presented. Finally, efforts for development of decision support systems with on-line measurement or model-based prediction of the salt concentra¬tions in the drainage solution for semi-closed soilless systems management under different environmental conditions are also presented and discussed.

Nutrient Use Efficiency and Economics of Salad Cucumber Using Drip Fertigation in Naturally Ventilated Polyhouse

An experiment was carried out in naturally ventilated polyhouse with four fertigation levels viz., 110, 100, 90 and 80 per cent recommended dose to determine suitable fertigation dose for salad cucumber under naturally ventilated polyhouse cultivation. Fertigation levels significantly affected (P < 0.05) cucumber yield. Plants that received 100 per cent recommended dose of fertigation (175:125:300 kg NPK ha) showed higher nutrient use efficiency of nitrogen, phosphorous and potassium (508.93, 712.50, 296.88 kg ha respectively) and recorded significantly higher yield (89.06 t ha) with highest water use efficiency (6167.78 kg ha cm). The economic analysis of cucumber production revealed that 100 per cent recommended dose of fertigation has resulted into maximum Benefit Cost (BC) ratio of 3.42. Both increased and decreased fertigation levels showed almost equal yield which is significantly less than 100 per cent recommended dose.

Dinámica de nutrientes en plantaciones forestales de &lt;i&gt;Azadirachta indica&lt;/i&gt; (Meliaceae) establecidas para restauración de tierras degradadas en Colombia

Azadirachta indica is a tree species which use is steadily increasing for restoration of tropical and subtropical arid and degraded lands throughout the world. The objective of this research study was to evaluate the potential of these plantations as an active restoration model for the recovery of soils under desertification in arid lands of Colombia. Litter traps and litter-bags were installed in twenty 250m2 plots. Green leaves and soil samples inside and outside this species plantations were taken, and their elemental concentrations were determined. Litterfall, leaf litter decomposition and foliar nutrient resorption were monitored for one year. The annual contributions of organic material, such as fine litterfall, represented 557.54kg/ha, a third of which was A. indica leaves. The greatest potential returns of nutrients per foliar litterfall were from Ca (4.6kg/ha) and N (2.4kg/ha), and the smallest potential returns came from P (0.06kg/ha). A total of 68% of the foliar material deposited in litter-bags disappeared after one year. The greatest release of nutrients was that of K (100%), and the least was that of N (40%). P was the most limiting nutrient, with low edaphic availability and high nutrient use efficiency from Vitousek´s index (IEV=3176) and foliar nutrient resorption (35%). Despite these plantations are young, and that they have not had forestry management practices, as an active restoration model, they have revitalized the biogeochemical cycle, positively modifying the edaphic parameters according to the increases in organic material, P and K of 72%, 31% and 61%, respectively. Furthermore, they improved the stability of aggregates and the microbe respiration rates. The forest plantation model with exotic species has been opposed by different sectors; however, it has been acknowledged that these projects derive many benefits for the restoration of biodiversity and ecosystemic functions. The conditions of severe land degradation demand the initial use of species, such as A. indica, that can adapt quickly and successfully, and progressively reestablish the biogeochemical cycle.

Influence of Drip Fertigation and Intercropping on Yield, Agronomic Efficiency and Partial Factor Productivity of Maize

Field investigations were carried at Tamil Nadu Agricultural University during kharif 2008 and 2009 to study the effect of drip fertigation on nutrient use efficiency of maize (Zea mays) based intercropping systems. Results revealed that irrespective of different levels of fertilizer, fertigation significantly increased the partial factor productivity (PFP) and agronomic efficiency (AE) as compared to surface method of fertilizer application. Among the intercropping systems tested, higher nutrient use efficiency was realised under maize + vegetable coriander intercropping system. Partial Factor Productivity (PFP) decreased with increasing rates of fertigation. Drip fertigation with 50 per cent RDF in which 50 per cent of P and K as WSF resulted in higher PFP of 80.90 and 161.80 kg kg-1 N and P, respectively. The pooled data revealed that higher grain yield of maize (7309 kg ha-1) was observed under fertigation of 100 per cent RDF in which 50 per cent P and K as WSF. Drip fertigation of 100 per cent RDF (50 per cent P and K as WSF) increased the yield upto 55 per cent compared to surface irrigation and soil application of fertilizer. Fertigation with normal fertilizer increased the yield upto 18 kg per kg of nutrient applied, whereas water soluble fertilizer (50 per cent) increased the yield upto 25 kg per kg of nutrient applied.

Energetic environmental and economic assessment of three tree species and one herbaceous crop irrigated with primary treated sewage effluent

The energetic, environmental, and economic performance of four bioenergy plant species (Αcacia cyanophylla, Eucalyptus camaldulensis, Populus nigra, and Arundo donax), irrigated with pre-treated effluent in a three-year-field trial, was investigated. Results showed that irrigation was more energy demanding compared to other practices. A. cyanophylla achieved 34, 83, and 189% higher above ground biomass energy yield than E. camaldulensis, A. donax, and P. nigra, respectively. A. cyanophylla and E. camaldulensis had higher energy requirements but they achieved higher net energy yield and energy ratio. P. nigra (3.49 € GJ−1) and A. donax (2.34 € GJ−1) were found to have higher energy production cost compared to E. camaldulensis (1.65 € GJ−1) and A. cyanophylla (1.24 € GJ−1). P. nigra and A. donax had the highest nutrient use efficiency for nitrogen (NUE-N) and phosphorus (NUE-P), respectively. It was concluded that species with low NUE, which is opposite to current directions, and high water use efficiency (WUE) (i.e. plant species with relatively low water demands and great biomass allocation in leaves), are more suitable when irrigation with strong effluent occur and N removal is primary objective. Such plant species have comparatively lower energy requirements, which is consistent with the current trend for low energy inputs in agriculture. To mitigate the losses in plant biomass and reduce the adverse environmental impacts from nutrients, additional practices should be adopted. Our results help us to draw important conclusions in order to set criteria in the selection of suitable bioenergy crops and practices.

Hormones et obésité

We ask two questions concerning the creation and maintenance of boundaries between forest and fynbos biomes in the southern Cape, South Africa: 1) is the presence of forest vegetation constrained to nutrient-rich soils? and 2) do plant traits (specific leaf area, leaf area, leaf dry matter content, leaf nutrients) reflect underlying soil nutrient status? At seven paired sites where forest and fynbos occur adjacent to each other with identical geology and position in the landscape, we tested whether forest soils had a different nutrient status to that of fynbos soils. At three of these sites we measured a suite of plant traits and tested whether these traits were correlated with soil characteristics. The paired site comparisons found that forest soils had a higher nutrient status and higher soil C:N ratios than the fynbos soils. Nonetheless, when compared across sites many forest soils had a nutrient status that was equivalent or lower than some fynbos soils. In addition, the forest soils at our study sites are still relatively nutrient-poor when compared to those of other temperate ecosystems. Although fynbos vegetation had traits that confer higher nutrient use efficiency than forest, both forest and fynbos species seem to have traits that confer conservative resource strategies (e.g., low leaf N and high leaf dry matter content). We suggest that both fynbos and afrotemperate forest are dominated by communities that are adapted to nutrient-poor conditions, and that the increase in nutrient status observed in forest soils is driven by niche construction.

Investigation into the optimal fertilizer regime of Swietenia macrophylla (Mahogany)

With the increase of the population in Sri Lanka, and increase of the demand for timber, the requirement to produce wood in country in large scale as intensively managed plantations has become very important and urgent. As forest tree planting has to compete with agriculture for land, the land relegated to forestry is usually marginal and therefore fertilization and nutrient management are important requirements. The objective of the present study is to provide prescriptions for fertilization and on site nutrient management to obtain best growth and development in Mahogany plantations in wet zone of the country owned by the Touchwood Investments Ltd.The Study comprised of three parts; a pot trial and two field trials, was conducted in mahogany plantations located in three districts of Sri Lanka namely Kaluthara, Mathale and Rathnapura. With regard to pot trial, 16 combinations of N and P fertilizer levels with a constant K level were used on 6 months old seedlings planted on soil taken from Panthiya, Gomaragala and Ambanganga Estates. The second trial dealt with the biomass and nutrient distribution in component parts of the tree in different ages and assessing the Nutrient Use Efficiency. The third trial tried to establish a relationship between the site index and foliar nutrient content. The latter two trials were set up to provide an insight into nutrient management on site.A statistically significant (p&lt;0.05) relationship was observed in the fertilizer mixtures and height growth (square root) in the pot trial using Panthiya and Ambanganga soils. The responses to fertilizer mixtures were not significantly different in diameter growth and number of leaves generated during the trial period of 6 months. Further, in general treatments having more phosphorus (double or triple) than the treatment already in use (N15.45, P5.15, K15.45 kg/ha/six month) give better results in growth improvement. This was more intense in soils having comparative low initial levels of Phosphorus. Treatments having higher nitrogen levels than currently in use (more than N15.45) tended to retard growth. Plantations which are poor in soil nutrients gave a higher response to the fertilization.Nutrient content within tree components decreased in the order of stem &gt; branches &gt; leaves &gt; roots. A higher Nutrient Use Efficiency was observed in stem while foliage had the lowest. Nutrient distribution was almost independent from the plant age within the age series. A relationship was observed between site index and leaf nitrogen and calcium levels of similar aged plantations and therefore foliar levels of N and Ca can be used in comparing the productivity of sites and also to determine optimum level of nutrients. As the growth response to fertilizer applications is a long term process it is recommended that long term field experiments should be established and maintained.

A High Density Consensus Map of Rye (Secale cereale L.) Based on DArT Markers

BackgroundRye (Secale cereale L.) is an economically important crop, exhibiting unique features such as outstanding resistance to biotic and abiotic stresses and high nutrient use efficiency. This species presents a challenge to geneticists and breeders due to its large genome containing a high proportion of repetitive sequences, self incompatibility, severe inbreeding depression and tissue culture recalcitrance. The genomic resources currently available for rye are underdeveloped in comparison with other crops of similar economic importance. The aim of this study was to create a highly saturated, multilocus linkage map of rye via consensus mapping, based on Diversity Arrays Technology (DArT) markers.Methodology/Principal FindingsRecombinant inbred lines (RILs) from 5 populations (564 in total) were genotyped using DArT markers and subjected to linkage analysis using Join Map 4.0 and Multipoint Consensus 2.2 software. A consensus map was constructed using a total of 9703 segregating markers. The average chromosome map length ranged from 199.9 cM (2R) to 251.4 cM (4R) and the average map density was 1.1 cM. The integrated map comprised 4048 loci with the number of markers per chromosome ranging from 454 for 7R to 805 for 4R. In comparison with previously published studies on rye, this represents an eight-fold increase in the number of loci placed on a consensus map and a more than two-fold increase in the number of genetically mapped DArT markers.Conclusions/SignificanceThrough the careful choice of marker type, mapping populations and the use of software packages implementing powerful algorithms for map order optimization, we produced a valuable resource for rye and triticale genomics and breeding, which provides an excellent starting point for more in-depth studies on rye genome organization.

Rapeseed (Brassica napus L. var. oleifera) response to nitrogen fertilizer following different previous crops

This study was conducted in the crop years 2007-1010 and aimed to evaluate the effects of previous crops and use of nitrogen (N) fertilizer on rapeseed productivity in Ahwaz, Iran. The previous crops were: i) barley + clover; ii) rapeseed; iii) corn; iv) mung-bean; v) rice; and vi) wheat. N fertilizer was applied to rapeseed at rates of 0, 100, 160 and 220 kg ha-1. The effects of management on yield, and product oil content and oil yield were assessed. The effect of the previous crop and the use made of N fertilizer both affected rapeseed productivity. The results of two repeated experiments showed that the lowest seed and oil yields were obtained when unfertilized rapeseed followed rice. The highest seed and oil yields were obtained when rapeseed production followed mung-bean as the previous crop (range 160-220 kg ha-1 N rate). Among yield components, previous crops and N rates significantly influenced the silique number per unit area, and this showed a similar variation to that of seed yield. Data averaged across 2-year periods indicated that the highest oil content occurred in unfertilized rapeseed plots when the effects of the previous crop were not significant. Nevertheless, rapeseed following mung-bean receiving 150-220 kg ha-1 N rates produced the highest yield in the two years in which the experiment was repeated. Rapeseed following mung-bean and receiving 160 kg N.ha-1 had also the highest nutrient use efficiency parameters.

Seasonal nutrient dynamics and biomass quality of giant reed (Arundo donax L.) and miscanthus (Miscanthus x giganteus Greef et Deuter) as energy crops

The importance of energy crops in displacing fossil fuels within the energy sector in Europe is growing. Among energy crops, the use of perennial rhizomatous grasses (PRGs) seems promising owing to their high productivity and their nutrient recycling that occurs during senescence. In particular, nutrient requirements and biomass quality have a fundamental relevance to biomass systems efficiency. The objective of our study was to compare giant reed (Arundo donax L.) and miscanthus (Miscanthus × giganteus Greef et Deuter) in terms of nutrient requirements and cellulose, hemicelluloses and lignin content. This aim was to identify, in the Mediterranean environment, the optimal harvest time that may combine, beside a high biomass yield, high nutrient use efficiency and a good biomass quality for second generation biofuel production. The research was carried out in 2009, in San Piero a Grado, Pisa (Central Italy; latitude 43°41’ N, longitude 10°21’ E), on seven-year-old crops in a loam soil characterised by good water availability. Maximum above-ground nutrient contents were generally found in summer. Subsequently, a decrease was recorded; this suggested a nutrient remobilisation from above-ground biomass to rhizomes. In addition, miscanthus showed the highest N, P, and K use efficiency, probably related to its higher yield and its C4 pathway. Regarding biomass quality, stable values of cellulose (38%), hemicelluloses (25%) and lignin (8%) were reported from July onwards in both crops. Hence, these components appear not to be discriminative parameters in the choice of the harvest time in the Mediterranean environment. In conclusion, our results highlighted that, in our environment, a broad harvest period (from late autumn to winter) seems suitable for these PRGs. However, further research is required to evaluate the role of rhizomes in nutrient storage and supply during the growing season, as well as ecological and productive performances in marginal lands, in particular those where water availability may be a limiting factor.

OOS 38: Ecological Dimensions of Biofuel Production

OOS 38: Ecological Dimensions of Biofuel Production

Foliar nutrient dynamics in tidal and non-tidal freshwater forested wetlands

Foliar nutrient dynamics were studied at 8 forest stands (three non-tidal and five tidal) along the lower 30 km of the Apalachicola River system in Florida, USA, during 2008. At each site, we sampled canopy foliage and litterfall from three to four trees representative of the dominant overstory species. Foliage and litterfall were analyzed for a variety of elements including N and P and these data were used to examine differences in element concentrations, nutrient ratios (C:P, C:N, and N:P), nutrient use efficiency, and nutrient proficiency. Measurements of tree diameter at basal height (DBH) at each plot were used with species allometric equations to estimate forest litterfall dry weight and N and P flux in non-tidal and tidal wetlands. Both non-tidal and tidal wetlands showed evidence of P limitation based on N:P ratios, but absolute levels of P were determined to be extremely low in tidal wetlands based on higher nutrient use efficiencies (measures of both P resorption efficiency and proficiency). Differences in P concentrations and fluxes between tidal and non-tidal wetlands are probably related to longer inundation and hydrologic export observed in tidal wetlands. Using estimations of annual litterfall dry weight and nutrient concentrations, N and P flux in non-tidal swamps were 2–4 times greater than in tidal wetlands. This study demonstrates the change in nutrient dynamics as wetlands shift from tidal to non-tidal conditions.

Minimizing nutrient leaching and improving nutrient use efficiency of Liriodendron tulipifera and Larix leptolepis in a container nursery system

Fertilization is essential to seedling production in nursery culture, but excessive fertilization can contaminate surface and ground water around the nursery. The optimal fertilization practice is that which maximizes seedling growth and minimizes nutrient loss. We tested three fertilization strategies: (1) constant fertilization (2) a three-stage rate, and (3) exponential fertilization on Liriodendron tulipifera and Larix leptolepis containerized seedlings. Growth performance, nutrient uptake, and nutrient loss in leaching were measured. Height, root collar diameter, and dry weight of both species were not significantly different among treatments even though the nutrient supply of the exponential treatment was half that of the constant and three-stage treatments. Generally, nutrient losses in leached solutions were higher in constant and three-stage than the exponential treatment. Nutrient use efficiency was calculated as the ratio of the nutrient content of the seedlings to the amount of nutrient applied to the containers. The nitrogen use efficiency in the constant, three-stage, and exponential treatments was 63, 61, and 85% for yellow poplar, respectively, and 35, 30, and 53% for larch. Similar results were obtained for phosphorus and potassium. Thus, the exponential treatment had the highest nutrient use efficiency as well as the least nutrient loss. Adjusting fertilization rates can reduce soil and water contamination around the nursery without compromising growth performance, which reduces both producer’s investments and environmental impacts.

Invasive plant species as potential bioenergy producers and carbon contributors

CURRENT CELLULOSIC BIOENERGY SOURCES In the United States, bioenergy sources are being investigated in an effort to reduce dependence on foreign oil and the associated risks to national security and climate change (Koh and Ghazoul 2008; Demirbas 2007; Berndes et al. 2003). Multiple sources of renewable plant-based material have been identified and include agricultural and forestry residues, municipal solid waste, industrial waste, and specifically grown bioenergy crops (Demirbas et al. 2009; Gronowska et al. 2009). These sources are most commonly converted to energy through direct burning, conversion to gas, or conversion to ethanol. Annual crops, such as corn ( Zea Mays L.) and sorghum grain, can be converted to ethanol through fermentation, while soybean and canola are transformed into fatty acid methyl esters (biodiesel) by reaction with an alcohol (Demirbas 2007). Perennial grasses are one of the more viable sources for bioenergy due to their continuous growth habit, noncrop status, and multiple use products (Lewandowski el al. 2003). In addition, a few perennial grass species have very high water and nutrient use efficiencies producing large quantities of biomass on an annual basis (Dohleman et al. 2009; Grantz and Vu 2009). Cellulosic bioenergy research is widespread throughout the country…

Influence of Higher Doses of Nitrogen on Yield and Quality of Early Maturing Sugarcane Varieties

Field experiment was conducted at Agricultural Research Station, Perumallapalle during 2008–2009 and 2009–2010 to know the effect of levels of nitrogen on yield and quality of early maturing sugarcane varieties. Four varieties viz., 86V96, 93RR44, 99V30 and 2003V46 were tested under four nitrogen levels viz., 75, 100, 125 and 150% recommended dose of nitrogen. The results of the experiment indicated that yield and yield attributing characters were positively influenced by the increased dose of nitrogen than normal recommended dose. Among the varieties, 2003V46 responded both to lower levels and higher levels of nitrogen indicating high nutrient use efficiency of the variety. Where as the variety 99V30 responded to higher doses of nitrogen i.e. 150% recommended dose of nitrogen, requires higher fertilization compared to other varieties. Levels of nitrogen did not affect the quality parameters of juice.