NPK Compound Fertilizer Research Articles

Роль агроекологічних умов у реалізації генетичного потенціалу продуктивності сортів озимої пшениці Triticum aestivum L.

Роль агроекологічних умов у реалізації генетичного потенціалу продуктивності сортів озимої пшениці Triticum aestivum L.

Peranan Pupuk Organik dan NPK Majemuk terhadap Pertumbuhan Kelapa Sawit TBM 1 di Lahan Marginal

<p>ABSTRACT</p><p>Oil palm (Elaeis guineensis Jacq.) is the most efficient vegetable oil producer. It produces five to seven times more vegetable oil per hectare than the other vegetable oil producing crops. The objective of this research was to study the role of organic and NPK compound fertilizers application to one-year-old oil palm (Elaeis guineensis Jacq.) on marginal land. The research was conducted at IPB-Cargilll Teaching Farm of Oil Palm, Jonggol, Bogor, West Java from March 2013 to March 2014. The experiment was carried out as factorial experiment in a randomized block design with three replications. The first factor was organic fertilizer consisted of 0, 15, and 30 kg per palm. The second factor was NPK compound fertilizers 15:15:15 consisted of 0, 1.3 and 2.6 kg per palm. The results showed that no interaction effect between organic and NPK compound fertilizers on all of variables observed. Marginal soils in Jonggol required high rate of fertilizers to produce good performance of one-year-old oil palm. Application of 30 kg organic fertilizer per palm or 2.6 kg NPK compound fertilizers 15:15:15 per palm resulted in the highest vegetative growth of one-year-old oil palm on marginal land in Jonggol.</p><p>Keywords: cow dung, critical nutrient level, slow release fertilizer, Ultisols, vegetative growth</p>

The effect of NPK compound fertilizer (27%:6%:10%) compared to conventional fertilizers on productive tea plants of GMB 7 clone in the Andisols soil type

The effectiveness application of compound fertilizer NPK (27%:6%:10%) to increase  tea shoots had been tested in Experimental Garden of Research Institute for Tea and Cinchona Gambung, Bandung, West Java, from January 2006 to March 2007. Experi­mental design used was randomized block design with 6 treatments with five replication. The plot sizes were 20 x 20 m = 400 m2/plot. The tea clone tes­ted was GMB 7. The appli­cation of compound fertilizer NPK (27%:6%:10%) were twice a year (50%-50%) and conventional fertlization were 4 times a year (20%-30%-20%-30%). The composition of treatment was as follows: (A) 500 kg, (B) 600 kg, (C) 700 kg, (D) 800 kg/ha/year, and (E) conventional fertilizer recommended dosage of the Research Institute for Tea and Cinchona Gambung (480 kg urea + 357 kg ZA + 260 kg SP 36 + 300 kg KCl + 278 kg kieserit/ha/year), and (F) control (no fertilizer treatment). Parameters observed were: 1. soil and leaf analysis at before and after treatment, 2. weighting the potential and the yield components each time of plucking, and 3. technoeconomic analysis. The results showed that: statistical analysis of the components as well as potential yield, and nutrient analysis (N, P, K, Mg and Zn) of the mother leaves of GMB 7 clones and the soil demon­strated the significantly differences among the treatments of all the various doses of compound fertilizer NPK and conventional fertilizer application to control (no fertilizer treatment). Meanwhile, there were no significantly differences among the result of  the doses of compound fertilizer NPK, to the conventional fertilizer applications. Further­more, dose of compound fertilizer NPK (27%:6%:10%) for produc­tive tea plant was recommendated at 700 kg/ha rate and was equivalent to 189 kg N/ha/year or 63% of the dose of conventional fertilizer, but could provide equivalent result to conventional fertilizer application, and not only could save the buying cost of conventional fertilizer (urea, ZA, TSP/SP-36, KCl / MOP and kieserit) but also the cost of application cost in the field.

Pengaruh Pupuk Majemuk NPKS dan NPK terhadap Pertumbuhan dan Hasil Padi Sawah pada Inceptisol

<p>Rate of NPK fertilization on rice using NPK compound fertilizer needs to consider soil nutrient status and plant nutrient requirement. The research was aimed to determine the optimum rate of compound fertilizer and the effect of enriched S nutrient of NPKS compound (15-15-15-5S) and NPK compound fertilizer (15-15-15) on the growth and yield of rice. The experiments were conducted at two sites in Galuga, Ciampea Bogor, West Java from April to September 2013, using randomised complete block design with 3 replications. Experiment at site I consisted of 9 treatments: six levels of fertilizers NPKS i.e. 0; 150; 300; 450; 600; and 750 kg/ha, standard fertilizer, NPK compound fertilizer equivalent to standard, and standard fertilizer plus S. Rate of urea, SP-36, and KCl for standard fertilizer treatment was respectively 250, 75, and 50 kg/ha. At site II the treatments consisted of 6 levels of NPK compound fertilizer i.e. 0; 150; 300; 450; 600; and 750 kg/ha and the standard fertilizer with rate of 250 kg/ha of urea, 50 kg/ha SP-36, and 75 kg/ha KCl. Plot size was 4 m x 5 m planted with Ciherang variety. Data collection included chemical properties of soil before and after the experiment, plant height, number of tillers, straw weight, and dry grain weight and the nutrient uptake. The effectiveness of fertilizer was calculated by RAE (Relative Agronomic Effectiveness). Results showed that fertilizer NPKS (15-15-15-5S) at 600 kg/ha effectively increased dry grain weight from 3.63 t/ha to 4.67 t/ha, but was not significantly different from a standard fertilizer treatment. It increased dry grain weight by 29% compared to control. NPK fertilizer (15-15-15) effectively promoted growth and dry grain weight equivalent to standard fertilizer at rate of 300-750 kgha. The optimum rate of NPK compound fertilizer (15-15-15) was 440 kg/ha as was shown with the production performance of 4.12 t/ha with RAE by 58%. NPKS compound fertilizer with rate of 750 kg/ha showed the highest uptake of N, P, and K nutrients and significantly increased the available P in the soil. Whereas NPK compound fertilizer with a rate of 600 kg/ha indicated the highest P nutrient uptake. Fertilizer enrichment with sulfur on NPKS fertilizer (15-15-15-5S) did not significant affect on grain dry weight.</p>

Pengaruh Pupuk Majemuk NPK + Zn terhadap Pertumbuhan, Produksi dan Serapan Zn Padi Sawah di Vertisol, Sragen

Vertisol is a soil that has neutral to slightly alkaline pH. Zinc availability decreases with increasing pH. The existence of symptoms micronutrients scarcity, especially zinc, also caused by the use of highly yielding seeds with unbalanced fertilization. In addition, Zn uptake by plants is sustainability process which resulted in a decrease in nutrient levels of Zn in the root zone. The aim of the research was to determine the optimum Zn formula that can be added to the NPK compound fertilizer and to determine the effectiveness of the fertilizer on the growth and yield of rice. The experiment was arranged by completely randomized block design with 10 treatments and 3 replicates of each treatment. NPK compound fertilizer dose was given 300kg / ha. The result of this study showed that the compound fertilizer NPK + Zn had no effect on plant height, number of tillers and weight of the plant. The additional dose compound of 2% Zn to the dose of compound fertilizer NPK + Zn did not increase the yield. There was a tendency NPK treatment +0.75% Zn deliver the highest results. NPK compound fertilizer application + Zn significantly increased the uptake of Zn.

Effects of variety and manuring on the growth, yield and nutritional quality of watermelon (<i>Citrullus lanatus</i> L.) in a rainforest zone of Nigeria

The effects of variety and manure application on the growth, yield and nutritional quality of watermelon ( Citrullus lanatus L.) were investigated during the rainy and late cropping seasons in Akure, a rainforest zone of Nigeria. Treatments were a factorial combination of five watermelon varieties and three manure types laid out in a randomized complete block design (RCBD) with three replications. The watermelon varieties were Crimson Sweet, Charleston Grey, Kaolac, Anderson and Sugarbaby, while the manures which were applied at 3 weeks after planting, were organomineral fertilizer (OMF) (5 t/ha), NPK (compound) fertilizer (200 kg/ha) and an unmanured control. The watermelon varieties tested responded differently in terms of growth and yield components due to differences in their genetic composition. In the rainy season, Charleston Grey performed well in terms of growth (biomass) but produced poor fruit yield while Kaolac and Anderson recorded high fruit yields. Late season favored growth and yield in Crimson Sweet and Kaolac, however, Kaolac produced good fruit yields as both rainy and late season crop. Fruit quality parameters such as the number of rotten and cracked fruits differed among the varieties, in both rainy and late season, Charleston Grey and Kaolac produced the highest number of rotten and cracked/split fruits. Sugarbaby and Anderson performed best in both seasons while Charleston Grey is not adequately adapted to rainy season growing environmental conditions. The NPK fertilizer enhanced higher growth and yield over OMF and unmanured control in both seasons. Significant interactions between variety and manuring were found for growth and fruit yield characters of watermelon. In the rainy season crop, application of NPK and organomineral fertilizer enhanced fruit yield components of watermelon varieties (Kaolac, Anderson, Crimson Sweet and Sugarbaby). In the late season, NPK fertilizer enhanced number of fruits per plant in Charleston Grey, highest mean fruit diameter and mean fruit weight per plant in Anderson. The chemical and proximate constituents of fruits of watermelon varieties were significantly affected by manure application. In the rainy season, NPK enhanced fruit contents of N, P, K, moisture, total solids and vitamin C in most varieties except in Anderson. In late season, NPK enhanced the nutritional (total solids) contents of the varieties while OMF enhanced fruit contents of P, Ca, crude fiber, vitamin C and total solids in some of the varieties. However, unmanured Anderson had highest vitamin C content in the late season. It is concluded that application of NPK and OMF fertilizer enhance growth, yield and nutritional quality of watermelon varieties in both rainy and late season in the study area.

DETERMINANTS OF FERTILIZER MICRODOSING-INDUCED YIELD INCREMENT OF PEARL MILLET ON AN ACID SANDY SOIL

SUMMARYRecent studies have reported the benefits of fertilizer microdosing in increasing crop yields in low input cropping systems. Little information is however available on the mechanisms underlying this effect. The objective of this study was therefore to explore the root-based mechanisms governing the growth enhancing phenomena of the fertilizer microdosing technology. A two-year experiment was conducted at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Research Station in Niger. Four treatments comprising (i) 2 g hill−1of diammonuim phosphate (DAP), (ii) 6 g hill−1of compound fertilizer NPK, (iii) broadcasting of 200 kg ha−1of compound fertilizer NPK (recommended rate) and (iv) unfertilized control was arranged in a randomized complete block design with four replications. On average, fertilizer microdosing treatments (2-g DAP hill−1and 6-g NPK hill−1) achieved 86% and 79% of the grain yields recorded from broadcasting of 200-kg NPK ha−1, respectively, in 2013 and 2014. The leaf area index and leaf chlorophyll content significantly increased with fertilizer microdosing at the early stage of millet growth. At the same stage, fertilizer microdosing enhanced the lateral root length density in the topsoil (0–20 cm) by 72% and 40% at respective lateral distances of 25 cm and 50 cm from the centre of the hill compared with broadcast of 200-kg NPK ha−1. Fertilizer microdosing did not significantly change soil pH in the root zone. It is concluded that the positive effect of fertilizer microdosing in increasing millet yield results from the better exploitation of soil nutrients due to early lateral roots proliferation within the topsoil.

Peran Pupuk Organik dalam Meningkatkan Efektivitas Pupuk NPK pada Bibit Kelapa Sawit di Pembibitan Utama

<p><br />Main nursery is the first step affecting oil palm’s age and productivity. Good plant growth will produce high quality and yield of oil palm. The demand of oil palm seedlings for extensification and replantation increases continuously, and therefore this need to be supported by precise fertilization programs. The objectives of this experiment were to investigate the role of organic fertilizer and to obtain the best organic-NPK fertilizer combination in increasing the effectiveness of the use of NPK fertilizer for the growth of oil palm (Elaeis guineensis Jacq.) seedling in the main nursery. The experiment was conducted from December 2011 to September 2012 at IPB Teaching Farm Dramaga Bogor. The treatment was arranged in a factorial randomized block design with three replications. The first factor was amount of organic fertilizer consisted of 0:6, 1:6, 2:6, and 3:6 of the soil volume (6 kg). The second factor was NPK fertilizer rates, i.e., 0.0, 127.5, 255, and 382.5 g NPK per plant. The results showed that application of organic fertilizer increased the effectiveness of NPK fertilizer and could be a substitute for NPK fertilizer in oil palm seedlings. The best combination treatment was 2:6 (organic fertilizer:top soil) and 382.5 NPK g per plant with effectiveness of 158.9, 209.1 and 170.1 % for plant height, leaf number and stem diameter, respectively. The efficiency of N, P, and K application were 56.2, 11.1, and 29.0% for the same variables, respectively. Based on morphological variables, recommended rate of an NPK compound fertilizer 15-15-15 was in the range of 396.05 g per seedling for eight months. Recommended NPK were 7.00, 12.59, 37.58, 56.41, 36.74, 87.00, 86.60, and 72.97 g per seedling for first to eighth months, respectively.</p><p>Keywords: chlorophyll, fertilizer recomendation, morphological and physiological response, nutrient balance</p>

A green route for preparation of low surface area SiO2 microspheres from wheat straw ash with activated carbon and NPK compound fertilizer as by-products

Every components of the wheat straw ash and all the chemicals involved in this route have been effectively used.

Multilayer‐coated NPK compound fertilizer hydrogel with controlled nutrient release and water absorbency

ABSTRACTA novel trilayered controlled‐release nitrogen, phosphorous, and potassium (NPK) fertilizer hydrogel was prepared by dipping the NPK fertilizer granules sequentially in 7% w v−1 poly(vinyl alcohol) (PVA) and 2% w v−1 chitosan (CS) solutions and then cross‐linking the CS layer (cross‐CS) via glutaraldehyde vapor deposition. Different NPK fertilizer hydrogels were then synthesized by inverse suspension polymerization of the dried PVA/cross‐CS bilayer‐coated fertilizer granules in various molar ratios of acrylamide (AM) and acrylic acid (AA) monomers, and polymerization with varying molar ratios of ammonium persulfate, N,N,N′,N′‐tetramethylethylenediamine and N,N′‐methylenebisacrylamide (N‐MBA). The water dissolution time of the obtained PVA/cross‐CS/poly (AA‐co‐AM) trilayer‐coated NPK fertilizer hydrogel granules was prolonged, while the water absorbency increased with increasing AA contents, and decreased with increasing N‐MBA contents in the outer poly(AA‐co‐AM) coating. The optimal trilayer‐coated NPK fertilizer hydrogel obtained released 84 ± 18, 63 ± 12, and 36 ± 15% of the N, P, and K nutrients, respectively, after a 30‐day immersion in water. The release phenomena of the N, P, and K nutrients of the fertilizer hydrogel obeyed both the Korsmeyer‐Peppas and Ritger‐Peppas models with a pseudo‐Fickian diffusion mechanism. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41249.

English

This study was done to determine the effect of initial node strength on dry matter yield of cassava. Studies were conducted at the Waterloo Research Campus, University of Trinidad and Tobago using the sets of Mexican variety (Mx) at 6 months with 1 to 3 nodes, 4 to 9 cm, and dry matter of 6 to 15 g/set. The crop was established at 60 × 80 cm and treated with a compound NPK fertilizer. Growth analysis (functional approach) was carried from 20 to 340 Days after emergence (DAE), and the best fit polynomial regression applied. The results indicated that tuberization started after 120 DAE and tuber dry weight increased with increasing set size (YTDW = -1177 + 9.90D - 1.26-2 D2 + 37.7N2). The 3 node sets produced (P > 0.05) the highest tuber yield. The leaf area ratio (LAR) showed (P > 0.001) a quadratic response (Ylar = 12.8 - 1.94 H - 2.39 N + 0.08 H2 + 0.18 N*H), peaked at 2 g/cm2/day1, and declined at harvest. Both the net assimilation rate (NAR) and the relative growth rate (RGR) were not affected by the number of nodes, however, the NAR peaked 0.046 g/m2/day at 60 DAE. The initial strength of 3 nodes sets proved to be superior to the single node sets. Key words: Cassava, growth analysis, tuberization, nodes, sets.

Optimasi Dosis Pupuk Organik dan NPK Majemuk pada Tanaman Kelapa Sawit Belum Menghasilkan

ABSTRACT Optimum fertilization is not only proposed for obtaining desireable quality and quantity of the plant, but also to avoid excess fertilizer causing toxicity and environmental damage. The objective of this research was to study and to determine an optimum rate of organic and NPK compound fertilizers for immature oil palm. The experiment was carried out at IPB-Cargill Oil palm Teaching Farm, Jonggol, from March 2013 to March 2014. The treatments was laid out in a factorial randomized complete block design with three replications. The first factor was organic fertilizer, i.e. 0, 15, 30 and 45 kg organic fertilizer plant-1, and the second was NPK compound fertilizer, i.e. 0, 0.65, 1.3, 1.95 and 2.6 kg NPK compound fertilizer plant-1. The result showed that vegetative growth increases with fertilizer application. The height and stem girth of plant were significantly affected by interaction between organic and NPK compound fertilizers, however there was no significant effect on frond production, frond length and leaf area. N, P leaf content of plant were affected by interaction between organic and NPK compound fertilizers, however there was no effect on K leaf content, chlorophyll and number of stomata. Based on the height and stem girth regression equation, the optimum recommendation rate of organic and NPK compound fertilizers for immature first year oil palm are 40.7 kg organic fertilizer plant-1 and 1.9 kg NPK compound plant-1 Keywords: inorganic fertilizers, nutrient level, stem girth, vegetative growth

Aplikasi Dosis Pupuk NPK Majemuk terhadap Pertumbuhan dan Hasil Tanaman Semangka pada Lahan Rawa Lebak

Watermelon come from arid tropical and subtropical regions of Africa. Watermelon is an annual plant that grows and requires full sun. Lebak swamp soil is known to have the properties and properties of acid sulphate soils that affect the physical, chemical and biological properties of the soil. Fertilizers are the key to soil fertility. Compound fertilizer is a fertilizer that contains several nutrients, for example nutrients (nitrogen), potassium (K) and phosphorus (P). This study aims (i) to obtain influence and (ii) the best dosage of various applications of NPK Compound fertilizer dosage on the growth and yield of watermelon plants on lebak wetland. The study was conducted in Teluk Buluh Village, Banjang District, Hulu Sungai Utara Regency in July - September 2013, this study used a single randomized block design (RBD) with 5 treatments and 5 replications so that there were 25 experimental units. The factors tested were various doses of Compound NPK fertilizer, namely m1: 0.333 t.ha-1 (200 g / bed), m2: 0.666 t.ha-1 (400 g / bed), m3: 0.999 t.ha-1 ( 600 g / bed), m4: 1,332 t.ha-1 (800 g / bed) and m5: 1,665 t.ha-1 (1000 g / bed). The results of this study indicate that the dosage of Compound NPK fertilizer given to watermelon plants in swampland area had a significant effect on plant length and number of leaves aged 25 HST and 30 HST and had a very significant effect on the fruit weight and number of watermelon plants with the best treatment is m3: 0.999 t.ha-1 (600 g / bed).

Slow-release fertilizer to increase grain N content in spring wheat

Low grain protein often restricts the use of grain lots for milling in Finland. Nitrogen availability during grain-filling may restrict grain protein accumulation, particularly in high yielding environments. Slow-release fertilizers could potentially sustain nitrogen availability during the grain-filling period. The aim of this study was to increase plant nitrogen uptake, grain yield and grain protein response of spring wheat cultivar ‘Amaretto’, using combinations of a regular and slow-release compound NPK fertilizer. Fertilizer treatment effects on grain yield was modest, however, slow-release fertilizer treatments lowered grain protein content as well as grain, straw and total plant N compared with control treatment. The total plant N was 10 to 27 kg ha-1 lower following application of slow-release fertilizer. The results clearly indicate that the release of N by the slow-release fertilizer tested in this trial was too slow for cool Finnish growing conditions.

English

Pumpkin (Cucurbita pepo L.) young leaves and vines are consumed as vegetables among the rural dwellers in Southwest Nigeria. It is a cheap source of protein, vitamins, fibres and antioxidants in their diet. Due to the intensive cultivation of available lands which affects the nutrient status of most soils and their productivity, the need to apply fertilizer on pumpkin became pertinent. Therefore, nitrogen, phosphorus and potassium (NPK) fertilizer influence on biomass accumulation in pumpkin was investigated for two consecutive seasons in 2010 at the Research Farm of Obafemi Awolowo University, Ile-Ife, Nigeria. NPK (15:15:15) compound fertilizer was applied at the rates of (0, 50, 100, 150, 200 and 250 kg ha-1) to C. pepo at 2 weeks after planting (WAP). At 8 WAP, the following morpho-physiological traits: vine length, vine diameter, number of internodes, internodes length, vine weight, number of leaves, total fresh and dry biomass assessed were significantly influenced by season and fertilizer effects. The combined analysis of variance (ANOVA) results showed that the effects of season (S) and fertilizer (F) are significant effect on all the traits. Season effect showed that the early season was better (p = 0.05) while the application of fertilizer beyond 100 kg of NPK per hectare was not statistically beneficial for biomass yield and its components. However, the significant S X F interaction on the total dry matter fitted well into a quadratic equation with significant R2 values. The response curves showed higher response to fertilizer in the early than late planting season and a maximum biomass yield was attained at the application of 205 kg and 244 kg ha-1 of NPK (15-15-15) for early and late season cultivations, respectively. Key words: Biomass, nitrogen, phosphorus and potassium (NPK) fertilizer, pumpkin, dry matter, morpho-physiological trait, quadratic equation.

Agricultural Technologies for Enhancing the Phytoremediation of Cadmium-Contaminated Soil by Amaranthus hypochondriacus L.

Three pot experiments were carried out to evaluate the phytoextraction efficiency of cadmium (Cd) by an amaranth (Amaranthus hypochondriacus L.). To enhance phytoremediation potential, this study examined the effect of fertilization, repeated harvests, and growth time on the efficiency of Cd removal from soil. The result showed that fertilizing with NPK increased dry biomass by a factor of 4.2, resulting in a large increment of Cd accumulation. Repeated harvests had a significant effect on the plant biomass and thus on overall Cd removal and an optimal cutting position influenced the amount of Cd extracted from soils. Plant growth time was found to significantly affect the amount of Cd extracted by A. hypochondriacus. This study indicates that A. hypochondriacus has great phytoremediation potential in Cd-contaminated soil. For best practice, the recommendation is to maximize the phytoextraction efficiency of A. hypochondriacus by repeated harvests, harvesting at the squaring stage (soon after the flower begins to appear), and apply NPK compound fertilizer as base application.

EFFECTS OF SOME FERTILIZERS TREATMENTS ON GROWTH OF YOUNG PEACH TREES ( Prunus persica ) CV. DIXIRED FOR BEGINNING OF FRUITING

This study was conducted in the pomology field / Horticulture and Landscape Design Dept .during 2008 and 2009 growing seasons to study the response of peach trees cv. Dixired for mineral and organic fertilizers . Compound fertilizer NPK with three ratios of N : P : K ( 1 : 0.5 : 0.5 ) ( 1 : 0.75 : 0.75 ) and ( 1 : 1 : 1 ) for N : P : K respectively ) with three leveles of nitrogen ( 38 , 57 and 76 gm N / tree ) were applied at the middle of February , Meanwhile organic fertilizer ( sheep manure 1.83 % N ) were added at the beginning of January with three levels of nitrogen ( 38 , 57 and 76 gm N / tree ) , and control trees were unfertilizerd . Results indicated that the application of all treatments of mineral and organic fertilizers significantly increased leaves N , P , K , chlorophyll , carbohydrates and dry matter concentration , leaves area , tree height and main stem diameter as compared with control . The best results were obtained with the application of mineral fertilizer at two ratios ( 1 : 1 : 1 and 1 : 0.75 : 0.75 for N : P : K respectively ) at a rate of 76 gm N / tree and organic fertilizer at a rate of 76 gm N / tree .

Replacing inorganic fertilizer with anaerobic digestate may maintain agricultural productivity at less environmental cost

AbstractWe applied digestate generated from the anaerobic digestion of slurry, undigested slurry, or inorganic N (ammonium nitrate) or NPK compound fertilizer to pots of grass and a grass–clover mix grown in two soils. Crop yields were equal or enhanced with digestate, and analysis of soil water showed that there was less potential for loss of nutrients via leaching. Replacing inorganic fertilizer with digestate may therefore maintain grassland productivity but with less impact on the environment.

Different types of sub‐alpine grassland respond similarly to elevated nitrogen deposition in terms of productivity and sedge abundance

AbstractQuestionIncreasing emissions of reactive nitrogen (N) compounds threaten the composition of species‐rich communities even in remote alpine areas. In the few studies available from (sub‐)alpine grassland, N deposition altered species composition in favour of sedges, which are assumed to be less limited by phosphorus (P) compared to other species. Is the magnitude of the sedges' relative increase modified by availability of other nutrients, which is in turn influenced by site‐specific edaphic and climatic conditions?LocationSwiss Central Alps.MethodsWe selected ten sub‐alpine sites that covered a broad range of communities and soil conditions, including both calcareous Seslerietum as well as acidic Nardetum pastures. As a model species, Carex sempervirens Vill. was present at each site. For two consecutive years, in addition to a control, two treatments were applied to the vegetation: (1) 50 kg·N·ha−1·yr−1 as NH4NO3 and (2) compound NPK fertilizer comprising the same amount of N. Total above‐ground biomass, fraction of all sedges, leaf length and leaf N, P and potassium (K) content of C. sempervirens were recorded and analysed for their responses to treatments and interaction with variables linked to productivity and nutrient availability (including soil water potential, pH and soil P).ResultsBiomass production was stimulated across all sites on average by 30% with elevated N deposition, and by 60% with NPK fertilizer application, revealing the sites to be similarly co‐limited by N and by P and K. Also across all sites, the fraction of sedges was increased on average 33% by N addition, but remained constant with NPK application, suggesting stronger P and/or K co‐limitation in non‐sedge species. N treatment effects were consistent in their direction but varied between sites; nevertheless this variation could not be explained by the measured edaphic or climatic factors. However, by trend, sedges benefited more from N fertilization on sites with higher pH, but benefited less on very dry sites.ConclusionOur findings reveal that the observed increase of sedges is a general response of sub‐alpine grassland to elevated N deposition and thus can be regarded as universal both for Seslerietum as well as Nardetum pastures.

Growth, yield and antioxidant profile of pumpkin (Cucúrbita pepo L.) leafy vegetable as affected by NPK compound fertilizer

Pumpkin young leaf is an underutilized leafy vegetable in the Southwestern Nigeria. The objective of this study is to provide information on the influence of NPK fertilizer on the agronomic performance and antioxidant concentration of pumpkin leafy vegetable for the purpose of enhancing its cultivation and popularizing its utilization. The experiment was conducted in 2007 and 2008, at the Teaching and Research Farm, Obafemi Awolowo University, Ile-Ife, Nigeria. The experiment was a randomized complete block design with 3 replications. Compound fertilizer, NPK /15:15:15/ was used and added as ring dressing in four levels; 0, 90, 180, 270 kg/ ha-1. Data were recorded for several growth and leaf yield parameters. At the seventh week after planting, the harvested young leaves extracts were analyzed for antioxidant activities and antioxidant phenolic compounds concentration using different antioxidant assays. The significant highest estimates for vine length, leaves number, stem diameter, number of branches and number of tendrils per plant and total young leaf yield were resulted from plants treated with 180 and 270kg/ha-1. It is concluded that 180 kg/ha-1 of NPK fertilizer is required for optimal yield and antioxidant composition of pumpkin leafy vegetable.