Forest floor vegetation in Sweden

In boreal forests, dwarf-shrubs (Vaccinium spp.) often dominate the forest floor and are key-stone species in ecosystems due to their importance for nutrient cycling and as a major food source for herbivores. Forestry affects the vegetation both directly through management and indirectly by altering the forest structure. Forest fertilization with N at the end of the rotation period is a common practice in Swedish boreal forests. Even higher timber production can be achieved if fertilization with multi-nutrient fertilizer is applied early in the rotation period, but the effects on forest floor vegetation have not been studied. The objectives of this thesis were to increase knowledge regarding how 1) intensive fertilization in young forest affects forest floor vegetation; 2) background deposition of N influences the effects of N addition; and 3) to relate observed changes in common species abundances to changes in forest structure. Fertilization decreased the abundance of many common forest plant species while only few species increased (I). Surprisingly, also species known as nitrophilous decreased in abundance. Paper I shows that the decrease in availability of light induced by fertilization is a crucial factor behind this change. Consequently, fertilization reduced both species richness, species diversity and the between site (β) diversity (II). In areas where the background N deposition was low (4 kg ha-1 yr-1), the effects of N addition were larger than in areas with intermediate (16 kg ha-1 yr-1) deposition (III). Key-stone species among the forest floor vegetation of boreal Sweden (e.g. Vaccinium myrtillus) were found to decrease in abundance (IV). These species are strongly dependent on aspects of forest structure, such as forest density and age, and likewise, temporal changes in species abundance coincided with corresponding changes in forest structure (IV). In conclusion, in large parts of Sweden the prevailing forest management is incompatible with a productive forest floor vegetation possessing a high diversity of plant species, and this situation will only be exacerbated by more intensive use of fertilization regimes. To avoid associated cascading effects from the decreased abundance of key-stone species, forestry intensity needs to be relaxed on the landscape level which would likely result in a considerable loss of timber production. Compensation for this loss through intensified forestry on other areas would indicate the need for altered forest zoning

Organic or mineral fertilization

To meet Swedish environmental goals organic farming will play an important role in the development of a sustainable and high quality food production system. However, several conflicts exist, such as the achievement of high yields without the use of chemical fertilizers or pesticides and the minimization of nutrient losses. In this thesis the effect of organic fertilizers compared to mineral fertilizers on plant product quality was investigated. Tomato yield and quality aspects such as taste and chemical composition were measured. Three greenhouse experiments were performed at the Swedish University of Agricultural Sciences in Uppsala during 2002 and 2004. Organic fertilizers, based on chicken manure or fresh grass clover mulch, were compared to mineral fertilizer nutrient solutions with ammonium or nitrate as the dominant nitrogen source. In both years yields from the mineral fertilized tomato plants were higher than from the organic fertilized ones. However, plant nitrogen status was similar for all treatments and the limiting nutrient in the organic grass-mulch treatment appeared to be sulphur, as the addition of mineral sulphur increased the yield. The effects on quality appeared to be more complex. While taste test scores and vitamin C contents in 2002 were highest in the organic or ammonium-fertilized tomatoes and lowest in the nitrate-fertilized tomatoes, in 2004 the results were contrary. Taste is a complex quality aspect, affected by sugars, acids and other secondary compounds (aromatic flavour compounds), which apart from nutrient supply are affected by environmental conditions as sunlight and temperature that are beyond the grower’s control. It was concluded that organic or mineral fertilizers are not the major factors affecting yield and product quality. A balanced nutrient supply is important for yield and quality, irrespective nutrient source. A combination of organic and mineral fertilizers should be considered in order to achieve a resource saving and balanced nutrient supply and a high quality tomato yield

Sustainable rubber production through good latex harvesting practices: An update on mature rubber fertilization effects on latex cell biochemistry and rubber yield potential

From 2008 to 2012, under a joint funding by the Institut Français du Caoutchouc (IFC) and its affiliated societies (Michelin, SIPH and Socfinco), a network of large scale experiments has been set up and followed up in 5 agro-industrial plantations to study the influence of a gradient of fertilization of mature rubber trees on latex physiological parameters and rubber yield potential. Experiments were set up on clone PB260 (Socfindo Tanjung Maria and Aek Pamienke plantation in North Sumatra, Indonesia, SAPH-Toupah and SOGB-Grand Bereby plantations in Côte d'Ivoire) and on clone IRCA109 (RENL-Osse River plantation in Nigeria). During the first 3 years (2008/09 to 2010/11), the trees were tapped downward in S/2 d4. During the 4th year (2011/12), the trees were tapped upward in S/4 d4. Each experiment has been designed with a similar protocol: Split plot design with stimulation intensity as the main treatment and fertilizer rate as secondary treatment, with 4 replications. The 3 stimulation intensities (main plots) were INT1 (normal stimulation intensity adapted to the clone, according to Cirad stimulation recommendation grid), INT2 (intensified stimulation: INT1 + 2 stimulations/y) and INT3 (intensified stimulation: INT1 + 4 stimulations/y). The 4 fertilization rates (secondary plots) were IF0 (No fertilization control), IF1 (single dose as the standard Cirad recommendation : 50g N, 40 g P2O5, 90 g K2O per tree per year, applied in a single application 45 to 60 days after complete refoliation), IF2 (double dose : 100 g N, 80 g P2O5, 180 g K2O per tree per year) and IF3 (triple dose: 150 g N, 120 g P2O5, 270 g K2O per tree per year). The 12 main plots (4 replications x 3 stimulation intensities) were fitted to 12 tapping tasks selected for their homogeneity (girth and production) before trial implementation. After 4 years, maximum cumulative production (kg/ha) was always observed with a fertilized treatment (IF2 or IF3) combined with intensified stimulation (INT2 or INT3). Without fertilization (IF0), intensification of stimulation (INT2 or INT3) resulted in a decreased production (overexploitation) or in a reduced response to stimulation. However, these effects of combined intensification and fertilization were often below +10% when compared to the production of the unfertilized control (INT1 x IF0) and therefore hardly statistically significant at a 5% risk. Regarding the latex physiological parameters, the average latex sucrose level was significantly increased by fertilization when compared to the absolute control, even though the increased production, showing a positive physiological change in latex sugar loading or in latex metabolism. Pi and RSH latex contents were also generally increased but less significantly. This indicates that an accurate NPK fertilization might sustain a good latex physiological profile in case of intensified ethephon stimulation and would help to prevent any risk of overexploitation, likely mainly because of an improved sugar translocation towards the latex sink, due to K+ likely. This opens the way to specific recommendations of clonal stimulation recommendations depending on fertilization practices. (Résumé d'auteur

Effects of Nitrogen Fertilization on Monoterpenes of Jack Pine Seedlings and Weight Gain of Jack Pine Budworm (Lepidoptera: Tortricidae)

Nine-month old jack pine (Pinus banksiana) seedlings were grown in a greenhouse under four nitrogen fertilization regimes. Levels of total nitrogen and five monoterpenes in new foliage were measured. Fertilization resulted in four significantly different levels of foliar nitrogen; means ranged from 1.8-4.5 percent dry weight. Contrary to predictions of resource availability theory, seedlings grown under the highest fertilization regime had higher foliar monoterpene levels than seedlings in the other treatments. Newly molted, sixth-instar female jack pine budworm (Choristoneura pinus pinus [Lepidoptera: Tortricidae]) larvae were allowed to feed for four days on new foliage of the seedlings. Larvae that fed on low-nitrogen seedling gained less weight and process more vegetation than did larvae on high- nitrogen seedlings. Larval weight gain was positively related to foliar nitrogen

Enzymatic browning of potatoes is greatly reduced with organic fertilization compared to mineral fertilization

Enzymatic browning of tubers owing to mechanical injury is assessed to indicate bad quality, mainly for visual reasons. Browning is also a serious problem during processing of potatoes. The effect of farmyard manure and mineral fertilization at three levels (50, 100, 150 kg total N per hectare) on darkening of potato extract was investigated in three years in a field trial. The extinction of the extract was measured at 400 nm for two days at three dates during the storage period from autumn to spring. The extract of organically fertilized tubers hat a lower extinction compared to the mineral treatments. This difference occurred right at the beginning of the test with the fresh extract as well as during the following two days, when darkening continued with all samples, but with different extent. Whereas increasing manure levels reduced browning, higher amounts of mineral fertilizer intensified the dark colour. During storage from October to April the extinction showed no clear tendency. Polynomial regressions were calculated for the extinction values during the two days after production of the extracts. The R2 values decreased during storage from 0.95 - 0.98 in November to 0.80 - 0.91 in February. This may be interpreted as a hint of progressing disintegration

Langzeitversuch Darmstadt

In 1980 a fertilization trial started at the Institute for Biodynamic Research in Darmstadt, Germany, comprising farmyard manure treatments with and without biodynamic preparations and mineral fertilization, each at various levels. The objective of the project was to study the product quality of vegetables and of rye. After this four year project, interesting differences began to emerge with respect to the soil parameters of organic and mineral treatments. Thus the trial was continued. After some years of a transitional period without particular investigations, a detailed soil biological project was carried out in 1989-1991, focusing on the effects of fertilization upon C- and N-dynamics, enzyme activities and microbial biomass in the soil. A third experimental period (from 1992 to 1999) has focused on the yield formation of cultivated crops and the long-term effects of fertilization treatments upon soil and crop development. From 2000 until now, the effects of changed fertilization treatments on soil organic matter development, soil biological activity, crop growth and yield is investigated

Assessing the Impact of Climate Change on China's Grain Sector and International Trade

This study analyzes the potential impact of climate change on China's corn, wheat, and rice, domestic agricultural markets, and the international markets out to the year 2050. The study provides a brief background and reviews research literature of climate change effects on China's crop yields. The paper presents the potential impact of climate change on China's yields and attempts to quantify the domestic and global market impacts. The analysis has four scenarios, which assumes two future levels of greenhouse gas emissions with the effects of CO2 fertilization and no CO2 fertilization. A 27-country commodity partial equilibrium simulation mathematical programming model (PEATSim) is used for this analysis. Results indicate under CO2 fertilization, which increases yields, China's grain imports may decrease leading to a decrease in international prices. Under no CO2 fertilization, yields decrease, China's grain imports may increase leading to increased international prices.China, trade, climate change, GHG, CO2 fertilization, rice, wheat, corn, dynamic partial equilibrium simulation mathematical model., Environmental Economics and Policy, International Relations/Trade,

Cryopreservation of common carp sperm

Experiments were carried out to investigate the effect of five extenders (sucrose, glucose, fructose, KCl and a saline carp sperm extender) and two cryoprotectants (dimethyl-sulfoxide (DMSO) and methanol) on the cryopreservation of common carp sperm. Freezing of sperm using glucose extender and methanol as cryoprotectant resulted in the highest post-thaw motility, fertilization as well as hatching rates (63 ± 9%, 74 ± 15% and 67 ± 17% vs. 87 ± 5%, 84 ± 14% and 69 ± 14% using fresh sperm, respectively). In general, sugar-based extenders combined with methanol as cryoprotectant yielded higher motility, fertilization and hatching rates than ionic extenders in combination with DMSO. The jelly-like agglutination observed after thawing in samples frozen with sugar-based extenders did not reduce fertilization and hatching rates. Frozen–thawed sperm samples were able to successfully fertilize 10 g (8000) eggs

Organic Fertilization In A “Tomato – Pea” Rotation In Southern Italy

The use of alternative to mineral fertilizers is an important issue in organic systems. A four-year field experiment to evaluate the effects of organic fertilizers on yield and quality of processing tomato and proteic pea in rotation, was carried out in Southern Italy. The fertilization treatments aimed to supply 100 kg ha-1 of N for tomato and 60 kg ha-1 of P2O5 for pea and were: 1) an organic biological fertilizer (BIO); 2) an experimental compost obtained by olive residues, sludge and straw mixture (COMP); 3) a control managed with traditional chemical fertilizers (ammonium nitrate and perphosphate, MIN). At harvest, the main productive and qualitative parameters were assessed. Tomato fruit yield did not differ among the fertilization treatments, but unripe fruit yield was higher in the MIN and BIO treatment; MIN showed also smaller fruit than BIO and COMP. The N availability during crop cycle influenced the mean fruit weight and maturity date. No difference among treatments was observed for pea in rotation with tomato and, similarly, on the wheat cropped without fertilization following the two crops. The possibility to use organic fertilizer for processing tomato and proteic pea has been evaluated and the conclusion is that organic fertilization is comparable to mineral one from a productive and qualitative point of view