Another group is formed by the stabilized nitrogenfertilizers containing additives in their composition, which act as inhibitors of the urease enzyme and of the nitrification reaction. Urease inhibitors, such as NBPT, reduce the enzyme activity in the soil, and retain the N in the amide form for longer. In this context, it is possible to list some benefits related to the stabilization of urea with NBPT: late volatilization peak, which provides longer period of time for the incorporation of urea by the rainwater; reduction of volatilization losses due to excessive urea hydrolysis in the soil surface; increase of nitrogen uptake and of crop yield (Watson et al., 2008). Since NBPT reduces the conversion of urea to ammonium, it can be said that this molecule also indirectly influences nitrification due to the reduction of NH 4 + ions concentration in the soil for nitrate
In addition to stabilized urea , there is another group that belongs to the coated or encapsulated fertilizers. These fertilizers are produced via the addition of compounds that cover the urea granules, reduce their exposure to water and air, and block volatilization. Various products have been developed to suit ammonia volatilization and enhance urea efficiency, thus creating ample innovation possibilities; the products include sulfur, polymers, polystyrene, polyesters, polyurethane, fatty acids, latex, petroleum by-products, magnesium and calcium phosphate, gypsum, Azadhiractha (Neem tree) extract and wax (Trenkel, 2010; Chien; Prochnow; Cantarella, 2009).
The range of N 2 O emission from soils in literature is wide and is strongly affected by the source and rate of fertilization, as well as by climate and soil characteristics (Clayton et al., 1997). The emissions found in the present study, however, can be considered as large, since the relative losses of N through N 2 O emission for only 15 days of evaluation are similar to annual losses from soils following application of nitric sources of N fertilizers (0.4 to 3.1 %), ammonium- based fertilizers (0.2 to 0.4 %), amidic-based fertilizers (0.24 to 0.8 %) and with microbial activity inhibitor (0.1 to 0.52 %) (Bouwman, 1996; Maggiotto et al., 2000; Dobbie & Smith, 2003; Jones et al., 2005). One factor that can explain the large N 2 O emissions of
The higher grain yield in the N fertilization than the control treatment (without N) was only observed in the 2009/2010 season (Table 2). The influence of soil fertility on crop response was described by Mulvaney et al. (2001) and the results of that study reinforced the concept to take the previous crop into consideration when planning N fertilization, as also discussed by Amado et al. (2002). Agricultural soil managements that use organic matter input and recycling in soil, e.g., the no-tillage system, intensify the microbial activity and its role in mineralizing N from organic sources for plants (Cantarella, 2007). Therefore, the lack of response to N fertilizers in the 2010/2011 growing season would be a consequence of both climatic conditions and the composition of the soil residuum (richer in N than residues of the previous season). Due to this mechanism, Amado et al. (2002) suggests the use of lower N doses for crops sown after leguminous crops.
The plants fertilized with coated urea showed higher values for SD, EIH and EP as already highlighted. Thus, it is inferred that this source provided higher N use by plants, because the losses were reduced. In contrast, in other studies (MEIRA et al. 2009; SORATTO et al. 2010; CIVARDI et al. 2011), the authors found no differences between urea and sources of slow release, because the application of nitrogen was followed by a irrigation and/or occurred in the middle of a rainy season.
Crop residues on the soil surface of no-till systems can intensify ammonia volatilization from N fertilizers applied to cereal crops. This study assessed the magnitude of N losses through ammonia volatilization from urea applied to no-till winter (wheat) and summer crops (maize) on a Typic Hapludox in the south-central region of Paraná, southern Brazil. In addition, the potential of alternative N sources (urea with urease inhibitor, liquid fertilizer, ammonium nitrate and ammonium sulfate) and different urea managements (fertilizer applied in the morning or afternoon) were evaluated. Two experiments with maize and wheat were carried out for two years, arranged in a randomized block design with four replications. Nitrogen volatilization losses were assessed with a semi-open static collector until 21 days after fertilization. In winter, the losses were low (<5.5 % of applied N) for all N sources, which were not distinguishable, due to the low temperatures. In the summer, volatilization rates from urea were higher than in the winter, but did not exceed 15 % of applied N. The main factor decreasing N losses in the summer was the occurrence of rainfall in the first five days after fertilization. Urea with urease inhibitor, nitrate and ammonium sulfate were efficient to decrease ammonia volatilization in maize, whereas the application time (morning or afternoon) had no influence.
On the other hand, the data obtained for the N cover application fitted a linear equation showing an increase over the 2 years of cultivation (Figure 2B). The same pattern was reported by Cazetta et al. (2008) and Gitti et al. (2012a), for upland rice. This finding is likely due to an increase in the productive potential associated with the crop rotation system, which makes the plants use more nutrients, especially nitrogen, what is reflected in the higher N content in the leaves. According to Troeh & Thompson (2007), plants uptake nitrogen when they are in active growth. Therefore, the nitrogen deficiency could decrease growth and yield. It is important to point out that, even in treatments where N was not applied, the values obtained for the content of foliar nitrogen are within the range of 27-35 g kg -1 , which is considered
On the other hand, daily volatilization peaks were reduced in all N fertilizers, when irrigation was applied immediately after N fertilization, compared to the treatments without irrigation and irrigation before fertilization. The highest volatilization peak was observed from slow-release fertilizer, one day after fertilization, followed by urea, 2 days after fertilization, and urea with urease inhibitor, 4 days after fertilization (Figure 2). The application of 10 mm water by sprinkler irrigation was effective to reduce the daily NH 3 loss rates from all N fertilizers,
Nitrogen is an essential element for plant growth. Among of all nitrogenfertilizers urea is considered the most widely used due its high N content but its potential is limited by its high solubility in water and losses up to 50% is related. To overcome this problems a range of technologies have been developed with the aim of improving the urea efficiency. All alternatives imply in reducing final N content. In this sense, this work describes a study a one-step method to prepare slow-release nitrogen fertilizer through the modification of thermoplastic starch by blending with melamine. Therefore, characterizations and release kinetics was done for the composite as well as the greenhouse experiments to show how the true role of melamine in the composites fertilizers.
BROOKES, P.C.; LANDMAN, A.; PRUDEN, G.; JENKINSON, D.S. Chloroform fumigation and the release of soil nitrogen: a rapid direct extraction method to measure microbial biomass nitrogen in soil. Soil Biology and Biochemistry, v.17, p.837-842, 1985. ERNÝ, J.; BALÍK, J.; PAVLÍKOVÁ, D.; ZITKOVÁ, M.; SÝKORA, K. The influence of organic and mineral nitrogenfertilizers on microbial biomass nitrogen and extractable organic nitrogen in long- term experiments with maize. Plant, Soil and Environment, v.49, p.560-564, 2003.
The link between various air pollutants and hospitalization for epilepsy has come under scrutiny. We have proposed that exposure to air pollution and speciically the pervasive agricultural air pollutant and greenhouse gas, nitrous oxide (N 2 O), may provoke susceptibility to neurodevelopmental disorders. Evidence supports a role of N 2 O exposure in reducing epileptiform seizure activity, while withdrawal from the drug has been shown to induce seizure-like activity. Therefore, we show here that the statewide use of anthropogenic nitrogenfertilizers (the most recognized causal contributor to environmental N 2 O burden) is signiicantly negatively associated with hospitalization for epilepsy in all three pre-speciied hospitalization categories, even after multiple pollutant comparison correction (p<.007), while the other identiied pollutants were not consistently statistically signiicantly associated with hospitalization for epilepsy. We discuss potential neurological mechanisms underpinning this association between air pollutants associated with farm use of anthropogenic nitrogenfertilizers and hospitalization for epilepsy.
Despite the importance of the use of a physical mixture of conventional, stabilized and controlled-release nitrogenfertilizers, studies indicate that evaluate the use of blends with different technologies in addition to urea are still scarce (Noellsch et al., 2009; Grant et al., 2012) in areas with coffee plants. In this context, the present study was conducted to quantify the losses of N-NH 3 by conventional N fertilizers (urea and ammonium nitrate) and physical mixtures of granules (blends) of urea + (urea + NBPT) and controlled-release urea applied in drip irrigated coffee system.
Environmental laws encourage the adoption of harvest forms of sugarcane that dispense the previous burning of the crop stubble, which reflects back on the fertilization practices, not only in terms of amounts but also of sources and application forms. Commonly, sugar cane fertilizers are water-soluble and consequently readily available to the crop. Among the most typical nitrogenfertilizers are urea, sulfate and ammonium nitrate (Cantarella et al., 2007, Vitti et al., 2008).
different combinations of these additives – were evaluated as to N losses by volatilization and leaching. The losses in laboratory-developed formulations were compared with those of commercial fertilizers coated with the same additives (Super N, FH Nitro Mais, and FH Nitro Gold). The evaluations were made in greenhouse conditions, using a Ultisol accommodated in PVC columns. Nitrate and ammonium leaching was evaluated in the solution percolated through the soil columns. Ammonia volatilization was measured with a semi-open static chamber. The incorporation of urease inhibitors (NBPT, H 3 BO 3 , and Cu +2 ) into the urea granules was
In the first cut, there was fit to the quadratic regression model for nitrogen; notwithstanding, it was not possible to determine the rate of highest production due to the linear regression fit of potassium, which had growing behavior, with an increase of 63.85%, when the combination of higher rates of nitrogen and potassium was compared with the absence of fertilization with these nutrients (Figure 1A).
on the time scale of nitrogen turnover in the ocean. Altabet also examines high res- olution δ 15 N records from several sites considered to be sensitive to oceanic average δ 15 N and finds no detectable change over the last 3 000 years, implying a balanced marine nitrogen budget through the latest Holocene. This would imply that either the losses of nitrogen from the ocean have increased in recent times or, as noted above,
One of the most important of these changes is the addition of new nitrogen in the system by the biological fixation on agricultural land especially due to the expansion of soybean in the region. Soybean occupied almost 6.5 million ha in 2009, which is half of the arable land of the Amazon region (Figure 3). Approximately 85% of the soybean cultivated in the Amazon region is in the State of Mato Grosso, the most important producer of soybean in the country. More surprising yet is that according to the IBGE, there was no soybean before 1975 in this state. In 1975, the IBGE recorded only 350 ha of soybean, which increased to 1,000 ha in 1977, and then jumped to 70,000 ha in 1980, soaring to 1.5 million ha in 1990, and then continued to surge from approximately 3.0 million ha in 2000 to almost 6 million ha in 2009. This vigorous expansion of soybean area has introduced new nitrogen to the system, growing from near zero in the 1970s up to Table 2. Input and output nitrogen fluxes and relative
Therefore, it is clear that most of the nitrogen input in the Amazon basin is derived from natural sources, whereas in watersheds of the State of São Paulo, New England, Ecuador and Poland, most of the sources were anthropogenic. It is important to note that in specific areas of developing countries where economic development is vigorous, such as in the Piracicaba and Guayas basins in Brazil and Ecuador, respectively, anthropogenic inputs of nitrogen are in the same order of magnitude or even higher than inputs in highly populated regions of developed countries such as New England in the USA or in transition economies like in Poland (Table 5).
Research was conducted on experimental fi eld within hydro- ameliorated cropland located in Western Pannonian subregion of Croatia (45°33´N, 16°31´E) near Park of nature Lonjsko polje. Th e soil type of trial site is drained distric Stagnosol. Terrain is fl at with average altitude 97.2 m. Th e experiment had 10 treatments with diff erent nitrogen fertilization levels, whence quantities of phosphorus (P) and potassium (K) were constant for all treat- ments (120 kg P ha -1 and 180 kg K ha -1 ). Only four treatments
The diets formulated from sorghum cultivars with higher concentrations of condensed tannins resulted in lower nitrogen use by the sheep. However, no decrease in the microbial nitrogen supply for intestinal absorption was identified. The study did not identify any anti-microbial action of the sorghum condensed tannins, but the hybrids that presented high levels of CT contributed to an important reduction in nitrogen retention.