Type Of Nitrogen Fertilizer Research Articles

Effects of different nitrogen fertilizer types and rates on cotton leaf senescence, yield and soil inorganic nitrogen

ABSTRACT The effects of different nitrogen fertilizer types and rates on cotton leaf photosynthesis, yield and soil inorganic nitrogen were studied in two years of field experiments. Seven treatments were carried out: (1) Polymer-coated urea (PCU) mixed with urea (1:1 ratio) applied once at 126 kg N ha−1 (70% BBF); (2) PCU mixed with urea (1:1 ratio) applied once at 180 kg N ha−1 (100% BBF); (3) urea applied once at 126 kg N ha−1 (70% U1); (4) urea applied once at 180 kg N ha−1 (100% U1); (5) urea applied twice at 126 kg N ha−1 (70% U2); (6) urea applied twice at 180 kg N ha−1 (100% U2); and (7) no nitrogen fertilizer (Control). The seed cotton yield of the mixed treatment increased by 6.27–17.69% on average per year compared with the U2 and U1 treatments at the same nitrogen rate. The net profit and nitrogen recovery efficiency increased by 15.53–46.68% and 4.37–16.32%, respectively. Leaf photosynthesis and soil inorganic nitrogen also increased. Compared with the 100% BBF treatment, the 70% BBF treatments, with 30% reduced N, had similar effects on cotton growth. These results provide a scientific basis for highly efficient fertilization during cotton cultivation.

Impacts of nitrogen fertilizer type and application rate on soil acidification rate under a wheat-maize double cropping system

Nitrogen (N) fertilizer-induced soil acidification in Chinese croplands is well-known, but insight in the impacts of different N fertilizer management approaches (fertilizer type and rate) on soil acidification rates is very limited. Here, we conducted a field experiment on a moderate acid soil to quantify soil acidification rates in response to N fertilization by different fertilizer types and N rates through monitoring the fate of elements (mainly nutrients) related to H+ production and consumption. Two N fertilizer types (urea and NH4Cl) and three N rates (control, optimized and conventional, 0/120/240 kg N ha−1 for wheat, 0/160/320 kg N ha−1 for maize) were included. Nitrogen addition led to an average H+ production of 4.0, 8.7, 11.4, 29.7 and 52.6 keq ha−1 yr−1, respectively, for the control, optimized urea, conventional urea, optimized NH4Cl and conventional NH4Cl plots. This was accompanied with a decline in soil base saturation of 1–10% and in soil pH of 0.1–0.7 units in the topsoil (0–20 cm). Removal of base cations by crop harvesting and N transformations contributed ~70% and ~20% to the H+ production in the urea treated plots, being ~20% and ~75% in the NH4Cl treated plots, respectively. The large NH4+ input via fertilization in the NH4Cl treated plots strongly enhanced the H+ production induced by N transformations. The low contribution of N transformations to the H+ production in the urea treated plots was due to the limited NO3− leaching, induced by the high N losses to air caused by denitrification. Increased N addition by urea, however, strongly increased H+ production by enhanced plant uptake of base cations, mainly due to a large potassium uptake in straw. Our results highlight the important role of optimizing fertilizer form and N rate as well as straw return to the field in alleviating soil acidification.

Physiological quantification and molecular detection (BeNRT1.1) of neosinocalamus (bambusa emeiensis) treated with different types of nitrogen fertilizers

Nitrogen based fertilizers have great potential for the ontogenesis and improvement of plants on sustainable basis. This study aims to unveil the effects of nitrogen based fertilizers on physiology, biochemistry and photochemistry of Bambusa emeiensis L. C. Chia & H. L. Fung; along with cloning and expression of a nitrate transporter gene from NRT1 family (BeNRT1.1). Our data revealed that NO3−N has a very positive effect on the basal diameter of clumping. The plants treated with NO3−N demonstrated a decrease in the fiber length along with the cellulose content; while the increase has been observed in the lignin content and nitrate reductase activity. Furthermore, the fertilizers NO3−N and (−CONH2) are observed to trigger the soluble protein content in the base of the shoot. While the plants treated with NH4+-N shown morphological effects on the thickness of the inner fiber strand and the height of central vascular bundles. It was found that the parenchyma cells between the two adjacent vascular bundles were significantly thicker than that of the control group. The NH4+-N also increased the sugar content at the base of the shoots and increased the glutamate synthase activity. The different kinds of nitrogen fertilizers also have positive effects on chlorophyll content. Moreover, the NRT gene was cloned and characterized; which demonstrated that the gene BeNRT1.1 (Accession No. KY421770), have an open reading frame (ORF) of 1611 bp, encoding a total of 536 amino acid residues. Phylogenetic analysis showed that the amino acid residues of BeNRT1.1 were similar to that of AtNRT1.1 genes in Arabidopsis thaliana which is known for nitrate transport. qRT-PCR data revealed that BeNRT1.1 was highly expressed in the base of the shoots when treated with NO3−N fertilizer.

Substitution of manure for chemical fertilizer affects soil microbial community diversity, structure and function in greenhouse vegetable production systems.

Soil microbial communities and enzyme activities together affect various ecosystem functions of soils. Fertilization, an important agricultural management practice, is known to modify soil microbial characteristics; however, inconsistent results have been reported. The aim of this research was to make a comparative study of the effects of different nitrogen (N) fertilizer rates and types (organic and inorganic) on soil physicochemical properties, enzyme activities and microbial attributes in a greenhouse vegetable production (GVP) system of Tianjin, China. Results showed that manure substitution of chemical fertilizer, especially at a higher substitution rate, improved soil physicochemical properties (higher soil organic C (SOC) and nutrient (available N and P) contents; lower bulk densities), promoted microbial growth (higher total phospholipid fatty acids and microbial biomass C contents) and activity (higher soil hydrolase activities). Manure application induced a higher fungi/bacteria ratio due to a lower response in bacterial than fungal growth. Also, manure application greatly increased bacterial stress indices, as well as microbial communities and functional diversity. The principal component analysis showed that the impact of manure on microbial communities and enzyme activities were more significant than those of chemical fertilizer. Furthermore, redundancy analysis indicated that SOC and total N strongly influenced the microbial composition, while SOC and ammonium-N strongly influenced the microbial activity. In conclusion, manure substitution of inorganic fertilizer, especially at a higher substitution rate, was more efficient for improving soil quality and biological functions.

Assessing manure and inorganic nitrogen fertilization impacts on soil health, crop productivity, and crop quality in a continuous maize agroecosystem

Sustainable agricultural production requires an inclusive framework that concurrently considers the impacts of production methods on soil health, crop productivity, and crop nutritional quality. However, few studies have directly examined the potential associations among management impacts on soil health (SH), crop productivity, and crop quality. We evaluated these linkages in a continuous maize experiment with treatments varying in nitrogen (N) fertilizer amount and type (zero input control, inorganic N, and manure-based N treatment). We evaluated select SH indicators after six cropping years, and computed physical, chemical, biological, nutrient, and overall SH indices using the Soil Management Assessment Framework (SMAF). Crop yields, mineral nutrient concentrations (denoted with brackets), and nutrient uptake were analyzed in years six and seven. Manure application increased biological SH indicators compared to the control and inorganic N treatments and also increased available potassium (K), zinc (Zn), copper (Cu), and phosphorus (P). Overall SH indices were higher in the inorganic N and manure treatments than in the control but did not differ between the two N sources, despite the large exogenous sources of C, N, and nutrients applied via manure. The SMAF tool only directly considers P and K in terms of soil nutrients—other nutrient benefits of manure application (i.e., increases in total soil N, available Cu and Zn) were not accounted for, suggesting that the SMAF nutrient SH index should be modified to account for the impacts of management practices on nutrient availability. Crop yields were higher in treatments with higher overall SH, supporting the linkages between SH and crop productivity. Despite widely differing nutrient inputs and soil fertility levels, we found no yield differences between the two N sources. However, there were notable treatment impacts on crop quality. Grain [N] was 40% greater in the urea and manure treatments than in the control. Grain [P], [K], and [Mg], important elements in livestock nutrition, were 10% to 28% greater in the manure treatment than in the urea treatment. In addition, although a yield dilution of grain [Zn] occurred in the urea treatment, the dilution effect was mitigated in the manure treatment, likely due to increases in available Zn. Overarchingly, our results suggest that management practices that maintain or improve SH and nutrient availability also improve maize productivity and nutritional quality, which could have cascading positive impacts on animal and human nutrition.

How are annual CH4, N2O, and NO emissions from rice–wheat system affected by nitrogen fertilizer rate and type?

Although the effect of controlled-released fertilizer (CRF) on methane (CH4) and nitrous oxide (N2O) emissions has been investigated from many rice–wheat rotation systems, most studies were conducted either in the rice or in the wheat seasons. Few studies measured CH4, N2O, and nitric oxide (NO) emissions from rice–wheat rotation systems simultaneously. In this study, one-year outdoor pot experiments and two-year field experiments were conducted to investigate the effects of altering nitrogen (N) fertilizer type from traditional fertilizer (TF) (e.g., compound fertilizer and urea) to CRF and reducing 30% of the local conventional N application rate on CH4, N2O, and NO emissions from a typical Chinese rice–wheat rotation system. Results showed that the annual cumulative N2O emissions and EFN2O in the CRF treatment decreased by 3.91%–16.7% and 9.23%–20.7% compared with the TF treatment, respectively. These emissions also significantly decreased by 26.0%–34.4% and 18.1%–28.5% when local conventional N fertilizer application rate was decreased by 30% (P < .05). However, neither altering fertilizer type nor reducing 30% N fertilizer application rate affected CH4 emissions (P > .05), and the reduction effect of CRF on NO emissions could only be detected at the CRF fertilization rate at 270 kg N ha−1 per season but not at 190 kg N ha−1 per season. The annual total global warming potential in CRF treatment decreased by approximately 1.47%–9.17% compared with that in TF treatment. Moreover, this potential decreased by 8.29%–15.4% when 30% of the N application rate was reduced. Therefore, altering N fertilizer type from TF to CRF and applying optimal N rate should be encouraged as a partial substitution N fertilizer management strategy for the sustainable development of rice–wheat rotation systems.

Effect of Nitrogen Fertilizer Types and Microelements on Growth, Yield and Chemical Constituents of Tuberous Root of Sweet Potato (Ipomoean batatas L, Lam)

Effect of Nitrogen Fertilizer Types and Microelements on Growth, Yield and Chemical Constituents of Tuberous Root of Sweet Potato (Ipomoean batatas L, Lam)

Soil acidity, lime application, nitrogen fertility, and greenhouse gas emissions: Optimizing their joint economic management

Soil acidity is a major limiting factor for crop production in many farming systems worldwide. Lime application is the most common practice to mitigate soil acidity. There are complex economic interactions between application of lime and nitrogen fertilizer, with the greenhouse gas emissions associated with the use of these inputs adding further complexity. We employ a non-linear dynamic optimization model to determine economically optimal application strategies for lime and nitrogen fertilizer accounting for the social cost of the resulting emissions of greenhouse gases. The model is applied in three zones with different rainfall levels, in the northern wheatbelt of Western Australia. Rainfall has important influences on results through its effect on the dissolution and leaching of lime, leaching of nitrogen, and the yield potential of crops. Results show that nitrogen-related decisions, such as the type of nitrogen fertilizer and crop rotation, have a substantial impact on optimal lime application rates and resulting emissions. For example, the use of ammonium sulfate, rather than urea, reduces emissions. Similarly, by allowing a reduction in nitrogen fertilizer use the incorporation of legume crops like lupin can reduce emissions by 50%, relative to a wholly non-legume crop rotation. Although carbon pricing reduces emissions, the magnitude of the reductions is modest in all modeled scenarios. The private cost to farmers of a carbon tax in this case study region is small, although the net social benefit of the carbon tax in this case study is smaller still, even without accounting for the transaction costs of operating the tax system.

Strengthening role and the mechanism of optimum nitrogen addition in relation to Solanum nigrum L. Cd hyperaccumulation in soil

Solanum nigrum L. has a high potential for the remediation of Cd-contaminated soil, and nitrogen fertilizer supply is an effective method to further improve its phytoremediation potential. The soil pot culture experiment was used to explore 4 kinds of nitrogen fertilizers the best fertilizer addition concentrations and their strengthening mechanisms. The results showed that S. nigrum biomass increased with increasing N doses until 800 mg kg−1, where the biomass reached maximum and no longer improved (p < 0.05). However, Cd concentration accumulated by S. nigrum and the extractable Cd concentration in soil did not show a significant decrease (p < 0.05). In this experiment, when N fertilizer was added at 800 mg kg−1 (NH4HCO3, NH4Cl, (NH4)2SO4 and CH4N2O fertilizers), the biomass of the aboveground S. nigrum parts improved to the maximum under (NH4)2SO4 and CH4N2O treatments, i.e. 5.86 g pot−1 and 5.83 g pot−1, increased by 5.92- and 5.89-fold, respectively (p < 0.05), compared to the controls without N fertilizers addition. At the same time, Cd phytoaccumulation in plants was elevated to 128.40 μg pot−1 and 129.14 μg pot−1, increased by 6.20- and 6.24-fold, respectively (p < 0.05), compared to control with no fertilizer added. The results of this experiment demonstrated that Cd phytoextraction capacity (μg pot−1) was the strongest under (NH4)2SO4 and CH4N2O treatments at N content of 800 mg kg−1, when plant nutrient recovery reached the maximum, and these 2 types of nitrogen fertilizers could be utilized to remediate Cd-contaminated soil in field experiments or even in practice.

Wheat growth and nitrogen use efficiency under drip irrigation on semi-arid region

Irrigation water is limiting factor for crop production in arid and semi-arid regions. Modern irrigation system such as drip irrigation are widely used in Egypt and also used in other countries especially have limited irrigation water resources. Drip irrigation provides the efficient use of limited water resources with increasing water productivity (WP). Application of nitrogen to wheat is needed to ensure the N availability throughout the growing season due to its important role in promoting both vegetative and reproductive growth. A field experiment was carried out during growing season of 2017/2018 at a private farm located at a newly reclaimed sandy soil at El-Sadat district El-Menofiya governorate , Egypt to study the effect of two nitrogen fertilizer types (ordinary and slow release N fertilizers) as urea 46.5%N and urea formaldehyde (38%N) with four application rates i.e., 0, 40, 60 and 100 kg N fed -1 (1 feddan=4200 m 2 ) combined with drip irrigation moisture depletion from filed capacity (FC) (I1=100% of FC) and (I2=50% of FC) on wheat crop. The results showed that application of water depletion at (I1) through drip irrigation along with 100 kg N fed -1 , from two sources of nitrogen recorded the highest yield of straw and grain and the nitrogen content as well as nitrogen use efficiency compared with the other rate and levels of nitrogen and irrigation, respectively. Also, water productivity increased with irrigation I1 FC and nitrogen levels and reached the highest values at 100 kg N fed -1 as fertigated urea compared with urea formaldehyde as slow release fertilizer.

Effect of Deficit Irrigation, Air injection and Nitrogen Fertilization on Water Productivity of Carrot under Subsurface Drip Irrigation System.

A field study was conducted in 2017-2018 to evaluate the effect of deficit irrigation, air injection and nitrogen fertilization on yield and water productivity of carrot under subsurface drip irrigation system. Experimental treatments were three levels ofdeficit irrigation (60%, 80% and 100%) of full crop water requirements and three types of nitrogen fertilizer(nitric acid(HNO3)48 % N, urea CO(NH2)2 46% N and ammonium nitrate(NH4NO3)33.5% N, with air injection treatment (12% air by volume of water). The results show that the yield and water productivity as well as the length of carrot root significantly increased for air injection treatments. On the other hand, the carrot diameter increase was not significant. The highest value of the carrot root yield (19.487 ton/fed) was obtained due to deficit irrigation 60% (I60%) and ammonium nitrate(NH4NO3)with air injection. Also, treatment of deficit irrigation (I80%) and urea fertilization CO(NH2)2 with air injection resulted 17.437 (ton/ fed) carrot roots which was significantly higher than that of non-air injection treatments. Also,the highest values of water productivity of carrot were 185.189 and 101.376 kg/m3obtained due to(I60%) with (NH4NO3)and co(NH2)2underair injection treatments, respectively. The highest lengths of carrot (cm) were 19.800 and 19.000 (cm)obtained due to (I80%) with CO(NH2)2and (I100%) with (NH4NO3), under air injection treatments, respectively. The highest values of carrotdiameter were 42.153 and 41.260 (mm) obtained due to treatment of full irrigation(I100%) and(NH4NO3) fertilizer withoutair injection and the treatment (I80%) and CO(NH2)2 fertilizer with air injection, respectively. Data from this study indicate that carrot yield and its water productivity can be improved byaerated sub surface drip irrigation system(SSDI).

Impact of nitrogen fertilizer, greenhouse, and crop species on yield-scaled nitrous oxide emission from vegetable crops: A meta-analysis

Abstract Vegetable production is recognized as an important anthropogenic source of nitrous oxide (N2O) emission. An improved understanding of yield-scaled N2O emission from vegetable production can promote innovation for climate smart cropping. In this study, we performed a meta-analysis to quantify yield-scaled N2O emission from six types of vegetable crops, to elucidate the effects of greenhouse cultivation and different types of nitrogen (N) fertilizers on yield-scaled N2O emission from vegetable crops. Significant differences were observed in N2O emission factor (EF) and area- and yield-scaled N2O emissions among the six vegetable types. Stem and seed vegetables showed the lowest and highest area- and yield-scaled N2O emissions, respectively. The average yield of all of the vegetables was significantly higher in greenhouses than in open fields. However, only leafy vegetables were observed to have significantly lower yield-scaled N2O in greenhouses than in open fields. Emissions of yield-scaled N2O in response to inorganic N application rate differed among the different vegetable types. The replacement of inorganic N fertilizer with manure significantly reduced yield-scaled N2O emission from leafy vegetables, but significantly enhanced that from fruit vegetables. Enhanced-efficiency N fertilizer (EENF) significantly increased yield, and significantly reduced area- and yield-scaled N2O emissions from all of the vegetable types; however, it was less effective for root vegetables and open field cultivation.

Effects of fertilizer type and rate on summer maize grain yield and ammonia volatilization loss in northern China

In this study, we analyzed the effects of different maize varieties with nitrogen utilization efficiency, fertilizer type, and rate on the ammonia volatilization emission of farmland. Aimed to seek the best matching method to improve grain yield and fertilizer utilization efficiency of summer maize simultaneously. In field experiments, we choose two maize varieties with different nitrogen utilization efficiency (Zhengdan958, Z and Lainong14, L) as material. Set four different fertilizer treatments (200 kg N hm−2 inorganic fertilizer (U1), 100 kg N hm−2 inorganic fertilizer (U2), 200 kg N hm−2 organic fertilizer (M1), and 100 kg N hm−2 organic fertilizer (M2) to study their effect on NH3 emission and loss, maize grain yield, and nitrogen accumulation. Ammonia volatilization accounted for 8.61–21.68% of applied N. Under the same variety, ammonia volatilization accumulation after fertilization was as follows: U1 > U2 > M1 > M2. Ammonia volatilization rates increased first and then gradually decreased after the fertilization. The ammonia volatilization loss and cumulative loss increased due to increased nitrogen fertilizer application rate. The average nitrogen accumulation and harvest index of 200 kg N hm−2 N treatments were higher than 100 kg N hm−2 N treatments, and the difference between the inorganic fertilizer and organic fertilizer was not significant. In 2016 and 2017, the average yield of Zhengdan958 was 11,758.79 kg hm−2, which was 15.78% higher than that of Lainong14, and the difference between the two fertilizer types was not significant. The average yield of 200 kg N hm−2 N treatment was 11,959.42 kg hm−2, which was 20.13% higher than those of 100 kg N hm−2 N treatment. By changing the type of fertilizer, replacing chemical fertilizers with organic fertilizer can reduce the loss of ammonia volatilization and promote the synergistic improvement to yield and resource utilization efficiency. Among them, using nitrogen-efficient varieties and using organic fertilizer instead of chemical fertilizer was beneficial to reduce the loss of ammonia volatilization, increase the accumulation of nitrogen, and promote the growth of maize to obtain high yield.

Nitrogen Fertilizers Shape the Composition and Predicted Functions of the Microbiota of Field-Grown Tomato Plants

The microbial communities thriving at the root−soil interface have the potential to improve plant growth and sustainable crop production. Yet, how agricultural practices, such as the application of either mineral or organic nitrogen fertilizers, impact on the composition and functions of these communities remains to be fully elucidated. By deploying a two-pronged 16S rRNA gene sequencing and predictive metagenomics approach, we demonstrated that the bacterial microbiota of field-grown tomato (Solanum lycopersicum) plants is the product of a selective process that progressively differentiates between rhizosphere and root microhabitats. This process initiates as early as plants are in a nursery stage and it is then more marked at late developmental stages, in particular at harvest. This selection acts on both the bacterial relative abundances and phylogenetic assignments, with a bias for the enrichment of members of the phylum Actinobacteria in the root compartment. Digestate-based and mineral-based nitrogen fertilizers trigger a distinct bacterial enrichment in both rhizosphere and root microhabitats. This compositional diversification mirrors a predicted functional diversification of the root-inhabiting communities, manifested predominantly by the differential enrichment of genes associated to ABC transporters and the two-component system. Together, our data suggest that the microbiota thriving at the tomato root−soil interface is modulated by and in responses to the type of nitrogen fertilizer applied to the field. [Formula: see text] Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Changes in weed community with different types of nitrogen fertilizers during the fallow season

Manipulation of crop fertilization may be an important part of integrated weed management systems. The objective of this study is to investigate the responses of weed community and composition in the fallow season to the different types of nitrogen fertilization. Six treatments were conducted over four consecutive years, including no N fertilizer (N0), conventional prilled urea (PU), polymer coating of sulfur-coated urea (PSCU), urea with nitrification inhibitor (UNI), urea-formaldehyde (UF), and controlled-release bulk blending N fertilizer (70% full dosage of PSCU plus 30% full dosage of prilled urea, BBF). Weed species composition, dominant species biomass, and soil properties were investigated, and indices of weed species diversity were calculated. The results indicated that Mazus japonicus (Thunb.) Kuntze and Alopecurus japonicus Steud. dominated the N0 treatment, whereas Alopecurus japonicus Steud. dominated all N–fertilized treatments. The PSCU treatment produced the greatest shoot biomass (657 g m−2) of Alopecurus japonicus Steud. The N0 treatment had the highest total weed density (365 plants m−2) and Shannon-Wiener index (1.39). Application of PSCU or UF led to significantly lower Shannon-Wiener and higher Simpson indices than did the PU treatment due to high residue soil N contents. The UNI treatment not only produced the highest 4-year average grain yield of double rice, it also maintained a relatively diverse weed community in the fallow season.

ВЛИЯНИЕ ПРИЕМОВ ОБРАБОТКИ ПОЧВЫ И УДОБРЕНИЙ НА УРОЖАЙНОСТЬ И ЗАСОРЕННОСТЬ ПОСЕВОВ КУКУРУЗЫ

The article presents the results of studies, conducted from 2014 to 2016 in the Western Kama region of the Republic of Tatarstan, for the purpose of comparative study the basic soil cultivation methods and the introduction of various types of nitrogen fertilizers for crop, cultivated for silage. Predecessor - annual grasses (vetch + oats). The dynamics of weediness of crops, its air-dry mass and green mass yield of corn in the phase of milk-wax ripeness were determined. For three years of research, the highest corn yield of green mass was obtained in the sixth variant (background + N120) - 406.6 centner per hectare. Economically advantageous was the dose of ammonia N120, where payment of one kilogram of active matter of fertilizers for the dumping of plowing amounted to 159 kg of green mass.

Effects of Different Sources of Nitrogen on Endophytic Colonization of Rice Plants by Azospirillum sp. B510.

Azospirillum sp. B510, a free-living nitrogen-fixing bacterium isolated from the stems of rice (Oryza sativa cv. Nipponbare), was investigated to establish effective conditions for the colonization of rice plants. We analyzed the effects of the nitrogen sources KNO3, NH4Cl, urea (CO[NH2]2), and NH4NO3 at different concentrations (0.01–10 mM) on this colonization. Nitrogen promoted plant growth in a concentration-dependent manner, with minor differences being observed among the different nitrogen sources. Bacterial colonization was markedly suppressed on media containing NH4+ concentrations higher than 1 mM. Since concentrations of up to and including 10 mM NH4+ did not exhibit any antibacterial activity, we analyzed several factors affecting the NH4+-dependent inhibition of endophytic colonization, including the accumulation of the reactive oxygen species H2O2 and the secretion of the chemotactic substrate malic acid. The accumulation of H2O2 was increased in rice roots grown on 1 mM NH4Cl. The amounts of malic acid secreted from NH4-grown rice plants were lower than those secreted from plants grown without nitrogen or with KNO3. Although the bacterium exhibited chemotactic activity, moving towards root exudates from plants grown without nitrogen and KNO3-grown plants, this activity was not observed with root exudates from NH4+-grown plants. NH4+, but not NO3−, caused the acidification of growth media, which inhibited plant bacterial colonization. These NH4+-dependent phenomena were markedly suppressed by the stabilization of medium pH using a buffer. These results demonstrate that the type and concentration of nitrogen fertilizer affects the colonization of rice plants by Azospirillum sp. B510.

Maximizing land productivity by diversified cropping systems with different nitrogen fertilizer types

Six field experiments were conducted in Giza Agricultural Research Station, Egypt during 2010, 2011 and 2012 growing seasons to study the effect of two types of N fertilizers (urea and urea form as slow-release (UF)) on intercropping cowpea with sunflower and intercropping wheat with pea. A split plot design with three replications was used. The results indicated that insignificant effect of cropping systems was found for sunflower and significant effect was found for cowpea yield. Significant effect of N fertilizers was found on sunflower and insignificant effect was found for cowpea yield. Furthermore, insignificant effect of interaction of cropping systems and N fertilizers was found for sunflower and significant effect was found for cowpea yield. With respect to wheat and pea intercropping, both crops were significantly affected by intercropping system. Significant effect of N fertilizers was found on wheat and insignificant effect was found for pea yield. Both wheat and pea were significantly affected by the interaction of cropping system and N fertilizers. Yield advantage was achieved because land equivalent ratio exceeded 1.00. Dominance analysis proved that leguminous crop is dominated component. Thus, the studied intercropping systems could be recommended to farmers due to its beneficial returns.

Control Effect of Side Deep Fertilization with Slow-release Fertilizer on Ammonia Volatilization from Paddy Fields

In order to reduce the ammonia volatilization in paddy fields, seven treatments were evaluated. These included three slow-release nitrogen fertilizers[sulfur-coated urea (SCU); resin-coated urea (RCU); release bulk blending fertilizer (RBB)], two fertilization modes[single base fertilization (B) and combined with panicle fertilizer (BF)], and conventional split fertilization (CN). The effects of side deep fertilization for slow-release nitrogen fertilizers on ammonia volatilization and surface water nitrogen dynamics were examined using a rice transplanter with a fertilizer sowing mechanism in the Taihu Lake region. The results showed that total nitrogen and ammonium nitrogen concentration in the surface water of the SCU treatment in the base period were higher, and those for RCU and RBB were lower than in the CN treatment. The cumulative ammonia volatilization during the whole rice season varied among different types of slow-release nitrogen fertilizers from 3.84% to 28.17% of the total N applied. The nitrogen loss from ammonia volatilization using the three slow-release nitrogen fertilizers was decreased when compared with conventional split fertilization. The ammonia volatilization loss exhibited the following relationship for the treatments:CN, B-SCU > BF-SCU, BF-RBB, BF-RCU, B-RBB, and B-RCU. When the slow-release nitrogen fertilizers were applied in single base fertilization, the total ammonia volatilization for the SCU was significantly higher than those for the RCU and RBB, while no significant differences were detected when these three slow-release fertilizers were combined with panicle fertilizer. Moreover, although the ammonia volatilization of BF-SCU was lower than that of B-SCU, those of BF-RCU and BF-RBB were higher than those with the B-RCU and B-RBB treatments, respectively. There are no significant differences for nitrogen volatilization when any of these three different fertilizers are applied as B or BF. The results for the emissions during ammonia volatilization during different stages indicated that the ammonia volatilization of SCU at the basal-tillering fertilization stage (7.54%) and the tillering-panicle fertilization stage (16.04%) were higher than those of the panicle fertilization-mature stage. The N loss from ammonia volatilization for RBB in the base-tillering fertilization stage (2.91%) increased more than in the tillering-panicle fertilization stage and panicle fertilization-mature stage. For RCU treatment, the highest rate for ammonia volatilization was detected at the panicle fertilization-mature stage (2.75%). Compared with the single base fertilization mode, ammonia volatilization during the panicle fertilization-mature stage was increased when combined with panicle fertilizer (BF) for the slow-release fertilizer. There was no obvious correlation between the N loss with ammonia volatilization for the three slow-release nitrogen fertilizers and the concentration of ammonium nitrogen in surface water during the panicle fertilization-mature stage.

Life cycle air quality impacts on human health from potential switchgrass production in the United States

Switchgrass is a promising bioenergy feedstock, but industrial-scale production may lead to negative environmental effects. This study considers one such potential consequence: the life cycle monetized damages to human health from air pollution. We estimate increases in mortality from long-term exposure to fine particulate matter (PM2.5), which is emitted directly (“primary PM2.5”) and forms in the atmosphere (“secondary PM2.5”) from precursors of nitrogen oxides (NOx), sulfur oxides (SOx), ammonia (NH3), and volatile organic compounds (VOCs). Changes in atmospheric concentrations of PM2.5 (primary + secondary) from on-site production and supporting supply chain activities are considered at 2694 locations (counties in the Central and Eastern US), for two biomass yields (9 and 20 Mg ha−1), three nitrogen fertilizer rates (50, 100, and 150 kg ha−1), and two nitrogen fertilizer types (urea and urea ammonium nitrate). Results indicate that on-site processes dominate life-cycle emissions of NH3, NOx, primary PM2.5, and VOCs, whereas SOx is primarily emitted in upstream supply chain processes. Total air quality impacts of switchgrass production, which are dominated by NH3 emissions from fertilizer application, range widely depending on location, from 2 to 553 $ Mg−1 (mean: 45) of dry switchgrass at a biomass yield of 20 Mg ha−1 and fertilizer application of 100 kg ha−1 N applied as urea. Switching to urea ammonium nitrate solution lowers damages to 2 to 329 $ Mg−1 (mean: 28). This work points to human health damage from air pollution as a potentially large social cost from switchgrass production and suggests means of mitigating that impact via strategic geographical deployment and management. Furthermore, by distinguishing the origin of atmospheric emissions, this paper advances the current emerging literature on ecosystem services and disservices from agricultural and bioenergy systems.