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A novel coated urea (MVCU) was prepared, and its application effect was verified by field trials of oilseed rape in three main cultivation areas. Meanwhile, the nutrient release and coating layer changes of MVCU in static water at 25 °C and different soils were systematically evaluated. MVCU showed a long nutrient release time under static water (77 days) and soil incubation (140 days) conditions due to the slow degradation of the coating layer in MVCU, and its nitrogen release coincided well with oilseed rape nitrogen demand. The above results were further confirmed by FT-IR spectra and SEM analysis. Compared with conventional urea (U), the field trials of MVCU in the three main cultivation areas showed high nitrogen utilization efficiency and yield advantages in oilseed rape. The field trials results indicated that the MVCU significantly enhanced the aboveground dry matter (28.7%), the seed nitrogen concentration (9.5%) and aboveground nitrogen accumulation (42.5%) of oilseed rape at the mature stage as compared to that of the U. The oilseed rape yield enhanced by 932.8 kg/hm2, the average growth rate was 65.1%, and nitrogen utilization efficiency increased by 21.2%. In short, MVCU has the advantages of excellent slow-release performance and strong applicability, and its yield-increasing effect on oilseed rape could reach or even be better than that of traditional fertilization. [ABSTRACT FROM AUTHOR]

Enhanced efficiency fertilizers, such as urea treated with a urease inhibitor, controlled-release fertilizers (CRFs), and fertilizer blends, compose important strategies for improving efficiency in nitrogen (N) use by plants and mitigating ammonia (N-NH3) emissions. The physical mixture of fertilizers in blends can favor synchronization of N-release from the fertilizers and N-uptake by coffee plants and also dilute the costs of acquiring a pure CRF, making fertilizer blends more accessible to growers. To investigate this, a field experiment was conducted over two consecutive crop years with Coffea arabica with the aim of evaluating nitrogen fertilizer technologies at application rates ranging from 0 to 450 kg N ha−1. The fertilizers were characterized, and analyses were performed to quantify N-release from the fertilizers, ammonia volatilization, and nutritional and yield aspects of the coffee plant. The fertilizers used were urea (UCon), urea treated with N-(n-butyl) thiophosphoric-triamide (UNBPT), urea-coated with polymer of the E-Max technology (with 41%N (EMax41) or 43%N (EMax43)), and blends of UNBPT with E-Max (Blend41–Blend43). The cumulative N-release for EMax41 always remained below that for EMax43, just as occurred for Blend41 in relation to Blend43. Over the two crop years, the greatest volatilization of N-NH3 occurred with UCon (~25%) and the least with EMax41 (9%). The results indicate that the technologies mitigated the N-NH3 emissions in relation to UCon [EMax41 (63% mitigation) > Blend41 (43%) > EMax43 (32%) > UNBPT (28%) > Blend43 (19%)]. Crop management affects coffee yield. The yield increase went from 20% in the first crop year to 75% in the second, with better results from fertilizers containing CRF. We present information that can assist fertilizer producers and coffee growers, and, above all, we seek to contribute to environmental action for the reduction of agricultural NH3, clarifying potential strategies for mitigation of these emissions and strategies that generate advances in research on technologies for coffee growing. [ABSTRACT FROM AUTHOR]

Soil salinization has increased over recent years and is negatively affecting crop productivity. Nutrient application is an effective strategy to improve abiotic stress tolerance in crops. The application of coated fertilizers has emerged as an excellent approach to mitigate the adverse impacts of soil salinity. Therefore, the present study was conducted to determine the effects of zinc and sulfur coated urea on the performance of wheat growing under saline conditions. The study comprised of diverse salinity stress levels; 0, 6 and 12 dS m-1, cross combined with normal urea (NU), zinc coated urea (ZCU) and sulfur coated urea (SCU). Salinity stress reduced wheat yield by impairing leaf water status, reducing photosynthetic pigments, osmolytes accumulation, potassium (K) and nitrogen (N) uptake while increasing sodium (Na) and chloride (Cl) uptake and hydrogen peroxide (H2O2), malondialdehyde (MDA) and electrolyte leakage (EL) accumulation. The application of ZCU increased the wheat yield by enhancing photosynthetic pigments, leaf water status, antioxidant activities, osmolytes accumulation, and reducing H2O2, MDA and EL accumulation. Furthermore, the significant increase in growth and yield of wheat with ZCU and SCU was also linked with improved K and N uptake, higher nitrogen use efficiency (NUE) and reduced Na and Cl concentration. Thus, the application of ZCU could be an effective approach to improve wheat productivity under saline conditions.

Abstract Background Lignin played an important role in the establishment of coated fertilizers coating material as a substitute for petrochemical raw materials. However, so far, the lignin-based coated fertilizers was limited in only the poor slow-release performance. To achieve good slow-release performance of lignin-based coated fertilizers, hydrophilic of lignin need to be resolved to establish an green and better controllable lignin-based coated fertilizers. Results In the study, a novel green double layer coating with lignin-based polyurethane (LPU) as the inner coating and epoxy resin (EP) as the outer coating was effectively constructed for coated urea. Fourier transform infrared spectra confirmed that lignin and polycaprolactone diol successfully reacted with Hexamethylene diisocyanate. The loss weight and water contact angle (WCA, 75.6–63.6°) of the LPUs decreased with the increased lignin content. The average particle hardness of the lignin-based double-layer coated urea (LDCU) first increased from 58.1 N (lignin of 30%) to 67.0 N (lignin of 60%), but then decreased to 62.3 N (lignin of 70%). The release longevity of the coated urea was closely related to the preparation parameters of the coating material. The optimal cumulative nutrient release rate (79.4%) of LDCU was obtained (lignin of 50%, –CNO/–OH molar ratios of 1.15, EP of 35%, and coating ratio of 5%). The aggregates of hydrone on the LDCU caused the dissolution and swelling of nutrients, and then the diffusion of nutrients through the concentration gradient. Conclusions A though the nutrient release of the LDCUs was affected by many factors, the successful development of the LDCUs will help improve the rapid development of the coated fertilizer industry.

Polycaprolactone-based polyurethane coated urea ( PCU1 'PCU2 'PCU3) with 4 '6 and 8 coating materials were prepared by using biodegradable polycaprolactone polyol. In order to explore the controUed release properties' the coatings structure' nutrient release rate and longevity of polycaprolactone- based polyurethane coated urea were determined by using scanning electron microscopy' static pure water incubation method and soil incubation method. The results showed that the surface of the coated urea was covered with polycaprolactone-based polyurethane coating' and created a physical barrier' so that coated urea had better nutrient controlled release effect. With the increase of the amount of coating material the longevity of coated urea was prolonged. The longevity of PCU1 'PCU2 and PCU3 were 31.60'86.65 d' and 260. 11 d in static pure water' respectively. The nutrient release pattern of polycaprolactone-based polyurethane coated urea in static pure water and rubber plantation soil are similarity' but the soil incuba¬tion method significantly shorted the longevity of PCU3 ' the longevity of PCU3 in soil was 206.54 d' which was 53.57 d shorter than that in static pure water. [ABSTRACT FROM AUTHOR]

ABSTRACTDry direct-seeded rice (DDSR) cultivation is expected to reduce production costs compared with transplanted rice (TPR); however, its low N use efficiency (NUE) has hindered cost reduction. We conducted DDSR field experiments for 3 years using a standard cultivar (‘Akitakomachi’) and a high-yielding cultivar (‘Yumiazusa’) grown with a single application of coated urea (CU) or split applications of normal urea (NU) to determine factors limiting yield and NUE and compared growth and yields of TPR grown in adjacent fields. DDSR yield was lower than that of TPR at comparable N levels by 11% due to low fertilizer recovery rate, crop NUE (CNUE, yield per unit N uptake), and poor grain filling by meteorological factors. Crop N uptake at maturity in DDSR was similar to or even greater than that in TPR, but poor vegetative growth in DDSR and low crop N uptake until panicle formation (PF) resulted in limited spikelet density and CNUE compared with TPR. Analysis of the N uptake pattern suggests that enhancing early leaf development can improve N uptake until PF and thus CNUE in DDSR. NU yielded as much as CU, so it can potentially reduce the cost of production because of its lower price, but the optimal N proportion and application stage in the split application needs scrutinizing. ‘Yumiazusa’ had better initial growth, CNUE, and yield than ‘Akitakomachi’ in DDSR. To leverage these traits for further yield improvements, we also need to consider suitable phenological characteristics to ensure favorable climatic conditions during the grain-filling period.

Background: Lignin played an important role in the establishment of coated fertilizers coating material as a substitute for petrochemical raw materials. However, so far, the lignin-based coated fertilizers was limited in only the poor slow-release performance. To achieve good slow-release performance of lignin-based coated fertilizers, hydrophilic of lignin need to be resolved to establish an green and better controllable lignin-based coated fertilizers. Results: In the study, a novel green double layer coating with lignin-based polyurethane (LPU) as the inner coating and epoxy resin (EP) as the outer coating was effectively constructed for coated urea. Fourier transform infrared spectra confirmed that lignin and polycaprolactone diol successfully reacted with Hexamethylene diisocyanate. The loss weight and water contact angle (WCA, 75.6–63.6°) of the LPUs decreased with the increased lignin content. The average particle hardness of the lignin-based double-layer coated urea (LDCU) first increased from 58.1 N (lignin of 30%) to 67.0 N (lignin of 60%), but then decreased to 62.3 N (lignin of 70%). The release longevity of the coated urea was closely related to the preparation parameters of the coating material. The optimal cumulative nutrient release rate (79.4%) of LDCU was obtained (lignin of 50%, –CNO/–OH molar ratios of 1.15, EP of 35%, and coating ratio of 5%). The aggregates of hydrone on the LDCU caused the dissolution and swelling of nutrients, and then the diffusion of nutrients through the concentration gradient. Conclusions: A though the nutrient release of the LDCUs was affected by many factors, the successful development of the LDCUs will help improve the rapid development of the coated fertilizer industry. [ABSTRACT FROM AUTHOR]

Introduction: Energy and protein sources are of prime importance for ruminants as they stimulate microorganisms in the rumen and enhance the productive functions of the animals. Many species of rumen microorganisms can use ammonia as a nitrogen source for their growth and formation of microbial biomass that is key to meet the amino acid needs of the host animal. Because low-quality forages (<7% CP) are often limiting in protein, a positive relationship exists between ruminally degradable protein (RDP) supplementation and forage utilization (Koster et al., 1996). In contrast, it has been shown that forage intake did not affect mature ewes fed low-quality grass hay in response to increasing levels of supplemental RUP (Swanson et al., 2000). Similarly, Salisbury et al. (2004) reported no difference in roughage intake in wethers consuming low-quality hay supplemented with high or low RUP. However, those researchers suggested that RDP from forage could have been adequate to support ruminal fermentation. Urea is the main NPN source used in ruminants diets. However, there are still concerns regarding its use due to the rapid release of ammonia (NH3–N), which can be faster than its use by microorganisms for protein synthesis. The efficiency of protein synthesis from urea depends, among other factors, on energy availability in the rumen (Russell et al., 1992). Despite evidence of positive effects of RUP supplementation of fiber digestion, little information has been published observing the influence of slow-release urea (SRU) supplementation on the nutrient digestibility and DMI of ewe’s fed by low-quality forage. Also, feed sorting behavior that could be related to fiber digestibility in the rumen, has not been investigated in ruminant animals fed by increasing levels of slow-release coated urea. Therefore, the objective of this study was to determine how urea supplementation affects feed intake, nutrient digestibility, ruminal NH3–N, blood urea nitrogen concentration and feed sorting behavior in ewes. Material and methods: A total of 28 Arabian ewes (40±2 kg live weight) were used in a completely randomized design with four treatments for 60 days. Experimental diets included 1- control (no urea), 2-1.2% conventional urea, 3- mixture of conventional and coated urea (Optigen®) (50:50 mixture; 0.6% and 0.675% ration DM respectively), and 4- coated urea (1.35% ration DM). Ewes were housed individually in pens (1.3 m×1.5 m) in an open shed building and were allowed ad libitum access to feed and water throughout the trial. All diets contained 60% forage (wheat straw) and 40% concentrate (60 : 40; forage : concentrate). The ingredients and chemical composition of the rations fed to ewes are shown in Table 1. The ewes were fed the total mixed rations ad libitum twice daily at 0800 h and 1700 h and had free access to fresh water at all times. Feed offered and refusal of each lamb were recorded daily. Digestibility was measured by the total collection of feces during a 5-d period. Samples of ruminal fluid were collected from each ewe 0 (before morning feeding), 3, 6 and 9 h post-feeding using a stomach tube attached to an Erlenmeyer flask and vacuum pump. The first 50 ml of collected rumen fluid was discarded to avoid saliva contamination. The remaining was filtered through four layers of cheesecloth. Rumen fluid pH was measured using a portable pH meter. Blood samples were taken from each lamb at the same time as ruminal fluid sampling by venipuncture of the jugular vein in 10-mL tubes treated with sodium heparin. Samples were centrifuged in a refrigerated centrifuge at 850 × g for 30 min within 30 min of sampling, and the plasma was frozen at −20 °C until used. The sorting index was calculated as the ratio of actual intake to the expected intake of particles retained on each sieve of the PSPS (Leonardi and Armentano 2003). The predicted intake of an individual fraction was calculated as the product of the DMI of the total diet multiplied by the DM percentage of that fraction in the fed TMR. A sorting index of 100, >100 and <100 indicated no sorting, sorting for, and sorting against respectively. Data were analyzed using a GLM procedure of SAS 9.2 (SAS Institute, Inc., Cary, NC). Comparisons between treatments were completed with Tukey’s test. Treatment effects were declared significant at P≤0.05. Results and discussion: The results showed that the experimental treatments had no significant effect on intake of dry matter, organic matter, neutral detergent fiber and acid detergent fiber. Crude protein intake was lower in the control treatment relative to the other treatments (P <0.05). This finding was expected urea-containing diets designed to have higher CP content. Apparent digestibility of dry matter, crude protein, neutral detergent fiber and acid detergent fiber was not affected by the treatments. Apparent digestibility of organic matter increased in animals who received coated urea relative to the control treatment (P < 0.05). The ruminal pH of ewes was not affected by dietary treatments before morning feeding and 9 hours post-feeding. An increase in rumen pH was observed in coated urea treatment relative to the control group, 3 and 6 hours post-feeding (P < 0.05). Animals fed coated urea also had higher rumen pH compared to those fed common urea and a mixture of coated urea and common urea (P < 0.05). Rumen ammonia nitrogen concentrations were higher in all urea-containing treatments compared to the control treatment, 3 hours post-feeding (P = 0.002). At 9 hours post feeding, coated urea treatment had higher ammonia nitrogen concentration than common urea and mixture of coated urea and common urea treatments and lowest concentration observed in the control treatment (P = 0.009). Blood urea nitrogen was also higher in 3 and 6 hours post feeding in all urea-containing treatments than the control treatment (P <0.05). Ewes fed a mixture of conventional and coated urea sorted in favor of medium particles relative to other treatments (P = 0.03). Regardless of treatments ewes sorted against the longest ration particles (>19 mm) and sorted for fine particles (<4 mm) dietary particles. Conclusion: Results of this study showed that increasing levels of coated urea in diets containing low-quality forage have the potential to keep higher rumen ammonia nitrogen concentration for a longer period but this increase didn’t have a positive effect on nutrients digestibility compared to conventional urea. [ABSTRACT FROM AUTHOR]

Dry direct-seeded rice (DDSR) cultivation is expected to reduce production costs compared with transplanted rice (TPR); however, its low N use efficiency (NUE) has hindered cost reduction. We conducted DDSR field experiments for 3 years using a standard cultivar ('Akitakomachi') and a high-yielding cultivar ('Yumiazusa') grown with a single application of coated urea (CU) or split applications of normal urea (NU) to determine factors limiting yield and NUE and compared growth and yields of TPR grown in adjacent fields. DDSR yield was lower than that of TPR at comparable N levels by 11% due to low fertilizer recovery rate, crop NUE (CNUE, yield per unit N uptake), and poor grain filling by meteorological factors. Crop N uptake at maturity in DDSR was similar to or even greater than that in TPR, but poor vegetative growth in DDSR and low crop N uptake until panicle formation (PF) resulted in limited spikelet density and CNUE compared with TPR. Analysis of the N uptake pattern suggests that enhancing early leaf development can improve N uptake until PF and thus CNUE in DDSR. NU yielded as much as CU, so it can potentially reduce the cost of production because of its lower price, but the optimal N proportion and application stage in the split application needs scrutinizing. 'Yumiazusa' had better initial growth, CNUE, and yield than 'Akitakomachi' in DDSR. To leverage these traits for further yield improvements, we also need to consider suitable phenological characteristics to ensure favorable climatic conditions during the grain-filling period. [ABSTRACT FROM AUTHOR]

In order to improve the slow‐release effectiveness of waterborne polymer coated fertilizers, an environment‐friendly coated urea was developed by zeolite and waterborne polymer of starch soluble, polyvinyl alcohol, sodium carboxymethyl cellulose, and chitosan. The properties of different mesh and content of zeolite on the membranes and the slow‐release property of coated urea were investigated. Zeolite decreased water vapor, ammonium permeability and porosity of waterborne polymer with an increased ammonium adsorption, and contributed to improve the slow‐release effectiveness of coated urea. In particular, zeolite‐modified waterborne polymer of 200 mesh and 3% content had best effect with 10.8%, 16.5%, and 59.8% decrease of water absorption capacity, water vapor permeability and ammonium permeability, 17.7% increase of water contact angles. Zeolite‐modified waterborne polymer coated urea for the coating contents of 7% had the best effect on the nutrient accumulate release rate. Therefore, zeolite‐modified waterborne polymers have potential to improve the slow‐release effectiveness of coated urea. [ABSTRACT FROM AUTHOR]

Coated urea can improve nitrogen use efficiency (NUE) for crops, while it is also identified as a potential source of microplastics (MPs). Organic fertilizer (OF) shows potential to promote MPs degradation. However, little is known about the influence of OF incorporated with coated urea on MPs accumulation, NUE, and gaseous N loss (NH 3 and N 2 O) in paddies. Therefore, a field experiment was conducted to address this gap, with five fertilization treatments, viz., urea (un-coated) with full rates (U), coated urea with full rates (CU), coated urea with reduced rates (RCU), 70 % coated urea blending 30 % urea with reduced rates (RBU), and RBU blending OF (ORBU). The results showed that, compared with U, the CU increased the number of MPs by 62.2–117.4 %. The ORBU significantly reduced the weight of MPs by 53.2 % through decreasing large-particle size. Additionally, the ORBU enhanced the effect of CU on increasing grain yield and NUE, mainly due to the improvement in the yield components and N uptake. The distribution of NH 4 + in water and soil was a major factor driving NH 3 and N 2 O emissions. The ORBU elevated activities of N-assimilation enzymes, decreased water NH 4 + and NH 3 emissions, and increased soil NH 4 + and ammonium-oxidation bacteria and (nirK + nirS)/ nosZ , ultimately increased soil N 2 O emissions compared with RBU. However, the reduction in NH 3 much outweighed the increase in N 2 O emissions. In conclusion, this study highlighted coated urea as a source of MPs pollution, emphasized OF amendment as a strategy to diminish MPs accumulation, and found that OF incorporated with coated urea could increase grain yield and N uptake of rice while mitigating gaseous N loss in paddies. [Display omitted] • Coated urea application increased microplastics (MPs) in a dose-dependent. • Organic fertilizer amendment reduced the MPs from coated urea. • Organic fertilizer amendment decreased water NH 4 + and NH 3 emissions. • Organic fertilizer amendment increased N 2 O emissions by enhancing N-cycling genes. • The reduction in NH 3 much outweighed the increase in N 2 O emissions. [ABSTRACT FROM AUTHOR]

Given the significance of nitrogen (N) as the most constraining nutrient in agro-ecosystems, it is crucial to develop an updated model for N fertilizers management to achieve higher crop yields while minimizing the negative impacts on the environment. Coated urea is touted as one of the most important controlled-release N fertilizers used in agriculture to reduce cropland emissions and improve nitrogen use efficiency (NUE) for optimal crop yields. The sustainability of coated urea depends on the trade-offs between crop productivity, NUE and greenhouse gas emissions (CO 2 , CH 4 and N 2 O); however, role of various agro-edaphic factors in influencing these trade-offs remains unclear. To determine the effects of soil properties, climatic conditions, experimental conditions, and type of coated urea on greenhouse gas emissions, NH 3 losses, crop productivity, and NUE, we conducted a meta-analysis using data from 76 peer-reviewed studies. Our results showed that the application of coated urea under field conditions contributed to a greater reduction in N 2 O emissions (−48.67%) and higher NUE (58.72%), but crop yields were not significant. Across different climate regions, subtropical monsoon climate showed a perceptible mitigation for CO 2 , CH 4 and NH 3 (−78.38%; −83.33%; −27.46%), while temperate climate reduced N 2 O emissions by −70.36%. For different crops, only rice demonstrated reduction in CO 2 , CH 4 , N 2 O and NH 3 losses. On the other hand, our findings revealed a mitigating trade-off between CO 2 and CH 4 emissions on medium-textured soils and N 2 O emissions on fine-textured soils. A significant reduction in N 2 O and NH 3 losses was evident when coated urea was applied to soils with a pH > 5.5. Interestingly, application of coated urea to soils with higher C/N ratios increased NH 3 losses but showed a noticeable N 2 O reduction. We found that polymer-coated urea reduced CH 4 and N 2 O emissions and NH 3 losses at the expense of higher CO 2 emissions. Moreover, application of a lower dose of coated urea (0–100 kg N ha−1) enhanced CO 2 and CH 4 mitigation, while N 2 O mitigation increased linearly with increasing dose of coated urea. Most importantly, our results showed that the application of coated urea leads to a large mismatch between NUE, crop yields and greenhouse gas mitigation. By and large, the application of coated urea did not correspond with higher crop yields despite significant reduction in the emissions and improved NUE. Overall, these results suggest that site-specific agro-edaphic conditions should be considered when applying coated urea to reduce these emissions and N volatilization losses for increasing NUE and crop yields. • Coated urea led to greater NUE by reducing N 2 O emissions under field conditions. • Rice unequivocally exhibited significant GHGs mitigation and reduced NH 3 losses. • Coated urea reduced CO 2 -CH 4 emissions on medium and N 2 O on fine-textured soils. • Crop yields did not match the improved NUE and GHGs mitigation effects of coated urea. • Efficacy of coated urea fertilizers could depend on the given agro-edaphic conditions. [ABSTRACT FROM AUTHOR]

Enhanced efficiency fertilizers, such as urea treated with a urease inhibitor, controlled-release fertilizers (CRFs), and fertilizer blends, compose important strategies for improving efficiency in nitrogen (N) use by plants and mitigating ammonia (N-NH3) emissions. The physical mixture of fertilizers in blends can favor synchronization of N-release from the fertilizers and N-uptake by coffee plants and also dilute the costs of acquiring a pure CRF, making fertilizer blends more accessible to growers. To investigate this, a field experiment was conducted over two consecutive crop years with Coffea arabica with the aim of evaluating nitrogen fertilizer technologies at application rates ranging from 0 to 450 kg N ha−1. The fertilizers were characterized, and analyses were performed to quantify N-release from the fertilizers, ammonia volatilization, and nutritional and yield aspects of the coffee plant. The fertilizers used were urea (UCon), urea treated with N-(n-butyl) thiophosphoric-triamide (UNBPT), urea-coated with polymer of the E-Max technology (with 41%N (EMax41) or 43%N (EMax43)), and blends of UNBPT with E-Max (Blend41–Blend43). The cumulative N-release for EMax41 always remained below that for EMax43, just as occurred for Blend41 in relation to Blend43. Over the two crop years, the greatest volatilization of N-NH3 occurred with UCon (~25%) and the least with EMax41 (9%). The results indicate that the technologies mitigated the N-NH3 emissions in relation to UCon [EMax41 (63% mitigation) > Blend41 (43%) > EMax43 (32%) > UNBPT (28%) > Blend43 (19%)]. Crop management affects coffee yield. The yield increase went from 20% in the first crop year to 75% in the second, with better results from fertilizers containing CRF. We present information that can assist fertilizer producers and coffee growers, and, above all, we seek to contribute to environmental action for the reduction of agricultural NH3, clarifying potential strategies for mitigation of these emissions and strategies that generate advances in research on technologies for coffee growing.

Novel lignin/paraffin/epoxy resin composite coated urea (LPECCU) was successfully prepared. Paraffin and epoxy resin (ER) were used to improve the slow-release properties of the lignin-based polyurethane (LPU) coated urea. The relationships among the N release characteristics, liquid-solid rate, –CNO/–OH molar rate and film formation rate in the coating material of LPECCU were investigated. The results showed that the water contact angle (WCA) of the LPU-paraffin increased with the rate of liquid-solid rate (73.61–88.19°) and –CNO/–OH molar rate (65.17–82.24°) increased. The average particle hardness of LPECCU decreased with the increased of liquid-solid rate (57.10–66.80 N) and the reduced of –CNO/–OH molar rate (48.11–63.00 N). The LPECCU emerged compact micro-structure, low sustained release and high compressive resistance by adding paraffin and ER. The coating material of LPECCU appeared excellent biodegradability in the soil. The optimal N cumulative release rate (72.49 %) of LPECCU was obtained (liquid-solid rate of 1.43, –CNO/–OH molar rate of 2, and the film formation rate of 6.66 %). The lettuce growth study was conducted to further evaluate the pot application of the LPECCU. In comparison to conventional urea, LPECCU could improve the total dry matter accumulation and N use efficiency of the lettuce. • Novel lignin/paraffin/epoxy resin composite coated urea (LPECCU) was prepared. • The release longevity of LPECCU was related to preparation of coating material. • The coating material appeared excellent biodegradability in the soil. • The LPECCU could improve the N use efficiency and growth of lettuce. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is an important macro-nutrient required for crop production and is considered an important commodity for agricultural systems. Urea is a vital source of N that is used widely across the globe to meet crop N requirements. However, N applied in the form of urea is mostly lost in soil, posing serious economic and environmental issues. Therefore, different approaches such as the application of urea coated with different substances are used worldwide to reduce N losses. Urea coating is considered an imperative approach to enhance crop production and reduce the corresponding nitrogen losses along with its impact on the environment. In addition, given the serious food security challenges in meeting the current and future demands for food, the best agricultural management strategy to enhance food production have led to methods that involve coating urea with different nutrients such as sulfur (S) and zinc (Zn). Coated urea has a slow-release mechanism and remains in the soil for a longer period to meet the demand of crop plants and increases nitrogen use efficiency, growth, yield, and grain quality. These nutrient-coated urea reduce nitrogen losses (volatilization, leaching, and N2O) and save the environment from degradation. Sulfur and zinc-coated urea also reduce nutrient deficiencies and have synergetic effects with other macro and micronutrients in the crop. This study discusses the dynamics of sulfur and zinc-coated urea in soil, their impact on crop production, nitrogen use efficiency (NUE), the residual and toxic effects of coated urea, and the constraints of adopting coated fertilizers. Additionally, we also shed light on agronomic and molecular approaches to enhance NUE for better crop productivity to meet food security challenges. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is an important macro-nutrient required for crop production and is considered an important commodity for agricultural systems. Urea is a vital source of N that is used widely across the globe to meet crop N requirements. However, N applied in the form of urea is mostly lost in soil, posing serious economic and environmental issues. Therefore, different approaches such as the application of urea coated with different substances are used worldwide to reduce N losses. Urea coating is considered an imperative approach to enhance crop production and reduce the corresponding nitrogen losses along with its impact on the environment. In addition, given the serious food security challenges in meeting the current and future demands for food, the best agricultural management strategy to enhance food production have led to methods that involve coating urea with different nutrients such as sulfur (S) and zinc (Zn). Coated urea has a slow-release mechanism and remains in the soil for a longer period to meet the demand of crop plants and increases nitrogen use efficiency, growth, yield, and grain quality. These nutrient-coated urea reduce nitrogen losses (volatilization, leaching, and N2O) and save the environment from degradation. Sulfur and zinc-coated urea also reduce nutrient deficiencies and have synergetic effects with other macro and micronutrients in the crop. This study discusses the dynamics of sulfur and zinc-coated urea in soil, their impact on crop production, nitrogen use efficiency (NUE), the residual and toxic effects of coated urea, and the constraints of adopting coated fertilizers. Additionally, we also shed light on agronomic and molecular approaches to enhance NUE for better crop productivity to meet food security challenges.

An ample quantity of water and sufficient nutrients are required for economical rice production to meet the challenges of ever-increasing food demand. Currently, slow-release nitrogenous fertilizers for efficient inputs utilization and maximum economic yield of field crops are in the limelight for researchers and farmers. In this study, we evaluated the comparative efficacy of conventional urea and coated urea (zinc and neem) on rice grown under aerobic and anaerobic regimes in greenhouse conditions. For the aerobic regime, field capacity was maintained at 80–100% to keep the soil aerated. On the other hand, for the anaerobic regime, pots were covered with a polythene sheet throughout the experimentation to create flooded conditions. All forms of urea, conventional and coated (zinc and neem), improved plant growth, gas exchange, yield, yield contributing parameters, and quality characteristics of rice crop. However, better performance in all attributes was found in the case of zinc-coated urea. Gas exchange attributes (photosynthetic rate, 30%, and stomatal conductance 24%), yield parameters like plant height (29%), tillers per plant (38%), spikelets per spike (31%), grains per panicle (42%), total biomass (53%), and grain yield (45%) were recorded to be maximum in rice plants treated with zinc-coated urea. The highest grain and straw nitrogen contents, grain protein contents, and grain water absorption ratio were also found in plants with zinc-coated urea applications. In irrigation practices, the anaerobic regime was found to be more responsive compared to the aerobic regime regarding rice growth, productivity, and quality traits. Thus, to enhance the productivity and quality of rice grown in anaerobic conditions, zinc-coated urea is best suited as it is more responsive when compared to other forms of urea. [ABSTRACT FROM AUTHOR]

Nitrogen (N) application to agricultural fields warrants curtailing nitrous oxide (N2O) emission and ammonia (NH3) volatilization for improved use efficiency with a less environmental footprint of N. As a means of mitigating N2O emissions, the efficacy of nitrification inhibitors (NIs) is well established but the efficacy of NIs in reducing NH3 volatilization is not well understood. The study investigated the efficacy of neem oil, pomegranate leaf extract, and dicyandiamide (DCD) coating on prilled urea for reducing N2O emissions and the trend of NH3 release using static air closed chamber technique in an incubation room. The results showed that all NIs reduced N2O flux in the order of 37%-42% by DCD urea, 19%-34% by neem oil coated urea (NOCUs), and 11%-16% by pomegranate leaf extract coated urea (PLECU). However, over uncoated urea, 43%-54% NH3 flux was increased by DCD, 10%-32% by NOCUs, and significantly the least increase (5%-14%) in NH3 cumulative flux was shown by PLECU. Dicyandiamide significantly reduced N2O flux more than all other treatments, and PLECU showed the least increase in NH3 emission when compared with other coated treatments. Hence, it is suggested that neem oil and pomegranate leaf extract could be used successfully not only for mitigating N2O emission, but also lessen environmental damages in association with managed N intense agriculture. Moreover, research focus on the increase in NH3 volatilization using DCD needs serious attention, especially in alkaline calcareous soils. [ABSTRACT FROM AUTHOR]

An ample quantity of water and sufficient nutrients are required for economical rice production to meet the challenges of ever-increasing food demand. Currently, slow-release nitrogenous fertilizers for efficient inputs utilization and maximum economic yield of field crops are in the limelight for researchers and farmers. In this study, we evaluated the comparative efficacy of conventional urea and coated urea (zinc and neem) on rice grown under aerobic and anaerobic regimes in greenhouse conditions. For the aerobic regime, field capacity was maintained at 80–100% to keep the soil aerated. On the other hand, for the anaerobic regime, pots were covered with a polythene sheet throughout the experimentation to create flooded conditions. All forms of urea, conventional and coated (zinc and neem), improved plant growth, gas exchange, yield, yield contributing parameters, and quality characteristics of rice crop. However, better performance in all attributes was found in the case of zinc-coated urea. Gas exchange attributes (photosynthetic rate, 30%, and stomatal conductance 24%), yield parameters like plant height (29%), tillers per plant (38%), spikelets per spike (31%), grains per panicle (42%), total biomass (53%), and grain yield (45%) were recorded to be maximum in rice plants treated with zinc-coated urea. The highest grain and straw nitrogen contents, grain protein contents, and grain water absorption ratio were also found in plants with zinc-coated urea applications. In irrigation practices, the anaerobic regime was found to be more responsive compared to the aerobic regime regarding rice growth, productivity, and quality traits. Thus, to enhance the productivity and quality of rice grown in anaerobic conditions, zinc-coated urea is best suited as it is more responsive when compared to other forms of urea.

Resulting from the positive effect on rice productivity, the application of biochar and controlled-release urea in the form of polymer-coated urea (PCU) in crop production attracts more and more interest. However, field studies considering the combined effect of biochar and PCU are rare. This 2-year study examined the combined effects of biochar and PCU on yield, yield components, plant height, plant nitrogen concentration and nitrogen recovery efficiency in a waterlogged rice field. Experimental treatments combined two biochar rates (0 and 2800 kg ha−1) and three nitrogen rates (0, 120 and 180 kg N ha−1). The results showed a yield decrease under biochar application without nitrogen fertilizer. The application of 120 kg N ha−1 PCU and biochar had the highest yield in 2017. No significant differences of grain yields were indicated between 120 and 180 kg N ha−1. High grain yield and nitrogen use efficiency was obtained with 120 kg N ha−1 PCU. Therefore, 120 kg N ha−1 PCU can be recommended for rice production in this area. [ABSTRACT FROM AUTHOR]

Urea–nitrogen is commonly lost through ammonia (NH3) volatilization, denitrification, and nitrate (NO3−) leaching. Rejected sago starch (RSS), which is a by-product of sago flour extraction, could be used to minimize NH3 volatilization from urea. Urea granules were coated with different concentrations of RSS (2%, 3%, 4%, 5%, and 6%), and their effects on NH3 emission, soil pH, exchangeable ammonium (NH4+), and available NO3− were determined. The urea was coated with RSS and homogenized using a mini rotary machine. The RSS-coated urea granules were dyed to differentiate their concentrations. The effectiveness of the RSS as a coating material was determined using a closed-dynamic air flow system. The soil used in the NH3 volatilization was the Bekenu series (Sandy loam, Typic Paleudults). This study compared seven different mixture treatments: soil alone (S), 5 g of uncoated urea (U), 5 g of 2% RSS-coated urea (CU1), 5 g of 3% RSS-coated urea (CU2), 5 g of 4% RSS-coated urea (CU3), 5 g of 5% RSS-coated urea (CU4), and 5 g of 6% RSS-coated urea (CU5). Urea coated with RSS, particularly CU1, effectively minimized NH3 loss and improved the retention of soil exchangeable NH4+ and available NO3− compared with uncoated urea because the RSS serves as a barrier to minimizing the concentration of NH3 from urea hydrolysis. Urea could be coated with RSS at the 2% concentration to enhance urea–N efficiency through a reduction in NH3 emission from urea. RSS-coated urea could be an alternative for farmers because of its controlled release of N and economical benefits. Field planting using rice as a test crop to solidify the effectiveness of RSS-coated urea in improving N retention from urea is still ongoing. [ABSTRACT FROM AUTHOR]

To elucidate the effects of slow-release fertilizers on nitrous oxide (N2O) emission from fields with winter wheat cultivation in cool-temperate regions, we conducted a two-year field experiment in Hokkaido. Four types of fertilizer treatment, i.e., urea (U), coated urea (CU), coated calcium nitrate (CC), and no nitrogen fertilizer (NN) were investigated. In the U treatment, urea was applied at 40 and 90 + 60 kg N ha−1 in autumn and in spring, respectively. In the CU and CC treatments, all the nitrogen (190 kg N ha−1) was applied using coated fertilizers in autumn for the first cultivation, whereas nitrogen was applied at 130 kg N ha−1 using the coated fertilizers in autumn and the remaining 60 kg N ha−1 was applied using urea in spring for the second cultivation. The magnitudes and seasonal courses of N2O flux did not largely differ among the treatments (i.e., types of fertilizer), including the NN treatment in most of the experimental periods except that the N2O fluxes were higher in the U and CU treatments than in the CC and NN treatments at the beginning of the second wheat cultivation. In all the treatments, the N2O flux showed the highest peak immediately after basal fertilization, followed by other small peaks in autumn. After the next spring, the N2O flux consistently remained low until the wheat harvest including immediately after the end of snowmelt and after supplemental fertilizations. Cumulative N2O emissions tended to be lower in the CC treatment than in the U and CU treatments, although these differences in the emissions were not statistically significant. Although the wheat grain yields were lower in the CU and CC treatments than in the U treatments, the differences were small for the second wheat cultivation. These results indicate that reduction in N2O emission with no decrease in the wheat yield can be achieved by the basal application of slow-release nitrate fertilizer combined with the supplemental application of conventional fertilizer in winter wheat cultivation in Hokkaido, although further studies are still necessary to determine the optimum allocation levels of the basal and supplemental nitrogen applications. [ABSTRACT FROM AUTHOR]

Low nitrogen (N) use efficiency from urea fertilizers due to environmental losses results in high cost of fertilizers for agricultural productions. Coating of urea with biodegradable polymers makes them effective for control and efficient N release. In this study, starch and polyvinyl alcohol (PVA) were used in combination with acrylic acid (AA), citric acid (CA) and maleic acid (MA) for the coating of urea prills. Different formulations of the coating were prepared and applied on urea prills such as urea coated with starch (10%) and PVA (5%) with acrylic acid: 2, 4 and 6% (USP-A2, USP-A4, USP-A6), with citric acid: 2, 4 and 6% (USP-C2, USP-C4, USP-C6), and with maleic acid: 2, 4 and 6% (USP-M2, USP-M4, USP-M6). After urea coating in fluidized bed coater, all uncoated and coated urea samples were characterized by scanning electron spectroscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), crushing strength and UV-Vis spectroscopy. The morphological and XRD analysis indicated that a new uniform coating with no new phase transformation occurred. Among all urea coated samples, USP-A2 and USP-C2 showed the highest crushing strengths: 12.08 and 13.67 N with nitrogen release efficiency of 70.10 and 50.74% respectively. All coated urea samples improved the spinach plants’ foliage yield, chlorophyll content, N-uptake and apparent nitrogen recovery (ANR) than uncoated urea and control plants. However, USP-A2 and USP-C2 provided promising results among all coated samples with dry foliage yield (2208 ± 92 and 2428 ± 83 kg/ha), chlorophyll (34 ± 0.6 and 34 ± 0.4 mg/g), N-uptake (88 ± 4 and 95 ± 6 kg/ha) and ANR (59 ± 4 and 67 ± 6%). Therefore, urea prills coated with a combination of biodegradable polymers can be a better choice for the farmers to enhance agronomical productions by controlling the fertilizer nutrient release rate.

Urea coated with only sulfur is prone to cracking and exhibits poor controlled-release characteristics. Conversely, employing polymers as the sole coating material is expensive and not easily biodegradable. To address these challenges, polysulfide castor oil–based polyols with varying sulfur contents (PSOPs-30 %, PSOPs-40 %, PSOPs-50 %, and PSOPs-60 %) were successfully synthesized using a simple chemical process. This process utilized castor oil and elemental sulfur as primary raw materials. Subsequently, PSOPs-30 % and PSOPs-40 % were cured to form films (P-30 % and P-40 %) and coated urea (PSCUF-30 % and PSCUF-40 %). The synthesis process, mechanism, and physical and chemical properties of PSOPs revealed that the amount of sulfur involved in polymerization was not proportional to the initial amount of sulfur added. The structure and thermal stability of PSOPs were characterized using Fourier-transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR), and thermogravimetric analysis (TGA). Minor variations in crosslinking degree and sulfur content between P-30 % and P-40 % caused some differences in mechanical properties, shore hardness, water absorption, and water contact angles. TG-FTIR analysis of P-30 % and P-40 % indicated the generation of carbonyl sulfide throughout the process, predominantly in the early stage and very few in the later stage. The cumulative nitrogen release times for PSCUF-40 %–7.0 % and PSCUF-30 %–7.0 % were 50 and 60 days, respectively. In terms of degradability, whether in distilled water or NaOH solution with pH 8, the degradation rate of P-40 % was higher than that of P-30 %, reaching 6.55 % and 6.92 % over 70 days. In addition, methyl ricinoleic (MCO) was utilized as a polyol to prepare PCUF-MCO for comparative analysis. • Polysulfide castor oil-based polyols with a low cost were prepared using castor oil and elemental sulfur. • The film has the advantages of low cost, good mechanical properties, low water absorption, and good thermal stability. • Degradation rate reached 6.92 % for 70 days in NaOH solution. • The cumulative nitrogen release time of coated urea was more than 60 days. [ABSTRACT FROM AUTHOR]

Fertilizer encapsulation through polymer membranes can reduce fertilizer losses and minimize environmental pollution. In this paper, an emulsion of ethyl cellulose (EC)/vinyl acetate (VAc)/butyl acrylate (BA) was successfully prepared by pre-emulsified semi-continuous seed emulsion polymerization. EC/BA/VAc films showed biodegradability. The influence of the EC content on the properties of EC/BA/VAc films was also investigated by DSC, a water absorbency analysis, etc. Controlled-release urea encapsulated by EC/BA/VAc latex was prepared in a film coating machine and conformed to the standards for slow-release fertilizers of the Committee of European Normalization. The release of urea from controlled-release urea encapsulated by EC/BA/VAc latex containing 0%, 5%, 10%, and 15% EC was 75.1%, 65.8%, 70.1% and 84.1%, respectively, after 42 days, and controlled-release urea encapsulated by EC/BA/VAc latex (5% EC) had the best controlled-release ability. Therefore, controlled-release urea encapsulated by EC/BA/VAc latex has many potential applications in agricultural industry.

Urea–nitrogen is commonly lost through ammonia (NH3) volatilization, denitrification, and nitrate (NO3−) leaching. Rejected sago starch (RSS), which is a by-product of sago flour extraction, could be used to minimize NH3 volatilization from urea. Urea granules were coated with different concentrations of RSS (2%, 3%, 4%, 5%, and 6%), and their effects on NH3 emission, soil pH, exchangeable ammonium (NH4+), and available NO3− were determined. The urea was coated with RSS and homogenized using a mini rotary machine. The RSS-coated urea granules were dyed to differentiate their concentrations. The effectiveness of the RSS as a coating material was determined using a closed-dynamic air flow system. The soil used in the NH3 volatilization was the Bekenu series (Sandy loam, Typic Paleudults). This study compared seven different mixture treatments: soil alone (S), 5 g of uncoated urea (U), 5 g of 2% RSS-coated urea (CU1), 5 g of 3% RSS-coated urea (CU2), 5 g of 4% RSS-coated urea (CU3), 5 g of 5% RSS-coated urea (CU4), and 5 g of 6% RSS-coated urea (CU5). Urea coated with RSS, particularly CU1, effectively minimized NH3 loss and improved the retention of soil exchangeable NH4+ and available NO3− compared with uncoated urea because the RSS serves as a barrier to minimizing the concentration of NH3 from urea hydrolysis. Urea could be coated with RSS at the 2% concentration to enhance urea–N efficiency through a reduction in NH3 emission from urea. RSS-coated urea could be an alternative for farmers because of its controlled release of N and economical benefits. Field planting using rice as a test crop to solidify the effectiveness of RSS-coated urea in improving N retention from urea is still ongoing.

Copyright of Journal of Soil Sciences & Agricultural Engineering is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nitrogen is indispensable for aggrandizing productivity of crop but the losses associated due to swift transformation and release pattern are subjected to various losses leading to pitiful amount left for crop uptake, pollution and resource wastage. Present study was conducted to evaluate the efficacy of coated urea and nitrogen rates on baby corn growth, yield and NUE. The experiment comprised varieties PHM-1 and HM-4, coated urea (NCU, ZCU, SCU and PU) and nitrogen levels @180, 150, 120 kg N/ha along with the control. The study revealed that PHM-1 obtained significantly higher plant height, no. of cobs and weight of dehusked cob that led to significant increase of 18.47 and 19.67 % higher husked and dehusked cob yields over HM-4 which attained 12.6% higher fodder yield over latter. The baby corn cob yield and fodder yield were significantly higher in coated urea over prilled urea. The husked and dehusked yield of baby corn was higher in neem-coated urea over prilled urea by 14.81 and 14.37% respectively. H o w e v e r , a reduction of 59.9% in total fodder yield was recorded in control when compared to 180 kg N ha. Also, NPK uptake was higher then PHM-1 and uptake by coated urea was higher then prilled urea along with high uptake for 180 kg N/ha, further the AE and higher PE of baby corn cob was found highest in variety PHM-1 although for fodder, the higher AE was recorded in HM-4, whereas ANR was higher in PHM-1.

Nitrogen (N) fertilizers may acidify the soil mainly after nitrification followed by nitrate leaching. The rate of N released and the dynamic of its reactions in the soil may interfere in soil acidification. This experiment was carried out to evaluate the N release rate and the soil acidification caused by N fertilizer application. Treatments include urea, ammonium nitrate, and six coated fertilizers, all applied at the rate of 300 mg kg−1 N, in addition to control, with no N. They were homogeneously mixed with 100 g of soil and allocated in plastic pots with the moist soil. Mineral N and soil pH were evaluated at 4, 7, 14, 21, 28, 35, 42, 49, and 56 days after fertilizer application. All N fertilizers decreased linearly the soil pH over time, except for ammonium nitrate. Ammonium was the N form predominant in the soil up to day 35 for all fertilizers, except for ammonium nitrate. Urea coated with sulfur + polymers released 90% of its N only from 42nd day after application, differing from other fertilizers. Nitrogen coated fertilizers were not efficient in reducing soil acidification and only urea coated with sulfur plus polymers showed characteristics of a slow-release fertilizer. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To improve the use efficiency of fertilizer and to reduce the rate of nitrogen release, a coated urea was prepared using clay-polymer nanocomposites (CPU). Sepiolite and chitosan were used to form nanocomposites with different clay mineral/polymer ratios. The nanocomposites and CPUs were characterized using several techniques including Fourier Transform Infrared (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) specific surface area measurement. The FTIR examination revealed functional groups related to chitosan that interacted with sepiolite. The nitrogen release of CPUs was examined in the sand column showing that 75% of nitrogen content of CPU samples released in about 25 d, much longer than that of urea (3 d) and the rate of release of nitrogen was reduced by increasing the proportion of sepiolite in the clay/polymer nanocomposites. The release mechanism of CPUs was evaluated and the results showed the mechanism was not Fickian diffusion but anomalous diffusion. The nutrient use efficiency of CPUs was studied under greenhouse conditions using Zea mays (corn) as the test plant and a significant efficiency improvement was observed. The results showed that the CPUs with slow-release properties could be considered as efficient N fertilizers in agricultural and horticultural applications. [ABSTRACT FROM AUTHOR]

The knowledge of type of fodder/forages fed to animal is very important to determine how to best meet the amount of nutrients required for animal maintenance and production. The following study was undertaken to boost nutritive value of baby corn fodder. The primary objective of the study was to assess the amenable agronomic traits, viz. cultivars, sources of urea and nitrogen levels in manipulating the quality factors of baby corn fodder, viz. dry matter content, crude protein, ether extract, ash content, acid detergent fibre, dry matter intake, dry matter digestibility, neutral detergent fibre, net energy requirement, total digestible nutrients, relative feed quality and relative feed value. The experiment was piloted during 2016–17 and 2017–18 at research farm of Agronomy section, ICAR-National Dairy Research Institute, Karnal, India. The treatments consisted of two varieties of baby corn (PHM-1 and HM-4), four-coated urea (Neem coated urea, zinc coated urea, sulphur coated urea and prilled urea) and four nitrogen levels (180, 150, 120 kg N/ha and control). All the quality parameters of fodder improved with progression in dose of fertilizer nitrogen. The highest values of said indices were statistically cogent with application of nitrogen at level 180 kg/ha whereas, DM, NDF and ADF showed a significant reduction at 180 kg N/ha compared to control (no fertilizer applied). The baby corn fodder fertilized with nitrogen dose 180 kg/ha showed better crude protein content, had less fibre, improved dry matter digestibility and intake, more digestible nutrients and higher feed value and quality.

High fertilizer inputs augment the reactive nitrogen level in soil, air, and water. Unused reactive nitrogen acts as a pollutant and harms natural resources. This study focused on the thermal processing of corn starch into a coating material using di-sodium tetraborate and urea. The processed corn starch was coated over granular urea in a vertical bed coating reactor. The chemically modified starch, when compared with native starch, exhibited better stability and mechanical strength over time. The modified starch looked like a weak gel, and its loss modulus was dominated by the storage modulus. However, for native starch, the viscous component dominated the elastic component, especially at lower angular frequencies. The nitrogen release from the coated urea was remarkably slower than the uncoated one. A small difference in the peak and final starch viscosities in the presence of urea and borate revealed low thermal cracking of the starch molecules. The surface of the granular urea that was coated with chemically modified corn starch was uniform, dense, hard, and least porous. The uncoated urea granules became released into water in 6 min under gentle shaking, whereas the coated urea took almost 32 min to completely release. [ABSTRACT FROM AUTHOR]

In this work, the polyurethane coated urea (PCU) and PE coated urea (PECU) were prepared by spraying the coating material. The isocyanates coatings on the surface of urea and granule inorganic compound fertilizer (NPK) were prepared and their infrared spectra were compared. The polyurethane coatings of PCU was analyzed by IR. The interface morphology between the PU coating and PE coating PECU and the surface of urea was compared by scanning electron microscope. The inner and outer surfaces morphology of polyurethane coatings was studied. The results showed that the peak of -NCO groups in the infrared spectrum of the coating on urea was weaker than of the coating on NPK, while the peaks of N-H, C-N and C = O were all relatively stronger, which proved that -NH2 in urea reacted with -NCO during the coating formation. SEM images showed that there was an obvious gap between PE coating and its urea core, while PU coating was tightly bonded with the surface of urea core, and the inner surface of PU coating had something undissolved after fully dissolved in water, which further illustrated that urea participate in the reaction of isocyanates with polyols. All of this results demonstrated that the amine group (-NH2) in urea reacted with the -NCO group in isocyanates and urea linkage (-NH-CO-NH-) was formed in the polyurethane coating. [ABSTRACT FROM AUTHOR]

To address nitrogen (N)-related environmental pollution, development of an economical, slow-release urea fertilizer is the need of the hour. A study was conducted on the reduction of nitrogen released from granular urea fertilizer by applying sulfur, gypsum, bentonite, and starch as coating material. Paraffin wax was used as a binder. The dissolution rates were studied by changing the composition of coating mixture using high-performance liquid chromatography. SEM was used to study the morphology of coated urea in terms of smoothness and uniformity. The ultraviolet spectroscopy analysis further authenticated the release behavior of coated urea in terms of nitrogen concentration. Coating material reduced the release rate of nitrogen from urea fertilizer, significantly. Mixture of sulfur and gypsum coating on urea gave slowest release rate of nitrogen from urea fertilizer, i.e., 37%, as compared to uncoated urea and thus seems to be the most promising binding material for product development. [ABSTRACT FROM AUTHOR]

[Objective]The objective of this study is to investigate the possibility of single application of nitrogen fertilizer during the entire growing season of Maize through testing the characteristics of nitrogen release of both sulfur-coated and polymer-coated urea respectively under simulating and field conditions in situ. [ Method] In 2013 , both indoor simulating experiment and field experiment in situ were carried out, and only the field experiment in situ in 2014. Release-in-water method is used for indoor simulating and release-in-soil method in field with 94, 188 kg • hm-2N rates and single and double application ( pop-up at seeding and side-dressing at stem-elongation) methods resulting 7 treatments in total. Treatments were arranged in RGB with three replicates. Nitrogen rate was set at 156 kg • hm-2 and the number of treatments was 6 with 4 replicates in 2014. [ Result] The results showed that at 20 °C , the initial nitrogen release rate in water for SCU was bigger than 40. 00 % , and declined to 1.67 % /day in the 10 day middle period, while the lowest release rate of 0. 38 %/day was found in the 50 days long later period. Higher temperature increased the nitrogen release rate of SCU and shortened the release period. At 20 °C for the PCU in water release, four nitrogen release periods were distinguished as 0.30, 0.95, 0.45, andO. 14 %/day respectively. When the temperature was increased to 30 °C 9 the nitrogen release rate increased to 1.82 %/dav and the release period shortened from 155 to 44 days. Under the field conditions at 94, 188, 156 kg • hm-2 nitrogen rates, nitrogen release rate of single application of SCU was characterized by being higher in early stage and lower in later stage at 94 kg • hm-2 , while the double application method showed a relatively lower available nitrogen due to the split application at stem elongation. The nitrogen release model of both PCU and HUP (half urea plus half polymer-coated-u-rea) were comparable to that of double application of urea. [ Conclusion] It is concluded that both single application of PCU and single application could replace the conventional double nitrogen application method while the single application of SCU could not. [ABSTRACT FROM AUTHOR]

The concentration of Cu (Copper) and Zn (Zinc) decreases upon flooded conditions of rice soil. To assess the effects of flooding and application of Cu and Zn coated urea on changes in Eh, pH and solubility of Cu and Zn, a glasshouse experiment was conducted at Universiti Putra Malaysia. Rice plants (30 days old seedlings of type MR-219) on two soils (riverine and alluvium and marine alluvium) were transplanted. Nine treatments with variable rates and combinations of Cu and Zn coated urea were applied. The sources of fertilizers were copper sulfate and zinc sulfate. Eh values decreased with flooding time in both soils. The changes of Eh values were more negative in control treatments and stabilized after 3 weeks of submergence. The Eh variation was not observed affectively in the treated soils however, soil pH increased with flooding time. During the 3rd week of submergence, pH was neutral (pH 7.0). In both soils, Cu and Zn treated soil showed lower Eh and higher pH values as compared to untreated soil. Concentration of Cu and Zn in soil solution decreased with flooding. The higher Cu and Zn contents in soil were recorded in treated soils. Reduced solubility of Cu and Zn in control soils was related to larger changes in Eh and pH values. Mean comparison with Tukey's HSD (Honest Significant Difference) test showed that Cu and Zn solubility decreased with decreased Eh and increased pH in the soil solution (p < 0.05%). [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)