Application Of Polymer-coated Urea Research Articles

Polymer-coated urea applied at one-time mechanical topdressing increases nitrogen use efficiency and rice yield in the cold area

Context The application of slow and controlled release fertilisers can reduce nitrogen loss, but the research is still scarce in the cold rice region of China. Aims The study was conducted to screen slow-release or controlled-release fertilisers which can meet the nitrogen demand of rice and reduce NH3 volatilisation in different pH soils. Methods This experiment includes four fertilisation treatments: no fertiliser (control), urea, urea with N-(n-butyl) thiophosphorictriamide (NBPT), and polymer-coated urea (PCU). The amounts of urea-N, pH, ammonium-N (NH4+-N) in the surface water, and NH3 volatilisation were determined. Thereafter, to evaluate the effects of one-time mechanical topdressing of PCU mixed with compound fertilisers along with farmers’ fertilisation practice (FFP), field experiments carried out in wide soil pH differences were conducted. Key results Cumulative NH3 volatilisation was reduced in the NBPT treatment compared with the urea treatment. There was no significant difference between urea-N, NH4+-N, and pH in the surface water under PCU and control. NH3 volatilisation of PCU is negligible and significantly prolongs the soil nitrogen storage time. In the subsequent experiment, PCU blend increased yield, dry matter, nitrogen uptake, and the partial factor productivity of applied nitrogen (PFPN) compared to FFP. Conclusions PCU treatment slows down urea release and reduces ammonia volatilisation from paddy fields. In turn, it reduces ammonia-nitrogen levels and pH in surface water and further slows down the rate of ammonia volatilisation. Implications Application of PCU as a one-time mechanical topdressing fertiliser in rice fields in cold regions saves nitrogen fertiliser, increases crop yields, and reduces labour.

Split application of polymer-coated urea combined with common urea improved nitrogen efficiency without sacrificing wheat yield and benefits while saving 20% nitrogen input.

Controlled-release nitrogen fertilizer (CRNF) has been expected to save labor input, reduce environmental pollution, and increase yield in crop production. However, the economic feasibility is still controversial due to its high cost. To clarify the suitable application strategy of CRNF in promoting the yield, nitrogen use efficiency and income on wheat grown in paddy soil, four equal N patterns were designed in 2017-2021 with polymer-coated urea (PCU) and common urea as material, including PCU applied once pre-sowing (M1), PCU applied 60% at pre-sowing and 40% at re-greening (M2), 30% PCU and 30% urea applied at pre-sowing, 20% PCU and 20% urea applied at re-greening (M3), and urea applied at four stage (CK, Basal:tillering:jointing:booting=50%:10%:20%:20%). In addition, M4-M6, which reduced N by 10%, 20% and 30% respectively based on M3, were designed in 2019-2021 to explore their potential for N-saving and efficiency-improving. The results showed that, compared with CK, M1 did not significantly reduce yield, but decreased the average N recovery efficiency (NRE) and benefits by 1.63% and 357.71 CNY ha-1 in the four years, respectively. M2 and M3 promoted tiller-earing, delayed the decrease of leaf area index (LAI) at milk-ripening stage, and increased dry matter accumulation post-anthesis, thereby jointly increasing spike number and grain weight of wheat, which significantly increased yield and NRE compared with CK in 2017-2021. Due to the savings in N fertilizer costs, M3 achieved the highest economic benefits. With the 20% N reduction, M5 increased NRE by 16.95% on average while decreasing yield and net benefit by only 6.39% and 7.40% respectively, compared with M3. Although NRE could continue to increase, but the yield and benefits rapidly decreased after N reduction exceeds 20%. These results demonstrate that twice-split application of PCU combined with urea is conducive to achieving a joint increase in yield, NRE, and benefits. More importantly, it can also significantly improve the NRE without losing yield and benefits while saving 20% N input.

A combination of straw incorporation and polymer-coated urea offsets soil ammonia and nitrous oxide emissions in winter wheat fields

The combined effects of straw incorporation (SI) and polymer-coated urea (PCU) application on soil ammonia (NH3) and nitrous oxide (N2O) emissions from agricultural fields have not been comprehensively evaluated in Northwest China. We conducted a two-year field experiment to assess the effects of combining SI with either uncoated urea (U) or PCU on soil NH3 emissions, N2O emissions, winter wheat yields, yield-scaled NH3 (INH3), and yield-scaled N2O (IN2O). Five treatments were investigated, no nitrogen (N) fertilizer (N0), U application at 150 kg N ha–1 with and without SI (SI+U and S0+U), and PCU application at 150 kg N ha–1 with and without SI (SI+PCU and S0+PCU). The results showed that the NH3 emissions increased by 20.98–34.35% following SI compared to straw removal, mainly due to increases in soil ammonium (NH4+-N) content and water-filled pore space (WFPS). SI resulted in higher N2O emissions than under the S0 scenario by 13.31–49.23% due to increases in soil inorganic N (SIN) contents, WFPS, and soil microbial biomass. In contrast, the PCU application reduced the SIN contents compared to the U application, reducing the NH3 and N2O emissions by 45.99–58.07 and 18.08–53.04%, respectively. Moreover, no significant positive effects of the SI or PCU applications on the winter wheat yield were observed. The lowest INH3 and IN2O values were observed under the S0+PCU and SI+PCU treatments. Our results suggest that single PCU applications and their combination with straw are the optimal agricultural strategies for mitigating gaseous N emissions and maintaining optimal winter wheat yields in Northwest China.

Single-Time Mechanical Deep Placement Fertilization Using Bulk Blending Fertilizer on Machine-Transplanted Rice: Balanced Yield, Nitrogen Utilization Efficiency, and Economic Benefits

Despite growing interest in controlled-release N fertilizers (CRNFs) because of their potential for enhancing nitrogen use efficiency (NUE) and economic returns, their comprehensive impact on machine-transplanted rice remains to be understudied. To address this gap, here, we present a two-year field experiment that assessed the impact of CRNF using mechanical deep placement fertilization (DPF) on rice cultivation. The study involved three CRNF types (bulk blending fertilizer (BBF), polymer-coated urea (PCU), and sulfur-coated urea (SCU)) and two fertilization methods (DPF and broadcast application), with a high-yield split fertilization of urea as a control (CK). The results showed that DPF, especially with SCU, greatly enhanced soil NH4+-N concentrations, NUE, rice yield, and economic benefits compared to broadcast application. BBF consistently exhibited superior NUE and notable economic benefits, regardless of the application method used. Conversely, single-time application of PCU was less favorable for rice growth. In conclusion, for optimal economic benefits and NUE, DPF combined with single-time application of SCU is recommended. However, if deep application is not feasible and only broadcasting is possible in rice cultivation, BBF emerges as the ideal choice for both high NUE and significant economic returns. This research offers insights for improved nitrogen management in machine-transplanted rice, effectively optimizing yield, NUE, and profitability.

Controlled-release nitrogen fertilizer application mitigated N losses and modified microbial community while improving wheat yield and N use efficiency

The extensive application of traditional fertilizer has greatly contributed to wheat yield, accompanied by massive nitrogen (N) loss and environmental pollution. Controlled-release nitrogen fertilizer (CRNF) is expected to improve N use efficiency (NUE) in agricultural systems. Unfortunately, the mechanism by which CRNF reduces N loss and its response to soil microbial communities remains unclear. In this study, common urea, polymer-coated urea (PCU), sulfur-coated urea (SCU) and urea-formaldehyde (UF) were used as materials to analyze the effects of split application of different N sources on wheat yield, NUE, soil N balance, soil bacterial diversity and functional abundance. The results showed that PCU and SCU significantly improved yield relative to urea, with an average increase of 18.20% and 15.73%, respectively. N uptake by wheat in PCU, SCU and UF was increased by 18.76%, 14.26% and 7.75% compared to that in urea, respectively. CRNF increased the mineral N content of the topsoil (0−20 cm) but decreased the mineral content in the deeper soil (40−60 cm). CRNF was observed to significantly decrease cumulative N2O emissions, as well as apparent N loss compared with urea, which was reduced by 39.45%, 30.74% and 11.68% in PCU, SCU and UF, respectively. In addition, PCU decreased soil bacterial diversity but increased the abundance of microbes involved in N cycle, such as Firmicutes, Actinobacteriota and Bacteroidota, which could regulate soil nitrate concentrations. The results indicated that split application of PCU was conducive to promoting N uptake by wheat, increasing topsoil mineral N content, reducing N leaching into deeper soil and N2O emissions, thereby alleviating N loss while increasing NUE and wheat yield.

Effects of coated and briquette urea on yield and nitrogen use efficiency of rice at Rampur, Chitwan, Nepal

Nitrogen is one of the most limiting element for the growth and yield of rice. However, the imbalance use of conventional urea leads to loss of nitrogen from rice field, decrease nitrogen use efficiency, increase environmental pollution and cost of cultivation. This study was done to evaluate the response of polymer coated urea (PCU) and urea briquette (UB) on the yield and nitrogen use efficiencies (NUE) of rice on a sandy loam soil. The experiment was conducted at the agronomy research farm of Agriculture and Forestry University during the rainy season of 2018 in a randomized complete block design with three replications for each treatment (T1 - control, 0 kg N ha-1; T2- Prilled urea, 150 kg N ha-1 single application at basal; T3- Prilled urea, 150 kg N ha-1 standard split application; T4-PCU, 150 kg N ha-1 single application at basal; T5-UB, 150 kg N ha-1 single application at basal). The data on yield, and NUE were recorded and analyzed by using R studio. The physical and economic maximum dose of Nitrogen for these different types of urea were also calculated. Compared with single application of Prilled urea (3698 kg ha-1), rice fertilized with Prilled urea with standard split application (4747 kg ha-1), single application of PCU (5183 kg ha-1) and BU (4787 kg ha-1) had significantly higher grain yield and NUE. Economic maximum dose of nitrogen was reduced greatly for the single application of PCU (124 kg N ha-1) compared to Prilled urea with standard split application (167 kg N ha-1). Single application of PCU and UB can be considered as an alternative nitrogen fertilizer for rice even in the sandy loam soil.

Polymer-coated urea application can increase both grain yield and nitrogen use efficiency injaponica-indicahybrid rice

AbstractWe investigated whether the one-time application of polymer-coated urea (PCU) before transplanting could simultaneously improve the grain yield and nitrogen use efficiency (NUE) ofjaponica-indicahybrid rice (JIHR) through a field experiment. The local high-yield JIHR cultivar Chunyou-927 was field grown during the rice-growing seasons in 2019 and 2020. The experiment consisted of three treatments: no nitrogen application (0N), application of conventional urea (CU), and the one-time application of PCU. Grain yield was 1.0–1.3 t/ha higher, and agronomic NUE (kg grain yield increase per kg N applied) was 5.2–5.9 kg/kg higher, respectively, under the PCU treatment compared with the CU treatment across the two study years. When compared with the CU treatment, the PCU treatment could (1) improve root morphological trait, (2) reduce redundant vegetative growth during the early growth period, (3) increase matter production during the mid and late growth period, and (4) increase plant activity during the grain-filling period. Overall, our findings indicate that one-time PCU application before transplanting of the JIHR cultivar holds great promise for increasing grain yield and NUE.

Contrasting response of wheat to one-time root zone fertilization of ordinary and polymer coated urea for grain yield and nitrogen use efficiency

Appropriate fertilization methods and high efficiency of N fertilizers are crucial to achieve high yields and curtail N losses. This study documented the comparative effectiveness of one-time root zone fertilization (ORZF) and polymer coated urea (PCU) as alternate ways to enhance grain yield and reduce potential N losses in wheat. The study was planned using two N fertilization methods [split-surface broadcasting (SSB) and ORZF], two N sources [ordinary urea (OU) and PCU] along with a control treatment following a completely randomized design. The SSB proved more efficient by showing 9% higher grain yield than ORZF, irrespective of N sources. The PCU resulted in 8% and 10% more grain yield than OU when applied through SSB and ORZF method, respectively. Likewise, maximum total N uptake was achieved with PCU than OU with an increment of 15% (SSB) and 7% (ORZF). The NUE indices remained statistically similar between methods, however, SSB showed higher values than ORZF. On the other hand, N sources had a pronounced effect on these indices which improved considerably with the PCU than OU under both methods. Maximum N losses were quantified with the OU in both methods (56% in SSB, and 54% in ORZF). Conversely, these losses were significantly reduced to 42% in SSB and to 48% in ORZF with the addition of PCU. The findings suggested that the application of PCU can be an effective way to improve wheat productivity and reduce N losses but ORZF is not a suitable alternative to SSB for wheat crops.

Twice-split application of controlled-release nitrogen fertilizer met the nitrogen demand of winter wheat

As a new long-acting fertilizer, controlled-release nitrogen fertilizer (CRNF) has been shown to increase crop yield and improve nitrogen use efficiency (NUE) of fertilizer in many production systems. However, due to the limitation of nutrient release longevity of CRNF and the nitrogen demand characteristics of winter wheat (Triticum aestivum L.), further study is needed on the appropriate application technology of CRNF. In the present study, using polymer-coated urea (PCU) and sulfur-coated urea (SCU) as materials, the characteristics of nitrogen release from one-time or twice-split application of CRNF and its effect on the nitrogen uptake and growth of wheat were investigated in a two-year field experiment. The results indicated that nitrogen release from the twice-split application of PCU and SCU was synchronized with the nitrogen demand of wheat at different stages. Compared with urea multiple-split application (CK) and CRNF one-time application (PCU1 and SCU1), CRNF applied twice, at pre-sowing and re-greening (PCU2 and SCU2), maintained a high level of soil inorganic nitrogen after jointing, which met the second peak demand for nitrogen and improved the nitrogen uptake of wheat. Both PCU2 and SCU2 were found to be beneficial in delaying the senescence of leaves and the decline of photosynthetic performance after anthesis, which significantly increased the accumulation of post-anthesis dry matter and significantly affected the grain yield, with an increase of 9.96–15.11 % compared with multiple-split application of urea. PCU2 and SCU2 also improved NUE by 6.71–10.33 %. The results of this study demonstrate that CRNF applied twice was a good fertilization method for synchronizing nitrogen release from fertilizer and the nitrogen demand of wheat, thus improving wheat yield and NUE and decreasing the labor required for fertilizer application.

Assessing the Potential of Polymer Coated Urea and Sulphur Fertilization on Growth, Physiology, Yield, Oil Contents and Nitrogen Use Efficiency of Sunflower Crop under Arid Environment

Nitrogen and sulphur are fundamental macronutrients for the production of sunflower crop. Nitrogen is required consistently in larger amounts for sunflower production while common urea has more losses due to high solubility. On the other hand, sulphur application increases oil contents and availability of other essential nutrients (N, P, and K). Therefore, combined application of polymer coated urea with sulphur fertilization might be a promising option which can increase achene yield, oil contents, and nitrogen use efficiency (NUE). However, no particular studies have been conducted to explore the main and interactive effects of polymer coated urea and sulphur fertilization on growth, physiology, yield, oil contents, and NUE under arid field conditions. Hence, the current field experiment consisted of two nitrogen fertilizers [polymer coated urea (PCU) and common urea (CU)] and three sulphur fertilizer rates [S0 (0), S1 (30) and S2 (60) kg ha−1)] in a split-plot arrangement under randomized complete block design (RCBD) during spring season of 2019 and 2020. Experimental results revealed that growth, physiology, yield, oil contents, and NUE of sunflower crop were significantly improved with the application of nitrogen fertilizers, sulphur fertilizer rates, and their interaction. Meanwhile, NUE, achene yield and oil contents were increased by 16.0–17.2%, 16.5–17.0%, and 2.96–3.19% respectively with the application of PCU compared with CU. Furthermore, NUE, achene yield and oil contents were also increased by 12.8–13.3%, 13.1–13.7%, and 10.7–10.9%, respectively, due to sulphur fertilization of 60 kg ha−1compared with no sulphur application. Similarly, NUE, achene yield, and oil contents were increased by 32.9–39.5%, 31.7–32.6%, and 13.1–13.2% respectively with the application of PCU in combination with sulphur fertilization of 60 kg ha−1compared with CU × S0, which also evidenced a clear and positive interaction between nitrogen and sulphur. Conclusively, PCU (130 kg ha−1) in combination with sulphur fertilization of 60 kg ha−1 is promising option for obtaining higher achene yield, oil contents, and NUE for sunflower crop under arid environment, and hence, it might be a good agronomic adaptation strategy for sustainable production of sunflower.

Growing season nitrate leaching as affected by nitrogen management in irrigated potato production

AbstractNitrate leaching from potato (Solanum tuberosum L.) production is of great concern because of its potential effects on water resources. Suction lysimeters were used in combination with a one‐dimensional flow model to quantify NO3–N leaching under irrigated potato produced on sandy soils near Québec City, QC, Canada. The 3‐yr (2010−2012) study compared a single application of polymer‐coated urea (PCU) and split‐applied soluble N fertilizers (ammonium nitrate, AN; ammonium sulfate, AS) at three N rates (120, 200, and 280 kg N ha−1) in addition to an unfertilized control. Fertilizer N application increased total seasonal NO3–N leaching. A single application of PCU increased total seasonal NO3–N leaching in 2011 compared with AN and AS, which was attributed to a greater soil NO3–N concentration under the PCU treatment in combination with increased rainfall during the tuber bulking phase (60−90 d after planting). Total seasonal NO3–N leaching in 2012 was reduced with PCU and AS compared with AN, which was attributed to reduced soil NO3–N concentrations between planting and hilling when rainfall was high. Regardless of the fertilizer N source, NO3–N leaching was primarily driven by precipitation, as leaching occurred when elevated soil NO3–N concentrations coincided with excess water in the soil. The results suggest that a single application of PCU is an effective strategy for reducing NO3–N leaching in years when there is significant rainfall during the period between planting and hilling.

Volatilization of ammonia in tropical soil with different moisture after application of polymer-coated urea

Nitrogen fertilizer has a significant participation in the cost of agricultural production. It is less efficient agronomically and requires more studies to find strategies to be absorbed by crop. Polymer-coated urea is an alternative for the production of increased efficiency fertilizers. Validation of this technology should be performed for safe adoption in agriculture. The objectives of this work were to evaluate the nitrogen losses by volatilization of ammonia and the nitrogen contents in the nitric (N-NO3-) and ammoniacal (N-NH4+) forms in the tropical soil after application of urea sources. Three greenhouse experiments with different soil moisture conditions were carried out after application of urea, urea treated with NBPT and urea coated with Policote polymer as treatments. Then volatilization of ammonia, N-NO3- and N-NH4+ contents in the soil was evaluated. The volatilization of ammonia was observed after using Policote-coated urea, which was similar to urea treated with NBPT. However, both of which were lower than that observed under urea application. In dry or very humid soil, the ammonia volatilization rate was low. The reduction of the volatilization of ammonia in the soil with Policote-coated urea was related on the humidity, whereas more effective when the conditions were more propitious to the volatilization of ammonia. The Policote-coated urea increased the content of N-NH4+ in the tropical soil compared to urea. The content of N-NH4+ in the soil was higher than N-NO3- after application of fertilizers due to the low organic matter content.

Nitrogen source and rate effects on residual soil nitrate and overwinter NO3-N losses for irrigated potatoes on sandy soils

Residual soil NO3-N (RSN) is susceptible to loss during the non-growing season. This 5 yr study investigated the effects of three N fertilizer sources [ammonium nitrate (AN), ammonium sulfate (AS), and polymer-coated urea (PCU)] applied at four rates (60, 120, 200, and 280 kg N ha−1) plus an unfertilized control on RSN following potato production and on overwinter NO3-N changes in an irrigated sandy soil in Quebec, Canada. Composite soil samples were collected at the 0–15, 15–30, 30–60, and 60–90 cm depths immediately after potato harvest in fall and again in the following spring from 2008 to 2012. Residual soil NO3-N content within the 0–30 cm depth (RSN0–30) was highly correlated with the RSN content in the 0–90 cm depth (RSN0–90), indicating that RSN0–30 can be used as an indicator of soil profile NO3-N accumulation. Overall, RSN0–90 increased with fertilizer N application rate, particularly for above the minimum fertilizer N rate required to maximize yield (Nmax), and was generally higher for years with greater pre-plant soil NO3-N. The split application of AN and AS resulted in lower RSN0–90 than the single application of PCU at above Nmax. Overwinter losses of soil NO3-N were generally increased with increasing RSN0–90 in fall. The results suggest that reducing the fertilizer N rate is more important than the choice of N source in managing RSN.

Polymer-coated urea effects on maize yield and nitrogen losses for hilly land of southern China

The rational nitrogen (N) application rate for crops depends not only on yield but also on the environmental cost of N loss to the surrounding ecological environment. To explore the environmental and economic optimal N rate (EEONR) for dryland maize in the hilly areas of southern China, a field experiment was conducted with spring maize from 2015 to 2017. Common urea (CU, control, 240 kg N ha−1) and four polymer-coated urea (PCU) fertilization levels (100PCU, 90PCU, 80PCU, 70PCU, which respectively denotes 0, 10%, 20% and 30% reduction of PCU–N application based on the control) were employed in this trial. Maize yield, N loss and economic return were investigated over 3 years. The results were as follows: (1) relative to CU, a 0–20% reduction in the PCU-N application rate did not significantly affect the maize yield during the three consecutive years, however, a 30% reduction in the PCU-N application rate led to significant yield loss in the third year despite the consistent yields achieved in the first 2 years. (2) PCU application significantly abated N loss to the environment, and as N application rate decreased, N loss significantly reduced. Our results showed that a 0–30% reduction in the PCU-N application rate mitigated N loss by 12.8–46.1% via N2O, NH3, runoff and leaching, and the two main N-loss pathways were leaching (55.2–62.2%) and NH3 volatilization (29.8–36.0%). (3) A 0–30% reduction in the PCU-N application rate resulted in a deficit, ranging from 784 to 2438 CNY ha−1 for increased earnings over CU because of the high purchase price of PCU. The net economic benefit was calculated from the N input cost, yield economic income and environment cost of N lost in the treatments with 0, 10%, 20% and 30% reduction of PCU-N and were − 1820 to 14,479, 402 to 14,612, 2306 to 14,613, and 3941 to 14,205 CNY ha−1, respectively, and the net economic benefit of the CU plot was − 4003 to 14,671 CNY ha−1. In summary, our findings suggest that reducing the PCU-N application rate by 20% is a reasonable EEONR for spring maize cultivation in hilly areas of southern China.

Assessing the Benefit of Polymer‐Coated Urea for Corn Production on Irrigated Sandy Soils

Core Ideas Polymer‐coated urea led to greater yields compared to other N fertilizers when all applied preplant. The performance of preplant polymer‐coated urea is reduced in high rainfall years. Split application of ammonium sulfate consistently produced the greatest yields on irrigated sands. Nitrification inhibitor showed little impact on corn yield on irrigated sandy soils. Polymer‐coated urea (PCU) is an enhanced‐efficiency fertilizer product that can potentially increase N use efficiency, thereby reducing N losses to the environment. However, the optimum timing and rates of PCU application under varying seasonal precipitation is less known. Here we studied the response of corn (Zea mays L.) yield and N use efficiency to N timing (preplant, sidedress, and split application) and rates (112–280 kg N ha−1) of PCU, ammonium sulfate (AS), and urea, including a control treatment without N, on an irrigated sandy soil (90% sand) in central Wisconsin from 2003 to 2006. The effect of N rate on grain yield was significant in 2003, 2004, and 2005, but not in 2006. Grain yield and N recovery efficiency (RE) with preplant PCU was greater in 2004 and 2005, and similar in 2003 and 2006 compared with preplant AS or urea. Preplant PCU had similar or greater yield and RE compared with split‐applied AS in 3 yr, but lower yield and RE in the year with the greatest early season rainfall. Nitrification inhibitor (dicyandiamide) showed little impact on corn yield. These results indicated that PCU, when applied preplant, was agronomically and environmentally advantageous over the other N fertilizer sources and typically performed as well as split application of other N fertilizers. However, under conditions where there is a lot of early season rainfall, use of preplant PCU would still result in N losses and then crops would need supplemental N to achieve high yields.

Controlled-release fertilizer enhances rice grain yield and N recovery efficiency in continuous non-flooding plastic film mulching cultivation system

Non-flooding plastic film mulching (PM) cultivation is a promising water-saving technology for rice cultivation. However, because the N fertilizer can only be applied before transplanting due to technical difficulties with later applications, it results in excessive vegetative growth and potential N shortages during the reproductive stages, which may limit grain yield potential. The use of polymer-coated urea (PCU), a slow release N fertilizer, has become one of the best management practices for increasing crop yield and improving N recovery efficiency in traditional flooded rice cultivation (TF), but has not been tested in PM cultivation. The objective of the eight-year (2008–2015) field experiment in the present study was to compare the effects of PCU with a conventional prilled urea fertilizer (PU) and a control (no N fertilizer applied; CK) on grain yield, N recovery efficiency, yield components, and soil nutrients under PM and TF cultivation systems. Within fertilizer treatment, plant N uptake and N recovery efficiency were almost always significantly higher in the PM than the TF cultivation treatments. PCU application significantly increased these parameters in both cultivation systems, but usually by significantly more with PM cultivation. Compared to the PU treatment, PCU significantly increased rice grain yield in both cultivation systems every year (by means of 11% and 15% in the TF and PM, respectively), except for TF in the first year. Within fertilizer treatment, yields of PM and TF were similar. In comparison with PU, the use of PCU had no effect on soil organic matter or alkali-hydrolyzable N. However, PM cultivation decreased these parameters. In conclusion, PCU application increased the N recovery efficiency and N availability in both cultivation systems during the reproductive stages of rice, and thus improved rice grain yield. We demonstrated that the application of PCU is a practical N fertilizer management technique that improves rice grain yield and N recovery efficiency, and is an effective solution to fertilization challenges in PM rice cultivation systems.

Producing more grain yield of rice with less ammonia volatilization and greenhouse gases emission using slow/controlled-release urea.

Ammonia (NH3) volatilization and greenhouse gas (GHG) emission from rice (Oryza sativa L.) fields contaminate the atmospheric environment and lead to global warming. Field trials (2013-2015) were conducted to estimate the influences of different types of fertilization practices on grain yield, NH3 volatilization, and methane (CH4) and nitrous oxide (N2O) emissions in a double rice cropping system in Central China. Results showed that grain yields of rice were improved significantly by using slow/controlled-release urea (S/C-RU). Compared with farmers' fertilizer practice (FFP) treatment, average annual grain yield with application of polymer-coated urea (CRU), nitrapyrin-treated urea (CP), and urea with effective microorganism (EM) treatments was increased by 18.0%, 16.2%, and 15.4%, respectively. However, the effects on NH3 volatilization and CH4 and N2O emissions differed in diverse S/C-RU. Compared with that of the FFP treatment, the annual NH3 volatilization, CH4 emission, and N2O emissions of the CRU treatment were decreased by 64.8%, 19.7%, and 35.2%, respectively; the annual CH4 and N2O emissions of the CP treatment were reduced by 33.7% and 40.3%, respectively, while the NH3 volatilization was increased by 18.5%; the annual NH3 and N2O emissions of the EM treatment were reduced by 6.3% and 28.7%, while the CH4 emission was improved by 4.3%. Overall, CP showed the best emission reduction with a decrement of 34.3% in global warming potential (GWP) and 44.4% in the greenhouse gas intensity (GHGI), followed by CRU treatment with a decrement of 21.1% in GWP and 31.7% in GHGI, compared with that of the FFP treatment. Hence, it is suggested that polymer-coated urea can be a feasible way of mitigating NH3 volatilization and CH4 and N2O emission from rice fields while maintaining or increasing the grain yield in Chinese, the double rice cropping system.

Polymer‐Coated Urea Application Could Produce More Grain Yield in “Super” Rice

Core Ideas Polymer‐coated urea could increase both grain yield and nitrogen use efficiency in rice production, particularly in super rice.Larger sink size, more productive tillers and deeper root distribution are important agronomic performances in super rice.Higher plant activities are important physiological traits in super rice. Extensive economic reforms have resulted in a significant decrease in the involvement of rural labor force in rice (Oryza sativa L.) production in China. One of the most effective ways in minimizing the use of labor in field management while maintaining or even increasing grain yield is by using polymer‐coated urea (PCU) instead of conventional urea (CU). This study investigated whether super rice (SR) cultivars could exhibit better yield performance and nitrogen use efficiency (NUE) under PCU application than non‐super rice (NSR) cultivars. Two representative SR cultivars and two representative NSR cultivars were field grown. Three treatments, no nitrogen application (0N), CU application, and PCU application, were conducted, the application N rate of CU and PCU were both 200 kg N ha−1. Compared to NSR cultivars, SR cultivars had larger sink size, more productive tillers, larger root biomass and deeper root distribution, higher root oxidation activity at mid‐ and late grain‐filling period, greater aboveground biomass production at mid‐ and late growth stages, and greater nonstructural carbohydrate (NSC) accumulation in the stem and more nonstructural carbohydrate per spikelet (NPS) at anthesis under PCU. Polymer‐coated urea increased grain yield and agronomic NUE by 11.6 and 5.5% in SR cultivars and 4.8 and 2.2% in NSR cultivars, respectively. We conclude that using PCU could increase both grain yield and NUE in rice production, especially in SR cultivars. Improved agronomic and physiological performance contributes to an increase in grain yield and NUE in SR cultivars under PCU.

Cumulative release characteristics of controlled-release nitrogen and potassium fertilizers and their effects on soil fertility, and cotton growth.

To investigate the interacting effects of polymer coated urea (PCU) and polymer coated potassium chloride (PCPC) on cotton growth, an experiment was conducted with containerized plants in 2014 and 2015. There were two kinds of nitrogen fertilizer, PCU and urea, which were combined with PCPC at three application rates (40, 80 and 120 kg ha−1). The kinds of nitrogen fertilizer formed the main plot, while individual rates of PCPC were the subplots. The results suggested N and K release patterns for PCU and PCPC in the soil were closely matched to the N and K requirements by cotton. Soil inorganic nitrogen contents significantly increased by using PCU instead of urea, and the same trend was observed with soil available potassium contents, which also had increased rates. Meanwhile, the number of bolls and lint yields of cotton in the PCU treatments were 4.9–35.3% and 2.9–40.7% higher than from urea treatments. Lint yields also increased by 9.1–12.7% with PCPC80 and PCPC120 treatments compared with PCPC40 treatment at the same nitrogen type. Hence, application of PCU combined with 80 kg ha−1 of PCPC fertilizer on cotton increased the yields and fertilizer use efficiencies in addition to improving fiber quality and delaying leaf senescence.

Effects of polymer coated urea and sulfur fertilization on yield, nitrogen use efficiency and leaf senescence of cotton

Nitrogen (N) and sulfur (S) fertilization play important roles for improving cotton yield, but no studies have been implemented to explain their interaction on yield, nitrogen use efficiency and physiological characteristics of cotton. In order to investigate the interaction effects of polymer coated urea (PCU) and S fertilization on the contents of inorganic N and available S, enzymes activities of leaves and yield of cotton, the field experiment with different types of N fertilizers and S rates was carried out in 2014 and 2015. The experiment consisted of two N fertilizer types including PCU and common urea fertilizer (Urea) in combination with three S rates (0, 60 and 120kgha−1) in the split-plot design, where the types of N fertilizer were the main plot and S rates were the subplots. The results indicated that the N release characteristic of PCU in field condition was closely matched to the N requirements of cotton, the contents of soil nitrate nitrogen (NO3−-N) and ammonium nitrogen (NH4+-N) were significantly increased from the first bloom stage to the initial boll-opening stage by using PCU compared with urea. And the content of available S was significantly increased in full boll setting stage. Meanwhile, the number of bolls and lint yields of PCU were 7.03–8.91% and 5.54–11.17% higher than urea treatments. Lint yields were also increased 3.77–9.26% by S fertilization, evidencing a clear interaction between N and S, but no significant difference was observed between S60 and S120 treatments. In addition, the N apparent recovery use efficiency (RUE) and agronomic use efficiency (AUE) were increased, fiber length and strength were improved, the nitrate reductase and peroxidase activities and photosynthetic rates (Pn) were enhanced by PCU and S fertilization. However, the lint percentage, micronaire and fiber elongation were neither affected by the type of N fertilizers and S rates, nor by their interaction. Consequently, the application of PCU combined with 60kgha−1 sulfur fertilizer on cotton could not only increase the yield and nitrogen use efficiency but also improve the fiber quality and physiological properties of leaves.