Placement Of Nitrogen Fertilizers Research Articles

Spatial Analysis of UAS-generated Data to Evaluate Nitrogen Fertilizer Placement Alternatives, Predict and Map End-of-Season Rice Yield

Spatial Analysis of UAS-generated Data to Evaluate Nitrogen Fertilizer Placement Alternatives, Predict and Map End-of-Season Rice Yield

Optimizing crop yields while minimizing environmental impact through deep placement of nitrogen fertilizer

Nitrogen (N) serves as an essential nutrient for yield formation across diverse crop types. However, agricultural production encounters numerous challenges, notably high N fertilizer rates coupled with low N use efficiency and serious environmental pollution. Deep placement of nitrogen fertilizer (DPNF) is an agronomic measure that shows promise in addressing these issues. This review aims to offer a comprehensive understanding of DPNF, beginning with a succinct overview of its development and methodologies for implementation. Subsequently, the optimal fertilization depth and influencing factors for different crops are analyzed and discussed. Additionally, it investigates the regulation and mechanism underlying the DPNF on crop development, yield, N use efficiency and greenhouse gas emissions. Finally, the review delineates the limitations and challenges of this technology and provides suggestions for its improvement and application. This review provides valuable insight and reference for the promotion and adoption of DPNF in agricultural practice.

Slow-release fertilizer deep placement increased rice yield and reduced the ecological and environmental impact in Southeast China: A life-cycle perspective

An unreasonable application of nitrogen fertilizer leads to increased agricultural greenhouse gas (GHG) emissions and carbon footprint (CF). To solve this issue, slow-release fertilizer and deep placement of nitrogen fertilizer are recommended, and have been proven effective in improving nitrogen utilization efficiency and reducing nitrogen loss. However, the deep placement of fertilizer increases the cost of mechanical fuel and labor, especially in the hilly and mountainous areas of southeast China and the comprehensive effects throughout the life cycle of crop production, including economic benefits, energy flow, and environmental and ecological advantages, resulting from different application strategies for nitrogen fertilizer, are still largely unknown. In this work, a two-year field trial was conducted in Fujian Province, China, from 2021 to 2022. The main objectives of the study were to investigate the yield and GHG emissions resulting from the deep placement of slow-release fertilizer (DSK) and to assess the carbon footprint, energy use efficiency, and net economic and ecological benefits from a life-cycle perspective. The results showed that compared with deep placement of urea (DCK), slow-release fertilizer broadcasting (SK), and the traditional fertilization mode practiced by farmers (CK), the average annual yield of rice under DSK treatment significantly increased by 8.78%, 15.18%, and 23.54% respectively. Compared with CK, the contents of indole-3-acetic acid (IAA) and trans-Zeatin Riboside (t-ZR) under DSK were significantly increased and the dry matter translocation amount, Non-Structural Carbohydrates (NSC) translocation amount and Nitrogen translocation amount were significantly increased by 22.79%, 49.60% and 41.47% respectively. GHG emissions were indirectly reduced by the transport of above-ground substances to grains. The average cumulative CH4 emissions were significantly reduced by 25.34% in the DSK treatment, compared to the CK treatment, primarily as a result of decreased methanogenic gene abundance of mcra gene. Additionally, N2O emissions decreased significantly by 48.97%, compared to the CK, mainly due to a decrease in nirK gene abundance and an increase in nosZ gene abundance in denitrifying bacteria. Furthermore, the carbon footprint of the DSK treatment significantly decreased by 38.74% compared to the CK treatment, while net energy income and net ecological and economic benefits increased by 43.83% and 76.43%, respectively. Comprehensive analysis showed that deep placement of slow-release fertilizer is a sustainable nitrogen fertilizer management mode that helps to balance grain yield, environmental footprint, and economic benefits in southeast China.

The Effect of Deep Placement of Basal Nitrogen Fertilizer on Gaseous Nitrogen Losses and Nitrogen Use Efficiency of Paddy Fields under Water-Saving Irrigation in Northeast China

As a widely implemented irrigation regime for paddy fields, water-saving irrigation (WSI) is capable of ensuring water resource security and improving nitrogen use efficiency (NUE). Higher gaseous nitrogen losses (GNL) lead to a low recovery rate of basal nitrogen, and this is the primary reason that restricts further improvements in the NUE under WSI. The deep placement of nitrogen fertilizer (DPN) is considered an efficient agricultural management measure to reduce GNL. However, the effects of WSI combined with the deep placement of basal nitrogen fertilizer on NUE, GNL, and rice yield in paddy fields remain largely unknown. In this study, a 2-year field experiment was conducted to measure GNL (N2O emissions and NH3 volatilization), NUE, and rice yield. Four treatments were utilized: (i) conventional flooding irrigation + broadcast of nitrogen fertilizer (110 kg N hm−2, CFN); (ii) water-saving irrigation + deep placement of basal nitrogen fertilizer (110 kg N hm−2, WSN); (iii) water-saving irrigation + deep placement of basal nitrogen fertilizer (99 kg N hm−2, WSN1); (iv) water-saving irrigation + deep placement of basal nitrogen fertilizer (88 kg N hm−2, WSN2). The results showed that the GNL in paddy fields under treatment ranged from 5.29 to 10.67 kg hm−2. Deep placement of basal nitrogen fertilizer mitigated the GNL of the paddy fields under WSI. The GNL of CFN was significantly higher than those of WSN1 and WSN2 by 26.9% and 54.0% in 2021 and 14.4% and 23.3% in 2022, respectively (p < 0.05). Under WSI, the deep placement of basal nitrogen fertilizer reduced the GNL primarily via the reduction of NH3 volatilization. NH3-N of CFN was higher than those treatments under WSI. The rice yield of CFN was significantly lower than those of WSN and WSN1 by 22.4% and 21.6% in 2021 and 4.6% and 1.5% in 2022, respectively. (p < 0.05). Moreover, the NUE of each treatment under WSI was higher than that of CFN. These changes exhibited similar trends in 2021 and 2022. These results demonstrated that deep placement of basal nitrogen fertilizer is an effective practice to ensure food and environmental security under WSI.

Retraction: Deep placement of nitrogen fertilizer improves yield, nitrogen use efficiency and economic returns of transplanted fine rice.

Retraction: Deep placement of nitrogen fertilizer improves yield, nitrogen use efficiency and economic returns of transplanted fine rice.

Optimum Rate and Deep Placement of Nitrogen Fertilizer Improves Nitrogen Use Efficiency and Tomato Yield in Nepal

In Nepal, blanket fertilizer recommendations without considering diverse soil types, nutrient status, climate and crop management practices along with imbalanced fertilization practices by farmers, mainly “urea fertilizer,” have resulted in reduced nitrogen use efficiency (NUE) and productivity in tomato production. Optimizing the rate of nitrogen (N) fertilizer, application time and improved application methods could increase crop yields and NUE and reduce environmental costs. This study was conducted to identify the optimum N rate and application method for increased tomato yield and NUE. Multilocation trials (n = 28) conducted in a randomized complete block design with nine treatments across five districts included the omission of N, P and K (N0, P0, K0), variable N rates of 100, 150, 200 and 250 kg ha−1 (N-100, N-150, N-200 and N-250), use of urea briquettes (UB) with deep placement (UBN-150) and a control (CK). N input in UB was reduced by 25% from the recommended N rate of 200 kg ha−1 considering its expected higher NUE. Yield responses from an NPK omission plot revealed N as the most limiting plant nutrient. Applications of fertilizer at N-100, N-150, N-200 and N-250 increased tomato yield by 27%, 35%, 43% and 27%, respectively, over N0. Tomato yields responded quadratically to the added N fertilizers with optimum rates ranging from 150 to 200 kg ha−1 across districts. UBN-150 significantly increased tomato yield by 12% over N-150 and produced a similar yield to N-200 (the recommended rate). The highest partial factor productivity of nitrogen (PFPN) was observed at N-100 and the highest agronomic efficiency of N (AEN) was at N-200. Deep placement of UB at-150 increased PFPN by 8% and 21% and AEN by 27% and 21% compared with N-150 and N-200, respectively. These results have positive implications for developing efficient N fertilization strategies to increase tomato yields and reduce environmental impacts in Nepal.

Deep placement of nitrogen fertilizer increases rice yield and energy production efficiency under different mechanical rice production systems

Increasing energy output and improving energy production efficiency is essential to ensure the long-term sustainability of rice production systems in China. Present study assessed the energy input/output and its production efficiency for manual transplanted rice with manual broadcasting fertilizer (TR-MBF), mechanical pot-seedling transplanted rice synchronized with deep fertilization (MPST-DF), and mechanical hill direct-seeding rice synchronized with deep fertilization (MHDS-DF) in a three-year field experiment. Two rice cultivars i.e., Yuxiangyouzhan (YXYZ, inbred rice) and Wufengyou615 (WFY615, hybrid rice) were used to determine the energy input/output and production efficiency of each system. Results depicted that the MHDS-DF and MPST-DF treatment substantially improved the grain yield by 20.9% and 32.3% for WFY615 and YXYZ owing to enhanced total above-ground biomass (TAB) and leaf area index (LAI), respectively. Means across years and cultivars for energy input in the TR-MBF, MPST-DF, and MHDS-DF were remained 31918.0, 35267.1 and 36036.7 MJ ha−1, respectively. The energy consumed by diesel and fertilizer for energy inputs in the production system exceeds 70% of the total energy input. Moreover, the three rice production systems were highly dependent on non-renewable energy. The highest output energy and net energy were obtained for MHDS-DF and MPST-DF treatments with 221517.2 and 185670.0 MJ ha-1, respectively. Among the three rice production systems, the highest energy use efficiency, energy productivity efficiency, energy profitability efficiency was found in MPST-DF, which was slightly higher than MHDS-DF. However, the human energy profitability efficiency of MHDS-DF treatment was significantly higher than other treatments. Therefore, MHDS-DF and MPST-DF could be best alternative technologies than conventional rice production systems with improved energy input and energy production efficiency in South China. Furthermore, both MHDS-DF and MPST-DF would also be suitable in the regions with lack of labor force for rice production.

Effect of variety and nitrogen fertilizer managements on the growth and yield of Transplant aman rice managements

Varietal selection and appropriate placement of nitrogen fertilizer could reduce the magnitude of nitrogen losses to a considerable extent and improve its use efficiency for better grain production. An experiment was carried out during the period from July to December at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh to evaluate the effect of variety and nitrogen fertilizer management on the growth and yield of transplant aman rice. The treatments consisted of three varieties viz. BR11, BRRI dhan49 and Binadhan-7, and five nitrogen fertilizer managements viz. two depth of placement of USG (Urea Super Granule) and three split applications of prilled urea. The experiment was laid out in a randomized complete block design with three replications. The results showed that the effect of variety and nitrogen fertilizer management significantly influenced all the yield contributing characters except weight of 1000- grains, non-effective tillers hill-1 and panicle length. The highest grain yield (3.69 t ha-1) was obtained from Binadhan-7. In the case of nitrogen fertilizer management, the highest grain yield (4.32 t ha-1) was found from the 6 cm depth placement of USG. The highest grain yield (4.82 t ha- 1) was observed from the interaction of Binadhan-7 with the 6 cm depth of placement of USG. It may be concluded that Binadhan-7 with 6 cm depth of placement of USG appeared as the promising practice to maximize the yield of transplant aman rice.
 Res. Agric., Livest. Fish.8(3): 281-289, December 2021

Deep placement of nitrogen fertilizer in autumn improves N utilization by spring tea (Camellia sinensis L.)

AbstractBackgroundThe efficient use of fertilizers depends very much on their proper placement, and the effects of fertilizer placement on the woody perennial plant tea (Camellia sinensis L.) are not clearly understood.MethodsA 15N mini‐plot field experiment was conducted to investigate the effects of four common techniques of fertilizer placement techniques. 15N‐labeled urea was applied in October by surface broadcasting, surface broadcasting with 3–5 cm soil incorporation, shallow (3–5 cm), and deep (10–15 cm) side dressing (DSD). The proportion of N derived from 15N‐labeled fertilizer (Ndff%) was estimated in root, and soil samples were collected 15 and 43 days after fertilization (DAA15 and DAA43) and in young shoots collected in the following spring.ResultsMost fertilizer 15N was located in the soil near the placement position at DAA15 and 15N had moved downward but maintained a similar distribution in the soil profile at DAA43. The distribution of fibrous root Ndff% in the soil profile was very similar to that of soil Ndff%. DSD resulted in the highest shoot Ndff%, the estimated amount of 15N in young shoot derived from 15N‐label fertilizer (shoot 15N), and its percentage related to the amount of 15N‐labeled fertilizer input (REFN%). Thus, DSD of urea as basal application in autumn maintained a higher and prolonged N supply in the middle and deep soil layers, thereby improving fertilizer‐N absorption and utilization in the following spring tea. However, direct broadcasting of urea on the soil surface resulted in low N availability in the soil and utilization by tea plants.ConclusionOur results demonstrate that DSD of N fertilization should be recommended for tea planting to increase N use efficiency and reduce environmental losses in forms of runoff and volatilization.

Deep placement of nitrogen fertilizer improves yield, nitrogen use efficiency and economic returns of transplanted fine rice.

Rice (Oryza sativa L.) feeds to two-third of the global population by serving as staple food. It is the main export commodity of several countries; thus, contributes towards foreign exchange earnings. Unfortunately, average global rice yield is far below than its genetic potential. Low nitrogen (N) use efficiency (NUE) is among the major reasons for low average yield. Current study evaluated the impact of nitrogen fertilizer application methods (conventional and deep placement) on growth, yield-related traits, chlorophyll contents, photosynthesis rate, agronomic N-use efficiency (ANUE), partial factors productivity of applied N (PFP) and economic returns of two different transplanted rice varieties (Basmati-515 and Super-Basmati). Fertilizer application methods significantly affected allometry, yield-related traits, chlorophyll contents, photosynthesis rate, ANUE, PFP and economic returns. Deep placement of N-fertilizer (DPNF) observed better allometric traits, high chlorophyll contents, photosynthesis rate, ANUE, PFP, yield attributes and economic returns compared to conventional application of N-fertilizer (CANF). Similarly, Basmati-515 had better allometric and yield-related traits, chlorophyll contents, photosynthesis rate, ANUE, PFP and economic returns than Super-Basmati. Regarding interactions among N-fertilizer application methods and rice varieties, Basmati-515 with DPNF resulted in higher chlorophyll contents, photosynthesis rate, ANUE, PFP, allometric and yield related traits and economic returns than CANF. The lowest values of these traits were observed for Super-Basmati with no application of N-fertilizer. Both varieties had better yield and economic returns with DPNF compared to CANF. It is concluded that DPNF improved yield, ANUE and economic returns; therefore, should be opted to improve productivity of transplanted fine rice. Nonetheless, lower nitrogen doses need to be tested for DPNF to infer whether it could lower N use in rice crop.

Deep placement of nitrogen fertilizer increases rice yield and nitrogen use efficiency with fewer greenhouse gas emissions in a mechanical direct-seeded cropping system

Deep placement of nitrogen fertilizer is a key strategy for improving nitrogen use efficiency. A two-year field experiment was conducted during the early rice growing seasons (March–July) of 2016 and 2017. The experimental treatments comprised two rice cultivars: Wufengyou 615 (WFY 615) and Yuxiangyouzhan (YXYZ), and three N treatments: mechanical deep placement of all fertilizers as basal dose at 10 cm soil depth (one-time deep-placement fertilization, namely OTDP fertilization); manual surface broadcast (the common farmer practice) of 40% N fertilizer at one day before sowing (basal fertilizer) followed by broadcast application of 30% each at tillering and panicle initiation stages; and no fertilizer application at any growth stage as a control. One-time deep-placement fertilization increased grain yield of both rice cultivars by 11.8%–19.6%, total nitrogen accumulation by 10.3%–13.1%, nitrogen grain production efficiency by 29.7%–31.5%, nitrogen harvest index by 27.8%–30.0%, nitrogen agronomic efficiency by 71.3%–77.2%, and nitrogen recovery efficiency by 42.4%–56.7% for both rice cultivars, compared with the multiple-broadcast treatment. One-time deep-placement fertilization reduced CH4-induced global warming potential (GWP) by 20.7%–25.3%, N2O-induced GWP by 7.2%–12.3%, and total GWP by 14.7%–22.9% for both rice cultivars relative to the multiple-broadcast treatment. The activities of glutamine synthetase and nitrate reductase were increased at both panicle-initiation and heading stages in both rice cultivars following one-time deep-placement fertilization treatment. Larger leaf area index at heading stage and more favorable root morphological traits expressed as larger total root length, mean root diameter, and total root volume per hill were also observed. One-time deep-placement fertilization could be an effective strategy for increasing grain yield and nitrogen use efficiency and lowering greenhouse-gas emissions under mechanical direct-seeded cropping systems.

Timing, Source, and Placement of Nitrogen Fertilizer Increases Wheat Yield and Protein Content in High Yielding Environments

Timing, Source, and Placement of Nitrogen Fertilizer Increases Wheat Yield and Protein Content in High Yielding Environments

N2O and CO2 Emissions from Bare Soil: Effect of Fertilizer Management

The paper presents the results of a laboratory experiment focused on the assessment of the effect of different methods of application of ammonium nitrate (TD—top dressing and DP—deep placement) on N2O and CO2 emissions from soil without crop cover. Nitrogen application increased soil N2O–N fluxes by 24.3–46.4%, compared to untreated soil (NIL). N2O–N emissions from TD treatment were higher by 12.7%, compared to DP treatment. Soil CO2–C fluxes from DP treatment were significantly higher by 17.2%, compared to those from NIL treatment. Nonetheless, the differences between soil CO2–C fluxes from DP and TD treatments, as well as from TD and NIL treatments, were of no statistical significance. The cumulative greenhouse gas (GHG) emissions (a sum of cumulative soil emissions of CO2–C and N2O–N after conversion to the equivalent of CO2–C) from both N-fertilized soils were similar, and higher by 20% than from untreated soil. The obtained data show that the effect of reduction of N2O–N soil emissions gained by deep placement of nitrogen fertilizer was completely lost through an increase in CO2–C emissions from the soil. This suggests that deep placement of nitrogen fertilizers in sandy soil without crop cover might not lead to a mitigation of soil GHG emissions.

Straw Incorporation Coupled with Deep Placement of Nitrogen Fertilizer Improved Grain Yield and Nitrogen Use Efficiency in Direct-Seeded Rice

The purpose of this study is to understand how grain yield and nitrogen use efficiency were affected by straw incorporation coupled with deep placement of nitrogen fertilizer in direct-seeded rice in South China. The experimental treatments comprised deep placement of N fertilization coupled with straw return (DS) and without straw return (DO) as well as surface broadcasting of N fertilizer coupled with straw return (SS) and without straw return (SO), whereas no fertilizer placement and no straw return were taken as a control (FS0) in two rice cultivars, i.e., Yuxiangyouzhan (YX) and Wufengyou615 (WF), grown in early and late season of 2018. Results depicted that, compared with FS0, DS significantly (P < 0.05) improved grain yield by 68.7–115.9% owing to higher net photosynthetic rate (Pn) at the heading stage, larger total aboveground biomass, and leaf area index (LAI). Compared with DO, the nitrogen recovery efficiency (NRE) and nitrogen agronomic use efficiency (NAE) in DS were increased by 19.3–188.6% and 1.9–33.8%, respectively. Furthermore, the nitrate reductase (NR) activity of the flag leaves at heading stage for DS was increased by 10.6–93.0% as compared with DO treatment. Therefore, straw incorporation coupled with deep placement of nitrogen fertilizer could be a feasible technique with the increase of grain yield and nitrogen use efficiency in direct-seeded rice (DSR) in South China.

Deep Placement of Nitrogen Fertilizer Affects Grain Yield, Nitrogen Recovery Efficiency, and Root Characteristics in Direct-Seeded Rice in South China

Deep placement of nitrogen (N) fertilizer has become one of the effective management practices for increasing crop yield and improving N recovery efficiency (NRE). However, it is unclear how different N fertilization depths affect grain yield, nitrogen use efficiency, and root characteristics in direct-seeded rice (DSR) in South China. Here, we conducted stainless steel-box experiment to evaluate the effects of different N fertilization depths at four fertilization depths (0, 4, 8, and 12 cm, written as D0, D4, D8, and D12, respectively) with a conventional ammonium bicarbonate fertilizer (TN???=???17.7%) (150 kg N ha???1) and a control (no N fertilizer applied, CK) on grain yield, NRE, and root characteristics of DSR. The results indicated that both D8 and D12 significantly increased grain yields by 72.91 and 81.84%, respectively, compared with CK. The highest nitrogen agronomic efficiency (NAE) and NRE were found under D12 treatment, which were increased by 165.42 and 129.45% compared to D0, respectively. We also found that deep placement of N fertilizer (both D8 and D12) could also promote rice root growth such as larger root length, root superficial area, and thicker root diameter. Furthermore, nitrate reductase (NR), glutamine synthetase (GOGAT), and glutamine synthetase (GS) activities of flag leaves at the heading stage were also increased. The result shows that both 8 and 12 cm are relatively reasonable fertilization depths depended on adopted rice varieties when ammonia bicarbonate fertilizer is used in DSR production.

Study of nitrogen use efficiency and yield of rice influenced by deep placement of nitrogen fertilizers

Continuous increase of nitrogen fertilizer use adversely affecting the soil health as well as the environment. It necessitates the systematic study of the impact of nitrogen (N) fertilizer use-reduction on crop yield. In this article, the effects of deep placement of nitrogen fertilizers on nitrogen use efficiency (NUE) and yield of rice variety “BRRI dhan46” were investigated and compared for three N formulations: urea super granule (USG), NPK briquettes and prilled urea (PU). The experiment was conducted in randomized complete block design (RCBD) with eight N treatments replicated three times. The treatments were applied by varying doses (0, 52, 78 and 104 kg ha-1) of nitrogen fertilizers in a known identical soil and weather condition. Applications of PU, USG and NPK briquettes exhibited significant differences on yield attributes of rice. Results revealed maximum grain yield of 6.391 t ha-1 (54% increases over control) for the dose USG 104 kg ha-1 which is statistically similar to the dose USG 78 kg ha-1 and NPK briquettes 104 kg ha-1. The deep placement of USG and NPK briquettes enhanced both the recovery of applied N and N use efficiency compared to broadcast application of prilled urea. However, USG 78 kg ha-1 showed maximum apparent N recovery, N use efficiency, gross margin and marginal benefit-cost ratio. Thus, an application of 78 kg ha-1 USG can be recommended for profitable cultivation of rice variety BRRI dhan46.&#x0D; SAARC J. Agri., 17(1): 93-103 (2019)

Influence of irrigation water regimes and patterns of nitrogen placement combined with soil compaction on wheat (Triticum aestivum L.) growth

Irrigation management and pattern of nitrogen application associated with soil compaction are critical factors in wheat growth. This study aimed to evaluate the effect of irrigation regimes and patterns of nitrogen fertilizer placement in presence of soil compacted layer on some wheat growth parameters

Effect of the Nitrification Inhibitor 3,4-Dimethylpyrazole Phosphate on the Deep Placement of Nitrogen Fertilizers for Soybean Cultivation

The deep placement of urea fertilizer (DMU) containing 1% (W/W) of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on soybean growth and seed yield was as effective as those of the coated urea (CU) and lime nitrogen (LN) in a field research. The average seed yields were high in LN (464 g·m−2) and DMU (461 g·m−2) and relatively low in CU (405 g·m−2), U (396 g·m−2), and Cont (373 g·m−2) treatments. The accumulations of dry matter and nitrogen in soybean shoots were higher in the plants with deep placement of CU, LN, and DMU than U and Cont. The daily nitrogen fixation activity and daily nitrogen absorption rate were calculated based on the relative ureide method. Both nitrogen fixation activity and nitrogen absorption rate were higher in DMU, CU, and LN compared with control treatment, suggesting that the deep placement of DMU did not repress nitrogen fixation. Soil incubation test was performed using the same field soil with DMU, U, LN, and urea with DMPP 1%, 2%, and 4%. DMU inhibits nitrification similar to the pattern of LN until 8 weeks. The increasing DMPP concentration did not markedly increase the nitrification inhibition. From these results, it was concluded that urea fertilizer with 1% DMPP is efficient for deep placement of N fertilizer for soybean cultivation due to its lower price compared with CU and LN.

Efficacy of Deep Placement of Nitrogen Fertilizers on N Use Efficiency and Yield of Boro Rice (cv. BRRI Dhan29)

The efficiency of nitrogen (N) fertilizers in rice culture is low due to their losses in different ways. An experiment was, therefore, conducted at the Soil Science Field Laboratory of Bangladesh Agricultural University, Mymensingh during boro season of 2016 to evaluate the effect of deep placement of N fertilizers on N use efficiency and yield of BRRI dhan29 under alternate wetting and drying (AWD) condition. The soil was silt loam in texture having pH 6.07, organic matter content 1.10%, total N 0.055%, available P 3.6 ppm, exchangeable K 0.22 me% and available S 11.76 ppm. The experiment was laid out in a randomized complete block design with three replications. There were eight treatment combinations including T1 (Control), T2 (PU, 130 kg N/ha), T3 (USG, 130 kg N/ha), T4 (USG, 104 kg N/ha), T5 (USG, 78 kg N/ha), T6 (NPK briquette, 129 kg N/ha) and T7 (NPK briquette, 102 kg/ha) and T8 (NPK briquette, 78 kg N/ha). All the treatments except T6, T7 and T8 received 25 kg P and 64 kg K /ha as TSP and MoP, respectively. Treatments T6, T7, T8 received NPK briquette fertilizer. Prilled urea (PU) was applied in three equal splits. Urea super granule (USG) and NPK briquettes were applied at 10 day after transplanting (DAT) and the briquettes were placed at 8-10 cm depth in the centre of four hills in alternate rows. The results demonstrate that all the yield components except 1000-grain weight responded significantly to the deep placement of N fertilizers in the form of USG and NPK briquette. The grain and straw yields of BRRI dhan29 were also influenced significantly due to deep placement of N fertilizers under AWD condition. The highest grain yield (6163 kg/ha) was recorded for T3 [USG, 130 kg N/ha) which was statistically similar with T4 (USG, 104 kg N/ha). The highest straw yield (6415 kg /ha) was also found in T3 [USG, 130 kg N/ha]. The lowest grain yield (3266 kg/ha) and straw yield (3637 kg/ha) were found in T1 (Control). The N uptake by BRRI dhan29, N use efficiency and apparent N recovery also showed significant response to the application of PU, USG and NPK briquettes. The maximum N use efficiency of 28.88% was noted in T5 followed by T4 with the value of 26.46% and the minimum value of 17.55% was observed in T2. The results revealed that the deep placement of N fertilizers accelerated the N uptake, N recovery and N use efficiency by BRRI dhan29. Based on grain yield and cost-benefit analysis, it can be concluded that application of 130 kg N/ha as USG is useful for the profitable cultivation of boro rice, BRRI dhan29.

Nitrogen Management for Seed Production from Endophyte‐Free Tall Fescue Grown on Claypan Soil

Core Ideas Pastures may be replanted with endophyte‐free seed to avoid harmful alkaloids. Better N management may be required for endophyte‐free fescue seed production. Nitrogen fertilizer placement has little effect on endophyte‐free seed production. Fescue seed yield may be maximized with 150 lb N/acre applied in late winter. Nitrogen fertilization affects tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] forage production, but data are limited regarding seed production from endophyte‐free tall fescue grown on the claypan soils of the eastern Great Plains. A field study was conducted from fall 1998 to spring 2001 to determine the effects of N fertilizer timing (late fall or late winter), N placement (surface broadcast, spoke [point injection at 3 inches deep], and knife [subsurface band at 4 inches deep]), and N rate (0, 50, 100, 150, and 200 lb/acre) on endophyte‐free tall fescue seed yield, yield components, and harvested seed germination. The soil was a Parsons silt loam (fine, mixed, thermic Mollic Albaqualf), which is a typical claypan soil of the area. Seed yield response to N rates to 100 lb N/acre was similar regardless of application timing, but in two of three years, greater N rates applied in late fall improved seed production to about 400 lb/acre. Even though all components of seed yield responded to N fertilization, panicles/ft2 had the highest correlation (r = 0.83) with seed yield and showed greater response in 1999 to N applied in late fall at a higher rate compared with fewer panicles/ft2 at lower rates of N applied in late winter. The effect of N fertilization on germination of harvested seed was small. Fertilizer N placement had little effect on measured variables. In summary, increasing N rate to 150 lb/acre and applying it in late winter has the potential to maximize production of endophyte‐free tall fescue seed.