Apparent Nitrogen Recovery Efficiency Research Articles

Organic fertilizer substitutions maintain maize yield and mitigate ammonia emissions but increase nitrous oxide emissions.

Organic fertilizer can improve soil structure and enhance the nutrient content in soil and is beneficial to sustainable agricultural development. However, the influence of organic fertilizer substitutions on NH3 and N2O emissions from farmland is unclear. Thus, we set up an organic substitution field experiment in Northeast China. The experiment included six treatments: single application of chemical fertilizers (NPK: 250kg N ha-1); NO10, 10% reduction in chemical nitrogen fertilizers (225kg N ha-1) + chicken manure (25kg N ha-1); NO20, 20% reduction in chemical nitrogen fertilizers (200kg N ha-1) + chicken manure (50kg N ha-1); NO30, 30% reduction in chemical nitrogen fertilizers (175kg N ha-1) + chicken manure (75kg N ha-1); NO40, 40% reduction in chemical nitrogen fertilizers (150kg N ha-1) + chicken manure (100kg N ha-1); and no-nitrogen fertilizer (CK). This experiment investigated the effects of partial substitution of chemical nitrogen fertilizer with organic fertilizer on NH3 and N2O emissions and nitrogen use efficiency in a maize field. The results showed that, compared with chemical N, organic fertilizer mitigated NH3 volatilization but promoted the soil N2O total emissions during the whole growth stage. NH3 cumulative volatilization decreased with the increase in the substitution rate of organic fertilizer. Compared with the NPK treatment, the cumulative volatilization of NH3 in the NO30 and NO40 treatments decreased by 15.24 and 17.92%, respectively. The NO40 treatment had the highest N2O emission in the whole growth stage, and the N2O emission of the NO40 treatment increased by 10.72% compared to the NPK treatment. Moreover, the yield, partial factor productivity (PFP), nitrogen harvest index (NHI), and apparent nitrogen recovery efficiency (NRE) of NO30 treatment were the highest of all treatments, and the yields, PFP, plant N accumulation, grain N accumulation, and the cumulative emissions of NH3 and N2O were similar to N20 treatment. In conclusion, nitrogen fertilizer use efficiency was enhanced, decreasing environmental pollution from livestock under organic fertilizer substitution conditions. We suggested 20% or 30% substitution rates of organic fertilizer were proper.

Chemically and biologically activated biochars slow down urea hydrolysis and improve nitrogen use efficiency

Biochar is considered as a potential technology to enhance chemical fertilizer use efficiency through intensification of the interactions between nutrients and the functional groups on biochar surfaces. However, little is known on how application of activated biochars mixed with urea would influence nitrogen mineralization and crop performance in rice paddy fields. Here, a fresh sawdust biochar (FBC) (~400°C) was activated chemically with 15% H 2 O 2 and biologically with a nutrient solution mixed with a soil inoculum to obtain a chemically (CBC) and a biologically (BBC) activated biochar, respectively. The chemical and surface properties of these biochars were evaluated by spectroscopic methods (FTIR and 13 C-NMR) and by potentiometric charge determination. The N retention capacity of biochars and their interaction with the hydrolysis of urea were examined in a laboratory-based incubation. Additionally, a field trial was carried out in a paddy rice plot with these biochars after mixing at a ratio of 1:1 with or without urea. Our results showed that both activated biochars increased negative surface functional groups and negative charges after the activation process, especially in the case of CBC which was more effective than BBC. Both activated biochars contributed to a significant reduction in urea-biochar suspension pH while increasing N retention in a batch incubation. Despite the enhanced surface properties of the activated biochars, a similar increase in biomass and grain yield was observed for the three biochars in the field experiment. Similarly, apparent nitrogen recovery efficiency and agronomic efficiency were significantly higher in the three biochars than in control. Altogether, the results indicate that the application of urea mixed with biochar could enhance crop performance, especially in the case of activated biochars that would also enhance N retention in the soil preventing eventual N losses.

Evaluating combined effect of different coated urea with PGPR on yield and nitrogen use efficiency in lowland rice by regression model and principal component analysis approach

Nitrogen (N) loss is a key problem in rice fields, which results in low nitrogen use efficiency (NUE) of applied N and could be a major limitation from economic and environmental perspectives. In order to improve the NUE, use of slow or controlled released N fertilizers could be a potential alternative to the conventional N inputs. With this objective to evaluate the effect of different slow-release fertilizers on NUE and grain yield of rice, a pot experiment was conducted during kharif 2017 at Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University Varanasi. The experiment comprised thirteen treatments including control, Polymer (PCU) and Neem coated urea (NCU) and their combination with Farm yard manure (FYM) and Plant growth promoting rhizobacteria (PGPR). The combined application of PCU, NCU, FYM and PGPR in treatment T12 provided highest grain yield 47.98 gpot−1and followed by T8 46.60 gpot−1. The result showed that, compared with the PCU treatment T2 (PCU100 Split), the Agronomic efficiency (AE) and Apparent nitrogen recovery efficiency (ANR%) of the mixed doses of coated urea treatment T12 (PCU50 NCU50 FYM10 PGPR Basal) increased by 20.38% and 28.48% respectively. Therefore, application of FYM and PGPR with coated urea improved rice yield, nutrient uptake and their use efficiency and potentially recommended in eastern plain of the Indo-Gangetic Plain for the sustainable production of rice crop.

Controlled-release N fertilizer to mitigate ammonia volatilization from double-cropping rice

Controlled-release nitrogen fertilizer (CRNF) can effectively enhance crop yields and raise the efficiency of nitrogen fertilizer in agroecosystems. In the present study, the volatilization of NH3 was determined by airflow enclosure chamber technique after the application of different CRNF rates in double-cropping rice fields in southern China for continuous 3 years. The early and late season rice (ESR and LSR) were cultivated each year. The results showed that the total NH3 volatilization losses ranged from 25 to 56 kg N ha−1 in ESR and from 32 to 61 kg N ha−1 in LSR. The loss of N to the total applied N ranged from 12 to 29% in ESR and from 12 to 27% in LSR. The application of CRNF significantly reduced the cumulative NH3 volatilization losses by 20–43% for ESR and by 20–32% for LSR compared with conventional urea application. CRNF in LSR was less effective to reduce NH3 volatilization than that in ESR. Furthermore, the application of 80% of N rate in the form of CRNF gave higher grain yield and apparent nitrogen recovery efficiency (ANRE) than that of application of 100% of N rate from conventional urea. CRNF can effectively reduce NH3 volatilization, and increase rice yield and ANRE. Considering higher price of CRNF, the application of CRNF at lower (20% applied N) rate than conventional urea in LSR may be a reasonable fertilization strategy for improving N use efficiency, environment effectiveness, and sustaining the development of rice production systems in double-cropping rice.

Sustainable and Profitable Nitrogen Fertilization Management of Potato

Nitrogen fertilization is indispensable to improving potato crop productivity, but there is a need to manage it suitably by looking at environmental sustainability. In a three-season experiment, we studied the effects of five nitrogen (N) fertilization rates: 0 (N0), 100 (N100), 200 (N200), 300 (N300) and 400 (N400) kg N ha−1 on crop N uptake, apparent nitrogen recovery efficiency (ANRE), tuber yield, nitrogen use efficiency (NUE), nitrogen uptake efficiency (NUpE), nitrogen utilization efficiency (NUtE) and agronomic nitrogen use efficiency (AgNUE) of five different potato cultivars: Daytona, Ninfa, Rubino, Sieglinde and Spunta. The economically optimum N fertilizer rates (EONFR) were also calculated. In seasons with high soil nitrogen availability for the crop (about 85 kg ha−1 of N), tuber yield increased only up to N100 and ANRE was about 50%; in seasons with medium (from 50 to 60 kg ha−1 of N) soil N availability, tuber yield increased up to N200 and ANRE was about 45%. Rubino and Sieglinde (early cultivars) responded for tuber yield only up to N100; Daytona, Ninfa, Spunta (late cultivars) up to N200, showing the highest values of NUE, NUpE, NUtE and AgNUE at N100. EONFR ranged from 176 to 268 kg ha−1 in relation to cultivar and season, but the reduction by 50% led to a tuber yield decrease of only around 16%. The adoption of cultivars characterized by high AgNUE at a low N rate and a soil nitrate test prior to planting, are effective tools to achieve a more sustainable and cost-effective nitrogen fertilization management.

IMPROVEMENT OF SANDY SOIL CHARACTERISTICS AND ITS PRODUCTIVITY OF WHEAT CROP USING ORGANIC AND MINERAL-N FERTILIZATION

A field experiment was carried out on sandy soil at the Farm of Ismailia Agric. Res. Station, Ismailia Governorate, Egypt (Latitude, 30o 35' 41.901 N and longitude, 32o 16' 45.834 E) during the two successive growing winter seasons, i.e., 2016 / 2017 and 2017 / 2018 on wheat plant ( Triticum aestivum L.) variety Misr 1, to study the individual and combined effect of organic fertilizers (farmyard manure or potassium humate) and mineral nitrogen fertilization levels ( 0, 50, 75 and 100 kg N fed.-1 as ammonium nitrate 33.5 % N) on plant growth, yield and its components as well as nutrient contents, apparent nitrogen recovery efficiency (ANRE) and agronomical efficiency, also on some chemical and physical properties of the studied soil. Application rates of farmyard manure (FYM) were 0 and 5 ton fed.-1, while potassium humate at rates of 0 and 5 kg fed.-1. The layout of the experiment was a split- plot design, with the main plots arranged in a randomized complete blocks design, with three replicates. The results showed that, there are a significant increases of the estimated growth parameters, i.e. plant height (cm), spike length (cm), number of tillers/ plant, number grains/ spike as well as straw and grain yields of wheat plants and their content (concentration and uptake) of the determined macro- ( N, P and K) and micro- (Fe, Mn and Zn) nutrients and protein content as a result of N, FYM and K-humate applications in both individually and together. The highest values of these determinations were found in the plants fertilized by N + FYM followed by these resulted from the treatment of N + potassium humate, except weight 1000 grains, grain yield and K content which gave the highest values with the treatment of N + potassium humate. In addition, individual applications of N resulted in a decrease in the soil content of available macro- (N, P and K) and micro- (Fe, Mn and Zn) nutrients, but increased the soil content of available compared with the control treatment. On the other hand, there are an increase of soil content of available macro- and micro-nutrients under study as a result of individual applications of FYM and K-humate with the superior increase of FYM compared with that with K-humate, except the soil content of available K. Also, the soil content of OM was decreased with the increase of added N, but increased as a result of FYM and K-humate applications alone. Soil bulk density was increased in the fertilized by N alone and decreased in the soil fertilized by individual applications of FYM and K-humate. The obtained data from this study concluded that, under sandy soil conditions, organic fertilizers played a major role in sandy soil fertility and its productivity of wheat plants and it's become more efficiency if its application in combination with mineral nitrogen fertilization.

Effect of nitrogen management modes on grain yield, nitrogen use efficiency and light use efficiency of wheat

A nitrogen management experiment with three nitrogen levels (0, 120, and 180 kg·hm-2, namely N0, N120, N180) and three nitrogen allocation modes (NA: base fertilizer 100%; NB: base fertilizer 70% + seedling fertilizer 30%; NC: base fertilizer 60% + jointing fertilizer 40%) was conducted at four sites (Chongqing, Renshou, Guanghan and Xichang) during two consecutive years, the SPAD value, canopy photosynthetic rate (CAP), photosynthetically active radia-tion (PAR) interception efficiency and grain yield were determined, and the nitrogen use efficiency and PAR use efficiency were calculated. The results showed that the SPAD of upper-most three leaves, CAP, PAR interception efficiency and grain yield were promoted with increasing nitrogen fertilizer, but nitrogen fertilizer use efficiency, productivity efficiency, uptake efficiency and use efficiency were decreased. The promoting effects of nitrogen fertilizer postponing were different among nitrogen levels, with the highest SPAD in N180 treatment and the highest CAP in N120 treatment. The light use efficiency of different nitrogen fertilization patterns differed among four sites. Furthermore, nitrogenous fertilizer postponing significantly increased nitrogen agricultural fertilizer use efficiency, productivity efficiency, uptake efficiency and apparent nitrogen recovery efficiency, but declined nitrogen use efficiency, and the performance of NC was better than NB. Among different sites, Guanghan had the highest SPAD, CAP, PAR interception efficiency and grain yield, Xichang had higher SPAD and nitrogen use efficiency, lower CAP and PAR use efficiency, Chongqing and Renshou had the lowest SPAD, light use efficiency, nitrogen use efficiency and grain yield. Biomass had significant positive relationships with grain yield, CPA, SPAD, and PAR interception efficiency. Therefore, the increase of nitrogen fertilizer could promote yield at all sites, and nitrogenous fertilizer postponing could further optimize grain yield component and improve nitrogen and light use effi-ciency. But the effects depended on the years and sites, thus a target nitrogen management mode should be site-specifically made.

Do no-till and pig slurry application improve barley yield and water and nitrogen use efficiencies in rainfed Mediterranean conditions?

Tillage and N fertilization strategies including mineral and organic sources need to be studied in combination given their importance on the production cost that farmers face and their potential interaction on crop performance. A four-year (2010–2014) experiment based on barley monocropping was carried out in NE Spain in a typical rainfed Mediterranean area. Two tillage treatments (CT, conventional tillage; NT, no-tillage) and three rates of N fertilization (0; 75kgNha−1, applied at top-dressing; 150kgNha−1, applied at pre-sowing and at top-dressing at equal rate), with two types of fertilizers (ammonium-based mineral fertilizer and organic fertilizer with pig slurry), were compared in a randomized block design with three replications. Different soil (water and nitrate contents) and crop (above-ground biomass, grain yield, yield components and N concentration in biomass and grain) measurements were performed. Water- and nitrogen use efficiencies (WUE and NUE) as well as other N-related indexes (grain and above-ground biomass N uptake; NHI, nitrogen harvest index; NAR, apparent nitrogen recovery efficiency) were calculated. Barley above-ground biomass and grain yield were highly variable and depended on the rainfall received on each cropping season (ranging between 280mm and 537mm). Tillage and N fertilization treatments affected barley grain yields. No-tillage showed 1.0, 1.7 and 6.3 times greater grain yield than CT in three of the four cropping seasons as a result of the greater soil water storage until tillering. Water scarcity during the definition of the number of spikes per m2 under CT would have compromised the compensation mechanism of the other two yield components. Pig slurry application led to the same (3 of 4 years) or higher (1 of 4 years) grain yield than an equivalent rate of mineral N fertilizer. Regardless the N origin, barley yield did not respond to the application of 150kgNha−1 split between pre-sowing and top-dressing compared to the 75kgNha−1 rate applied as top-dressing. A significant nitrate accumulation in the soil over the experimental period was observed under CT. Greater barley water use efficiency for yield (WUEy), N uptake and grain N content were found under NT than CT in three of the four cropping seasons studied. Moreover, for a given N rate, the use of organic fertilization increased significantly the WUEy as an average of CT and NT. When CT was used, a greater NHI was observed when using pig slurry compared with mineral N as an average of the four years studied. However, the use of different N fertilization treatments (rates or types) under CT or NT did not increase the NUE compared with the control. Our study demonstrates that the use of NT and the application of agronomic rates of N as pig slurry leads to greater barley yield and water- and nitrogen-use efficiencies than the traditional management based on CT and mineral N fertilization.

Grain yield and nitrogen use efficiency of various modern rice cultivars grown at different nitrogen levels

ABSTRACTField trials were conducted to study the responses of grain yield and nitrogen (N) use efficiency at five input rates (N0, N82.5, N165, N247.5, and N330 kg ha−1) in a set of nine of the most representative rice cultivars. Grain yields of rice across the nine cultivars were increased significantly by N level. All the cultivars contained a significant linear plus plateau or quadratic relationship between N levels and grain yields.The minimum yields (means of 2 years) at N0, N82.5, N165, N247.5, and N330 level all occurred in No. 2 cultivar. Compared with the grain yield of No. 2 at different N levels, those of the maximum cultivars increased by 37.1 (No. 8), 39.1 (No. 7), 48.4 (No.3), 43.3 (No. 4), and 43.9% (No. 3), respectively. In 2011, the highest average apparent nitrogen recovery efficiency (ANRE) in grain of the 4 N levels occurred in No. 3 cultivar (45.9%), followed by No. 4, No. 6, and No. 1, and the highest average agronomic efficiency (AE) in grain of the 4 N levels occurred in No. 9 cultivar [29.0 kg (kg N)−1], followed by No. 3, No. 1, and No. 4. For the second-season planting, the highest average ANRE occurred in No. 4 cultivar (28.4%), followed by No. 3, No. 5, and No. 6, and the highest average AE occurred in No. 5 cultivar [18.1 kg (kg N)−1], followed by No. 4, No. 3, and No. 7. Overall, No. 3 and No. 4 cultivars were the ideal ones that not only increased the grain yield but also improved the N use efficiency.

Corn Era Hybrid Response to Nitrogen Fertilization

Corn (Zea mays L.) N use is of continued interest due to agronomic performance and environmental issues. This 2‐yr study evaluated era hybrid response to fertilizer nitrogen (FN) rate in a factorial arrangement of one popular hybrid per five decades (1960–2000 eras) and five N rates (0–224 kg N ha−1). An additional hybrid per era was grown at 168 kg N ha−1. Hybrid productivity and nitrogen use efficiency (NUE) increased across the eras, but not between the 1980 and 1990 eras. Grain yield (GY) increased 65% and total plant biomass 43%, however, total plant nitrogen uptake (PNU) increased only 19% and across N rates was only higher for the 2000 era. At the agronomic optimum nitrogen rate (AONR), there was a linear GY increase of 0.13 Mg ha−1 yr−1 and GY N response of 0.091 Mg ha−1 yr−1, indicating considerable genetic gain. There was no trend in AONR across eras. For plant N status measures, SPAD readings decreased and canopy index values increased across eras. All NUE measures indicated significant improvement in NUE. The apparent nitrogen recovery efficiency (NRE) at N rates near the AONR of each era, however, was not highest for the most recent eras. Harvest index (HI), grain nitrogen harvest index (GNHI), and fraction of total PNU accumulated by R1 were the same among eras. The grain nitrogen concentration (GNC), however, was 24% lower for the 2000 compared to the 1960 era. Corn hybrid development across the 50‐yr period improved productivity and NUE, but not the AONR.

Determination of optimum nitrogen application rates in Zhejiang Province, China, based on rice yields and ecological security

Excessive nitrogen (N) fertilization in intensive agricultural areas such as the plain region of South China has resulted in low nitrogen use efficiency and serious environmental problems. To determine the optimum N application rate, grain yield, apparent nitrogen recovery efficiency (ANRE), apparent N loss, and ammonium (NH3) volatilization under different N application rates in the three years from 2012 to 2014 were studied. The results showed that the relationship between grain yields and N application rate in the three years were well fitted by quadratic equations. When N application rate reached 197 kg ha−1 in 2012, 199 kg ha−1 in 2013 and 196 kg ha−1 in 2014, the plateau of the grain yields appeared. With the increase of N application rate, the ANRE for rice decreased which could be expressed with sigmoidal equation; when N application rate was 305 kg ha−1 in 2012, 275 kg ha−1 in 2013 and 312 kg ha−1 in 2014, the curves of ANRE appeared turing points. Besides, the relationship between soil Nresidual and N application rate was fitted by the quadratic equation and the maximums of soil Nresidual were reached in the three years with the N application rate of 206, 244 and 170 kg ha−1, respectively. Statistical analysis indicated that NH3 volatilization and apparent N loss in three years all increased with the increasing N application rate. When the amount of NH3 volatilization increased to 11.6 kg N ha−1 in 2012, 40.5 kg N ha−1 in 2013 and 57.0 kg N ha−1 in 2014, the apparent N loss in the three years had obvious increase. To determine the optimum N application rate, the average N application on the plateau of the grain yield was considered as the lower limit while the average N application rate at the turning points of ANRE, the residual N in soil and apparent N loss was taken as the upper limit. According to the results in three years, the optimum N application rate for rice in Zhejiang was 197–255 kg ha−1.

Effect of different nitrogen level on nutrients accumulation, transfer and nitrogen utilization efficiency of dry land oil flax

Field experiments were carried out to determine the effect of different nitrogen application rates on nitrogen nutrient uptake,transfer and nitrogen utilization efficiency of dry land oil flax. The results indicated that different nitrogen application rates affected nitrogen nutrient uptake,accumulation and transfer at different growth stages,and changes tendencies were consistant. The amount of nitrogen translocation from leaf,translocation efficiency and contribution to grain were 89. 18%,83. 36% and 86. 36% higher than from stem. The nitrogen in grain,among which 47. 10%-57. 66% was transferred from leaf,22. 46%-30. 94% was transferred from stem and 21. 00%-30. 48% was absorbed from soil. The result indicated that compared to no nitrogen application,the yield of nitrogen treatments( as 27. 6,55. 2 and 82. 8 kg·hm-2) increased 10.21%,16.92% and 15.55%,respectively. The nitrogen transfer amounts,transfer efficiency and contribution efficiency of leaf and stem to grain were maximum when the nitrogen application rate was 55. 2kg·hm-2. With increased nitrogen application rate,apparent nitrogen recovery efficiency of oil flax first increased then decreased. The partial nitrogen factor productivity of oil flax decreased significantly. After taking into account of grain yield,nitrogen utilization efficiency and ecological environment,the recommended nitrogen fertilizer rate for dry land oil flax was 27. 6-55. 2kg·hm-2at the soil fertility level in our experiment.

Differences of Nitrogen Absorption and Utilization in Rice Varieties with Different Productivity Levels

The field experiment was carried out using 50 early-maturing late Japonica rice varieties, adopted in the region of Yangtze River, with seven nitrogen application levels (0, 150.0, 187.5, 225.0, 262.5, 300.0, 337.5 kg ha–1) to investigate the differences of the nitrogen absorption and utilization. We defined the highest rice yields under different nitrogen levels as the highest population productivity of N fertilization (HPPNF). The main results indicated that the top-and high-level yielding varieties had extremely significant larger amount of population spikelets than the middle- and low-level yielding varieties, and this superiority of total spikelets was mainly due to the extremely remarkable increase of spikelets per panicle. The nitrogen content and nitrogen absorption rate in plant at jointing, heading and maturity were all significantly increased with increasing productivity level. In transplanting to jointing and jointing to heading stages, there were no significant differences in ratio of nitrogen accumulation among four productivity levels, but a trend of decrease with the increase of productivity level. In heading to maturity stages, the ratio of nitrogen accumulation was significantly increased with increasing productivity level, which was 14.94% for top-level yielding cultivars. With the productivity level increasing, the apparent nitrogen recovery efficiency, agronomic nitrogen use efficiency and physiological nitrogen use efficiency were significantly increased. Taking into consideration of the production capacity and the apparent nitrogen recovery efficiency of all 50 rice varieties, 13 varieties with high yield and high nitrogen efficiency were selected and recommended.

Nitrogen Sources and Timing Effects on Nitrogen Loss and Uptake in Delayed Flood Rice

Field experiments were conducted in 2009 and 2010 in Louisiana and Mississippi to evaluate ammonia volatilization loss and subsequent effects on apparent nitrogen recovery efficiency (ANRE) and grain yield for rice (Oryza sativa L.). A semi‐open static chamber approach was used to measure ammonia volatilization loss from multiple N sources applied 10 days before flood (dbf) at the rate of 168 kg N ha−1. Cumulative ammonia volatilization losses for urea for Louisiana environments were 19 and 33% compared to 7% for both Mississippi environments. Urea + [N‐(n‐butyl) thiophosphoric triamide] (NBPT), urea + NBPT + dicyandiamide (DCD), and ammonium sulfate (AS) all minimized volatilization losses over all environments (range of 1.9–4.9%). Additionally, ammonia volatilization data fitted to the Gompertz model demonstrated that urea + NBPT and urea + NBPT + DCD had longer lag phases (7.2–7.7 d) relative to urea, AS, and urea + ammonium sulfate (UAS) blend (3.6 d). The same N sources and rate of N was applied 10, 7, 4, and 1 dbf to determine the effects on ANRE and yield. Apparent N recovery efficiency ranged from 43 to 71%. Grain yield was influenced by application time for two environments. Nitrogen application 10 dbf resulted in the least grain yield and yields tended to increase with fewer days between application and permanent flood. In Louisiana, urea + NBPT and urea + NBPT + DCD resulted in yields greater than urea alone. Where volatilization potential is substantial, NBPT should be included with the urea application to protect yield potential.

Precise Postponing Nitrogen Application and Its Mechanism in Rice

Leaf ages of nitrogen application for high yield and apparent nitrogen recovery efficiency were specified through applying nitrogen fertilizer once in middle stage of growth and development using early-maturing and late japonica rice-Wuyunjing 7, Wuxiangjing 14, Changyou 1 as materials. Based on this, we studied precise postponing nitrogen application and its mechanism. Results showed that leaf ages of nitrogen application to high yield and apparent nitrogen recovery efficiency were 3rd leaf and fourth leaf from the top in early-maturing and late japonica rice. Using nitrogen in 3rd and 4th leaf from the top, made more panicles and spikelets per panicle, larger total spikelets and stable filled-grain percentage and 1000-grain weight, and lower max number of stems and tillers, higher ratio of productive tillers to total tillers, higher nitrogen accumulation, max LAI, LAD and dry matter weight in population growth and development. Yield with "PPM" (precise promoting in the middle phase) of nitrogen was significantly more than that of CK. Compared to CK, there were more significantly apparent nitrogen recovery efficiency, physiological nitrogen use efficiency, agronomic nitrogen use efficiency and yield of ear nitrogen, but lower nitrogen requirement for 100 kg grain in "PPM" of nitrogen. Mechanism of high yield and apparent nitrogen recovery efficiency in "PPM" of nitrogne was that high ratio of productive tillers to total tillers and enough population panicles were formed through consolidating population panicles and controlling non productive tillering and low effective tillering; high grain-leaf ratio (filled grains per cm2 leaf area, grain weight per cm2 leaf area), enough quantity and good quality of dry matter in heading were obtained through forming large population spikeletes, high and appropriate LAI and fine canopy structure; intense source and smooth translocation, effective sink-filling ability were enlarged through enriching dry matter accumulation after heading and coordinating producton and translocation of dry matter from population stems and sheaths.

Residual effects of poultry litter on silage maize (Zea mays L.) growth and soil properties derived from volcanic ash

Poultry litter (PL) is a cheap alternative to conventional fertilizers. The use of PL in this way also reduces the environmental problems normally associated with its disposal. The residual effect of PL may reduce the amount of fertilizer (especially N fertilizer) required by subsequent crops. This study examines the residual effects of PL (with and without additional mineral fertilizer) on the properties of a volcanic ash soil and on silage maize (Zea mays) yields in central Chile. Poultry litter and mineral fertilizer were applied in 2002–2003 and their residual effects were determined in 2004–2006. The dry matter (DM) yield, nutrient balance and apparent nitrogen recovery efficiency (ANRE) of the silage maize were determined for each season, and the soil properties were analyzed at three depths (0–20, 20–40 and 40–60 cm) at the end of the third season. Crop yield showed a positive response to all fertilizer treatments. The residual effect, the nutrient balance, N uptake and ANRE also improved with fertilizer treatment, especially with the PL treatments. The average DM yield for the PL treatments was higher than that observed using mineral fertilizer by 2.8 and 1.2 Mg ha−1 in the third and fourth years, respectively. The ANRE was generally higher in the PL treatments, although it decreased over time (12.4 and 1.7% for the last 2 years, respectively). The mean ANREs for the mineral fertilizer treatment were 4.1 and 1.6% for the same years. The results suggest that the PL treatments had an important positive residual effect in terms of N supply. This should be taken into account when planning the next crop. After two annual applications of PL, slight increases were observed in soil NO3-N at a depth of 0–20 cm, and extractable P at depths of 20–40 cm and 40–60 cm. No other soil variables were significantly affected by any of the treatments. An additional source of K was found to be necessary to maintain an adequate soil K level.

Effects of nitrogen fertilizer on nitrogen use efficiency and yield of rice under different soil conditions

Four rice cultivars were used to study the effects of nitrogen fertilizer on nitrogen use efficiency, yield and characteristics of nitrogen uptake under two soil conditions (sandy and clay soil) in soil culture pool. The results were as follows. First, yield of rice in sandy and clay soil was increased by nitrogen application, and that in clay soil was higher than that in sandy soil, but the effect of nitrogen on yield increment was greater in sandy soil than in clay soil. Second, nitrogen utilization of rice was different under different soil conditions. Nitrogen harvest index (NHI) and physiological Nitrogen use efficiency (PNUE) were higher in sandy soil than in clay soil. Apparent Nitrogen recovery efficiency (ANRE), partial factor productivity for applied Nitrogen (PFP), and soil Nitrogen dependent rate (SNDR) were higher in clay soil than in sandy soil. Agronomic Nitrogen use efficiency (ANUE) was varied in different cultivars under different soil conditions. Third, N harvest index, agronomic N use efficiency, physiological N use efficiency, partial factor productivity for applied N, and soil N dependent rate were decreased significantly with the increment of the amount of nitrogen applied under two soil conditions. In sandy soil, ANRE was increased with the increasing nitrogen application and reached the highest value at high nitrogen level. However, in clay soil, ANRE was increased with the increasing of nitrogen application at first, and reached the highest value at medium nitrogen level, then decreased dramatically at high nitrogen level. Fourth, N uptake rate for rice straw and for rice grain and total N uptake rate for rice were higher in sandy clay soil than in sandy soil, but the difference between them was relatively small. Fifth, under different soil conditions, there were significant genotypic differences in the effects of applying nitrogen fertilizer on nitrogen use efficiency, yield, and characteristics of nitrogen uptake.

Effect of nitrogen management on yield attributes and nitrogen-use efficiency of late-sown wheat (Triticum aestivum L.) in western Uttar Pradesh

A field experiment was conducted during the winter (rabi) season 201617 at Meerut, Uttar Pradesh, to evalu- ate the nitrogen management for late-sown wheat (Triticum aestivum L.) crop. The experimental field condition was well-drained, sandy loam in texture, alkaline in reaction (pH 7.80), low in available nitrogen, medium in avail- able phosphorus and potassium with an electrical conductivity of 0.25dS/m. Eleven treatments comprising control, recommended dose of nitrogen (RDN) for a time as well as late-sown wheat with different application schedules were tested in randomized block design (RBD) with 3 replications. Yield-attributing characters were significantly better in the treatments where the major portion of N was applied during the early growth period. The highest grain yield was recorded in treatment (T ) where 50% of recommended N in accordance to timely sown wheat was ap- 8 plied at sowing. This treatment was found statistically similar to T T and T treatment Growth and yield-attributing 4, 6 10 . characters were comparatively higher in treatment T . Nutrient-use efficiency expressed in terms of agronomic effi- 8 ciency, apparent nitrogen-recovery efficiency and physiological efficiency were also worked out.