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1.
Leaf color chart (LCC) guides fertilizer nitrogen (N) application to rice as per requirement of the crop on the basis of a critical leaf color. Two field experiments were conducted to evaluate the effect of silicon (Si) and LCC based N management in aerobic rice. Following LCC-based N management, from 60 to 90 kg N ha?1 and 75 to 100 kg N ha?1 with 10–40% and 25–30% less fertilizer N was used without any reduction in yield as compared to the package of practices of 100 (50 kg N ha?1 as basal + two split of 25 kg N ha?1) kg N ha?1 respectively, during both the seasons. The highest grain yield was noticed with 90 kg N ha?1 (30 kg N ha?1 as basal + LCC-3) and 100 kg N ha?1 (50 kg N ha?1 as basal + two split of 25 kg N ha?1) along with the application of calcium silicate (CaSiO3) at 2 t ha?1 as sources of Si and on par with 60 kg N ha?1 (no basal + LCC-3) and 75 kg N ha?1 (30 kg N ha?1 as basal + LCC-3), respectively, during the season in 2008 and 2009. Higher fertilizer N use efficiency was recorded with Si and need-based N management using LCC-3 rather than recommended dose of fertilizer N.  相似文献   

2.
Application of a basal dose of fertilizer nitrogen (N) at sowing of maize has been always practiced in general recommendations in Egypt and elsewhere. A field experiment in two consecutive years (2015 and 2016) was conducted to assess the usefulness of application of a dose of N fertilizer at sowing of maize in calcareous soil at West Delta, Egypt. The treatments consisted of N fertilizer levels of 0, 240, 280, and 320 kg N ha?1 applied in three equal split doses. The first dose for each level was practiced at 0, 7, 14, and 21 days after sowing (DAS). The results indicated that practicing the first dose of N fertilizer at 0 or 7 DAS resulted in highest normalized difference vegetation index (NDVI) at early growth stage. However, the NDVI at later stages dramatically modified to reach highest when practicing the first dose at 14 or 21 DAS. Grain yields of maize when applying the first dose at 14 or 21 DAS were always significantly higher than when applied at 0 or 7 DAS. This was consistent with N fertilizer-use efficiencies. By just postponing the first dose of N from 0 to 14 DAS resulted in an increase of 7.7–13.5% in recovery efficiency and 1.1–2.7 kg grain kg?1 N in agronomic efficiency in both seasons. This study evidenced that application of N fertilizer early at sowing of maize is not necessary as it could resulted in low N-use efficiency.  相似文献   

3.
Sorghum is cultivated on Vertisols in the Ethiopian Highlands. An experiment was conducted in the Gumara-Maksegnit watershed in 2013 and 2014 to assess the effect of rate and timing of nitrogen fertilizer application on the possibility to shorten the maturity period and to improve the productivity of sorghum. The experiment was laid out as Randomized Complete Block Design with three replications. Treatments were nitrogen doses between 0 and 87 kg N ha?1 as urea applied at planting, at knee-height stage or in split doses at both stages. Results showed that application of 23, 41, 64 and 87 kg ha?1 N gave a yield increase of 40, 53, 62 and 69% over the control (0 kg N ha?1), respectively. In addition, split application of 41 kg ha?1, 64 kg ha?1 and 87 kg ha?1 of nitrogen fertilizer, half at planting and half at knee height stage, gave 19%, 15% and 18% increase in sorghum grain yield over a single dose application, respectively. Applying 87 kg ha?1 nitrogen fertilizer with split application half at planting and half at knee height stage, along with 46 kg ha?1 of P2O5, gave the highest grain yield and income.  相似文献   

4.
Because limited information is available about the validated use of a chlorophyll meter for predicting nitrogen requirements for optimum growth and yield of wheat after application of herbicides, field experiments were carried out in the winter seasons of 2011/2012 and 2012/2013 under different weed and N fertilization treatments. Five weeded treatments, application of herbicides 25 days after sowing (DAS), hand pulling once at 55 DAS and a weedy check were combined with four N application rates. Weeds were completely absent in the non-fertilized plots, either with metribuzin or hand pulling as well as in isoproturon-treated plots fertilized with 190 or 285 kg N ha?1. The grain yield was similar in the treatments of isoproturon × 190 kg N ha?1, isoproturon + diflufenican × conditional N treatment (113.9) or 190 kg N ha?1, hand pulling × conditional N treatment (104.8) or 285 kg N ha?1 and metribuzin × 190 kg N ha?1. Under weeded practices, conditional N treatment recorded the maximum nitrogen use efficiency and almost equaled the grain protein content of the 190 kg N ha?1 application rate. N application based on SPAD readings saved about 40.0% and 44.8% N with isoproturon + diflufenican or hand pulling, respectively, compared to the recommended rate (190 kg N ha?1) without noticeable yield loss.  相似文献   

5.
Appropriate nitrogen (N) management practices are of critical importance in improving N use efficiency (NUE), maize (Zea mays) yield and environmental quality. A six-year (2005–2010) on-farm trial was conducted in Ottawa, Canada to assess the effects of N rates and application methods on grain yield and NUE. In four out of the six-year study, grain yield increased by 60–77 kg ha?1 by sidedress, compared to 49–66 kg ha?1 for each kg N ha?1 applied at preplant. Grain yield response to N between the two strategies was similar in the other growing seasons. Sidedress strategy required 15 kg N ha?1 less of the maximum economic rate of N (MERN) than preplant application. Our results indicate that sidedress application of 90–120 kg N ha?1 with a starter of 30 kg N ha?1 resulted in greater yield, grain quality and NUE than preplant N application in this cool, humid and short growing-season region.  相似文献   

6.
Abstract

The experiment was conducted at Kulumsa, South East Ethiopia, using four levels of nitrogen (N) (0, 50,100 and 150?kg N ha?1) and four levels of phosphorus (P) (0, 35, 70 and 105?kg P2O5 ha?1) fertilizers arranged in 4?×?4 factorial arrangements in randomized complete block design with three replications. The available P was increased after harvest due to the application of N and P fertilizer at the rates of 100 or 150?kg N ha?1 and 70 or 105?kg P2O5 ha?1. More specifically, nutrients concentration and nutrient uptake were significantly (p?<?.01) varied among treatment combinations and nutrient use efficiency was declined by increasing N and P after optimum rates. The higher physiological efficiency of N (53.47?kg kg?1) and P (580.41?kg kg?1) and the highest apparent recovery of N (19.62%) and P (2.47%) was recorded from application of 50?kg N ha?1 and P at 70?kg P2O5 ha?1 and the highest agronomic efficiency of N (10.78?kg kg?1) and P (15.25?kg kg?1) was recorded from N at the rate of 50?kg N ha?1 and P at 35?kg P2O5 ha?1, respectively. The combination of N at 100?kg N ha?1 and P at 70?kg P2O5 ha?1 was promising combination that generated highest net benefit 488,878.5 ETB (Ethiopian birr) ha?1 with the highest marginal rate of return (36638%) and gave the highest seed yield (1858.82?kg ha?1) with yield increment of about 57.72% over the control.  相似文献   

7.
Maize (Zea mays L.) growth and yield are most sensitive to variations in plant density and nitrogen (N) in north-western Pakistan. This study was conducted on the Agricultural Research Farm of NWFP (North West Frontier Province) Agricultural University, Peshawar, from 2002–2004 to establish an accurate plant density and N management system aimed at high yield of maize. The 2 × 3 × 6 factorial experiment was designed having two plant densities (P1 = 60,000 and P2 = 100,000 plants ha?1) and three nitrogen rates (N1 = 60, N2 = 120 and N3 = 180 kg N ha?1) applied to the main plots, while six split application for N in different proportions were applied to subplots at different growth stages of maize in two equal (S1), three equal (S2), three unequal (S3), four equal (S4), five equal (S5) and five unequal splits (S6) at sowing and with 1st, 2nd, 3rd and 4th irrigation at two-week intervals. Growth rate and yield increased with elevated dose and number of N split applications. Improved endurance to high stands allowed maize to intercept and use solar radiation more efficiently, contributing to the remarkable increase in the crop growth rate and yield.  相似文献   

8.
氮肥用量及其分施比例对棉花氮利用和土壤氮平衡的影响   总被引：1，自引：0，他引：1  
The Yellow River valley is one of the three largest cotton production areas in China.An experiment was performed in cotton fields of Anyang,China from 2013 to 2014 to investigate the effects of nitrogen(N) application rate and the ratio between basal and topdressing N fertilizer on N balance in a soil-plant system,N use efficiency,and cotton yield.Five N application rates as treatments were applied with the same split application ratio.Half of the N(50% basal fertilizer) was applied at pre-planting and the other half(50% topdressing fertilizer) at the initial flowering stage.These treatments were:zero N(N0,control),90 kg N ha~(-1)(N90(5/5)),180 kg N ha~(-1)(N180(5/5)),270 kg N ha~(-1)(N270(5/5),a reduced N rate),and 360 kg N ha~(-1)(N360(5/5),a conventional N rate).Additional 2 split application ratios as treatments were applied with the same N rate of 270 kg N ha~(-1).The split application ratios between basal N and topdressing N were 30%:70%(N270(3/7)) and 70%:30%(N270(7/3)).Results demonstrated that soil NH_4-N content in the 0–60 cm layer and NO3-N content in the 0–20 cm layer increased with increased N rate at the squaring and boll-opening stages and then decreased to lower levels at the initial flowering and harvest stages.Soil NO_3-N content in the 20–60 cm layer after the initial flowering stage increased with the increase of topdressing N rate.Soil apparent N surplus varied at different growth stages,while the soil apparent N surplus over the entire growth period exhibited a positive relationship at N rates over 180 kg ha~(-1).Seed cotton yield of N270(3/7) was the highest of all treatments.Plant N uptake,N agronomic efficiency,and apparent N recovery efficiency of N270(3/7) were significantly higher than those of N270(5/5) and N270(7/3) in both growing seasons.These suggest both economic and ecological benefits in cotton production in the Yellow River valley could be created,by appropriately reducing total N application rate and increasing the ratio of topdressing to basal N fertilizer at the initial flowering stage.  相似文献   

9.
The agronomic benefits of manure application to increase rice production have been recognized, but the impact on global change has always been a controversial topic. This study was designed to determine the separate and combined effects of cattle manure (CM) and nitrogen (N) fertilizer on rice yield, N efficiency, and methane (CH4) emissions from rice cultivation. A pot-scale experiment was conducted with four levels (0, 60, 120, and 180 kg ha?1) of N from urea and two levels (120 and 180 kg ha?1) of N from combination of urea and CM (Urea:CM = 60:60 and 60:120). Rice yield and physiological N efficiency were obtained using agronomic measurements. To determine the global warming potential (GWP) of each treatment, CH4 emissions were measured throughout the rice-growing period. Grain yield (GY) was not significantly different between the treatments of 120 and 180 kg ha?1 regardless of N source. However, both rates of CM treatments enhanced CH4 emission and differences in GWP were significant. In conclusion, urea applied at 120 kg N ha?1 was optimal for rice productivity and environmental impact (EI) despite CM played a crucial role in improving the N efficiency and total N in the soil after harvest.  相似文献   

10.
Field experiments were conducted for two years to find out the appropriate sowing configuration and rate of nitrogen (N) for sustained yield and improved water use efficiency of hybrid Bt cotton irrigated through surface drip irrigation. Drip irrigation under normal sowing, in which equal quantities of water and N were applied as check-basin irrigation, resulted in an increase of 389 and 155 kg ha?1 in seed cotton yield compared with check-basin irrigation during the first and second year, respectively. Normal paired row sowing under a drip irrigation system, in which only 50% of irrigation water was applied compared with normal sowing, produced a yield similar to normal sowing under drip irrigation during both years, resulting in 22% higher water use efficiency. Dense paired row sowing under drip irrigation, in which only 75% irrigation water was applied compared with normal sowing, increased the mean seed cotton yield by 5% and water use efficiency by 19%. Decrease in the rate of nitrogen application (from 150 to 75 kg N ha?1) caused a decline in seed cotton yield and water use efficiency under all the methods of sowing, but the reverse was true for agronomic efficiency of N.  相似文献   

11.
Controlled-release urea (CRU) and its placement method in rice production were investigated during 2007 and 2008 seasons. Controlled-release urea was applied at 62.5, 125, and 187.5 kg nitrogen (N) ha?1, and the urea was 187.5 kg N ha?1. All the CRU treatments were applied to the nursery beds once, and they were brought into the paddy field during transplanting, while the urea treatment was split into three applications from the plowing to the harvest. The results showed that rice seedlings with CRUs germinated and grow well and there was no salt damage at the nursery stage. The CRU treatment with 125 kg N ha?1 had 33% less N than urea treatment (187.50 kg N ha?1), but it produced significantly higher grain and straw yields, higher total N uptake and total apparent N uptake efficiency. In addition, all the CRU treatments effectively decreased floodwater ammonium (NH4 +)-N and nitrate (NO3 ?)-N concentrations, pH, and N runoff.  相似文献   

12.
A field experiment was conducted to assess the effect of sulfur (S) fertilization on distribution of S in soil and use efficiency on blackgram in subtropical Inceptisol of acidic soil of Assam, India. Five levels of S were applied (0, 10, 20, 30 and 40 kg S ha?1) along with recommended dose of nitrogen, phosphorus and potassium. Available S content gradually decreased with the advancement of crop growth stages and lowest value was observed at 60 DAS. Different S fractions were found to increase with increasing levels of S application and 40 kg S ha?1 resulted the highest content for all S fractions. The grain and stover yield of blackgram increased significantly up to 20 kg S ha?1 which was 95.69% higher over control. Agronomic efficiency, apparent S recovery and recovery efficiency of S were higher at 10 kg S ha?1and found decreased with increase in level of S.  相似文献   

13.
Evaluation of any crop response to different nitrogen amounts is important for determining the amount that can be considered as optimum from economical and environmental point of view. This study was conducted to (1) evaluate the growth and yield of pumpkin (Cucurbita pepo L.) under different nitrogen rates and (2) determine the nitrogen use efficiency (NUE) of pumpkin in two growing seasons (2013 and 2014). In both growing seasons, nitrogen fertilizer (at three rates including 50, 150, and 250 kg ha?1) was band-dressed on the planted side of each furrow, coinciding with 4–6 leaves stage and flowering. Crop performance over 2 years was evaluated by measuring shoot dry matter, crop growth rate (CGR), leaf area index (LAI), leaf area duration (LAD), intercepted PAR (PARi), radiation use efficiency (RUE), shoot nitrogen uptake, water use efficiency (WUE), NUE, and fruit and seed yield. The results showed that in both growing seasons, the highest growth and yield of pumpkin were obtained by applying 250 kg N ha?1 (using urea fertilizer containing 46% nitrogen). Increased nitrogen rate from 50 to 250 kg ha?1 resulted in 87.3%, 27.0%, 62.1%, 87.5%, and 84.5% increase in shoot dry weight, RUE, WUE, fruit yield, and seed yield of pumpkin, respectively, across both growing seasons. However, higher application nitrogen rate decreased the NUE of pumpkin, i.e., the NUE decreased by 62.5% when the nitrogen rate increased from 50 to 250 kg ha?1. The effect of nitrogen applied in 2014 growing season on growth and yield of pumpkin was higher than that in 2013 growing season, which might be due to more suitable weather condition. In conclusion, the nitrogen rate of 250 kg ha?1 produced the highest amount of fruit and seed yield in pumpkin.  相似文献   

14.
The intensive winter wheat (Triticum aestivum L.)–summer maize (Zea mays L.) cropping systems in the North China Plain (NCP) rely on the heavy use of mineral nitrogen (N) fertilizers. As the fertigated area of wheat and maize in the NCP has grown rapidly during recent years, developing N management strategies is required for sustainable wheat and maize production. Field experiments were conducted in Hebei Province during three consecutive growth seasons in 2012–2015 to assess the influence of different N fertigation rates on N uptake, yield, and nitrogen use efficiency [NUE: recovery efficiency (REN) and agronomic efficiency (AEN)]. Five levels of N application, 0 (FN0), 40 (FN40%), 70 (FN70%), 100 (FN100%), and 130% (FN130%) of the farmer practice rate (FP: 250 kg N ha?1 and 205.5 kg N ha?1 for wheat and maize, respectively), corresponding to 0, 182.2, 318.9, 455.5, and 592.2 kg N ha?1 y?1, respectively, were tested. Nitrogen in the form of urea was dissolved in irrigation water and split into six and four applications for wheat and maize, respectively. In addition, the treatment “drip irrigation + 100% N conventional broadcasting” (DN100%) was also conducted. All treatments were arranged in a randomized complete block design with three replications. The results revealed the significant influence of both N fertigation rate and N application method on grain yield and NUE. Compared to DN100%, FN100% significantly increased the 3‐year averaged N recovery efficiency (REN) by 0.09 kg kg?1 and 0.04 kg kg?1, and the 3‐year averaged N agronomic efficiency (AEN) by 2.43 kg kg?1 and 1.62 kg kg?1 for wheat and maize, respectively. Among N fertigation rates, there was no significant increase in grain yield in response to N applied at a greater rate than 70% of FP due to excess N accumulation in vegetative tissues. Compared to FN70%, FN100%, and FN130%, FN40% increased the REN by 0.17–0.57 kg kg?1 and 0.03–0.34 kg kg?1and the AEN by 4.60–27.56 kg kg?1 and 2.40–10.62 kg kg?1 for wheat and maize, respectively. Based on a linear‐response relationship between the N fertigation rate and grain yield over three rotational periods it can be concluded that recommended N rates under drip fertigation with optimum split applications can be reduced to 46% (114.6 kg N ha?1) and 58% (116.6 kg N ha?1) of FP for wheat and maize, respectively, without negatively affecting grain yield, thereby increasing NUE.  相似文献   

15.
Maize (Zea mays L.) is an important food crop in the Guinea savannas of Nigeria. Despite its high production potential, drought, Striga hermonthica parasitsim, and poor soil fertility particularly nitrogen deficiency limit maize production in the savannas. Breeders at IITA have developed drought- and Striga-tolerant cultivars for testing, dissemination, and deployment in the region. Information on the response of these cultivars to N fertilization is, however, not available. This study evaluated grain yield, total N uptake (TNU), N uptake (NUPE), N utilization (NUTE), and N use efficiency (NUE) of selected maize cultivars along with a widely grown improved maize cultivar at two locations in the Guinea savannas of northern Nigeria. Maize grain yield increased with N application. The average grain yield of the maize cultivars was 76% higher at 30, 156% higher at 60, and 203% higher at 120 kg N ha?1 than at 0 kg N ha?1. This suggests that N is a limiting nutrient in the Nigerian savannas. Five drought-tolerant cultivars produced consistently higher yields when N was added at all levels. These cultivars had either high NUPE or NUTE confirming earlier reports that high N uptake or NUTE improves maize grain yield. The study also confirms earlier reports that maize cultivars that are selected for tolerance to drought are also efficient in uptake and use of N fertilizer. This means that these cultivars can be grown with application of less N fertilizer thereby reducing investment on fertilizers and reduction in environmental pollution.  相似文献   

16.
Brazil is a major world coffee producer, using increasing quantities of nitrogen (N) fertilizer as the monoculture expands across the savannas. The fate and efficiency of this fertilizer N were evaluated for one complete cropping cycle using 15N tracer, permitting an N balance at harvest. Annual rates of 200, 400, 600, and 800 kg N ha?1 year?1 of 15N-labeled urea and an unfertilized control were applied every 14 days via fertigation. The N concentration, percentage of N derived from fertilizer, quantity of N derived from fertilizer, and percentage of nitrogen derived from fertilizer per N rate was assessed for 8-year-old coffee trees. The most efficient N use was with 200 kg ha?1 year?1 because it presented the lowest losses and highest N recoveries in the crop. Conversely, the least sustainable rate was 800 kg ha?1 year?1, which presented the greatest losses and the lowest N recovery in the whole plant.  相似文献   

17.
Camelina (Camelina sativa (L.) Crantz) seed oil has desirable properties for producing advanced biofuels and as a healthy cooking oil. It has been grown for centuries, but basic recommendations for nitrogen (N) fertilizer requirements are still needed to support widespread industrial cultivation across North America. A replicated N-response plot-scale study was conducted on a northern Mollisol soil for two growing seasons to 1) determine seed and oil yield, seed oil content, and vegetative response; 2) determine indices of N use efficiency; and 3) measure post-harvest residual inorganic soil N as an index of environmental risk. Seed and oil yield response to N fertilization was described with a quadratic function, which predicted maximum seed yield (1450 kg ha?1) and oil yield (580 kg ha?1) at about 130 kg N ha?1. However, seed and oil yield did not differ significantly among N-rates above 34 kg N ha?1. Seed oil content averaged 400 g kg?1 among all N rates. Agronomic efficiency declined above 34 kg N ha?1, which coincided with an increase of post-harvest soil nitrate-N plus ammonium-N (residual N). Considering N use efficiency, simple cost analysis, and risk associated with residual N, a rate of 34 kg N ha?1 is recommended.  相似文献   

18.
From 2002 to date, a long-term field experiment has been conducted at Lake Carl Blackwell, Oklahoma, with different rates and times of nitrogen (N) fertilizer application to determine their effect on grain yield, protein and N uptake of winter wheat. Trend analysis for N rates (0, 50, 100, 150 and 200 kg N ha?1) and orthogonal contrasts for different application times (pre-plant, top-dressed in February and March) were performed. With increasing fertilizer N, wheat grain yield and protein content increased from 2110 kg ha?1 to 6783 kg ha?1 and from 8.96 to 17.19%, respectively. For grain yield, protein, and N use efficiency, split applications of N fertilizer were much more efficient than applying all N pre-plant. Large differences in grain yields were noted for different years at the same N rate (range exceeded 5.0 Mg ha?1) and that illustrated the need for making within-year-specific N rate recommendations.  相似文献   

19.
In view of widespread deficiencies, a long-term experiment was started at the International Crops Research Institute for the Semi-Arid Tropics, Patancheru, India in 2007 to identify economically efficient application strategy (full or 50% dose every or every second year) of sulphur (S) (30 kg ha?1), boron (B) (0.5 kg ha?1) and zinc (Zn) (10 kg ha?1). During the fourth year in 2010, balanced fertilization through adding S, B and Zn increased maize grain yield by 13–52% and soybean yield by 16–28% compared to nitrogen (N) and phosphorus (P) fertilization alone. Balanced nutrition increased N and P uptake, utilization and use efficiency for grain yield and harvest index indicating improved grain nutritional quality. The N, P plus 50% of S, B and Zn application every year recorded highest crop yields and N and P efficiencies indices and increased rainwater use efficiency with a benefit:cost ratio of 11.9 for maize and 4.14 for soybean. This study showed the importance of a deficient secondary nutrient S and micronutrients B, Zn in improving N and P use efficiency while enhancing economic food production.  相似文献   

20.
Inhibition of nitrification as a mitigation tool to abate nitrogen (N) losses and improve N use efficiency (NUE) is a promising technology. Nitrification inhibitor (dicyandiamide, DCD) was evaluated in two consecutive wheat-maize rotations (2015–2017), with two different N fertilizer levels applied in wheat (160, 220 kg N ha?1) and maize (180, 280 kg N ha?1). More NH4+-N contents (101% and 102% in wheat and 74% and 73% in maize) and less NO3–-N contents (37% and 43% in wheat and 46% and 57% in maize) were observed at both N levels treated with DCD compared to without DCD. Higher pH, lower EC and reduced NO3–-N accumulation were the other benefits of DCD. The NO3–-N accumulation within the 0–200 cm soil profile was significantly less at both N levels with DCD (66 mg kg?1 and 121 mg kg?1) compared to without DCD (96 mg kg?1 and 169 mg kg?1). Application of DCD also improved the growth and yield in both crops. Increase in NUE from 38% to 49% in wheat and 27% to 33% in maize with DCD at higher N level was also observed. Overall, the effectiveness of DCD in retarding the nitrification process was higher in wheat than maize.  相似文献   

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