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1.
Alternative N fertiliser management strategies are needed to increase N-use efficiency in wetland rice (Oryza sativa L.). In the wet season of 1993–1994, field experiments were conducted to evaluate the band placement of urea solution in comparison with broadcast prilled urea, neem-coated urea, or point-placement of urea supergranules. Both grain yield and N-use efficiency were higher with band placement of urea solution (50 or 100 kg N ha-1) compared to a conventional split application of prilled urea at 100 kg N ha-1. The total 15N recovery was 58.7 and 51.7% with band placement of urea solution at 50 and 100 kg N ha-1, respectively, compared with 47.8% for neem-coated urea and 28.5% for a conventional split application of prilled urea. Current address: Training Division, KVK, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India Pin 641 003  相似文献   

2.
A field study was conducted in the sub-humid tropical region of India to examine the effect of different nitrogen (N) management strategies on nitrate leaching, nitrous oxide (N2O) emission and N use efficiency in aerobic rice. Treatments were: control (no N), 120 kg N ha?1 applied as prilled urea (PU) in conventional method, 120 kg N ha?1 applied as neem coated urea (NCU) in conventional method, N applied as PU on the basis of leaf colour chart (LCC) reading, N applied as NCU on the basis of LCC reading, and 120 kg N ha?1 applied as PU and farm yard manure (FYM) in 1:1 ratio. Results showed that 3.4–16.1 kg NO3-N ha?1 was leached below 45 cm depth and 0.61–1.12 kg N2O-N ha?1 was emitted from aerobic rice during the growing season. NCU when applied conventionally reduced nitrate-nitrogen (NO3-N) leaching and N2O emission by 18.6% and 21.4%, respectively However when applied on the basis of LCC reading NCU reduced NO3-N leaching by 39.8% as compared to PU applied in conventional method. NCU when applied on the basis of LCC reading synchronized N supply with demand and reduced N loss, which resulted in higher yield and N use efficiency.  相似文献   

3.
In order to investigate the effect of nitrogen (N) and sulfur (S) fertilizers on yield and seed quality of three canola cultivars, a factorial based on randomized complete block experiment was conducted during 2005–2006 in Iran. Treatments included four nitrogen rates (0, 75, 150, and 225 kg N ha?1 source of urea), four sulfur rates (0, 100, 200, and 300 kg S ha?1), and three cultivars (‘Pf’, ‘Option-500’, and ‘Hyola-401’). Results indicated cultivar had a significant effect on all studied traits. ‘Option-500’ and ‘Hyola-401’ cultivars had the highest seed yield, protein content, and N:S ratio in seed. The levels of 150 and 220 kg N ha?1 resulted in the maximum protein content. Increasing N levels resulted in N content and decreased the oil content. The interaction effect between S and N levels showed the highest N content in seed was obtained with 300 kg S ha?1 and 225 kg N ha?1.  相似文献   

4.
Ammonium sulfate and urea are main sources of nitrogen (N) for annual crop production in developing countries. Two greenhouse experiments were conducted using ammonium sulfate and urea as N sources for upland rice grown on a Brazilian Oxisol. The N rates used were 0, 50, 100, 150, 3000, and 400 kg N kg?1 of soil. Yield and yield components were significantly increased in a quadratic fashion with increasing N rate. Ammonium sulfate X urea interaction was significant for grain yield, shoot dry matter yield, panicle number, plant height and root dry weight, indicating a different response magnitude of these plant parameters to two sources of N. Based on regression equation, maximum grain yield was achieved with the application of 380 mg N kg?1 by ammonium sulfate and 271 mg N kg?1 by urea. Grain yield and yield components were reduced at higher rates of urea (>300 mg kg N) but these plant parameters’ responses to ammonium sulfate at higher rates was constant. In the intermediate N rate range (125 to 275 mg kg?1), urea was slightly better compared to ammonium sulfate for grain yield. Grain yield was significantly related with plant height, shoot dry weight, panicle number, grain harvest index and root dry weight. Hence, improving these plant characteristics by using appropriate soil and plant management practices can improve upland rice yield.  相似文献   

5.
太湖地区稻麦轮作条件下施用包膜尿素的氮素循环和损失   总被引：8，自引：0，他引：8  
A field experiment was conducted to investigate the fate of ^15N-labeled urea and its residual effect under the winter wheat （Triticum aestivum L.） and summer maize （Zea mays L.） rotation system on the North China Plain. Compared to a conventional application rate of 360 kg N ha^-1 （N360）, a reduced rate of 120 kg N ha^-1 （N120） led to a significant increase （P 〈 0.05） in wheat yield and no significant differences were found for maize. However, in the 0-100 cm soil profile at harvest, compared with N360, N120 led to significant decreases （P 〈 0.05） of percent residual N and percent unaccounted-for N, which possibly reflected losses from the managed system. Of the residual fertilizer N in the soil profile, 25.6%-44.7% and 20.7%-38.2% for N120 and N360, respectively, were in the organic N pool, whereas 0.3%-3.0% and 11.2%-24.4%, correspondingly, were in the nitrate pool, indicating a higher potential for leaching loss associated with application at the conventional rate. Recovery of residual N in the soil profile by succeeding crops was less than 7.5% of the applied N. For N120, total soil N balance was negative; however, there was still considerable mineral N （NH4^＋-N and NO3^--N） in the soil profile after harvest. Therefore, N120 could be considered ngronomically acceptable in the short run, but for long-term sustainability, the N rate should be recommended based on a soil mineral N test and a plant tissue nitrate test to maintain the soil fertility.  相似文献   

6.
With respect to the important effects of nitrogen (N) on plant growth and fruit production, a five-year experiment was performed to evaluate the effects of different sources of N fertilization including chemical and organic on the quantity and quality of citrus fruit. Using five-year old trees, different types of fertilization including ammonium sulfate, urea coated with sulfur, ammonium nitrate and manure were tested using seven treatments in five replicates from 2002 to 2007. Different plant quantitative and qualitative parameters were determined. The most effective strategy on fruit yield production was the use of urea coated with sulfur and manure with 92.46 kg ha?1 fruit yield followed by ammonium sulfate and manure (87.06 kg ha?1) and ammonium sulfate (86.43 kg ha?1). The combination of mineral and organic fertilization may be the most suitable fertilization strategy for citrus production.  相似文献   

7.
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   

8.
Field experiments were carried out during rainy (kharif) and winter (rabi) seasons (June–April) of 2008–2010 at Indian Agricultural Research Institute (IARI), New Delhi, to study the productivity, nutrients uptake, iron (Fe) use-efficiency and economics of aerobic rice-wheat cropping system as influenced by mulching and Fe nutrition. The highest yield attributes, grain and straw yields (5.41 tonnes ha?1 and 6.56 tonnes ha?1, respectively) and nutrient uptake in rice was recorded with transplanted and puddled rice (TPR) followed by aerobic rice with Sesbania aculeata mulch. However, residual effect of aerobic rice with wheat straw mulch was more pronounced on yield attributes, grain and straw yields (4.20 and 6.70 tonnes ha?1, respectively) and nutrient uptake in succeeding wheat and remained at par with aerobic rice with Sesbania mulch. Application of iron sulfate (FeSO4) at 50 kg ha?1 + 2 foliar sprays of 2% FeSO4 was found to be the best in terms of all the yield attributes, grain and straw yield (5.09 and 6.17 tonnes ha?1, respectively) and nutrient uptake and remained at par with 3 foliar sprays of 2% FeSO4. Although residual effect of iron application failed to increase the yield attributes, yield and nutrient uptake nitrogen, phosphorus and potassium (N, P, K) except Fe. The highest system productivity, nutrient uptake, gross returns, net returns, B: C ratio and lowest cost of cultivation were recorded with aerobic rice with wheat straw and Sesbania aculeata mulch. Application of FeSO4 at 50 kg ha?1 + two foliar sprays of 2% FeSO4 was found better in respect of system productivity, nutrient uptake, gross returns, net returns, B:C ratio and cost of cultivation in aerobic rice-wheat cropping system. The Fe use efficiency values viz. partial factor productivity (kg grain kg?1 Fe), agronomic efficiency (kg grain increased kg?1 Fe applied), agrophysiological efficiency (kg grain kg?1 Fe uptake), physiological efficiency (kg biomass kg?1 Fe uptake), apparent recovery (%) utilization efficiency and harvest index (%) of applied Fe were significantly affected due to methods of rice production and various Fe nutrition treatments in aerobic rice and aerobic rice-wheat cropping system.  相似文献   

9.
A long-term study was conducted to study the impact of integrated nutrient management on soil quality in post-monsoon sorghum (Sorghum bicolor) at Solapur in Maharashtra State in Western India under All India Coordinated Research Project for Dryland Agriculture. The experiment was laid out with ten Integrated Nutrient Management Treatments in a randomized block design with three replications. The results of the study indicated that among all the integrated nutrient management treatments practiced, the application of 25 kg nitrogen (N) ha?1 through crop residue (CR) + 25 kg N ha?1 (urea) showed the highest soil quality index of 2.36, which was at par with other treatments receiving farmyard manure (FYM) and crop residues along with urea. The relative order of performance of the integrated nutrient management treatments in influencing soil quality was: T6: 25 kg N ha?1 (CR) + 25 kg N ha?1 (urea) (2.36) >T5: 25 kg N ha?1 (FYM) (2.31) > T7: 25 kg N ha?1 (FYM) +25 kg N ha?1 (urea) (2.30) = T8: 25 kg N ha?1 (CR) +25 kg N ha?1 (Leucaena loppings) (2.30) > T10: 25 kg N ha?1 (Leucaena loppings) +25 kg N ha?1 (urea) (2.17) > T4: 25 kg N ha?1 (CR:crop residues) (2.16) > T9: 25 kg N ha?1 (Leucaena loppings) (2.15) > T3: 50 kg N ha?1 (urea) (2.10) > T2: 25 kg N ha?1 (urea) (1.99) > T1: 0 kg N ha?1 (control) (1.77). The results of the study also indicated that average percent contribution of each soil key indicator towards soil quality indices was: pH (3.97%), EC (1.94%), organic carbon (18.6%), available P (2.80%), available K (6.57%), exchangeable Ca (7.02%), available S (3.45%), Available Zn (17.9%), dehydrogenase (DHA) (16.2%), microbial biomass carbon (MBC) (18.5%) and mean weight diameter (MWD) (3.14%). Thus, the results of the present study will be highly useful to the land managers in planning effective management of soil quality.  相似文献   

10.
The objective of this growth chamber study was to evaluate the effect of adding N-(n-butyl) thiophosphoric triamide (NBPT) and dicyandiaminde (DCD) to urea fertilizer, on the physiology and growth of cotton (Gossypiumhirsutum L.) under normal and high temperatures. Treatments consisted of two day temperature regimes, 30°C and 38°C, and five nitrogen fertilization applications: unfertilized control, 125 kg ha?1 of urea, 93 kg ha?1 of urea, 93 kg ha?1 urea + NBPT, and 93 kg ha?1 urea + NBPT + DCD. The addition of NBPT to urea fertilizer had positive effects on leaf chlorophyll, leaf area, dry matter, nitrogen (N) uptake, and N use efficiency. The absence of a significant interaction effect indicated that N fertilization was not influenced by temperature. Deficiency of N significantly decreased leaf chlorophyll, increased glutathione reductase, decreased protein and increased leaf nitrate reductase. Physiological changes under high temperature included increased plant N uptake, glutamine synthetase, leaf chlorophyll, protein content, plant height and leaf area were due to high N uptake and utilization.  相似文献   

11.
Nitrogen (N) is one of the most yield limiting nutrients in lowland rice production. Improving N use efficiency is essential to reduce cost of crop production and environmental pollution. A greenhouse experiment was conducted with the objective to compare conventional and polymer coated urea for lowland rice production. Grain yield, straw yield, panicle density, maximum root length, and root dry weight were significantly increased in a quadratic fashion with the increase of N rate from 0 to 400 mg kg?1 soil. Nitrogen source X N rate interactions for most of these traits were not significant, indicating that lowland rice responded similarly to change in N rates of two N sources. Based on regression equations, maximum grain yield was obtained with the application of 258 mg N kg?1 soil and maximum straw yield was obtained with the addition of 309 mg N kg?1 soil. Nitrogen use efficiency (grain yield per unit of N applied) was maximum for polymer coated urea compared to conventional urea. Root length and root dry weight improved at an adequate N rate, indicating importance of N fertilization in the absorption of water and nutrients and consequently yield. Polymer coated urea had higher soil exchangeable calcium (Ca) and magnesium (Mg), Ca saturation, Mg saturation, base saturation, and effective cation exchange capacity compared to conventional urea. There was a highly significant decrease in soil exchangeable potassium (K) with increasing N rates at harvest of rice plants.  相似文献   

12.
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   

13.
施用包膜尿素对水稻生长和氮磷流失的影响   总被引：8，自引：3，他引：5  
施用新型肥料是减少养分径流损失的重要途径。采用田间试验研究了施用包膜尿素对水稻生长和径流氮磷损失的影响,试验设置CK(习惯施肥)、PU1(减磷41%、减氮20%、施普通尿素)、PU2(PU1基础上减氮13%)、UR1(PU2基础上施包膜尿素)和UR2(UR1基础上减氮13%)5个处理。结果表明:PU1和UR1处理水稻氮磷含量与CK处理相近,PU1成熟期氮、磷总积累量比CK增加11.21,2.69kg/hm~2。PU1和UR1处理成熟期地上部生物量和籽粒产量高于CK处理,籽粒产量分别提高7.68%,5.77%。PU1、PU2、UR1和UR2处理径流总磷含量和累积流失量比CK处理低,减少13.18%~21.51%。施用包膜尿素(PU1、PU2)处理径流总氮、铵氮和硝氮含量低于施用普通尿素(CK、UR1、UR2)处理;稻田径流总氮、铵氮和硝氮累积流失量分别减少12.90%~26.91%,54.52%~49.38%和4.03%~15.95%,其中包膜尿素处理铵氮累积流失量显著(P0.05)小于普通尿素处理。施用包膜尿素和优化施肥能促进水稻对氮磷养分的吸收,提高水稻籽粒产量,显著减少稻田氮磷流失量,值得在水稻生产中推广应用。  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.
It was hypothesized that the application of eucalyptus biochar enhances nutrient use efficiencies of simultaneously supplied fertilizer, as well as provides additional nutrients (i.e., Ca, P, and K), to support crop performance and residual effects on subsequent crops in a degraded sandy soil. To test this hypothesis, we conducted an on‐farm field experiment in the Khon Kaen province of Northeastern Thailand to assess the effects of different application rates of eucalyptus biochar in combination with mineral fertilizers to upland rice and a succeeding crop of sugarcane on a sandy soil. The field experiment consisted of three treatments: (1) no biochar; (2) 3.1 Mg ha?1 biochar (10.4 kg N ha?1, 3.1 kg P ha?1, 11.0 kg K ha?1, and 17.7 kg Ca ha?1); (3) 6.2 Mg ha?1 biochar (20.8 kg N ha?1, 6.2 kg P ha?1, 22.0 kg K ha?1, and 35.4 kg Ca ha?1). All treatments received the same recommended fertilizer rate (32 kg N ha?1, 14 kg P ha?1, and 16 kg K ha?1 for upland rice; 119 kg N ha?1, 21 kg P ha?1, and 39 kg K ha?1 for sugarcane). At crop harvests, yield and nutrient contents and nitrogen (N) use efficiency were determined, and soil chemical properties and pH0 monitored. The eucalyptus biochar material increased soil Ca availability (117 ± 28 and 116 ± 7 mg kg?1 with 3.1 and 6.2 Mg ha?1 biochar application, respectively) compared to 71 ± 13 mg kg?1 without biochar application, thus promoting Ca uptake and total plant biomass in upland rice. Moreover, the higher rate of eucalyptus biochar improved CEC, organic matter, available P, and exchangeable K at succeeding sugarcane harvest. Additionally, 6.2 Mg ha?1 biochar significantly increased sugarcane yield (41%) and N uptake (70%), thus enhancing N use efficiency (118%) by higher P (96%) and K (128%) uptake, although the sugar content was not increased. Hence, the application rate of 6.2 Mg ha?1 eucalyptus biochar could become a potential practice to enhance not only the nutrient status of crops and soils, but also crop productivity within an upland rice–sugarcane rotation system established on tropical low fertility sandy soils.  相似文献   

16.
Dry bean (Phaseolus vulgaris L.) is an important legume worldwide and nitrogen (N) is most yield limiting nutrients. A field experiment was conducted for two consecutive years to evaluate response of 15 dry bean genotypes to nitrogen and rhizobial inoculation. The N and rhizobia treatments were (i) control (0 kg N ha?1), (ii) seed inoculation with rhizobia strains, (iii) seed inoculation with rhizobia strains + 50 kg N ha?1, and (iv) 120 kg N ha?1. Straw yield, grain yield, and yield components were significantly influenced by N and rhizobial treatments. Grain yield, straw yield, number of pods m?2, and grain harvest index were significantly influenced by year, nitrogen + rhizobium, and genotype treatments. Year × Nitrogen + rhizobium × genotype interactions were also significant for these traits. Hence, these traits varied among genotypes with the variation in year and nitrogen + rhizobium treatments. Inoculation with rhizobium alone did not produce maximum yield and fertilizer N is required in combination with inoculation. Based on grain yield efficiency index, genotypes were classified as efficient, moderately efficient, and inefficient in nitrogen use efficiency (NUE). NUE defined as grain produced per unit N applied decreased with increasing N rate. Overall, NUE was 23.17 kg grain yield kg?1 N applied at 50 kg N ha?1 and 13.33 kg grain per kg N applied at 120 kg N ha?1.  相似文献   

17.
Rice is staple food for more than 50% of the world's population. Nitrogen (N) is one of the most yield-limiting nutrients for lowland rice production around the world. Two field experiments were conducted at two locations for two consecutive years to evaluate N-use efficiency of 12 lowland rice genotypes. Growth, grain yield, and yield components were significantly influenced by N as well as genotype treatments. Location?×?year?×?genotype and location?×?year?×?N interactions were significant for most of the growth, yield, and yield components, indicating influence of these factors on yield and yield components. Overall, the most N-efficient genotypes measured in terms of grain yield were BRA 031032, BRA 031044, and BRA 02654 and the most inefficient genotypes were BRS Jaçana, BRS Fronteira, and BRA 02674. Genotypes had linear and quadratic responses to added N in the range of 0 to 200 kg ha?1. Nitrogen significantly influenced plant height, shoot dry weight, panicle number, and 1000-grain weights. Nitrogen-use efficiency (kg grain per kg N applied) varied from 33 to 49 kg grain per kg N applied, with an average value of 40 kg grain per kg N applied. The genotype BRA 031044 produced the greatest N-use efficiency, and the lowest N-use efficient genotype was BRS Fronteira. There was a significant linear association between N-use efficiency and grain yield.  相似文献   

18.
A long-term field experiment was conducted in Vertisols of Solapur (Maharashtra, India) to assess the effect of the integrated use of nutrients on yield, soil properties, and nutrient balance in post-monsoon sorghum. The highest crop yield (1.19 Mg ha?1) and available nutrients (308, 14.9, and 814 kg ha?1 nitrogen (N), phosphorus (P), and potassium (K), respectively) were recorded in the treatment of 25 kg N sorghum crop residue (CR) + 25 kg N Leucaena clippings (LCs), 25 kg N (CR) + 25 kg N (urea), 25 kg N farmyard manure + 25 kg N (urea), and 25 kg N (CR) + 25 kg N (LC), respectively. Most of the nutrients were depleted except K and Ca. The response ratio for N (16 kg kg?1) and partial factor productivity (33 kg kg?1) were considerably higher in the 25 kg N (CR) + 25 kg N (LC) treatment. Conjunctive use of organic ?and chemical fertilizers helped in reducing the nutrient losses and improved their use efficiency and yield sustainability.  相似文献   

19.
Based on experiments conducted during 1988–2009 on rainfed pearl millet/sorghum with 9 treatments in Vertisols, an efficient treatment for sustainable productivity is identified. Twenty kg of nitrogen (N) from farmyard manure (FYM) + 20 kg N (urea) + 10 kg phosphorus (P) ha?1 in pearl millet and 40 kg N (urea) + 20 kg P + 25 kg zinc sulfate (ZnSO4) ha?1 in sorghum gave maximum yield and rainwater-use efficiency, whereas 20 kg N (FYM) + 20 kg (urea) + 10 kg P ha?1 in pearl millet and 40 kg (urea) + 20 kg P ha?1 in sorghum and gave maximum soil N, P, and potassium (K) over years. The regression model of 20 kg N (crop residue) + 20 kg N (urea) + 10 kg P ha?1 gave maximum R2 for predicting sorghum equivalent yield separately through precipitation and soil variables, whereas 20 kg N (FYM) + 20 kg N (urea) + 10 kg P ha?1 gave maximum R2 under combined model of both variables. Treatment of 20 kg N (FYM) + 20 kg N (urea) + 10 kg P ha?1 was superior for attaining maximum sorghum equivalent yield of 1062 kg ha?1, net returns of Rs. 4805 ha?1, benefit/cost (BC) ratio of 1.50, and 127 kg ha?1 of soil N, 10.3 kg ha?1 of soil P, and 386 kg ha?1 of soil K over years.  相似文献   

20.
Dry direct-seeded aerobic rice (DSR) is an emerging attractive alternative to traditional puddled transplanted rice (PTR) production system for reducing labour and irrigation water requirements in the Indo-Gangetic plains (IGP) of India. The fertilizer N requirement of DSR grown with alternate wetting and drying water management may differ from that of PTR grown under continuous flooding due to differences in N dynamics in the soil/water system and crop growth patterns. Limited studies have been conducted on optimizing N management and application schedule for enhanced N use efficiency in DSR. Therefore, field experiments were conducted over 3 years in NW India to evaluate the effects of N rate and timing of its application on crop performance and N use efficiency. Interaction effects of four N rates (0, 120, 150, and 180 kg ha?1) as urea and four schedules of N application on yield and N use efficiency were evaluated in DSR. The N schedules included N application in three equal split doses (0, 35 and 63, and 14, 35 and 63 days after sowing, DAS) and four equal split doses (0, 28, 49 and 70; 14, 28, 49 and 70 DAS). There was no significant interaction between N rate and schedules on grain yield. Significant response to fertilizer N was observed at 120 kg N ha?1 and economic optimum dose for three equal split doses and skipping N at sowing was 130 kg N ha?1. Highest mean grain yield of 6.60 t ha?1 was obtained when N was applied in three equal split doses at 14, 35 and 63 DAS which was about 8.5% higher compared with N applied in four equal split doses at 14, 28, 49 and 70 DAS. Under the best N application schedule, agronomic N use efficiency (26 kg grain kg?1), recovery efficiency (49%) and physiological efficiency (53 kg kg?1) were comparable to the values reported in Asia for PTR. Results from our study will help to achieve high yields and N use efficiency in DSR to replace resource intensive PTR.  相似文献   

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