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1.
Drip irrigation in dry-seeded rice (DSR) is a new water-saving cultivation technology; however, very little is known of its productivity and water-saving capacities. The study was conducted for 2 years (2013 and 2014) in a split-plot design in three replicates with treatment combinations of four irrigation regimes [drip irrigation at 1.5, 2.25, and 3.0× pan evaporation (Epan) and flood irrigation at 3.0× Epan] and three nitrogen (N) levels (120, 150, and 180 kg ha?1). Drip irrigation in DSR resulted in higher grain yield (7.34–8.01 t ha?1) than flood irrigation (6.63–7.60 t ha?1) , with water savings of more than 40 %. Water-use efficiency with drip irrigation was higher (0.81–0.88 kg m?3) than flood irrigation (0.42–0.52 kg m?3) , being highest with drip irrigation at 1.5× Epan. Root density at soil depths of 15–30 cm was also higher in drip (0.86–1.05 mg cm?3) as compared to the flood (0.76–0.80 kg m?3)-irrigated crop. This study implicated that under water-scarce scenario, drip-irrigated DSR is a profitable, and water- and energy-saving technology. This study also suggested that policy focus in future must be tilted towards the promotion of solar-operated drip irrigation in those regions, where DSR is being promoted in the face of water and energy crisis.  相似文献   

2.
Soil and water pollution caused by organic waste is a concern for livestock-breeding areas. Nitrogen balance in a paddy-field water-purifying system in which cattle feces were applied was studied for 4 years to assess the suitability of the system for a subtropical area, Japan. Three successive harvestings using ratoon of forage rice following one rice transplanting were conducted with chemical fertilizer and high and low rates of cattle-feces application. Nitrogen load was 81.3–495.0 kg N ha?1 year?1, while nitrogen uptake was highly dependent on the yield of the first harvesting. Annual variation of forage rice yields was large, ranging from 15.5 to 26.8 Mg ha?1 owing to fluctuation in the yield at second and later harvestings. On average, nitrogen was lost by leaching at a rate of 2.3–3.4 kg N ha?1 year?1. The nitrogen content in soil at a depth of 0–5 cm increased up to 12.2 kg N ha?1 over the 4-year period compared with that before the field experiment. However, continuous application of cattle feces could slightly increase the nitrogen content in soil at a depth greater than 35 cm. Our results showed the ability of flooded forage rice to remove nitrogen at up to 320.1 kg ha?1 year?1 for a field to which cattle feces were applied. Further investigation is needed to produce a high and stable yield at second harvesting each year, to prevent the accumulation of soil nitrogen, and to assess gaseous nitrogen loss.  相似文献   

3.
In order to increase the efficacy of water and control the losses of fertilizer, it is necessary to assess the influence of level of fertilization on crop responses, movement and balance of water and solutes from fertilizers in the root zone. With this goal, the reported study was undertaken to determine the effect of fertilization on crop responses and fertilizer solute transport in rice crop field in a sub-humid and sub-tropical region. Field experiment was conducted on rice crop (cultivar IR 36) during the years 2003, 2004, and 2005. The experiment included four fertilizer treatments comprising different levels of fertilizer application. The fertilizer treatments during the experiment were: F1 = control with N:P2O5:K2O as 0:0:0 kg ha?1; F2 = fertilizer application of N:P2O5:K2O as 80:40:40 kg ha?1; F3 = fertilizer application of N:P2O5:K2O as 120:60:60 kg ha?1 and F4 = fertilizer application of N:P2O5:K2O as 160:80:80 kg ha?1. The results of the investigation revealed that the magnitudes of crop parameters such as grain yield, straw yield, and maximum leaf area index increased with increase in fertilizer application rate. The levels of fertilization had very little effect on water loss via deep percolation and water use by the crop. The levels of fertilization had considerable effect on N leaching loss and uptake of N whereas it had no significant impact on leaching loss of water-soluble phosphorus. This indicated that PO4-P leaching loss was very low in the soil solution as compared to nitrogen due to fixation of phosphorus in soils. The results also revealed that increase in level of fertilization increased water use efficiency considerably by increased crop yield. From the observed data of nutrient use efficiency, crop yield and environmental pollution, the fertilization rate of N:P2O5:K2O as 80:40:40 kg ha?1 (F2) was the most suitable fertilizer treatment for rice crop among studied treatments.  相似文献   

4.
The system of rice intensification (SRI) reportedly enhances yield with less water requirement. This claim was investigated to determine the effects of alternative cultivation methods and water regimes on crop growth and physiological performance. Treatment combinations compared SRI with the conventional transplanting system (CTS) using standard practices, evaluating both along a continuum from continuous flooding to water applications at 1, 3, 5, or 7 days after disappearance of ponded water (DAD), subjecting plants to differing degrees of water stress while reducing total water expenditure. SRI methods gave significant changes in plants’ phenotype in terms of root growth and tillering, with improved xylem exudation and photosynthetic rates during the grain-filling stage compared to CTS. This resulted in significant increases in panicle length, more grains and more filled grains panicle?1, greater 1,000-grain weight, and higher grain yield under SRI management. Overall, averaged across the five water regimes evaluated, SRI practice produced 49 % higher grain yield with 14 % less water than under CTS; under SRI, water productivity increased by 73 %, from 3.3 to 5.7 kg ha-mm?1. The highest CTS grain yield and water productivity were with the 1-DAD treatment (4.35 t ha?1 and 3.73 kg ha-mm?1); SRI grain yield and water productivity were the greatest at 3-DAD (6.35 t ha?1 and 6.47 kg ha-mm?1).  相似文献   

5.
The effect of controlled irrigation and drainage on N leaching losses from paddy fields was investigated by controlling root zone soil water content and water table depth using a lysimeter equipped with an automatic water table control system. Three treatments that combined irrigation and drainage managements were implemented: controlled irrigation (CI) + controlled water table depth 1 (CWT1), CI + controlled water table depth 2 (CWT2), and flooding irrigation (FI) + actual field water table depth (FWT). Controlled irrigation and drainage had significant environmental effects on the reduction of NH4 +–N and NO3 ?–N leaching losses from paddy fields by decreasing water leakage. The NH4 +–N leaching losses from CI + CWT1 and CI + CWT2 were 3.68 and 4.45 kg ha?1, respectively, which significantly reduced by 59.2 and 50.7 % compared with FI + FWT (9.02 kg ha?1). The NO3 ?–N leaching losses from CI + CWT1 and CI + CWT2 were 0.88 and 0.43 kg ha?1 with a significant reduction of 45.2 and 73.2 %, respectively, compared with FI + FWT (1.61 kg ha?1). The application of CI + CWT1 can be a pollution-controlled water management method of reducing N leaching losses from paddy fields.  相似文献   

6.
Three methods of rice cultivation were compared in a field experiment at New Delhi, India during 2012 for their water use and changes in nutrient availability of soil. The experiment was laid out in a split plot design with conventional transplanting (CT), system of rice intensification (SRI), and aerobic rice (AR) cultivation technologies. Five doses of nitrogen included 100 % (120 kg N ha?1), 125, and 150 % recommended dose of N(RDN) through urea, 75 % of RDN through urea (90 kg N ha?1) + 25 % of RDN (30 kg ha?1) through farm yard manure (FYM), and 100 % of RDN through FYM. Results revealed that status of available N in soil under rice at 45 and 90 days after sowing (DAS) was significantly higher in CT and SRI compared to AR method. Application of the highest dose of nitrogen through urea resulted in the highest availability of N (188.9, 174.2, and 135.2 kg ha?1 for 45 and 90 DAS and at harvest stage, respectively). The soil under AR recorded significantly low availability of phosphorus and iron. However, availability of K in soil was not affected significantly under adopted production techniques and nitrogen management. The recorded irrigation water productivity was maximum in AR cultivation (9.16 kg ha mm?1) followed by SRI (7.02 kg ha mm?1) with irrigation water saving of 54 and 36 %, respectively compared to CT.  相似文献   

7.
Weeds caused serious problem on yield reduction of basmati rice worldwide. Losses caused by weeds varied from one country to another, depending on the presence of dominant weeds and the control methods practiced by farmers; therefore, suitable plant population and weed management practices should be adopted. Keeping these in mind, a field experiment was carried out during kharif seasons of 2009 and 2010 at crop Research Centre of SVPUA&T, Meerut, India comprising 4 planting geometries, viz. 20, 30, 40, and 50 hills m?2 as main plot factor, and 5 weed management practices (Butachlor @ 1.0 kg ha?1, Butachlor @ 1.0 kg ha?1 fb (followed by) one hand weeding, Butachlor @ 1.0 kg ha?1 fb Almix @ 4 g ha?1, two hand weedings and weedy check) in a split plot design with 3 replications. Experimental results revealed that plant population of 50 hills m?2 proved superior over that of 20 hills m?2 in respect of weed density, weed dry weight, number of tillers m?2, yield attributes, grain, straw, and biological yields. The maximum grain yield (29.00 and 31.00 q ha?1) and straw yield (51.30 and 52.50 q ha?1) were recorded in 50 hills m?2 followed by 40 hills m?2 during 2009 and 2010, respectively. In respect of nitrogen, phosphorus, and potassium removal, a reverse trend was observed: the highest in 20 hills m?2 followed by 30, 40, and 50 hills m?2. As far as the weed management practices are concerned, both chemical and mechanical methods of weed control were found superior over weedy check. The lowest weed density, dry weight, and highest weed control efficiency, maximum length of panicle?1, number of panicle (m2), and 1000-grain weight and grain yield of 30.40 and 32.60 q ha?1 were recorded with two hand weedings which was at par with Butachlor @ 1.0 kg ha?1 fb one hand weeding over rest of the weed management practices.  相似文献   

8.
To study the radiation utilization efficiency, latent heat flux, and simulate growth of rice during post-flood period in eastern coast of India, on-farm trial was conducted with three water regimes in main plots (W 1 = continuous flooding of 5 cm, W 2 = irrigation after 2 days of water disappearance, and W 3 = irrigation after 5 days of water disappearance) and five nitrogen levels in subplots (N 1 = 0 kg N ha?1, N 2 = 60 kg N ha?1, N 3 = 90 kg N ha?1, N 4 = 120 kg N ha?1, and N 5 = 150 kg N ha?1) on a rice cultivar, ‘Lalat’. Average maximum radiation utilization efficiency (RUE) in terms of above ground dry biomass of 2.09 (±0.05), 2.10 (±0.02), and 1.9 (±0.08) g MJ?1 were computed under W 1, W 2, and W 3, respectively. Nitrogen increased the RUE significantly, mean RUE values were computed as 1.60 (±0.07), 1.78 (±0.02), 2.060 (±0.08), 2.30 (±0.07), and 2.34 (±0.08) g MJ?1 when the crop was grown with 0, 60, 90, 120, and 150 kg ha?1 nitrogen, respectively. Midday average latent heat flux (on clear days) varied from 7.4 to 14.9 and 8 to 13.6 MJ m?2 day?1 under W 2 and W 3 treatments, respectively, at different growth stages of the crop in different seasons. The DSSAT 4.5 model was used to simulate phenology, growth, and yield which predicted fairly well under higher dose of nitrogen (90 kg and above), but the model performance was found to be poor under low-nitrogen dose.  相似文献   

9.
Intermittent and prolonged dry spell during growth of transplanted rice is an important abiotic problem in north eastern region (NER). However, the productivity of rice in the region is very low, and this is mainly associated with reduced plant population, growth, and yield attributes with lower relative water content and leaf rolling with formation of soil cracks by erratic and aberrant rainfall. Keeping this in view, a field experiment on transplanted rice was conducted during two consecutive years 2011 and 2012 at NER of India, to evaluate the imposition of forced surface drainage (SD) at various growth stages (continuous drainage, SD at tillering, SD at panicle initiation, SD at booting, SD at flowering, SD at milking, and 15 days intermittent SD) and was compared with continuous flooding on growth and yield attributes, yield, relative water content, leaf rolling, and formation of soil cracks. Results revealed that continuous flooding has significant (p < 0.05) improved the plant population, growth and yield parameters, rice grain yield (3,406.7 kg ha?1) and straw yield (4,683.3 kg ha?1), relative water content maintained >90 %, no leaf roll, and soil crack. However, imposition of SD at tillering has lower tillers hill?1, but yield was compensated by improvement in yield attributes. As per the availability of water, growers of the region can utilize the water for scheduling of water and most critical stages can be avoided by moisture stress to obtain higher productivity.  相似文献   

10.
Tropical highland conditions in Mwea Kenya, ensure the high radiation and the large day–night temperature differences. Such conditions are generally believed to promote rice growth and yield, but the current grain yield is lower than the expectation. In the current standard N fertilizer practice in Mwea, 75 kg nitrogen (N) ha?1 is applied in three splits at fixed timing. The effects of increases in N fertilizer amount (125, 175, and 225 kg N ha?1) on rice growth and yield were evaluated to test the hypothesis that unachieved high rice grain yield in Mwea is due to insufficient amount of N fertilizer. Two popular lowland varieties in Mwea (Basmati 370 and BW196) and two varieties reported as high yielding in other countries (Takanari and IR72) were used. Shoot dry weight (DW) increased with increases in the amount of N fertilizer applied in three splits at fixed timing, irrespective of variety. It reached approximately 20 t ha?1 under increased N conditions (>75 kg N ha?1) in several cases, indicating that high biomass production could be achieved by increasing N application rate. However, the increased biomass did not increase grain yield, due to decreased grain filling under high N conditions in all varieties. Thus, N amounts above 75 kg ha?1 were ineffective for increasing grain yields in Mwea, where N fertilizer was applied in three splits at fixed timing. Increasing influence of low temperature under high N conditions may be one of the reasons for the decreased grain filling in Mwea.  相似文献   

11.
Deep placement of urea supergranules in wetland rice (Oryza sativa L.) or correct urea band application enables to protect nitrogen (N) from various loss mechanisms, but recovering of fertilizer N by plants depends upon geometric and agronomic factors. The objective of this study was to characterize the diffusion of ammoniacal N from the two urea sources, point or line application, in a typical paddy soil. A model of ammonia diffusion was developed for the two geometries. The relation between the N application rate and the transplanting geometry was studied in two fields using probes attached to urea supergranule of different mass (2 and 4 g). The transplanting pattern was adapted for obtaining 58 or 116 kg N ha?1 in the 4 g application. The ammoniacal nitrogen concentration was compared to the diffusion model prediction. The values of the diffusion coefficient were found to be 1.160 and 1.107 cm2 d?1. Ammonia disappearance below 10 mmol L?1 did not follow the same kinetics in the two treatments corresponding to 4 g application. Relative to the 2 g treatment, root ammonia uptake in the 4 g treatment was delayed and slowed in the classical geometry of 20 cm × 20 cm (116 kg N ha?1) when it was mainly delayed in the geometry provided with 58 kg N ha?1. This manipulation of the source–sink relationship enables to foresee possibilities for the development of new fertilizers adapted to wetland rice cultivation.  相似文献   

12.
Improper application of nitrogen (N) has led to high N losses and low N use efficiency in the lower reaches of Yangtze River in China. An effective method to solve such problems is the deep fertilized N in root zone (RZF). Limited information is available on the effect of RZF on the uptake of macronutrients (N, P and K) and rice yield. Field experiments, conducted from 2014 to 2015, compared the farmer fertilizer practice (FFP, with 225 kg ha?1 of N, split into three doses) and RZF using the same rate but placing N 5 cm away from rice roots in holes 10 cm deep (RZF10) or 5 cm deep (RZF5) as a single application. The highest mean yield (10.0 t ha?1) was obtained in RZF10, which was 19.5% more than that in FFP. Root zone fertilization of urea (whether 10 cm deep or 5 cm deep) resulted in greater accumulation of N, P and K in stem, leaf sheaths, leaf blades and grains compared to that in FFP in sandy and in loam soils. The uptake of N, P and K was the highest in RZF10 (average at 176.7, 66.2 and 179.1 kg ha?1, respectively), higher than that in FFP by 45.0, 17.0 and 22.6%, respectively. N apparent recovery efficiency was markedly higher in RZF10 (53.1%) than in FFP (27.5%). RZF10 significantly increased the N, P, K uptake compared with FFP under different N rates in both sandy and loam soils. These results suggest that the N, P and K input amount should be re-determined under RZF.  相似文献   

13.
Manganese (Mn) deficiency is prevalent in rice-growing regions resulting in poor paddy yield and human health. In this study, role of Mn, applied through various methods, in improving the productivity and grain biofortification of fine grain aromatic rice was evaluated. Manganese was delivered as soil application (SA) (0.5 kg ha?1), foliar spray (FA) (0.02 M Mn), seed priming (SP) (0.1 M Mn) and seed coating (SC) (2 g Mn kg?1 seed) in conventional (puddled transplanted flooded rice) and conservation (direct seeded aerobic rice) production systems at two different sites (Faisalabad, Sheikhupura) in Punjab, Pakistan. Manganese application, through either method, improved the grain yield and grain Mn contents of fine grain aromatic rice grown in both production systems at both sites. However, Mn application as SC and FA was the most beneficial and cost effective in improving the productivity and grain biofortification in this regard. Overall, order of improvement in grain yield was SC (3.85 t ha?1) > FA (3.72 t ha?1) > SP (3.61 t ha?1) > SA (3.36 t ha?1). Maximum net benefits and benefit–cost ratio were obtained through Mn SC in flooded field at Faisalabad, which was followed by Mn SP in direct seeded aerobic rice at the same site. However, maximum marginal rate of return was noted with Mn SC in direct seeded aerobic rice at both sites. In crux, Mn nutrition improved the productivity and grain biofortification of fine grain aromatic rice grown in both conventional and conservation production systems. However, Mn application as seed treatment (SC or SP) was the most cost effective and economical.  相似文献   

14.
施氮量对新疆滴灌冬小麦根系生长及产量的影响   总被引：1，自引：0，他引：1  
为探明滴灌冬小麦高产需氮肥规律,利用大田试验研究了N_0(0 kg·hm~(-2))、N_1(90kg·h~(-2))、N_2(180kg·h~(-2))、N_3(270kg·h~(-2))、N_4(360kg·h~(-2))施氮量对新冬18号0~60cm土层根系生长的影响及其与产量和氮肥利用率的关系。结果表明,随着施氮量的增加,拔节至成熟期间0~60cm土层根系干重、根长和根系活力均增加,N_3处理孕穗期小麦0~60cm土层根干重、根长分别较N_0处理增加11.93%、29.0%,增幅基本表现为0~20cm20~40cm40~60cm土层;N_3处理较N_0处理小麦产量增加30.35%,氮肥农学利用效率为6.90kg·kg-1。拔节期前后施适量氮肥可促进0~60cm土层根系生长和活力增强,是氮肥增产的重要原因。本试验条件下最适宜施氮量为180~270kg·h~(-2),可获得产量7 591.49~8 004.85kg·h~(-2),氮肥农学利用效率为6.90~8.06。  相似文献   

15.
灌水对不同小麦品种耗水特性和土壤硝态氮运移的影响   总被引：2，自引：0，他引：2  
为了解灌水对不同小麦品种耗水特性和土壤硝态氮运移的影响,在大田条件下,以济麦20和泰山22为材料,设置4种水分处理[W0处理（全生育期不灌水）、W1处理（灌底墒水＋拔节水）、W2处理（灌底墒水＋拔节水＋开花水）、W3（灌底墒水＋拔节水＋开花水＋灌浆水）],每次灌水量60mm,分析了不同灌水处理下小麦0～200cm土层土壤含水量、土壤水消耗量、土壤硝态氮运移及籽粒产量的差异。结果表明,（1）依据土壤含水量受灌水影响的程度和变异系数,将0～200cm土壤分为3个层次：活跃层（0～60cm）、次活跃层（60～140cm）和相对稳定层（140～200cm）。（2）两品种W1处理的冬前、开花和成熟期0～60cm土层土壤硝态氮含量低于W0处理;冬前期60～140cm土层高于W0处理,140～200cm土层与W0处理无显著差异;开花期60～140cm和140～200cm土层高于W0处理;成熟期0～60cm土层高于W2、W3处理,60～140cm和140～200cm土层低于W3处理。拔节期济麦20W1处理60～140cm和140～200cm土层土壤硝态氮含量高于W0处理,泰山22的低于W0处理。（3）济麦20各处理0～200cm土层土壤水消耗量均高于泰山22。济麦20W1处理0～60cm和60～140cm土层土壤水消耗量高于W2处理,籽粒产量、水分利用效率高于W2、W3处理;泰山22W2处理0～60cm土层的土壤水消耗量与W1处理无显著差异,60～140cm和140～200cm土层的土壤水消耗量低于W1处理,水分利用效率与W1处理无显著差异,但高于W3处理,籽粒产量高于W1、W3处理。济麦20和泰山22分别以底墒水、拔节水各灌60mm和底墒水、拔节水、开花水各灌60mm为节水、高产、氮素淋溶量低的最佳灌水模式。  相似文献   

16.
A field experiment was conducted during rainy seasons of 2009 and 2010 at New Delhi, India to study the influence of varieties and integrated nitrogen management (INM) on methane (CH4) emission and water productivity under flooded transplanted (FT) and aerobic rice (AR) cultivation. The treatments included two rice (‘PB 1’ and ‘PB 1121’) varieties and eight INM practices including N control, recommended dose of N through urea, different combinations of urea with farmyard manure (FYM), green manure (GM), biofertilizer (BF) and vermicompost (VC). The results showed 91.6–92.5 % lower cumulative CH4 emission in AR compared to FT rice. In aerobic conditions, highest cumulative CH4 emission (6.9–7.0 kg ha?1) was recorded with the application of 100 % N by organic sources (FYM+GM+BF+VC). Global warming potential (GWP) was significantly lower in aerobic rice (105.0–107.5 kg CO2 ha?1) compared to FT rice (1242.5–1447.5 kg CO2 ha?1). Significantly higher amount of water was used in FT rice than aerobic rice by both the rice varieties, and a water saving between 59.5 and 63 % were recorded. Under aerobic conditions, both rice varieties had a water productivity of 8.50–14.69 kg ha?1, whereas in FT rice, it was 3.81–6.00 kg ha?1. In FT rice, a quantity of 1529.2–1725.2 mm water and in aerobic rice 929.2–1225.2 mm water was used to produce one kg rice. Thus, there was a saving of 28.4–39.6 % total water in both the rice varieties under AR cultivation.  相似文献   

17.
As the challenges toward increasing water for irrigation become more prevalent, knowledge of crop yield response to water can facilitate the development of irrigation strategies for improving agricultural productivity. Experiments were conducted to quantify maize yield response to soil moisture deficits, and assess the effects of deficit irrigation (DI) on water productivity (water and irrigation water use efficiency, WUE and IWUE). Five irrigation treatments were investigated: a full irrigation (I1) with a water application of 60 mm and four deficit treatments with application depths of 50 (I2), 40 (I3), 30 (I4), and 20 mm (I5). On average, the highest grain yield observed was 1008.41 g m?2 in I1, and water deficits resulted in significant (p < .05) reduction within range of 6 and 33%. This reduction was significantly correlated with a decline in grain number per ear, 1000-grain weight, ear number per plant, and number of grain per row. The highest correlation was found between grain yield and grain number per ear. The WUE and IWUE were within range of 1.52–2.25 kg m?3 and 1.64–4.53 kg m?3, respectively. High water productivity without significant reduction in yield (<13%) for I2 and I3 compared to the yield in I1 indicates that these water depths are viable practices to promote sustainable water development. Also, for assessing the benefits of irrigation practices in the region crop water production functions were established. Maize yield response to water stress was estimated as .92, suggesting the environmental conditions are conducive for implementing DI strategies.  相似文献   

18.
Sewage contains several trace elements of environmental concern, and cadmium (Cd) is one of the most mobile elements in soil–plant system that can pose drastic effects on plants and human health due to its long persistence and non-biodegradability nature in environment. It is necessary to prevent its entry into food chain for better food quality and human health. Present study was designed to evaluate the effectiveness of different water management practices, viz. W1: flooding throughout the growing season, W2: flooding after 4 days of disappearance of standing water (DAD), W3: flooding till heading and after that flooding of soil after 4 days of DAD, W4: Aerobic condition throughout growing season (flooding after 8 days) for reducing Cd concentration in rice grain grown under varying levels of Cd (0, 20, 40 mg kg?1) spiked soil. Results revealed that grain yield declined with increasing Cd levels but maximum plant height (89.3 cm), straw yield (16.9 g) and grain yield (22.5 g pot?1) was observed where pots were flooded till heading and thereafter flooding. Cadmium concentration increased with increasing concentration of Cd in soil. Further, it is added that the lowest Cd concentration in shoot, grain and husk and translocation factor were observed under W3 when the soil was spiked with 40 mg kg?1. In crux, continuous flooding till heading and thereafter flooding after 4 DAD can significantly decrease the grain Cd concentration without compromise on yield.  相似文献   

19.
Methane (CH4) emission and water productivity were estimated in an experiment conducted during wet (rainy) season of 2010 at the research farm of Indian Agricultural Research Institute, New Delhi, India. Treatments comprising three methods of crop establishment viz., conventional transplanting (CT), system of rice intensification (SRI) and double transplanting (DT) were laid out in randomized block design with four replications. Scented rice (Oryza sativa L) variety ‘Pusa Basmati 1401’ was transplanted in puddle field. In CT and SRI 21 and 12-day-old seedlings, respectively, were transplanted while in DT overall 45-day-old seedlings were transplanted. In CT and DT flooded conditions while in SRI saturated conditions were maintained. Results indicated that among the methods of crop establishment, CT had maximum cumulative CH4 emission (32.33 kg ha?1) followed by DT (29.30 kg ha?1) and SRI (19.93 kg ha?1). Temporal CH4 flux fluctuated between 79.7 and 482.0 mg m?2 day?1 under CT; 46.0 and 315.0 mg m?2 day?1 in SRI and 86.7 and 467.3 mg m?2 day?1 in DT. Considerable temporal variations in the individual CH4 fluxes were observed. Flux of CH4 was generally higher in early stage of crop and peaked about 21 days after transplanting coinciding with tillering stage of crop. CH4 flux declined gradually from 75 days after transplanting and stabilized at the harvest stage of rice in all the three methods of transplanting. Global warming potential was highest in CT (807.4 kg CO2 ha?1) and lowest in SRI (498.25 kg CO2 ha?1). However, a reverse trend was observed with carbon efficiency ratio. The water savings to the extent of six irrigations was recorded in SRI over CT. A saving of 27.4 % irrigation water and 18.5 % total water was recorded in SRI over CT while the corresponding values of DT over CT were 14.5 and 9.8 %. Water productivity of SRI (3.56 kg/ha mm) was significantly higher as compared to DT (2.87 kg/ha mm) and CT (2.61 kg/ha mm).  相似文献   

20.
The widely adopted alternate wetting and drying (AWD) irrigation for rice production is increasingly needed to quantify the different water outflows and nitrogen leaching losses. We investigated the effects of AWD on percolation, water productivity, nitrogen leaching losses, and nitrogen productivity through in situ experiments. Results show that AWD reduced irrigation water without a significant impact on grain yields and increased the mean water productivity by 16.9 % compared with continuously flood irrigation (CFI). The mean nitrogen productivity of 135 kg ha?1 N level was 22.2 % higher than that of 180 kg ha?1 N level, although grain yields substantially increased because of nitrogen fertilization application. The percolation was also reduced by 15.3 % in 2007 and 8.3 % in 2008 compared to CFI. However, the cumulative percolation of the first 5 days after irrigation in AWD plots is significantly larger than that in CFI plots. The NH4 +–N and TN leaching losses of AWD and CFI had no significant variations while the NO3 ?–N leaching losses were increased caused by AWD. The total NH4 +–N, NO3 ?–N, and TN leaching losses of AWD in the first 3 days after irrigation were higher than that of contemporaneous CFI. The results indicate that the bypass or preferential flow and strengthened nitrification–denitrification nitrogen transformation processes because of alternate wetting and drying potentially decrease the water saving effectiveness and increase the NO3 ?–N loading to the groundwater.  相似文献   

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