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1.
System of rice intensification (SRI) has been disseminated in many countries because of its high yield, although the mechanism of yield increase has yet to be fully understood. The aims of this study were to clarify the actual water management of a skilled SRI farmer in irrigated paddy field of Indonesia and to examine the effect of intermittent water management on rice growth and yield. Yield and yield components were compared in the field experiments in the farmer’s fields under intermittent (SRI) or flooded (FL) irrigation for 4 years from 2013 to 2016. The daily mean water depth of SRI plots during 0–40 days after transplanting showed very shallow (ca. 2 cm) or little lower than soil surface and continued to be lower than soil surface during reproductive stage when panicles were formed. The yield of SRI significantly exceeded that of FL for 4 years by 13% (P?=?0.0004), so did the panicle numbers per area (P?=?0.036). The yield increase in SRI was associated with the increased number of panicles, which should have resulted from enhanced tiller development under shallow water level during the vegetative stage. The increased number of panicles was, however, counteracted by the reduced number of spikelets per panicle and resulted in nonsignificant increase in the spikelet density, defined as number of spikelets per unit area of crop. This dampening change in spikelet number per panicle could have been caused by limited supply of either nitrogen or carbohydrate during the panicle development stage under the intermittent water supply. A greater yield increase by SRI could be expected by improving nutrient or water management during the reproductive stage.  相似文献   

2.
System of Rice Intensification (SRI) often achieved higher yield than conventional practice. We identified the high-yielding farmers from the yield records of 1909 paddy fields belonging to an organic farmers’ association. Farmers whose yields were from 8.4 to 10.4 t ha?1 were interviewed and their fields surveyed. Their yields had increased by an estimated average of 40% following the adoption of SRI practices. They applied 2–12 t ha?1 of compost. Compared to the conventional practice, they shortened seedling age at transplanting from 27.4 to 17.6 days and reduced the number of seedlings per hill from 4–6 to 2–3, while hill spacing remained unchanged. Instead of intermittent irrigation which is recommended in standard SRI, they kept shallow flooding of 1–2 cm. Although they applied a lot of compost, no correlation was found between the amount of compost application and the yields. Instead, high-yielding farmers returned rice straw into waterlogged paddy after harvest, which presumably is an ideal condition for biological nitrogen fixation. This may occur around rice straw during decomposition under waterlogged condition and might supplement the negative nitrogen balance, thereby enabling the high yield as compared with conventional practices where the fresh rice straw is removed and/or burned.  相似文献   

3.
The system of rice intensification (SRI) developed in Madagascar has been controversial in part because there have been no large-scale, long-term evaluations of the impact of its alternative methods. This paper summarizes experience with the dissemination of SRI practices across eight provinces in Eastern Indonesia over nine seasons from 2002 to 2006 under a major irrigation project. The Decentralized Irrigation System Improvement Project (DISIMP) was financed by the Japanese Government with project management by a Nippon Koei consultant team. SRI has been introduced in Indonesia via several organizations and in different parts of the country starting in 2000. The evaluation reported here, made by the DISIMP technical assistance team, is based on data from 12,133 on-farm comparison trials that covered a total area of 9,429 ha. Under SRI management, average paddy yield increase was 3.3 t/ha (78%). This was achieved with about 40% reduction in water use, 50% reduction in chemical fertilizer applications, and 20% lower costs of production. The farmers whom DISIMP was assisting to take up SRI were usually cultivating their paddy fields individually within irrigation systems where it was difficult to reduce water applications as recommended for SRI. Accordingly, innovations had to be made in soil and water management to create relatively aerobic soil conditions so that farmers could get the more productive rice phenotypes expected from SRI practice. This article describes the modifications made to adapt SRI concepts, pointing to the value of introducing in-field ditches, which was confirmed through paddy tract surveys. This experience and analysis showed how SRI methods could be utilized within irrigation systems where water management was not (yet) tailored to SRI production practices. Subsequently, modifications in irrigation system management are being made to be more supportive of SRI cultivation.  相似文献   

4.
Field experiments were conducted at DRR farm located at ICRISAT, Patancheru, in sandy clay loam soils during four seasons, Kharif 2008, Rabi 2008–2009, Kharif 2009 and Rabi 2009–2010, to investigate growth parameters, water-saving potential, root characteristics, chemical, biological, and microbial properties of rhizosphere soil, and grain yield of rice (Oryza sativa L.) by comparing the plants grown with system of rice intensification (SRI) methods, with organic or organic + inorganic fertilization, against current recommended best management practices (BMP). All the growth parameters including plant height, effective tillers (10–45 %), panicle length, dry matter, root dry weight (24–57 %), and root volume (10–66 %) were found to be significantly higher with in SRI-organic + inorganic over BMP. With SRI-organic fertilization, growth parameters showed inconsistent results; however, root dry weight (3–77 %) and root volume (31–162 %) were found significantly superior compared to BMP. Grain yield was found significantly higher in SRI-organic + inorganic (12–23 and 4–35 % in the Kharif and Rabi seasons, respectively), while with SRI-organic management, yield was found higher (4–34 %) only in the Rabi seasons compared to BMP. An average of 31 and 37 % of irrigation water were saved during Kharif and Rabi seasons, respectively, with both SRI methods of rice cultivation compared to BMP. Further, total nitrogen, organic carbon%, soil dehydrogenase, microbial biomass carbon, total bacteria, fungi, and actinomycetes were found higher in the two SRI plots in comparison to BMP. It is concluded that SRI practices create favorable conditions for beneficial soil microbes to prosper, save irrigation water, and increase grain yield.  相似文献   

5.
A field experiment was conducted during the wet seasons of 2010 and 2011 at New Delhi, India to study the influence of organic, inorganic, and integrated sources of nutrient supply under three methods of rice cultivation on rice yield and water productivity. The experiments were laid out in FRBD with nine treatment combinations. Treatment combinations included three sources of nutrient supply viz., organic, integrated nutrient management, and inorganic nutrition and three rice production systems viz., conventional transplanting, system of rice intensification (SRI) and aerobic rice system. Results indicated that the conventional and SRI showed at par grain and straw yields but their yields were significantly higher than aerobic rice. Grain yield under organic, inorganic and integrated sources of nutrient supply was at par since the base nutrient dose was same. Plant growth parameters like plant height, tillers, and dry matter accumulation at harvest stage were almost same under conventional and SRI but superior than aerobic rice system. Root knot nematode infestation was significantly higher in aerobic rice as compared to SRI and conventional rice. However, organic, inorganic and integrated sources of nutrient supply did not affect nematode infestation. There was significant advantage in term of water productivity under SRI over conventional transplanted (CT) rice and less quantity of water was utilized in SRI for production of each unit of grain. A water saving of 34.5–36.0 % in SRI and 28.9–32.1 % in aerobic rice was recorded as compared to CT rice.  相似文献   

6.
An experimental study on the System of Rice Intensification (SRI) methods was conducted to investigate the feasibility of using them to conserve irrigation water and reduce non-point source (NPS) pollution in Korea. Eight experimental runoff plots were prepared at an existing paddy field. Runoff and water quality were measured during the 2010 growing season in which a Japonica rice variety was cultivated. The irrigation water requirements of SRI methods and conventional (CT) plots were 243.2 and 547.3 mm, respectively, meaning that SRI methods could save 55.6% of irrigation water. Runoff from SRI methods plots decreased 5–15% compared with that from CT plots. Average NPS pollutant concentrations in runoff from SRI methods plots during rainfall-runoff events were SS 89.4 mg/L, CODCr 26.1 mg/L, CODMn 7.5 mg/L, BOD 2.0 mg/L, TN 4.2 mg/L, and TP 0.4 mg/L. Except for CODCr and TN, these concentrations were significantly lower than those from CT plots. Measured pollution loads from SRI methods plots were SS 874 kg/ha, CODCr 199.5 kg/ha, CODMn 47 kg/ha, BOD 13 kg/ha, TN 36.9 kg/ha, and TP 2.92 kg/ha. These were 15.8–44.1% lower than those from CT plots. Rice plants grew better and healthier in SRI methods plots than in CT plots. However, rice production from SRI methods plots ranged between 76 and 92% of that of CT plots because the planting density in SRI methods plots was too low. It was concluded that SRI methods could be successfully adopted in Korea and could help save a significant amount of irrigation requirement in paddies and reduce NPS pollution discharge.  相似文献   

7.
System of rice intensification (SRI) is an alternate method of conventional puddled, transplanted, and continuously flooded rice cultivation for higher yield, water saving, and increased farmer’s income. The SRI may also have considerable impact on greenhouse gas emission because of difference in planting, water and nutrient management practices. A field experiment was conducted with three planting methods: conventional puddled transplanted rice (TPR), conventional SRI with 12-days-old seedling (SRI) and modified SRI with 18-days-old seedling (MSRI) to study their effect on methane and nitrous oxide emission. Seasonal integrated flux (SIF) for methane was highest in the conventional method (22.59 kg ha?1) and lowest in MSRI (8.16 kg ha?1). Methane emissions with SRI and MSRI decreased by 61.1 and 64 %, respectively, compared to the TPR method. Cumulative N2O–N emission was 0.69, 0.90, and 0.89 kg ha?1 from the TPR, SRI, and MSRI planting methods, respectively. An average of 22.5 % increase in N2O–N emission over the TPR method was observed in the SRI and MSRI methods. The global warming potential (GWP), however, reduced by 28 % in SRI and 30 % in MSRI over the TPR method. A 36 % of water saving was observed with both SRI and MSRI methods. Grain yield in the SRI and MSRI methods decreased by 4.42 and 2.2 %, respectively, compared to the TPR method. Carbon efficiency ratio was highest in the MSRI and lowest in the TPR method. This study revealed that the SRI and MSRI methods were effective in reducing GWP and saving water without yield penalty in rice.  相似文献   

8.
Recent water shortages in reservoirs have caused such problems as insufficient water and fallow rice fields in Southern Taiwan; therefore, comparing irrigation water requirements and crop production of paddy fields using a technique that differs from the conventional flood irrigation method is important. Field experiments for the second paddy field with four irrigation schedules and two repeated treatments were conducted at the HsuehChia Experiment Station, ChiaNan Irrigation Association, Taiwan. Experimental results demonstrate that irrigation water requirements for the comparison method, and 7-, 10- and 15-day irrigation schedules were 1248, 993, 848, and 718 mm, respectively. Compared to the conventional method of flooding fields at a 7-day interval, the 10- and 15-day irrigation schedules reduced water requirements by 14.6 and 27.3 %, respectively; however, crop yields decreased by 7 and 15 %, respectively. Based on the results, it was recommended that the ChaiNan Irrigation Association could adopt 10 days irrigation schedule and plant drought-enduring paddy to save irrigation water requirements for the water resource scarcity in southern Taiwan. The CROPWAT model was utilized to simulate the on-farm water balance with a 10-day irrigation schedule for the second paddy field. A comparison of net irrigation water requirements with the 10-day irrigation schedule from model and field experiment were 818 and 848 mm, respectively, and the error was 3.54 %.  相似文献   

9.
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   

10.
This paper reviews the constraints and challenges of paddy farming in Taiwan. Based on those evidences, a set of eco-friendly rice farming practices raised by SRI principles are proposed from exploratory SRI trials conducted in Taiwan. The trials show that even with less exact leveling in the SRI field than is ideally provided, the average yield for SRI was higher than for CP; with an aerobic soil situation, the combination of biocontrol agent application and SRI management was seen to give better rice blast control; and the highest paddy yield was obtained from single-seedling transplants from potted nursery trays which protect the young seedlings’ roots from shock or twisting, compared with the planting of more numerous seedlings grown on flat nursery trays by a mechanical rice transplanter. In conclusion, a conceptual framework for eco-friendly paddy farming is formulated to encourage farmers to practice SRI principles. Among the participants in this collaboration, a co-operating group of SRI farmers is organized under investor sponsorship to guarantee the quality and safety of food, integrating an inspection service and food-source traceability from field to market with the production process. It is seen that in Taiwan, SRI principles can be adopted by local farmers without need for additional premiums through eco-friendly collaboration that can raise simultaneously the productivity of land, capital, and irrigation water. In addition, this collaboration can take advantage of increasing consumer demand for safe food with fewer chemicals and for supporting a greater level of biodiversity.  相似文献   

11.
To evaluate the performance of new rice establishment methods viz., system of rice intensification (SRI) and integrated crop management (ICM), a field study was conducted during 2008–11 in South Garo Hills, Meghalaya, foot hills of Eastern Himalayas, India. Field demonstrations were undertaken during wet seasons of 2008–11 and socio-economic information in the context of farmer’s realities were obtained during 2010–11 using a well structured questionnaire administered to 134 farmers. The results indicated that the average higher productivity of rice under SRI and ICM demonstration was 209.9 and 185.4 %, respectively, over conventional rice culture (CRC). The SRI and ICM methods of rice cultivation could save seeds (97.56 and 60.98 %), saving water (78.05 and 63.66 %), reduce cost (70.33 %), higher yield etc. compared to CRC. The main reasons for non-adoption of SRI/ICM was related to involvement of more efforts, faith towards traditional practices, ignorance and lack of knowledge on scientific water management. The net-return of $816.69, $706.63 and $51.48/ha was realized under SRI, ICM and CRC, respectively. The co-efficient of multiple determinations (R 2) of the production function was 0.695 in SRI, 0.714 in ICM and 0.734 in CRC which indicated that about 69.5, 71.4 and 73.4 % of the variation in rice productivity under SRI, ICM and CRC, respectively were explained by the independent variable and remaining 30.5, 28.6 and 26.6 %., respectively in SRI, ICM and CRC were as a result of non-inclusion of some explanatory variables as well as other factors outside the farmers control.  相似文献   

12.
A field experiment was conducted to investigate the effects of intermittent versus continuous irrigation, together with different degrees of organic fertilization, on the growth and yield of hybrid rice, looking also at the functioning of the rhizosphere as this is a key element affecting crop performance. The crop management practices employed generally followed the recommendations of the System of Rice Intensification (SRI). The aim of the research was to learn how water management and organic fertilization together would affect crop outcomes. Under intermittent water application as recommended with SRI management (aerobic irrigation, AI), grain yield increased by 10.5–11.3%, compared to standard irrigation practice (continuous flooding, CF). The factor that contributed most to higher yield was increased number of grains per panicle. It was seen that under the range of organic fertilization treatments evaluated, intermittent irrigation compared with CF promoted greater dry matter production and higher leaf area index (LAI) during the main growth stages. Also, the combination of intermittent irrigation and organic material applications significantly increased soil redox potential (Eh), compared with CF, and also the numbers of actinomycetes in the rhizosphere soil. Actinomycetes were evaluated in this study as an indicator of aerobic soil biota. It was seen that with intermittent irrigation, the application of organic material improved the functioning of the rhizosphere and increased yield. However, these results based on 2 years of study reflect relatively short-term effects. The effects of longer-term water management and soil fertilization regimes should be also examined, to know whether these effects continue and, if they do, whether they become greater or less.  相似文献   

13.
A 2-year field experiment was conducted during the wet seasons (July–October) of 2008 and 2009 on a Typic Hapludoll Mollisol in Indo-Gangetic Plains Region (IGPR) to: (i) investigate the effects of field water re-ponding intervals and plant spacing on the growth, yield, and water productivity (WP) of two rice cultivars under system of rice intensification (SRI) management, and (ii) assess comparative performance of SRI versus ‘best management practices’(BMP) of rice cultivation. This experiment was designed with 14 treatments, 12 under SRI, and 2 BMP (controls). SRI treatments comprised of 3 irrigation regimes viz, irrigation at 1, 3, and 5 day(s) after disappearance of ponded water (DADPW), 2 plant spacings (20 × 20, 25 × 25 cm), and 2 rice cultivars (Pant Dhan 4 and Hybrid 6444). Two BMP (control) treatments comprised of standard cultivation recommendations for flooding and spacing. The experiment was laid-out in a factorial randomized complete block design with three replications. Statistical analysis of data revealed significant variations in root–shoot characteristics and rice yield under SRI between years, reflecting different rainfall patterns. During 2009, a low rainfall year, the panicle numbers m?2, dry root weight m?2, root volume m?2, filled spikelet number panicle?1, and filled spikelet weight panicle?1 were significantly higher, which resulted in a rice grain yield enhancement by 5.1 % over 2008, when there was unusually heavy rainfall. Climate × irrigation regime interaction revealed a non-significant influence of irrigation regimes on growth and yield during 2008, whereas in 2009, irrigation at 1 DADPW and 3 DADPW increased grain yield by 12.8 and 8 %, respectively over 5 DADPW. Better root–zone soil moisture regimes, balancing water, and oxygen availability were responsible for higher yields under irrigation at 1 and 3 DADPW. In 2008, soil moisture content (SMC) in 0–15 cm layer was 91, 86, and 82 % of field capacity (FC) at panicle initiation, and 88, 80, and 77 % at panicle emergence stage when irrigation was at 1, 3, and 5 DADPW, respectively; the lower layers (15–30, 30–45 cm) retained their SMC between 87 and 94 % of FC at both stages. During 2009, SMC in all the three layers at both stages was more than 85 % of FC when irrigating at 1 DADPW, and a little more than 70 % for the 0–15 cm layer and >80 % for the other two layers when irrigation was done at 3 DADPW. SMC dropped to below 60 % of FC in the 0–15 cm layer and remained between 67 and 77 % of FC in the other two layers, with lower yield resulting when irrigations were applied at 5 DADPW. However, WP was the highest with irrigation at 5 DADPW (38.5 kg ha cm?1). Wider plant spacing (25 × 25 cm) resulted in generally and significantly higher grain yield and WP. On an average, SRI (6.1 t ha?1) resulted in yield advantage of 0.9 t ha?1 over BMP (5.2 t ha?1). Overall, it is inferred that in SRI, wider planting (25 × 25 cm) with field re-ponding at 3 DADPW if there is adequate water availability and at 5 DADPW under limited water supply conditions, may lead to higher rice yields and WP in sub-humid tarai Mollisols of IGPR and comparable agro-climatic conditions in Indian sub-continent.  相似文献   

14.

Water management methods regulate water temperature in paddy fields, which affects rice growth and the environment. To understand the effect of irrigation conditions on water temperature in a paddy field, water temperature distribution under 42 different irrigation models including the use of ICT water management, which enables remote and automatic irrigation, was simulated using a physical model of heat balance. The following results were obtained: (1) Irrigation water temperature had a more significant effect on paddy water temperature close to the inlet. As the distance from the inlet increased, the water temperature converged to an equilibrium, which was determined by meteorological conditions and changes in water depth. (2) Increasing the irrigation rate with higher irrigation water amount increased the extent and magnitude of the effects of the irrigation water temperature. (3) When total irrigation water amount was the same, increasing the irrigation rate decreased the time-averaged temperature gradient effect over time across the paddy field. (4) Irrigation during the lowest and highest paddy water temperatures effectively decreased and increased the equilibrium water temperature, respectively. The results indicate that irrigation management can be used to alter and control water temperature in paddy fields, and showed the potential of ICT water management in enhancing the effect of water management in paddy fields. Our results demonstrated that a numerical simulation using a physical model for water temperature distribution is useful for revealing effective water management techniques under various irrigation methods and meteorological conditions.

  相似文献   

15.
Although the System of Rice Intensification (SRI) has been reported to produce higher paddy (Oryza sativa L.) yields with better-quality grains, little research has addressed the latter claim. This study investigated the interactive effects of rice cultivation methods with different irrigation schedules and plant density on the uptake and concentration of sulfur (S), zinc (Zn), iron (Fe), manganese (Mn) and copper (Cu) in the grain and straw of two rice cultivars during two rainy seasons in the northern plains of India. As the two seasons differed in amounts of rainfall, there were impacts of soil moisture differences on nutrient uptake. Plots with SRI cultivation methods enhanced the grain uptake and concentrations of S, Zn, Fe, Mn and Cu by 36, 32, 28, 32 and 63%, respectively, compared to conventional transplanting (CT). Under SRI management, the highest concentrations of S, Zn and Cu in the grain and straw occurred with irrigation intervals scheduled at 3 days after disappearance of ponded water (DADPW; 3D), whereas Fe and Mn concentrations in the grain and straw were higher with irrigation at 1 DADPW (1 D ) compared with plots under 3 D or 5 DADPW (5 D ). The higher nutrient uptakes were also manifested in higher grain yield in 1 D and 3 D plots (by 9 and 6%, respectively) compared with 5 D . Wider spacing (25 × 25 cm) compared with closer spacing (20 × 20 cm) significantly increased yield and the uptake and concentrations of all the said nutrients in the grains. When comparing the performance of two cultivars, the total uptakes of Zn, Fe, Mn and Cu in both grain and straw were significantly more in Hybrid 6444 than the improved variety Pant Dhan 4. Overall, SRI crop management compared to CT practices led to more biological fortification of rice grains with respect to S and the four micronutrients studied, giving a concomitant yield advantage of about 17% on average in this region.  相似文献   

16.
Taiwan’s average annual rainfall is high compared to other countries around the world; however, it is considered a country with great demand for water resources. Rainfall along with alternate wetting and drying irrigation is proposed to minimize water demand and maximize water productivity for lowland paddy rice cultivation in southern Taiwan. A field experiment was conducted to determine the most suitable ponded water depth for enhancing water saving in paddy rice irrigation. Different ponded water depths treatments (T2 cm, T3 cm, T4 cm and T5 cm) were applied weekly from transplanting to early heading using a complete randomized block design with four replications. The highest rainwater productivity (2.07 kg/m3) was achieved in T5 cm and the lowest in T2 cm (1.62 kg/m3). The highest total water productivity, (0.75 kg/m3) and irrigation water productivity (1.40 kg/m3) was achieved in T2 cm. The total amount of water saved in T4 cm, T3 cm and T2 cm was 20, 40, and 60%, respectively. Weekly application of T4 cm ponded water depth from transplanting to heading produced the lowest yield reduction (1.57%) and grain production loss (0.06 kg) having no significant impact on yield loss compared to T5 cm. Thus, we assert that the weekly application of T4 cm along with rainfall produced the best results for reducing lowland paddy rice irrigation water use and matching the required crop water.  相似文献   

17.
Rice is the main crop produced in the Senegal River Valley under the semiarid Sahelian climate where water resource management is critical for the resource use sustainability. However, very limited data exit on rice water use and irrigation water requirement in this water scarcity environment under climate change conditions. Understanding crop water requirements is essential for better irrigation practices, scheduling and efficient use of water. The objectives of this study were to estimate crop water use and irrigation water requirement of rice in the Senegal River Valley at Fanaye. Field experiments were conducted during the 2013 hot and dry season and wet season, and 2014 hot and dry season and wet seasons. Three nitrogen fertilizer treatments were applied to rice variety Sahel 108: 60, 120, and 180 kg N ha?1. Rice water use was estimated by the two-step approach. Results indicated that crop actual evapotranspiration (ETa) varied from 632 to 929 mm with the highest ETa obtained during the hot and dry seasons. Irrigation water requirement varied from 863 to 1198 mm per season. Rice grain yield was function of the growing season and varied from 4.1 to 10.7 tons ha?1 and increased with nitrogen fertilizer rate. Rice water use efficiency relative to ETa and irrigation requirements increased with nitrogen fertilizer rate while rice nitrogen use efficiency decreased with the nitrogen fertilizer rates. The results of this study can be used as a guideline for rice water use and irrigation water requirement for the irrigation design projects, consultants, universities, producers, and other operators within rice value chain in the Senegal River Valley.  相似文献   

18.
Water management is an important factor in regulating soil respiration and the net ecosystem exchange of CO2 (NEE) between croplands and atmosphere. However, how water management affects soil respiration and the NEE of paddy fields remains unexplored. Thus, a 2-year field experiment was carried out to study the effects of controlled irrigation (CI) during the rice season on the variation of soil respiration and NEE, with flooding irrigation (FI) as the control. A decrease of irrigation water input by 46.39% did not significantly affect rice yield but significantly increased irrigation water use efficiency by 0.99 kg m?3. The soil respiration rate of CI paddy fields was larger than that of FI paddy fields except during the ripening stage. Natural drying management during the ripening stage resulted in a significant increase of the soil respiration rate of the FI paddy fields. Variations of NEE with different water managements were opposite to soil respiration rates during the whole rice growth stages. Total CO2 emission of CI paddy fields through soil respiration (total R soil) increased by 11.66% compared with FI paddy fields. The increase of total R soil resulted in the significant decrease of total net CO2 absorption of CI paddy fields by 11.57% compared with FI paddy fields (p < 0.05). There were inter-annual differences of soil respiration and the NEE of paddy fields. Frequent alternate wetting and drying processes in the CI paddy fields were the main factors influencing soil respiration and NEE. CI management slightly enhanced the rice dry matter amount but accelerated the consumption and decomposition of soil organic carbon and significantly increased soil respiration, which led to the decrease of net CO2 absorption. CI management and organic carbon input technologies should be combined in applications to achieve sustainable use of water and soil resources in paddy fields.  相似文献   

19.
Sodic soils are characterized by high exchangeable sodium on exchange sites, soil pH greater than 8.5, relatively low electrical conductivity, low infiltration rate and dispersed clay. These characteristics restrict the capacity of soil to absorb water, resulting in poor infiltration. Evidently, these soils require application of irrigation water at shorter intervals for crop production. Thus, irrigation strategy for sodic soils differs from that of normal soils. An experiment to determine the suitable irrigation strategy along with methods of application namely: surface (farmer’s practice), sprinkler (double nozzle impact sprinkler), and low-energy water application device (LEWA) were initiated in the year 2012 for rice crop. Irrigation depths of 6 cm in case of surface method and 4 cm in case of sprinkler and LEWA methods were applied at each irrigation event. The irrigation events for rice were scheduled at 2-DAD (days after the disappearance of the ponded water), 3-DAD, and 4-DAD through surface method, and at daily, 1- and 2-day intervals (after initial ponding disappeared) by sprinkler and LEWA methods. Sprinkler and LEWA methods resulted in highest rice yield of 4.4 t ha?1 in irrigated plots at the 2-day interval which was at par with the highest yielding surface-irrigated plot scheduled at 2-DAD. At the same time, irrigation strategy of 2-day interval through sprinkler and LEWA methods registered water saving to the extent of 30–40% over 2-DAD under surface irrigation method. Results revealed that there could be substantial saving of water and energy (electricity and diesel) through the use of sprinkling devices for irrigating rice under sodic soil environments.  相似文献   

20.
A field experiment using system of rice intensification (SRI) techniques was conducted in Chiba, Japan during the 2008 rice-growing season (May–September) with eight treatment combinations in a split–split plot design (S–SPD) to observe the potential of SRI methods under the temperate climatic conditions in Japan. Intermittent irrigation with alternate wetting and drying intervals (AWDI) and continuous flooding throughout the cropping season were the two main-plot factors, while the effects of age of seedlings and plant spacing were evaluated as sub and sub–sub plot factors, respectively. The experiment results revealed that the proposed AWDI can save a significant amount of irrigation water (28%) without reduced grain yield (7.4 t/h compared with 7.37 t/h from normal planting with ordinary water management). Water productivity was observed to be significantly higher in all combinations of practices in the intermittent irrigation plots: 1.74 g/l with SRI management and AWDI as compared to 1.23 g/l from normal planting methods with ordinary water management. In addition, the research outcomes showed a role of AWDI in minimizing pest and disease incidence, shortening the rice crop cycle, and also improving plant stand until harvest. Synergistic effects of younger seedlings and wider spacing were seen in tillering ability, panicle length, and number of filled grains that ultimately led to higher productivity with better grain quality. However, comparatively better crop growth and yields when using the same SRI practices with ordinary water management underscore a need for further investigations in defining what constitute optimum wetting and drying intervals considering local soil properties, prevailing climate, and critical watering stages in rice crop management.  相似文献   

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