Impact of Rice-Catfish/Shrimp Co-culture on Nutrients Fluxes Across Sediment-Water Interface in Intensive Aquaculture Ponds

Exchange of nitrogen and phosphorus across sediment-water interface plays an important role in the management of nutrient recycling in the aquaculture pond. In this study, a plot experiment was conducted to study the effect of rice-catfish/shrimp co-culture on the micro-profile of oxygen(O_2), p H and nutrient exchange across sediment-water interface in the intensive culture ponds. The results showed that rice-catfish co-culture increased the concentration and penetrating depth of O_2, but decreased the p H value across the sediment-water interface, compared with catfish monoculture. Additional rice cultivation significantly reduced the flux rates of ammonium(NH_4~+) and nitrate(NO_3~-) across sediment-water interface in the catfish and shrimp ponds. The flux rates of NO_2~- and soluble phosphorus(PO_4~(3-)) showed no significant difference between rice-catfish/shrimp co-culture ponds and catfish/shrimp monoculture ponds. Rice only affected the dissolved inorganic nitrogen and phosphorus fractions in the sediment. The concentrations of NH_4~+ were significantly lower in the sediment of co-culture ponds than in the monoculture ponds. Additional rice cultivation also significantly reduced the content and percentage of dissolved inorganic phosphorus in the sediment of catfish ponds.     

稻鱼共作对养殖池塘沉积物-水界面微观剖面理化性质的影响

采用微电极系统研究了黄颡鱼-水稻共作和黄颡鱼单养两种模式下沉积物-水界面基本理化性质的变化。研究结果表明,与黄颡鱼单养相比,黄颡鱼-水稻共作可使沉积物-水界面附近O2浓度下降速率减慢,O2渗透深度增加71.4%,并使界面Eh值升高,改善塘底沉积物-水界面厌氧状况;黄颡鱼-水稻共作降低了界面附近pH值,比黄颡鱼单养低约一个单位。以上研究结果表明,养殖池塘种植水稻改变了沉积物-水界面的微环境,可能会影响界面物质迁移转化过程。     

丘陵山区稻鱼综合种养技术规程

稻田综合种养模式下稻谷和水产品价值协同提升,显著增加单位面积产值,并改善农田生态环境。该规程规定了稻鱼综合种养环境条件、品种选择、田间设施建设、稻鱼共生期管理及收获等管理技术,为丘陵山区稻田综合种养提供技术支持。     

水稻对富营养化水体生态修复效应及其研究进展

水体富营养化是制约我国农业可持续发展的重要因素。水稻具有显著的水质净化能力,利用水稻对富营养化水体进行生态修复成为植物修复的一个重要的研究方向。通过文献调研,总结了水稻对不同富营养化水体(湖泊、水库、污水河道、养殖尾水、农田退水和生活污水)修复效率,综合分析了不同修复模式(浮床种稻、稻田湿地和稻鱼共作)的技术特点、适用范围和影响因素,归纳总结了水稻对富营养化水体修复的主要作用机制,并对下一步的研究提出了相关建议。     

稻虾共作对稻田水体环境的影响

为探明稻虾共作对水体环境的理化性质和物质含量的影响,选择湖南省南县实施稻虾共作模式和中稻单作模式的稻田,分析稻虾共作前后的稻田水体物质变化和不同稻作模式下稻田水体环境变化差异.结果表明,相较于自然水体和中稻单作田间水体,稻虾共作田间水体的pH值提高了1.88%和1.37%,色度提高了42.19%和10.98%,TDS提高了1.66%和1.14%,电导率提高了13.08%和10.31%,氧化还原电位提高了14.15%和6.03%,溶解氧降低了17.20%和9.41%.稻虾共作改变了自然水体理化性质,对水体环境的影响程度比中稻单作模式更大,创造了适宜稻虾共同生长的水体环境,在抑制潜水蒸发、提高水体自净能力方面有积极作用.但水体溶氧量的降低,不利于水生植物的生长和部分物质的分解消化,影响稻田水质.在稻虾共作过程中,需充分利用水体环境变化的有利因素,合理人工增氧,以规避水体溶氧降低带来的影响.     

鱼塘种稻对养殖水体营养物质的去除作用研究

以黄颡鱼精养塘为例,探索鱼塘种植高秆型水稻对精养池塘水体氮磷养分等水质指标的修复作用。结果表明,在水稻生长期,种稻黄颡鱼精养塘水体氮、磷养分含量显著低于单养鱼池塘。在水稻收获期,单养鱼塘水体总氮(TN)和总磷(TP)含量高达11.98mg/L和0.52mg/L,超过了《淡水池塘养殖水排放要求》标准;而种稻鱼塘水体中TN、TP含量则仅为0.49mg/L和0.08mg/L,达到《淡水池塘养殖水排放要求》一级排放标准。种稻鱼塘水体中TN、NH4+-N、NO3--N、TP和PO43--P含量比不种稻单养鱼塘分别降低95.95%、98.09%、98.07%、84.47%和64.57%。种稻鱼塘COD含量和pH值低于单养鱼塘。可见,种稻能有效降低水体养分含量,改善养殖水体水质。     

饲料蛋白含量对稻-黄颡鱼共作模式气态氮排放、黄颡鱼生长和氮利用率的影响

【目的】明确饲料蛋白含量对稻-黄颡鱼共作模式下N₂O和NH₃挥发特征及黄颡鱼生长的影响,有利于稻-黄颡鱼综合种养的高效、绿色发展。【方法】采用盆栽模拟试验,以常规单养黄颡鱼模式为对照,系统研究了不同饲料蛋白含量对稻-黄颡鱼共作模式下N₂O和NH₃的排放特征、水体和底泥的氮含量以及黄颡鱼生长的影响。【结果】在相同蛋白含量下,稻-黄颡鱼共作模式的N₂O和NH₃挥发分别比单养黄颡鱼模式降低18.3%和76.20%,水体总氮和无机氮含量降低41.30%和48.85%,黄颡鱼蛋白累积量增加20.00%,氮利用率增加171.50%。在稻-黄颡鱼共作模式下,提高饲料蛋白含量会显著增加N₂O排放量和水体残留氮含量,但对NH₃挥发无显著影响;黄颡鱼特定生长率和蛋白累积量与饲料蛋白含量呈二次曲线关系。饲料氮利用效率随饲料蛋白含量增加呈线性降低趋势。【结论】综合考虑黄颡鱼生长和N₂O排放以及养殖水体氮残留等因素,确定稻-黄颡鱼共作模式饲料蛋白含量不宜超过43.04%。     

高海拔稻田养鱼与常规粳稻新品种选择试验探索

在以往试验的基础上,结合稻田养鱼的成功经验,通过不断完善试验方案,在高海拔养鱼稻田开展了粳稻新品种选择试验。结果为,养鱼稻田新品种比较试验田稻谷产量575.1 kg/667 m^2,鱼产量40.6 kg/667 m^2,周边非养鱼稻田稻谷产量645.2 kg/667 m^2,试验田稻谷价高,养鱼增收1497.3元/667 m^2。     

Characteristics of effluent load from a watershed including irrigation ponds

This paper describes an attempt to estimate the mass budget of irrigation ponds within a watershed and the possibilities to control the effluent load of nutrients from the watershed located in the Kyotanabe area. The paddy field lots were irrigated by the ponds and several mountain streams. In the study watershed, there were two ponds located on the upper and lower sides of a paddy area. Water could be pumped up from the lower pond to the upper pond as necessary. At the ponds, the total amount of nitrogen and phosphorus in the inflow loads including the sediment release was larger than those in the outflow loads. In SS, the effect of load reduction in the ponds was high. It is assumed that organic load reduction was not expected in the ponds. The study result indicates that it is possible to remove the nutrients in the ponds when a larger amount of water is pumped up than when the ponds are only in irrigation use. Moreover, the removal capacities of the nutrients could probably be increased in both ponds by controlling the amount of sediment releases. Electronic Publication     

根际氧环境对水稻幼苗根系微形态结构的影响及其生理机制

【目的】研究根际氧环境对水稻幼苗根系微形态建成的影响及其生理机制,以期为水稻幼苗理想根型的构建提供理论依据。【方法】以春优84和秀水09为材料,用国际水稻所营养液配方进行水培试验。秧苗移栽一周后用在线溶氧仪(氮气、氧气调节)设定低氧(0~1.0 mg/L)、中氧(2.5~3.5 mg/L)和高氧(>6.0 mg/L,饱和溶解氧处理,在水稻生长过程中用充气泵连续向水体中充入空气)和常规水培(CK,不进行氧调节,水稻移栽一周后水中氧含量约为0.3~2.5 mg/L) 4个氧处理,研究水稻幼苗生物量、根系微形态结构、根系分泌有机酸、呼吸强度等指标。【结果】1）各处理水稻幼苗根系直径为d₁(0~0.50 mm)、d₂(0.51~1.00 mm)和d₃(1.01~1.50 mm)的细根占总根的比例均超过90%,对水稻苗期根系形态构建尤为重要。中氧处理后,春优84直径为d₁、d₂和秀水09直径为d₁、d₃的根的根长和根表面积均明显高于对照。2）低氧处理减少地上部和地下部生物量,抑制细根(d₁)生长,促进粗根(d₅, 2.01~2.50 mm)的生长,降低呼吸强度,增加有机酸分泌量。中氧和高氧处理后水稻植株的生物量均有增加,但生理反应不尽相同。中氧处理后水稻根系呼吸强度上升,而高氧处理后根系呼吸强度降低。各氧处理均减少水稻幼苗根系生长素(IAA)含量,中氧和高氧处理与对照间差异达显著水平。高氧处理显著增加根系一氧化氮(NO)含量,其他处理间差异不显著。3）相关分析结果表明,两供试品种总根和细根(d₂)的各形态指标(根长、表面积和体积)均与根系有机酸分泌量、呼吸强度、NO含量正相关,与生长素(IAA)含量负相关。【结论】适当增氧(中氧)处理增加水稻幼苗根系呼吸强度和有机酸分泌量,根系生理活性增强;增加细根(直径为0~1.50 mm)的根长、吸收面积的占比,优化其根系形态结构。因此,生产上可以通过栽培措施改变根际氧环境调控分蘖期水稻根系微形态结构,增强根系功能。     

Changing Significance of Inland Fisheries for Livelihoods and Nutrition in Bangladesh

SUMMARY

Fish is an essential and irreplaceable food in the rural Bangladesh diet. Inland capture fisheries are still the main source of fish in the diet. Although wetlands and fish habitat have been lost to drainage and flood control, the contribution of aquaculture to total fish production has been increasing in the last two decades.

The contribution of different species to fish intake as well as micro-nutrient intakes has been investigated based on food consumption studies. The main distinction is between small indigenous fish species (SIS), which typically are caught in open waters and floodplains, and larger species including carps (which are now largely cultured in ponds) and other fishes. The contribution of nutrient-minerals and especially vitamin A–from SIS is particularly important. Some SIS have very high vitamin A contents, whereas other fish, including carps have low vitamin A content. SIS that are eaten whole are also an important source of calcium. In addition, fish as part of a meal can enhance the intake of minerals present in other foods. Lastly, SIS are well-liked by the rural poor and are considered tasty and nutritious.

Case studies of fisheries and aquaculture interventions in Bangladesh indicate that SIS still contribute more to fish consumption than do cultured species for both poor and rich households. Fish consumption levels and the proportion of SIS in the diet are seasonal, peaking in and immediately after the wet season. Examples of community initiatives to protect over-wintering fish in local sanctuaries and to restore fish habitat and migration routes appear to have increased fish catches and consumption. Where beel (lake) fisheries were enhanced by stocking carps, the user communities benefited from higher catches and incomes. However, it seemed that fish consumption for non-participants increase where fishing was not limited, but fell where they were excluded from fishing by participants.

Extension efforts have encouraged rapid growth in aquaculture production in the last two decades. A case study indicated that increases in production were sustained and that practices had spread from extension participants. Declining capture fisheries and increasing carp production mean that carps have become relatively cheaper, and it has been seen that the proportion of carps to other fish sold doubled in less than a decade in some local markets. However, poor rural consumers without ponds are now more dependent on purchased fish, and increased production of carp from ponds does not compensate for substantial declines in their SIS catches from open waters. Aquaculture in flooded rice fields would normally exclude the poor, but there have been attempts where NGOs have organized landless people to benefit from stocking carps.

SIS can be included in pond aquaculture systems, and on-farm experiments show this can complement carp production by increasing production and cash returns. A focus on incorporating vitamin A rich SIS in aquaculture combined with widespread and concerted efforts to restore and sustainably manage the floodplain fisheries (which are dominated by SIS) can result in an important food-based strategy to improve micro-nutrient deficiencies in poor people in Bangladesh and similar flood-plains.     

Effect of water management on soil respiration and <Emphasis Type="Italic">NEE</Emphasis> of paddy fields in Southeast China

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.     

深水灌溉对稻渔共生水稻抗倒伏性的影响研究进展

持续一定时间的深水灌溉是稻渔共生的必要条件。稻渔共生条件下水稻品种优质、高产、抗倒伏性状的优劣直接影响到稻谷量质安全。本文阐述了稻渔共生下水稻品种的筛选、倒伏的危害与抗倒伏评价体系的构建,以及深水灌溉对水稻茎秆力学、形态学和解剖学特征的影响等研究进展,旨在为稻渔共生高质量发展提供参考。     

Lack of acute toxicity of an anthraquinone bird repellent to non-target crayfish (Procambarus clarkii) associated with rice-crayfish crop rotations

Aeroz™ (9,10-anthraquinone (AQ)), a chemical rice seed treatment that effectively deters birds from depredating newly planted fields, could be an important management tool that enables rice producers to plant earlier in the season and increase yields. This bird repellent, while non-lethal to birds, has unknown toxicity to crayfish that often are closely integrated with rice production in southern regions of the USA. This study was conducted to assess if AQ, the active ingredient in Aeroz™, could be acutely toxic to the red swamp crayfish Procambarus clarkii (Girard), the crayfish species most often associated with rice cultivation, via seed ingestion and/or through their contact with chemical in pond water. Mortality data from a 96 h feeding study indicate that AQ-treated (1.76% by wt) rice seed was not acutely toxic to juvenile (∼3 mo.) crayfish through the ingestion exposure route. In addition, a 96 h aquatic acute toxicity test showed that the LC₅₀ of AQ in juvenile crayfish is >85 μg L⁻¹ and above the water solubility limit of AQ. These results indicate that very minimal, if any, acute toxicity would be observed in juvenile crayfish if exposed to AQ via ingestion or dissolved or suspended in the water column.     

Transferring water from irrigation to higher valued uses: a case study of the Zhanghe irrigation system in China

The Zhanghe irrigation system (ZIS) is located in the Yangtze River Basin approximately 200 km west of Wuhan in Hubei Province. The reservoir was designed for multiple uses—irrigation, flood control, domestic water supply, industrial use, aquaculture, and hydropower. Over a period of more than 30 years a steadily increasing amount of water has been transferred from irrigation to other uses. Activities on the part of government, irrigation system managers, and farmers made this transfer possible with only modest decline in rice production. Most important factor was the steady increase in rice yields. The water pricing system provided an incentive for ZIS to reduce irrigation releases. With the steady decline in releases, farmers were forced to find ways to save water. Farmers improved existing ponds and built new ones to store water (improved infrastructure). Access to pond water on demand facilitated the adoption of alternate wetting and drying (technology) particularly in dry years. The establishment of volumetric pricing (price policy) and water user associations (institutions) may also have provided incentives for adoption of AWD, but more research is needed to establish their impact. These activities taken together can be seen as potentially complementary measures. Farmers received no direct compensation for the transfer of water, but recently farm taxes have been reduced or altogether abolished. Further reduction in water releases from the ZIS reservoir could adversely affect rice production in normal or dry years.     

“稻+鱼+再生稻”模式对稻田土壤氮、磷、钾养分含量的影响

设置头季稻+鱼(或泥鳅)+再生稻的栽培模式,水稻品种选用黄华占和Y两优800,分析两种模式下土壤中全量氮、磷、钾含量与速效氮、磷、钾含量表现,结果表明:(1)稻鱼模式和稻鳅模式可增加土壤中全效养分含量,全氮、全磷、全钾含量在整个生育期内维持在一个相对稳定的状态,其中以稻鱼处理效果更明显,总体高于对照田.头季稻与再生季两个生育季内全氮、全磷处于相对稳定的状态,全钾含量则在再生季略有下降;(2)稻鱼模式和稻鳅模式提高了土壤中速效养分含量,孕穗期、灌浆期、成熟期含量比分蘖期时有所提升,稻鱼模式下土壤速效养分含量整体表现要高于稻鳅模式.两个水稻品种再生季的土壤速效养分含量变化规律性不明显,但整体维持在相对稳定水平.     

Experimental study on the influence of dissolved organic matter in water and redox state of bottom sediment on water quality dynamics under anaerobic conditions in an organically polluted water body

To understand aquatic environmental deterioration due to the anoxic state in an organically polluted water body, water quality dynamics under anaerobic conditions were examined through beaker-scale water quality monitoring. This study focused on the dynamic properties of NO₃–N, NH₄–N, PO₄–P, and sulfide from the biochemical reactions point of view, and based on anaerobic respiration activities, such as denitrification, iron reduction, and sulfate reduction. The specific aims of this study were to quantitatively estimate the impacts of the oxidative/reductive state of the sediment surface and the high/low concentrations of dissolved organic matter on the dynamic properties of water quality under anaerobic conditions. The beaker-scale water quality monitoring was carried out through continuous measurements of dissolved oxygen and oxidation–reduction potential (ORP), as well as periodic observations of water quality parameters for six cases that are composed from combinations of three experimental conditions: (1) concentration of dissolved organic carbon (DOC); (2) redox state of the sediment; and (3) concentration of NO₃–N. As a result, the temporal changes in ORP under anaerobic conditions exhibited a five-step process of decline without these conditions. Also, high DOC concentrations and oxidative states of the bottom mud accelerated the release of PO₄–P and sulfide generation through promoting biological iron reduction and sulfate reduction, because these conditions increase respiratory substrates for anaerobic microorganisms, such as iron and sulfate-reducing bacteria. It was concluded that our results would provide important information about the mechanisms of aqueous environmental deterioration due to organic pollution in closed water bodies.     

Assessment of the camellia seed meal impact on loaches in paddy fields

In Taiwan, Camellia seed meal is often sprayed on rice paddies during rice transplantation season to stop the growth of Pomacea canaliculata. However, the application of camellia seed meal endangers muciferous mollusks and fishes in paddy fields. Though researchers have examined the effects of the saponin in the camellia seed meal on Pomacea canaliculata, previous studies ignore the effects of saponin on fish. Loaches often inhabit the rivers, lakes, ponds, paddy fields, and canals of low elevation where there have muddy layer with plant chips. This study uses vanillin-sulfuric acid method and field tests on loaches in paddy fields to determine the duration of camellia seed meal’s effect on loaches (Misgurnue Angullicaudatus). Results indicated that the best application to stop the growth of Pomacea canaliculata is to seal the rice field immediately after transplantation, apply the camellia seed meal, and then irrigate the field 2?days after camellia seed meal application for the summer transplantation, and 3?days for the spring transplantation. Water should not be drained from the paddy field after the application of camellia seed meal to reduce the chance of endangering loaches in irrigation canals. Field Tests show that high water temperature during summer also has a negative effect on loaches in paddy fields and irrigation canals.     

Evaluation of the water-quality dynamics in a eutrophic agricultural pond by using a one-box ecosystem model considering several algal groups

The Okubo pond is an agricultural pond located in the Itoshima area of Fukuoka Prefecture, Japan. It was constructed for irrigating a nearby cultivated area. A monitoring program from August 11 to November 26, 2008, suggested the risk of eutrophication in the water body. The high total nitrogen concentration (1.34 mg/l), high total phosphorus concentration (0.06 mg/l) and extreme oxygen depletion (2 mg/l on 5 November 2008) exceeded the Japanese standards for paddy irrigation water. Furthermore, luxuriant algal blooming in October indicated a hypereutrophic status according to the OECD (1982) criteria. In this study, a one-box ecosystem model was developed to obtain an insight into the seasonal variations in the algal concentrations and chemical components of the Okubo pond with the aims of protecting its aquatic ecosystem and maintaining its water quality. The model was based on a completely mixed system and included 12 water-quality indices: green algae, blue-green algae, diatoms and dinoflagellates, cryptophytes, zooplankton, particulate organic matter, dissolved organic matter, phosphate–phosphorus, ammonia–nitrogen, nitrite–nitrogen, nitrate–nitrogen, and dissolved oxygen. The monitoring data were used to verify the model simulation. Model evaluation suggested good agreement between the predicted and the observed data for the seasonal variations in the algal, nutrient, and dissolved oxygen concentrations. To determine the sensitivity of the model parameters, a sensitivity analysis was conducted leading to the conclusion that the optimal temperature, growth rate, and respiratory rate of the four algal groups, especially the ideal temperature for blue-green and green algae are the most influential factors determining the variability affecting the model inference. From the model simulation, the water temperature and nutrient concentration were considered to be the key limiting factors controlling alternative algal blooms in this period.     

Logistic Regression Analysis on Factors Affecting Adoption of Rice-Fish Farming in North Iran

We evaluated the factors influencing the adoption of rice-fish farming in the Tavalesh region near the Caspian Sea in northern Iran.We conducted a survey with open-ended questions.Data were collected from 184 respondents(61 adopters and 123 non-adopters) randomly sampled from selected villages and analyzed using logistic regression and multi-response analysis.Family size,number of contacts with an extension agent,participation in extension-education activities,membership in social institutions and the presence of farm workers were the most important socio-economic factors for the adoption of rice-fish farming system.In addition,economic problems were the most common issue reported by adopters.Other issues such as lack of access to appropriate fish food,losses of fish,lack of access to high quality fish fingerlings and dehydration and poor water quality were also important to a number of farmers.