Long Term Effects of Farming System on Soil Water Content and Dry Soil Layer in Deep Loess Profile of Loess Tableland in China

Soil water is strongly affected by land use/cover in the Loess Plateau in China. Water stored in thick loessal soils is one of the most important resources regulating vegetation growth. However, soil water in the deep loess proifle, which is critical for maintaining the function of the“soil water pool”is rarely studied because deep proifle soil samples are dififcult to collect. In this study, four experimental plots were established in 2005 to represent different farming systems on the Changwu Tableland：fallow land, fertilized cropland, unfertilized cropland, and continuous alfalfa. The soil water content in the 15-m-deep loess proifles was monitored continuously from 2007 to 2012 with the neutron probe technique. The results showed that temporal variations in soil water proifles differed among the four farming systems. Under fallow land, the soil water content increased gradually over time, ifrst in the surface layers and later in the deep soil layers. In contrast, the soil water content decreased gradually under continuous alfalfa. The distributions of soil water in deep soil layers under both fertilized and unfertilized cropland were relatively stable over time. Thus farming system signiifcantly affected soil water content. Seven years after the start of the experiment, the soil water contents in the 15-m-deep proifles averaged 23.4%under fallow land, 20.3%under fertilized cropland, 21.6%under unfertilized cropland, and 16.0%under continuous alfalfa. Compared to measurements at the start of the experiment, both fallow land and unfertilized cropland increased soil water storage in the 15-m loess proifles. In contrast, continuous alfalfa reduced soil water storage. Fertilized cropland has no signiifcant effect on soil water storage. These results suggest that deep soil water can be replenished under the fallow and unfertilized farming systems. Dry soil layers （i.e., those which have soil water content less than the stable ifeld water capacity） in the subsoil of the Changwu Tableland region can be classiifed as either temporary dry soil layers or persistent dry soil layers. Temporary dry soil layers, which typically form under annual crops, often disappear during wet years. Persistent dry soil layers generally develop under perennial vegetation. Even after removing the vegetation, persistent dry soil layers remain for several decades. This study provides information useful for the conservation and utilization of soil water resources in the Loess Tableland.

Comparative Water Efficiency Analysis of Sole and Multiple Cropping Systems under Tunnel Farming in Punjab-Pakistan

Water scarcity is the growing concern of present times, requiring its efficient utilization deemed as necessity. Rapidly growing population has significantly exerted pressure on its demand, in Pakistan. In order to fulfill it, all factors of production are required to be used in the possibly most efficient way. Good quality and quantity of water are the growing concerns of producers in Pakistan and around the globe. The efficient water utilization is crucial to optimize the farm returns under the selected sole and multiple cropping systems. This study considered the water efficiency analysis of multiple and sole cropping systems, with the aim of finding out cropping patterns more efficient in terms of water utilization in Pakistan. In order to estimate the water efficiency analysis, the Data Envelopment Analysis (DEA) is run to find out the water efficient cropping systems among sole and multiple cropping systems. The Tobit analysis is also used to find out the factors affecting the water efficiency of selected farms in the study area. The results of the study report an inefficient water usage in terms of irrigation, the inefficient use of water instigates the wastage of one of the most important as well as scarce farm inputs especially water, in case of multiple cropping system. Around 51% and 13% of water inefficiency are present under multiple and sole cropping systems, respectively. Basin irrigation is the method for irrigation, used by the farmers of the study area approximating to be 95% - 97%. It is one of the most conventional and least efficient methods of irrigation. Only 2.67 and 4.67 percent of farms were using the Furrow irrigation method, which is way more efficient and steady as compared to Basin irrigation method, respectively. It appears as a requirement that the most efficient methods regarding water application in Pakistan should be recognized. Lack of management in water application on both selected cropping systems resulted in over utilization of water and depletion of one of the fundamental natural resource. In order to overcome the inefficiency in water management, farmers’ farming knowledge, adoption of new irrigation techniques, efficient application of inputs is needed.

Conception of Allocating Farming Water Resource with Option System

The uncertainty of natural fall results in the uncertainty of water resource, which brings difficulty in allocating farming water resource characterized by ＂more use when it is lack but less when enough＂. By analyzing the endurance of farming households of water price and the shortcoming of transaction system of farming water fight, options of farming water are deviated from water fight market, which allows farming households to evade the natural and market risks by means of purchasing call or put option contracts in order to raise the utilization ratio of water and to realize the allocation optimum.

Structure of Vegetables Farming and Farmer’s Perception of Soil and Water Degradation in Two Periurban Areas in Yaounde Cameroon

Vegetable farming is an activity sensitive to the dynamism of the population and to the level of intensification in the use of soil resources. A study was conducted in the peri-urban zones of Yaoundé to present the socioeconomic characteristics of vegetable farming and the farmers’ perception of soil and water degradation as a result of this activity. A semi-structured questionnaire was administered to this purpose in 2016 in two vegetable farming sites in Yaoundé, namely Nkolbisson and Nkolondom III. Results showed that most vegetable farmers from both sites (around 75%) lack training in agriculture while 74 and 90 didn’t benefit from training on management of pesticides. Spreading and landfilling of amendments are the two most popular ways of applying fertilizers. In fact, while the majority (35.4%) of these fertilizers is applied at planting time, the minority (4.9%) is applied several months before planting. Besides young plots are more exploited (52.4% and 30%) compared to older ones (2.4% and 5%) in Nkolondom III and Nkolbisson respectively, as they are more responsive to fertilizer application. As consequence, high rates of fertilizers are applied to the oldest farms. As for irrigation water, it is altogether polluted. Base on the above, the farmers’ perception of degradation is seen through the degradation of soils properties with time in the order of 14.3% to 60% and 15% to 44% at Nkolbisson and Nkolondom III respectively resulting in a gradual decrease of crop production (up to 50%). It is also seen through the polluted produce obtained from irrigation and cleaning water.

Fenlong Cultivation-the Fourth Set of Farming Methods Invented in China

The basic theory and effect of the new farming method of ＂Fenlong＂ cultivation which has been included in the main extension technology of Ministry of Agriculture of the People＇s Republic of China is fully illustrated for the first time, and it is the fourth set （generation） of farming modes and methods following manpower, animal and mechanical （tractor） farming. It follows the natural law to achieve soil activation, water saving, oxygen increase, warming and desalination through the active use of natural resources like soil, rainfall and solar energy, thereby promoting a new round of natural agricultural production and quality improvement and water con- servation, which has crop yield increase by 10%-30%, quality improvement of 5%, natural precipitation retaining increase by100%. The characteristics and mechanism are the use of spiral drill for one-time completion of the land preparation by drilling vertically to 30-50 cm of soil layer through high speed peeling. After instant high temperature and many fierce impacts, mechanical frictions, it could achieve the multiplication of the number of loose soil, soil physical modification and expansion of the soil nutrients, reservoirs, oxygen, microorganisms （＂Four pools＂）. Fenlong cultivation can give birth to new farming culture and civilization, and it can achieve the physical ＂desalinized＂ transformation and utilization of saline soil. The formation of Fenlong green farming technology system makes it possible to invent the farming tools of ＂serf-propelled Fenlong machinery＂ that has got the patent, and it is the method for farmland （dry land, paddy field） Fenlong cultivation, saline-alkali soil smash-ridging cultivation and for the abundance of grass ecology on degraded grassland. The application of Fenlong ＂4＋1＂ （arable, saline-alkali soil, grasslands, Sponge City＋rivers） green development in China can achieve the ＂double safety＂ of food and living space.

Performance of a water hyacinth(Eichhornia crassipes)system in the treatment of wastewater from a duck farm and the effects of using water hyacinth as duck feed

Nowadays, intensive breeding of poultry and livestock of large scale has made the treatment of its waste and wastewater an urgent environmental issue, which motivated this study. A wetland of 688 mz was constructed on an egg duck farm, and water hyacinth （Eichhornia crassipes） was chosen as an aquatic plant for the wetland and used as food for duck production. The objectives of this study were to test the role of water hyacinth in purifying nutrient-rich wastewater and its effects on the ducks＇ feed intake, egg laying performance and egg quality. This paper shows that the constructed wetland removed as much as 64.44% of chemical oxygen demand （COD）, 21.78% of total nitrogen （TN） and 23.02% of total phosphorus （TP）. Both dissolved oxygen （DO） and the transparency of the wastewater were remarkably improved, with its transparency 2.5 times higher than that of the untreated wastewater. After the ducks were fed with water hyacinth, the average daily feed intake and the egg-laying ratio in the test group were 5.86% and 9.79% higher, respectively, than in the control group; the differences were both significant at the 0.01 probability level. The egg weight in the test group was 2.36% higher than in the control group （P 〈 0.05）, but the feed conversion ratios were almost the same. The eggshell thickness and strength were among the egg qualities significantly increased in ducks fed with water hyacinth. We concluded that a water hyacinth system was effective for purifying wastewater from an intensive duck farm during the water hyacinth growing season, as harvested water hyacinth had an excellent performance as duck feed. We also discussed the limitations of the experiment.

Evaluation of Levels of Selected Heavy Metals in Kales, Soils and Water Collected from Irrigated Farms along River Moiben, Uasin-Gishu County, Kenya

There has been a rapidly increasing urbanization and industrialization as well as increased usage of agrochemicals in the recent few years which have resulted in accumulation of heavy metals in cultivated food, soils and water. This research aimed at establishing the levels of Zn2+, Cd2+, Cu2+, Cr2+, Mn2+, Fe2+ and Pb2+ metal ions in kales, soil and irrigation water on farms along river Moiben. Twenty seven samples of vegetables, soil and water samples were collected using purposive sampling method, that is, the samples were collected from the households who had kales in their farms. Samples were then dried, grounded, digested and analyzed using Inductive Couple Plasma-Optical Emission Spectroscopy (ICP-OES). The results showed that the Fe had the highest mean in soil and water with the values of 250.22 ± 85.37 and 0.72 ± 0.33 mg/kg respectively, while in kales Zn value was highest with a value of 0.0154 ± 0.007 mg/kg. The metal ion concentrations in the soils and the irrigation water were higher than in kales. The concentrations on the metal ions were following this order Fe > Mn > Zn > Cu > Cr > Pb > Cd for soil as well as for water but for the kales sample it followed slightly different order Zn > Fe > Mn > Cu > Cr > Pb > Cd. In soil samples, metal ions concentrations (mg/kg) were found to be high compared to the levels in water and kales. ANOVA tests revealed that the mean difference in heavy metals concentration from different stations within the area was insignificant (p > 0.05) with an exception of Cd (p = 0.001) in water samples, Fe (p = 0.007) in kales samples, Zn (p = 0.016) and Cd (p = 0.011) in the samples of soil. Results were compared to the acceptable levels set by World Health Organization (WHO) and the study showed that for kales, concentrations of the metal ions were all lower than the (WHO) set standards. For water samples, Fe, Pb, Mn metal ions were above the WHO set standards. The presence of the investigated heavy metals in the samples could be pointed to excessive use of agrochemicals as indicated by our earlier survey on the use of agrochemicals. We therefore recommend thorough investigations and monitoring of the said heavy metals in the commercially distributed agrochemicals.

Blue and Grey Water Footprints of Dairy Farms in Kuwait

In Kuwait, dairy farming faces challenges due to its significant water demands. The current study assessed seasonal patterns of water use to estimate the blue water footprint (WF) and grey WF per kg of fat protein corrected milk (FPCM) for confined dairy farming systems in Kuwait. Blue and grey WFs were evaluated using data from three operational farms. The average blue WF (L·kg-1 FPCM) was estimated to be 54.5 ± 4.0 L·kg-1 in summer and 19.2 ± 0.8 L·kg-1 in winter. The average grey WF (generated from milk house wastewater) was assessed on bimonthly basis and determined based on its phosphate (PO4) concentration (82.2 ± 14.3 mg·L-1) which is the most limiting factor to be 23.0 ± 9.0 L·kg-1 FPCM d-1. The outcomes indicate that enhancing the performance of dairy cows and adopting alternative water management strategies can play a role in minimizing the impacts of confined dairy farming systems in Kuwait on water quality and quantity.

The Impact of Rainbow Trout Farm Effluents on Water Quality of Koohrang River, Iran

The aim ,of this study was to assess the potential impact of trout farm effluents on water quality of Koohrang river （Chaharmahal va Bakhtiary province-Iran） where seven trout farms are localized and to determine the some physico-chemichal parameters of the farms. Monthly samples were taken from inflow, outflow and 1,500 meter lower than these farms have been measured and avaluated during 6 months. Measured physico-chemical water quality parameters were DO, BOD5, PO4, NO3, NO2, NH3, TH, PH, TDS, TSS. Monthly data were converted to mean values （-4- standard error） for comparison. Data on water quality parameters of inflow and outflow water and 1,500 meters lower than trout farms are given. Amount of outflow BOD5 in farms has significant difference with inflow water and again has been decreased in 1,500 meters, DO amount in outflow rather than inflow water decreased and in distance of 1,500 meters significant statistically increased （P 〈 0.01）. TSS amount between inflow and outflow of farms has not difference but in 1,500 meters distance has been increased （P 〈 0.01）. PH in inflow and outflow and 1,500 meters lower has not so statistical difference. TH in outflow rather than inflow has been increases and in 1,500 meters distance, its amount has been higher than outflow, too. But this difference has not been significant （P 〉 0.01）. Ammonia in farms outflow rather than inflow has been significant difference （P 〈 0.01）. In flow-through aquaculture systems like raceways and tanks, effluents are discharged to the environment with enhanced concentrations of nutrients and solids. Such effluents may have a serious negative impact on the quality of the receiving water when discharged untreated. The results of this study indicated that trout farm effluents had a impact on the water quality of Koohrang river, but in 1,500 meters distance these parameters modified and suitable for fish farming, as river self purified the environment.

Effect of Irrigation on Groundwater Dynamic Change in the Typical Irrigated Area of Qinghai Province

Under the influence of the natural and human factors, water table of irri- gated area Changes frequently, but it is mainly affected by irrigation water infiltration replenishment during the irrigation. 5 groundwater observation wells were constructed in experimental plot of the Daxia irrigated area to carry out the experiment of the effect of irrigation on groundwater dynamic change in this research. The results showed that the groundwater stage dynarnic change rule of spring and seedling irri- gation stage in the typical plot was fit to the hydrological geology condition of grade- I terrace of Huangshui river valley. On the whole, lateral canal water direction formed a line effect. The No. 1 and No. 2 observation well were the closest to the lateral canal, which received more supplies, and the water level was the highest; the No, 3 observation well took the second place; The No. 4 and No. 5 observation well accepted least supplies, and the water level was the lowest. The rangeability of water table of spring irrigation period was significantly higher than that of seedling irrigation period, this is mainly due to the difference value of intake water volume and drainage water volume of spring irrigation phase was significantly higher than the seedling irrigation phase.

Ridge-furrow plastic mulching with a suitable planting density enhances rainwater productivity,grain yield and economic benefit of rainfed maize

Soil surface mulching and planting density regulation are widely used for effective utilization of limited rainwater resources and improvement of crop productivity in dryland farming.However,the combined effects of mulching type and planting density on maize growth and yield have been seldom studied,especially in different hydrological years.A field experiment was conducted to evaluate the effects of mulching type and planting density on the soil temperature,growth,grain yield(GY),water use efficiency(WUE)and economic benefit of rainfed maize in the drylands of northern China during 2015-2017.Precipitation fluctuated over the three years.There were four mulching types(NM,flat cultivation with non-mulching;SM,flat cultivation with straw mulching;RP,plastic-mulched ridge plus bare furrow;RPFS,plastic-mulched ridge plus straw-mulched furrow)and three planting densities(LD,low planting density,45.0×10^3 plants/hm^2;MD,medium planting density,67.5×10^3 plants/hm^2;HD,high planting density,90.0×10^3 plants/hm^2).Results showed that soil temperature was higher with RP and lower with SM compared with NM,but no significant difference was found between RPFS and NM.More soil water was retained by soil mulching at the early growth stage,but it significantly varied at the middle and late growth stages.Maize growth was significantly improved by soil mulching.With increasing planting density,stem diameter,net photosynthetic rate and chlorophyll content tended to decline,whereas a single-peak trend in biomass yield was observed.Mulching type and planting density did not have significant effect on evapotranspiration(ET),but GY and WUE were significantly affected.There were significant interacting effects of mulching type and planting density on biomass yield,GY,ET and WUE.Compared with NM,RPFS,RP and SM increased GY by 57.5%,50.8%and 18.9%,and increased WUE by 66.6%,54.3%and 18.1%,respectively.At MD,GY increased by 41.4%and 25.2%,and WUE increased by 38.6%and 22.4%compared with those of at LD and HD.The highest maize GY(7023.2 kg/hm^2)was observed under MD+RPFS,but the value(6699.1 kg/hm^2)was insignificant under MD+RP.Similar trends were observed for WUE under MD+RP and MD+RPFS,but no significant difference was observed between these two combinations.In terms of economic benefit,net income under MD+RP was the highest with a 9.8%increase compared with that of under MD+RPFS.Therefore,we concluded that RP cultivation pattern with a suitable planting density(67.5×10^3 plants/hm^2)is promising for rainwater resources utilization and maize production in the drylands of northern China.

Regions and Their Typical Paradigms for Soil and Water Conservation in China

China is experiencing conflicts between its large population and scarce arable land,and between a demand for high productivity and the severe soil erosion of arable land.Since 1949,China has committed to soil and water conservation(SWC),for which eight regions and 41 subregions have been developed to improve the environment and increase land productivity.To obtain information from the regional planning and strategies for SWC and to explore whether SWC practices simultaneously contribute to soil conservation,ecosystem functioning,and the livelihoods of local farmers,and to summarize the successful experiences of various SWC paradigms with distinct characteristics and mechanisms of soil erosion,this paper systematically presents seven SWC regions(excluding the Tibetan Plateau region)and 14 typical SWC paradigms,focusing on erosion mechanisms and the key challenges or issues in the seven regions as well as on the core problems,main objectives,key technologies,and the performance of the 14 typical paradigms.In summary,the 14 typical SWC paradigms successfully prevent and control local soil erosion,and have largely enhanced,or at least do not harm,the livelihoods of local farmers.However,there remain many challenges and issues on SWC and socioeconomic development that need to be addressed in the seven SWC regions.China,thus,still has a long way to go in successfully gaining the win-win objective of SWC and human aspects of development.

Contribution of Vertical Farms to Increase the Overall Energy Efficiency of Urban Agglomerations

The 21st century keeps huge challenges for the system “city”. Shortage of resources and world population growth forces architects to think in spaces with increasingly more structural linkages. No era has shaped the system of a city like the oil age did. Its grown structures are dependent from cheap and easy to produce petroleum. The postmodern city, facing the end of cheap and abundant oil, is now dependent from this finite resource. To minimize the dependency from hydrocarbon energy it is necessary to increase urban density, to switch to renewable energy production and to create new spaces for multifunctional purposes. An essential problem of urban agglomeration, though, is the fact that distances between food production and consumption have increased drastically in the last fifty years. Cheap oil made it possible to implement a global food transportation network and it also supported intensive monocultural food production. Today’s food no more gets bought from local markets, but from labels. Its value is dependent from the brand-image, represented from the tertiary sector. The end of cheap fossil fuels carries a huge potential for architects and urban planners—we can move away from representing abstract, non-spatial processes and identities but creating spaces for dynamic local interactions. A promising typus for this might be the Vertical Farm.

Monitoring Trace Metals in Some Cultured Freshwater Fish Species in Saudi Arabia

Three species of freshwater fishes, Oreochromis niloticus, Clarias lazera and Cyprinus carpio, were collected in marketing size from some fish farms in Al-Kharj region, Riyadh area, Saudi Arabia and examined throughout the year 2012 for the following trace metals contents： chromium （Cr）, lead （Pb）, cobalt （Co）, nickel （Ni）, copper （Cu）, zinc （Zn）, iron （Fe） and cadmium （Cd）. The results showed no detection of Cd in all examined species, however, the mean values of other tested metals were within the standard permissible levels except for Pb which showed higher mean levels ranged from 2.05 ± 0.65 mg/kg to 5.30 ± 0.60 mg/kg in O. niloticus, 0.15 ± 0.13 mg/kg to 6.40 ± 0.10 mg/kg in C. lazera and 1.7 ± 0.20 mg/kg in C. carpio compared to the maximum permissible limits recorded by Saudi Arabia Standards Organization （SASO） for fish and shellfish. Consequently, from the public health point of view, efficient routine examination of cultured fishes to control trace metals during culture processes and before marketing is recommended.

Bacterial Microflora on Freshwater Prawn(Macrobrachium rosenbergii)and Culture Water Associated with Public Health Concern

Quantitative and qualitative analyses of important bacterial content for public health concern(total bacterial count,total coliforms,faecal coliforms,Salmonella and Vibrio cholerae)of cultured fresh water prawn and farm water which has significant role in order to manage sustainable aquaculture were carried out.Microbiological parameters of prawn(Macrobrachium rosenbergii)and farm water were determined by following the ISO standard methods.Total bacterial Count(standard plate count)found in prawn samples ranged from 5.55 to 5.71 log CFU/g while 4.13 to 4.18 log CFU/mL in water sample.On the other hand,total coliforms found in prawn sample ranged between 1.96 to 2.46 log CFU/g whereas in water sample 2.07 to 2.46 log CFU/mL total coliforms were detected.In case of faecal coliforms,the number ranged between 0.96 to 1.42 log CFU/g in prawn sample and 1.59 to 1.81 in water sample.While Vibrio cholerae was absent in both prawns and water sample and Salmonella was detected in two tested ponds for both prawn and water sample.

Effect of Puddling and Compaction on Water Requirements of Rice at Hamelmalo, Eritrea

Eritrean farmers can cultivate rice by harvesting runoff from >82% available non-agricultural land in agricultural watersheds for crop use and reducing percolation through optimization of tillage. Experiments were conducted with NERICA rice, N11, to optimize irrigation requirements and puddling and compaction to reduce percolation. Experimental field was adjacent to Anseba River at downstream end of the watershed and a pond on the upstream to intercept runoff. Irrigation treatments were runoff farming with maximum runoff application depth of 10 mm (I1), and 50 mm irrigation two (I2), five (I3), and seven (I4) days after disappearance of ponded water in main plots and puddling by one (T1), two (T2) and three (T3) passes of puddler and compaction by three (T4), four (T5) and five (T6) passes of 600 kg roller in sub plots in 3 replications. Soil profile was loam in the surface 0.45 m and coarse sandy loam below forming porous belt. Soil submergence was difficult to maintain, but water table was developed in soil profile due to inflow of seepage from the river and pond. Depth to the water table was within 1.5 ± 0.1 m for >2 months and receded down to 1.7 m by crop maturity. Soil wetness was near field capacity around 0.7 m depth and increased below due to natural sub-irrigation from the water table. Rice roots penetrated 0.8 m in the puddled plots and 0.7 m in the compacted plots. Residual soil moisture of 135 - 146 mm·m-1 after rice harvesting provides opportunity for planting rapeseed mustered following rice. Puddling was superior to compaction in loam soil. Puddling twice and irrigation 50 mm 7 days after ponded water vanished from surface was sufficient for optimum rice grain yield of 4346 kg·ha-1 and straw yield of 4458 kg·ha-1. Optimum puddling and irrigation schedules reduced crop duration by 6 days without significantly affecting yield. Production function showed that rice grain yield of 4789 kg ha-1 could be obtained by 1009 mm applied water through rainfall and irrigation.

Utilization of Landsat Data for Quantifying and Predicting Land Cover Change in the Bumbuna Watershed in Sierra Leone

Rural communities in third world countries are concerned over land use changes resulting from resource exploitation. This is the case for the Bumbuna watershed in Sierra Leone following impoundment of the Bumbuna reservoir in 2009. Farmers have increased activities along the riparian zones in protest against inundation of their farmlands. The dam operators warn this practice would threaten sustainable power supply;the farmers contend the reservoir is increasing and taking over their farms. However, it is difficult to resolve this issue without a means of quantifying the change and developing early warning systems for land cover in the watershed. This research presents a case for the use of remotely sensed Landsat data for quantification of land cover change and the development of predictive models to inform preparedness for imminent problems that may arise from land use practices. In situ water loggers, in combination with manual readings, recorded water levels in 30-minute intervals since 2009. These datasets combined with spectral values of Landsat 7 and Landsat 8 for the development of regression algorithms for predictive purposes. Digital photographs and satellite imagery illustrated the changes in land cover over time (a 33% water rise and 44% NDVI change from 2009 to 2015). These visual and spectral pictures confirm the usefulness of remotely sensed data for early warning systems in the watershed. Results of the regression analysis show Band 1 (Blue) and Band 4 (NIR) as statistically significant predictors for water level in the reservoir. The tests accounted for 84% (R2) of the data with p-values less than α at the 0.05 confidence level. However, future trials of the model will consider reducing the 4.6 error margin to minimize deviations from the observed data.

干旱地区水盐胁迫对水稻产量构成及稻谷品质的影响研究

针对宁夏引黄灌区传统稻田蒸发量大,盐渍化耕地占地面积广、改良问题难,土地生产力下降等问题。采用水稻滴灌旱作方式,以富源4号(96D10)作为研究对象,通过设置不同土壤水分水平(W1:高100%、W2:中80%及W3:低60%田间持水率)及盐分水平(S1:轻1.2 g/kg、S2:中3.1 g/kg及S3:重5.3 g/kg),探究不同水盐胁迫对水稻产量构成及稻谷品质的影响规律。结果表明,水盐胁迫对水稻产量及品质具有较为显著的影响,其中产量构成因素中,千粒重W3S3较W1S1下降15.89%(2021年)和15.58%(2022年),饱籽率W3S3较W1S1显著下降3.45%(2021年)和4.05%(2022年),单位产量W3S3较W1S1显著下降56.48%(2021年)和63.09%(2022年);品质方面整精米率W3S3较W1S1显著下降12.65%(2021)和13.56%(2022),垩白米率W3S3较W1S1显著上升164.71%(2021)和122.73%(2022),直链淀粉含量W3S3较W1S1显著下降5.97%(2021)和8.99%(2022),蛋白质含量W3S3较W1S1显著上升53.51%(2021)和61.82%(2022)。综合考虑,在节水目标下,采用滴灌旱作方式种植水稻,保持80%田间持水率加轻、中度盐碱化(≤4.0 g/kg)的土壤环境,可以保持较为接近充分灌溉条件下的产量构成水平和较好的稻谷品质水平。该结论可为宁夏引黄灌区盐碱地可持续利用及水稻的节水灌溉适应性研究提供理论依据。

养殖肥水喷灌条件下摇臂式喷头水力性能研究

【目的】研究不同喷灌介质对喷头水力性能的影响。【方法】以20PY2H摇臂式喷头为研究对象,在不同工作压力下测定了清水和养殖肥水2种喷灌介质对喷头压力-流量、喷头水量分布的影响。通过模拟计算和田间喷灌试验分析相结合的方法,探查喷灌介质、工作压力、组合间距、田间气象条件与喷灌均匀性之间的关系。【结果】(1)与清水灌溉相比,养殖肥水运行下喷头流量降低了2.06%~5.38%,射程前中段径向水量分布差异较大;(2)工作压力为200~300k Pa、组合间距为1.0R~1.4R条件下,MATLAB拟合出的CU模拟值为0.74~0.88,CU试验值为0.66~0.79。复杂的大田气象条件导致喷灌均匀系数下降了6.28%~12.78%。工作压力、喷头组合间距对清水运行喷灌均匀性的影响大于养殖肥水运行。【结论】养殖肥水喷灌更利于喷灌系统降低工作压力和增加喷头布置间距以降低设计成本。

稻虾共作稻田浮游植物群落格局及环境影响因子

为了解稻虾共作稻田浮游植物群落结构特征,对安徽省肥西县和全椒县国家级稻渔综合种养区稻田浮游植物进行了养殖前期、中期、后期三次调查,并探讨了其与环境因子的关系。结果表明,肥西、全椒分别观察到浮游植物6门55种、7门61种,两地的优势类群均为绿藻门和硅藻门。肥西、全椒浮游植物平均密度分别为3.50×10^(6)ind./L和7.90×10^(6)ind./L,平均生物量分别为1.49 mg/L和2.55 mg/L。对Margalef丰富度指数(D)、Shannon-Wiener多样性指数(H′)和Pielou均匀度指数(J)的分析表明:肥西三个养殖时期的D无显著差异,而H′和J均有显著差异;全椒三个养殖时期的H′、D和J均无显著差异。典型对应分析(CCA)表明:溶氧、pH、水温、叶绿素a是与肥西浮游植物群落结构相关性较强的环境因子;冗余分析(RDA)表明:总磷、高锰酸盐指数、pH、氨氮是与全椒浮游植物群落结构相关性较强的环境因子。浮游植物密度结果表明,两地稻田前期和中期水质为中营养状态,后期为富营养状态。