Irrigation and nitrogen fertiliser optimisation in protected vegetable fields of northern China:Achieving environmental and agronomic sustainability

Globally,sub-optimal use of nitrogen (N) fertiliser and elevated N irrigation groundwater have led to high leached nitrate (NO_(3)^(–)) losses from protected vegetable field systems.Optimising fertiliser and irrigation management in different soil types is crucial to reduce future N loads from such systems.The present 4-year study examined leached N loads from lysimeter monitoring arrays set up across 18 protected vegetable system sites encompassing the dominant soil types of northern China.The treatments applied at each field site were:1) a high N and high irrigation input treatment (HNHI);2) a low N but high irrigation input treatment (LNHI) and 3) a low N with low irrigation input treatment (LNLI).Results showed that the mean annual leached total nitrogen loads from the HNHI,LNHI and LNLI treatments were 325,294 and 257 kg N ha^(–1) in the fluvo-aquic soil,114,100 and 78 kg N ha^(–1) in the cinnamon soil and 79,68 and 57 kg N ha^(–1) in the black soil,respectively.The N dissolved in irrigation water in the fluvo-aquic soil areas was 8.26-fold higher than in the cinnamon areas.A structural equation model showed that N fertiliser inputs and leaching water amounts explained 14.7 and 81.8%of the variation of leached N loads,respectively.Correspondingly,reducing irrigation water by 21.5%decreased leached N loads by 20.9%,while reducing manure N and chemical N inputs by 22 and 25%decreased leached N loads by only 9.5%. This study highlights that protected vegetable fields dominated by fluvo-aquic soil need management to curtail leached N losses in northern China.

Modeling of Sensor Enabled IrrigationManagement for Intelligent Agriculture Using Hybrid Deep Belief Network

Artificial intelligence(AI)technologies and sensors have recently received significant interest in intellectual agriculture.Accelerating the application of AI technologies and agriculture sensors in intellectual agriculture is urgently required for the growth of modern agriculture and will help promote smart agriculture.Automatic irrigation scheduling systems were highly required in the agricultural field due to their capability to manage and save water deficit irrigation techniques.Automatic learning systems devise an alternative to conventional irrigation management through the automatic elaboration of predictions related to the learning of an agronomist.With this motivation,this study develops a modified black widow optimization with a deep belief network-based smart irrigation system(MBWODBN-SIS)for intelligent agriculture.The MBWODBN-SIS algorithm primarily enables the Internet of Things(IoT)based sensors to collect data forwarded to the cloud server for examination purposes.Besides,the MBWODBN-SIS technique applies the deep belief network(DBN)model for different types of irrigation classification:average,high needed,highly not needed,and not needed.The MBWO algorithm is used for the hyperparameter tuning process.A wideranging experiment was conducted,and the comparison study stated the enhanced outcomes of the MBWODBN-SIS approach to other DL models with maximum accuracy of 95.73%.

The effects of aeration and irrigation regimes on soil CO_2 and N_2O emissions in a greenhouse tomato production system

Aerated irrigation has been proven to increase crop production and quality, but studies on its environmental impacts are sparse. The effects of aeration and irrigation regimes on soil CO2 and N2O emissions in two consecutive greenhouse tomato rotation cycles in Northwest China were studied via the static closed chamber and gas chromatography technique. Four treatments, aerated deficit irrigation（AI1）, non-aerated deficit irrigation（CK1）, aerated full irrigation（AI2） and non-aerated full irrigation（CK2）, were performed. The results showed that the tomato yield under aeration of each irrigation regime increased by 18.8% on average compared to non-aeration, and the difference was significant under full irrigation（P〈0.05）. Full irrigation significantly increased the tomato yield by 23.9% on average in comparison to deficit irrigation. Moreover, aeration increased the cumulative CO2 emissions compared to non-aeration, and treatment effects were significant in the autumn-winter season（P〈0.05）. A slight increase of CO2 emissions in the two seasons was observed under full irrigation（P〉0.05）. There was no significant difference between aeration and non-aeration in soil N2O emissions in the spring-summer season, whereas aeration enhanced N2O emissions significantly in the autumn-winter season. Furthermore, full irrigation over the two seasons greatly increased soil N2O emissions compared to the deficit irrigation treatment（P〈0.05）. Correlation analysis indicated that soil temperature was the primary factor influencing CO2 fluxes. Soil temperature, soil moisture and NO3^- were the primary factors influencing N2O fluxes. Irrigation coupled with particular soil aeration practices may allow for a balance between crop production yield and greenhouse gas mitigation in greenhouse vegetable fields.

Technologies for Efficient Use of Irrigation Water and Energy in China

While the shortage of water and energy is a well-recognized worldwide natural resources issue, little attention has been given to irrigation energy efficiency. In this paper, we examine the potential energy savings that can be achieved by implementing improved irrigation technologies in China. The use of improved irrigation management measures such as a flow meter, irrigation scheduling, and/or regular maintenance and upgrades, typically reduces the amount of water pumped over the course of a growing season. The total energy saved by applying these improved measures could reach 20%, as compared with traditional irrigation methods. Two methods of irrigation water conveyance by traditional earth canal and low pressure pipeline irrigation （LPPI） were also evaluated. Our study indicated that LPPI could save 6.48x 109 kWh yr1 when applied to 11 Chinese provinces. Also, the COz emission was reduced by 6.72 metric tons per year. Among these 11 surveyed provinces, the energy saving potential for two provinces, Hebei and Shandong, could reach 1.45 x 109 kWh yr^-1. Using LPPI, potential energy saved and CO2 emissions reduced in the other 20 Chinese provinces were estimated at about 2.97×109 kWh yr-1 and 2.69 metric tons per year, respectively. The energy saving potential for Heilongjiang, a major agriculture province, could reach 1.77× 109 kWh yr-1, which is the largest in all provinces. If LPPI is applied to the entire country, average annual energy saving of more than 9 billion kWh and average annual CO2 emission reduction of more than 9.0 metric tons could be realized. Rice is one of the largest users of the world＇s fresh water resources. Compared with continuous flooding irrigation, intermittent irrigation （ITI） can improve yield and water-use efficiency in paddy fields. The total increments of net output energy and yield by ITI in paddy fields across China could reach 2.5× 1016 calories and l07 tons, respectively. So far only a small part of agricultural land in China has adopted water and energy saving technologies. Therefore, potential water and energy savings in China by adapting improved irrigation technology could be significant and should be carefully studied and applied.

Applying plant-based irrigation scheduling to assess water use efficiency of cotton following a high-biomass rye cover crop

Background:This study addressed the potential of combining a high biomass rye winter cover crop with predawn leaf water potential(ΨPD)irrigation thresholds to increase agricultural water use efficiency(WUE)in cotton.To this end,a study was conducted near Tifton,Georgia under a manually-controlled,variable-rate lateral irrigation system using a Scholander pressure chamber approach to measure leaf water potential and impose varying irrigation scheduling treatments during the growing season.ΨPDthresholds were-0.4 MPa(T1),-0.5 MPa(T2),and-0.7 MPa(T3).A winter rye cover crop or conventional tillage were utilized for T1-T3 as well.Results:Reductions in irrigation of up to 10%were noted in this study for the driest threshold(-0.7 MPa)with no reduction in lint yield relative to the-0.4 MPa and-0.5 MPa thresholds.Drier conditions during flowering(2014)limited plant growth and node production,hastened cutout,and decreased yield and WUE relative to 2015.Conclusions:We conclude thatΨPDirrigation thresholds between-0.5 MPa and-0.7 MPa appear to be viable for use in aΨPDscheduling system with adequate yield and WUE for cotton production in the southeastern U.S.Rye cover positively impacted water potential at certain points throughout the growing season but not yield or WUE indicating the potential for rye cover crops to improve water use efficiency should be tested under longer-term production scenarios.

Influence of Farmer Capacity Building in Institutional Linkages on Performance of Smallholder Irrigation Projects in Migori County, Kenya

The smallholder irrigation sector in Kenya is considered inadequately developed. The study views unawareness of critical success factors in the smallholder irrigation sector as contributing to poor performance of smallholder irrigation projects. Consequently, the study investigated influence of farmer capacity building in institutional linkages on performance of smallholder irrigation projects in Migori County, Kenya. The study embraced a pragmatic view of philosophy, and used cross sectional and correlation research design. The target population was 2815, and comprised farmers drawn from fifteen smallholder irrigation projects that receive water from River Kuja through Lower Kuja Project. The sample size was 341. The study used systematic random sampling procedure to draw the sample, and collected data using questionnaire. Data was analysed using descriptive and inferential statistics. The study established that farmer capacity building in institutional linkages has a significant influence on performance of smallholder irrigation projects (r = 0.803, R2 = 0.645, F (5, 331) = 120.254 and p < 0.000 < 0.05). Thus, the study recommends that Migori County Government come up with policies that link smallholder irrigation projects in Lower Kuja Project to institutions that provide land ploughing services, certified seeds and fertilisers, control of crop pests and diseases, transportation of farm produce and marketing of farm produce.

Implications of Design, Management and Recession Phase in Drip Irrigation on the Total Distribution Efficiency in Blueberry (Vaccinium corymbosum L.) Crops in Areas with High Slopes in Concordia, Argentina

The increase of human population generates the need to improve the efficiency of food production. A thorough planning is required following the scope of economic and sustainable development, being irrigation a basic tool, however water availability is restricted and it obliges farmers to progress increasing water productivity. Irrigation uses around 70% of total available fresh water, while irrigation water application efficiency is around 40%. Irrigation systems must follow strong criteria at the design stage to achieve high values of water productivity. Maintenance is indispensable to follow the original functioning level of those systems. At last the daily precise management of systems, following soil water potential, considering the effective rain storage at root depth of the crop and the evolution of daily evapotranspiration, preserving natural resources, are relevant to achieve low values of water footprint of this crop. In an 8 year drip irrigation system, the Uniformity Coefficient of Christiansen (UCC) measured was 95.14%;the Uniform Coefficient of the Minor Quart (UCMQ) was 93.16%. The Total Distribution Efficiency (EDT) was 95.13% when measurements finished while the irrigation systems is of. When measurements also considered the volume collected during the “recession phase in drip irrigation” and the “volume of water collected during recession phase in drip irrigation” collected at different points, EDT was 95.13%. Moreover it can be seen that when three different typical soil of the area were considered, the EDT was, 91.85%, 91.47% and 90.30% respectively, according with different water storage capacity of each soil. The Total Distribution Efficient is a strong method, to evaluate the design and management of drip irrigation systems, under different design criteria, management practices and maintenance of the systems. Water footprint in a blueberry (Vaccinium corymbosum L.) crop with drip and sprinkler anti-frost system, were measure and values obtained were 846, 310, 223, 212, 172 and 218 liters per kg of fresh fruit in the period 2010-2015. The UCC and the UCMQ reflects properly the irrigation design, while the EDT reflects irrigation design, management and maintenance. Water footprint is at last the strong tool to evaluate design and operation of the irrigation system and crop management.

A Study on Importance and Role of Irrigation and Hydropower Plant Operation in Integrated River Basin Management

In this study, 16 irrigation schemes (Baklan, Irgilli, Sutlac, Cal, Cürüksu, Nazilli, Saraykoy, Pamukkale, Sultanhisar, Akcay, Aydin, Topcam, Karpuzlu, Isikli, Gümüssu ve Soke) having 166,381 hectares, built by State Hydraulic Works (DSI), and operated by participatory irrigation managements, and 14 hydroelectric power plants (HPP) operated and built on dams, canals and rivers by the public and private sectors are examined in the Büyük Menderes basin which is an important basin in terms of the agriculture, energy and ecology projects. Integrated basin management practices and the importance and role of irrigation and hydropower plant operation in integrated basin management, how it should be, optimal use of available water resources for irrigation and hydroelectric power plant operation, irrigation relationship with canal hydropower plants, operated under integrated basin management of irrigation and hydropower plants, environment and the ecological effects have been studied, and integrated basin management with the existing basin management conditions in terms of hydropower plant and irrigation operation on the basis of data of 2015 have been compared, reached important conclusions, and made recommendations on the subject.

Arsenic Accumulation in Rice:Sources,Human Health Impact and Probable Mitigation Approaches

The human body loading with arsenic(As)through rice consumption is a global health concern.There is a crucial need to limit As build-up in rice,either by remediating As accumulation in soils or reducing As levels in irrigation water.Several conventional approaches have been utilized to alleviate the As accumulation in rice.However,except for some irrigation practices,those approaches success and the adoption rate are not remarkable.This review presents human health risks posed due to consumption of As contaminated rice,evaluates different biomarkers for tracing As loading in the human body,and discusses the latest advancement in As reducing technologies emphasizing the application of seed priming,nanotechnology,and biochar application for limiting As loading in rice grains.We also evaluate different irrigation techniques to reduce As accumulation in rice.Altering water management regimes significantly reduces grain As accumulation.Bio-and nano-priming of rice seeds improve germination and minimize As translocation in rice tissues by protecting cell membrane,building pool around seed coat,methylation and volatilization,or quenching harmful effects of reactive oxygen species.Nanoparticle application in the form of nano-adsorbents or nano-fertilizers facilitates nano-remediation of As through the formation of Fe plaque or sorption or oxidation process.Incorporating biochar in the rice fields significantly reduces As through immobilization,physical adsorption,or surface complexation.In conclusion,As content in cooked rice depends on irrigation source and raw rice As level.

Research,Extension,and Good Farming Practices Improve Water Quality and Productivity

Agriculture in southeastern Oregon and southwestern Idaho known collectively as the Treasure Valley has depended on furrow irrigation using heavy inputs of water and nitrogen （N） fertilizer. Crop rotations include onion, corn, wheat, sugar beet, potato, bean, and other crops. By 1986 groundwater had become contaminated with nitrate and residues of the herbicide chlorthal-dimethyl （DCPA）; an official groundwater management area was established by the Oregon Department of Environmental Quality along with an action plan and well monitoring network. The action plan allowed for a trial period to see whether voluntary changes would improve trends. Researchers, producers, and agencies cooperated to develop production options that had the possibility of being both environmentally protective and cost effective. Options were tested to improve irrigation practices, increase N fertilizer use efficiency on several rotation crops, and find a cost effective replacement for DCPA. Research demonstrated the opportunity for increased productivity through both irrigation scheduling and the adoption of drip and sprinkler systems. Fertilizer research demonstrated that smaller, more frequent N applications were more efficient than a single large application. Effective, lower cost herbicides replaced DCPA. Research results were effectively delivered through many means and voluntarily adopted. Both groundwater nitrate and DCPA residues are declining. Productivity has increased.

Effects of Interaction of Soil Moisture and Organic Matter on Powdery Mildew Disease and Growth of Heracleum moellendorffii Hance

Taking annual Heracl'eum moellendorffii Hance as the material,this research studied the epidemic dynamics of H.moellendorffii Hance powdery mildew and plant growth by using the interactive methods of soil moisture and soil organic matter.The results showed that the interaction of higher soil moisture content(60%-80%)and soil organic matter content(75-100 g•kg^(-1))had few diseases,dosease index and area under disease progression curve(AUDPC)compared with those of other treatments,thus could effectivley control powdery mildew disease.Moreover,higher soil moisture and organic matter content increased the yield,contents of soluble sugar,soluble protein,vitamin C and coumarin in H.moellendorffii Hance.

Coupling effects of water and nitrogen on photosynthetic characteristics,nitrogen uptake,and yield of sunflower under drip irrigation in an oasis

An experiment was conducted in an oasis area in northwest China to assess the coupling effects of water and nitrogen supply through drip irrigation on photosynthetic characteristics,nitrogen uptake,and yield of sunflower(Helianthus annuus L.),as well as the nitrate distribution in the root-zone soil.The experiment included three irrigation levels(210[W1],300[W2],and 390[W3]mm),three nitrogen levels(162[N1],232[N2],and 302[N3]kg/hm^(2)),and control treatment(no fertilization during whole growth period and only irrigated at the budding stage).A nitrogen content over-accumulation in the soil was observed under the low irrigation amount with high fertilizer supply,which cannot enhance the sunflowers’absorption of nitrogen.Excessive irrigation caused leach of the soil nitrogen,reduced nitrogen content in the root-zone soil(0-40 cm)and limited nitrogen uptake by the crop.Although low irrigation amount with high fertilizer supply can increase the nitrogen content in the soil,it cannot enhance the sunflowers’absorption of nitrogen.At the vegetative stage of sunflower growth,the accumulation of nitrogen in the organs was mainly concentrated in the leaves,while it was transferred to the flower disk at the reproductive growth stage.Reasonable coupling of water and nitrogen improved the transport of nitrogen from leaves and stems to the flower disk and promoted the formation of yield components.Six regression equations were established with irrigation and fertilization amount as independent variables,and seed rate,seed weight per flowerdisk,1000 grain weight,yield,water use efficiency and nitrogen partial factor productivity as dependent variables,respectively.Multiple regression and spatial analysis suggested that the irrigation amount of 241.62-253.35 mm and the fertilization application of 202.02-209.40 N kg/hm^(2)was a good irrigation strategy,under which all six factors exceed 75%of their maxima,and the yield of sunflower reached 3229.3 kg/hm^(2).

Increasing yield and agronomic efficiency of boro rice(Oryza sativa)by fertigation with bed planting compared with conventional planting

The fertigation technique with raised bed planting for transplanted boro(winter,irrigated)rice production is a research focus nowadays.A field experiment compared two cultivation methods:the fertigation technique within raised bed planting on boro rice,and fertilizer broadcasting in the conventional planting method.Compared to conventional fertilizer broadcasting,results showed that the new fertigation technique in raised bed planting increased grain yield of transplanted boro rice by up to 17.04%.It yielded a greater number of panicles per square meter,a greater number of grains per panicle,higher 1000-grains weight,and better plant growth attributes.Sterility percentage and weed infestation were lower.Thirty six percent of irrigation water and time for application could be saved.Water use efficiency for grain and biomass production was higher.The agronomic efficiency of nitrogen(N)fertilizer was significantly higher.This study concluded that fertigation in raised bed planting for transplanted boro rice is a new approach with higher yield and higher fertilizer and water use efficiency than the existing agronomic practice in Bangladesh.

Effects of drought stress on water consumption of poplar trees in an oasis shelterbelt of the Northwest China

The shelterbelt is an indispensable component of the oasis ecological system.However,drought stress can cause a large-scale decline in oasis shelterbelts.In this study,meteorological data,sapflow and soil moisture were measured to analyze the effect of drought stress on the water consumption of the oasis shelterbelt in the northwest China.Results showed that the most critical factor affecting the water consumption of an oasis shelterbelt is solar radiation,followed by relative humidity,temperature and precipitation,while the weakest factor is rainfall.Water consumption increases with solar radiation and air temperature rising,decreases with relative humidity increasing.A power index relationship between Poplar water consumption(Tr)and soil volumetric moisture content(SW)was found,which is expressed as follows:Tr=11.52/[1+e(-0.609SW+13.17)].Meteorological and soil drought stress severely restrict oasis shelterbelt water consumption.An improved understanding of the relationship between water consumption and drought stress in oasis shelterbelts would be beneficial for irrigation managements.