Critical attributes and considerations for selecting irrigation systems for wastewater

Proximity to subsurface drip irrigation emitters altered soil microbial communities in two commercial processing tomato fields

시설오이 지중관비에서 지중 점적호스를 30 cm에 매설 시에 텐시오미터를 이용한 자동관수센서의 적정 깊이를 제시하고자 2010-2011년까지 2년간에 걸쳐서 조사하였다. 오이의 생육은 텐시오미터 30 cm 깊이에서 낮았으나 텐시오미터 10 및 20 cm에서는 유의성 있는 차이는 없었다. 1년 및 2년차 수량에서도 텐시오미터 30 cm에서 각각 40.9 및 41.2 <TEX>$Mg\;ha^{-1}$</TEX>로 가장 적은 생산량을 나타내었나, 텐시오미터 10 cm에서는 57.0 및 56.9 <TEX>$Mg\;ha^{-1}$</TEX>, 텐시오미터 20 cm에서는 56.0 및 60.5 <TEX>$Mg\;ha^{-1}$</TEX>로 처리간의 차이가 없이 동일한 수량을 나타내었다. 오이재배에서 한 작기 당 질소 및 일일 물 공급량은 63 <TEX>$kg\;N\;ha^{-1}$</TEX>의 질소와 1.3 <TEX>$mm\;day^{-1}$</TEX>로 물이 공급된 텐시오미터 20 cm 처리에서 질소 및 수분 이용효율이 높았다. 또한 토양깊이 0-30 cm에 대한 뿌리길이에서도 텐시오미터 20 cm에서 0.87 <TEX>$cm\;cm^{-3}$</TEX>으로 유의성은 없었지만 가장 높은 값을 나타내었다. 이러한 결과로부터 시설오이에서 지중 점적호스를 30 cm 깊이에 매설 시에 텐시오미터를 활용한 자동관수센서의 적정 깊이는 20 cm인 것으로 판단되었다. Vegetables production in greenhouse are typically intensely managed with high inputs of fertilizers and irrigation water, which increases the risk of ground-water nitrate contamination. In 2010 and 2011, a study was conducted to determine the appropriate depth of soil moisture sensor for automatic irrigation control to use water and nitrogen efficiently under subsurface drip irrigation (SDI) systems. The irrigation line for SDI placed 30 cm below soil surface and tensiometer was used as soil moisture sensor. Three tensiometer treatments placed at 10 (SDI-T10), 20 (SDI-T20) and 30 cm (SDI-T30) depths below soil surface under SDI. These are also compared to SUR-T20 treatment where tensiometer placed at 20 cm below soil surface under surface drip irrigation (SUR) systems. The growth of cucumber was not statistically different between SUR and SDI without SDI-T30 treatment. Fruit yields (Mg/ha) were 57.0 and 56.9 (SDI-T10), 56.0 and 60.5 (SDI-T20), 40.9 and 41.2 (SDI-T30) and 56.6 and 54.3 (SUR-T20) for 2010 and 2011, respectively. Slightly higher total yield was observed in tensiometer placed 20 cm below the soil surface, although no significant differences were found between SDI-T10 and SDI-T20 under SDI treatments. In addition, nitrogen application rates and daily irrigation rates were lowest in SDI-T20 compared with other SDIs and SUR treatments. Nitrogen and daily irrigation application under SDI-T20 was lower than that under SUR-T20 by 6.0%. These findings suggested tensiometer 20 cm depth under SDI systems was best for cucumber production in greenhouse.

Over two growing seasons, we evaluated how irrigation strategies and lateral spacings under drip irrigation methods shape safflower physiology. A split-split plot design tested full irrigation (FI), partial root-zone drying (PRD), and deficit irrigation (DI) across three lateral spacings (L1 = 20, L2 = 40, and L3 = 60 cm) with surface (SD) and subsurface (SSD) drip irrigation systems. We monitored leaf area index (LAI), photosynthesis rate (An), stomatal conductance (gs), leaf transpiration rate (Tr), leaf water potential (LWP), and leaf to air vapor pressure deficit (VPD) and related these to seed yield. Relative to FI, water-saving irrigation strategies reduced seasonal irrigation by ~ 25–26%, and SSD applied ~ 7% less water than SD. Peak LAI was 3.95 (2018) and 4.88 (2019), and it significantly reduced by an average of 14% and 18% with water-saving irrigation and wider later spacing, respectively, in comparison to FI and 20 cm lateral spacing. Gas exchange parameters (An, gs, and Tr) decreased with wider lateral spacing and peaked under FI and 20 cm lateral spacing, though PRD and 40 cm spacing resulted in an acceptable physiological performance under water scarcity. The LWP was less negative under FI by roughly 18% compared to water-saving irrigation and by 24% under L1 compared to L3. The extinction coefficient (k) of spring safflower for SD and SSD was 0.62 and 0.70 on average during the two growing seasons. Subsurface drip irrigation showed slightly higher light extinction coefficient, suggesting altered canopy light absorption. Collectively, treatments optimized for gas exchange properties and seed yield were FI-L1-SSD. When water is scarce, the most effective saving strategy was PRD-L2-SSD, which maintained An, gs, LWP, and An/Tr better than DI while saving ~ 25% seasonal water compared to FI.

Growing concerns about climate change and water scarcity have intensified the need for sustainable turfgrass management, particularly by optimizing water‐use efficiency. This 2‐year field study evaluated the effects of rootzone construction methods and irrigation delivery systems on water retention characteristics and perennial ryegrass performance under 60% reference evapotranspiration (ETO) deficit irrigation. Three rootzone constructions (two two‐layered and one three‐layered) were investigated using sprinkler and subsurface drip irrigation (SDI) systems. Key parameters assessed included soil water tension, rootzone water storage (RWS), turfgrass quality (TQ), turfgrass coverage, and normalized difference vegetation index. Significant interactions between rootzone construction and irrigation systems were observed. The three‐layered SDI system demonstrated significantly higher RWS and TQ than the two‐layered SDI systems, which showed rapid RWS and TQ decline. While two‐layered sprinkler systems maintained acceptable TQ longer than their SDI counterparts, they proved to be less efficient than the three‐layered SDI system. These findings highlight the critical role of aligning rootzone design with irrigation methods in enhancing water‐use efficiency and turfgrass performance in water‐scarce environments. This study provides valuable insights for sustainable turfgrass management strategies in response to increasing water constraints.

The use of wastewater in agriculture is occurring more frequently because of water scarcity and population growth. Often the poorest households rely on this resource for their livelihood and food security needs. However, there are negative health implications of this practice that need to be addressed. WHO developed Guidelines for the Safe Use of Wastewater in Agriculture in 1989. The Guidelines are currently being revised based on new data from epidemiological studies, quantitative microbial risk assessments and other relevant information. WHO guidelines must be practical and offer feasible risk management solutions that will minimize health threats and allow for the beneficial use of scarce resources. To achieve the greatest impact on health, guidelines should be implemented with other health measures such as: health education, hygiene promotion, provision of adequate drinking water and sanitation, and other health care measures.

The use of wastewater in agriculture is an alternative to control surface water pollution, and helps to promote the rational use of water. Therefore, the objective of this study was to evaluate the obstruction and uniformity of application of treated wastewater in drip irrigation systems. The study was conducted in a greenhouse at the Universidade Federal de Campina Grande. The treatments were composed by the factorial combination of two factors: three types of water (supply water-ABAST, effluent of a constructed wetland system -WETLAND and upflow of anaerobic reactor effluent followed by constructed wetland system -UASB + WETLAND), and two drip irrigation systems (surface and subsurface), set in a completely randomized design, with four replications. The results indicated that the pH, suspended solids, total iron and coliforms of the WETLAND and UASB + WETLAND treatments represented a severe risk of clogging of drippers; the flow of the emitters increased as the service pressure was increased; values of CUC and CUD in surface and subsurface drip were classified as excellent in ABAST and WETLAND treatments. The degree of clogging reduced as pressure under surface and subsurface drip was increased.

The need to minimise consumer risk, especially for food that can be consumed uncooked, is a continuing public health concern, particularly in places where safe sanitation and hygienic practices are absent. The use of wastewater in agriculture has been associated with disease risks, though its relative significance in disease transmission remains unclear. This study aimed at identifying key risk factors for produce contamination at different entry points of the food chain. Over 500 produce and ready-to-eat salad samples were collected from fields, markets, and kitchens during the dry and wet seasons in Accra, Ghana, and over 300 soil and irrigation water samples were collected. All samples were analysed for E. coli, human adenovirus and norovirus using standard microbiological procedures, and real time RT-PCR. Finally, critical exposures associated with microbial quality of produce were assessed through observations and interviews. The study found that over 80% of produce samples were contaminated with E. coli, with median concentrations ranging from 0.64 to 3.84 Log E. coli/g produce. Prepared salad from street food vendors was found to be the most contaminated (4.23 Log E. coli/g), and that consumption of salad exceeded acceptable health limits. Key risk factors identified for produce contamination were irrigation water and soil at the farm level. Storage duration and temperature of produce had a significant influence on the quality of produce sold at markets, while observations revealed that the washed water used to rinse produce before sale was dirty. The source of produce and operating with a hygiene permit were found to influence salad microbial quality at kitchens. This study argues for a need to manage produce risk factors at all domains along the food chain, though it would be more effective to prioritise at markets and kitchens due to cost, ease of implementation and public health significance.

Simulation of soil wetting pattern with subsurface drip irrigation from line source

Increasing water demand and climate change reduced agricultural water resources in arid and semi-arid regions. Field experiments were conducted at Demo Farm, Faculty of Agriculture, Fayoum University. Potato tubers were planted during two seasons (2021 and 2022). Three deficit irrigations (DI): I1 (100% of ETc), I2 (80% of ETc) and I3 (60% of ETc). Two partial root zone drying (PRD) irrigations: (double laterals and single laterals). Three lateral depths: zero cm (surface drip irrigation) and 15 and 30 cm (subsurface drip irrigation, SDI). Some growth parameters and yield of the potato crop were determined. Results indicated that the highest mean values of plant growth and yield of potato plants were recorded with irrigation treatment I1 under PRD and SDI with buried lateral depth of 15 cm. Also, the highest values of physiological parameters were recorded with irrigation treatment I1 under PRD and SDI with buried lateral depth 15 cm. When DI treatments increased from I1 to I2 and I3, the mean values of potato yield decreased. Using PRD treatment led to increasing the values of potato yield at irrigation treatments I1, I2 and I3. It could be recommended when irrigation water is abundant, using the irrigation treatment I1, PRD irrigation under SDI with buried lateral depth at 15 cm to reach the maximum yield of the potato crop. Meanwhile, under water scarcity, using DI treatment I2, PRD irrigation under SDI with buried lateral depth at 15 cm, will save 20% of the IWA with a low decrease in potato yield.

The influence of several regulated deficit irrigation (RDI) strategies, applied under subsurface drip irrigation (SDI), on vegetative development and yield parameters in mature almond (Prunus dulcis (Mill.) D.A. Webb, cv. Cartagenera) trees was analysed during a 4-year field experiment. Five treatments were applied: T1 (100% crop evapotranspiration (ETc), full season); T2 (irrigated at 100% ETc except in the kernel-filling stage (20% ETc)); T3 (equal to T2 but in SDI); T4 (SDI, 100% ETc, except in the kernel-filling stage (20% ETc) and post-harvest (75% ETc)); T5 (SDI, 100% ETc except in the kernel-filling stage (20% ETc) and post-harvest (50% ETc). A close correlation between applied water, plant water status (Ψpd) and tree growth parameters was observed. After four years, the vegetative development in T5 was reduced significantly due to a larger annual cumulative effect of water stress on growth processes, resulting in a smaller tree size (trunk and branch growth, canopy volume and pruning weight) compared to other treatments. Moreover, water stress during kernel-filling produced a significant reduction in the leaf expansion rate and a stimulation of premature leaf abscission, resulting in a smaller tree leaf area in this treatment. SDI produced a greater horizontal distribution of fine roots in the soil profile than surface drip system. The RDI practices applied under subsurface drip irrigation stimulated a deeper root development (40–80 cm) than surface treatments (0–40 cm), producing also a higher root density in the subsurface treatments watered the least (T4 and T5). Water stress during the pre- and post-harvest periods had no important effect on bud development, bloom, fruit growth or fruit abscission. Moreover, there were no significant reductions in kernel dry weight or kernel percentage. Reductions in kernel yield were significant compared to T1, being of 11% in T2, 15% in T3, 20% in T4 and 22% in T5. Water use efficiency (kg m−3) was increased significantly in the SDI treatments T4 and T5. A significant correlation between kernel yield and tree growth parameters was observed. We conclude that the application of overall reductions of water use of up to 50% during high water stress sensitivity periods (such as post-harvest) under SDI system, is a promising alternative for water management in semiarid regions in order to improve water use efficiency. Nevertheless prolonged water stress during kernel-filling and post-harvest can reduce excessively the vegetative development of almond, negatively affecting the long-term yield response.

Water is an essential component of life in the world. In addition to being crucial to keeping plants alive, water is also used in various areas, such as landscape irrigation, decorative pools, and ponds. The use of water more efficiently is getting more and more important day by day because of the increasing demands of different sectors. In cities with limited water resources, such as Konya, water should be used even more efficiently to reduce irrigation water quantities and prevent water losses. The potential use of the sub-surface drip irrigation method in the irrigation of green areas in Selçuklu district of Konya province was investigated, and the sub-surface drip irrigation method was compared with the fixed sprinkler irrigation method (pop-up) in terms of irrigation parameters (amount of irrigation water applied, plant water consumption) and plant characteristics (germination, plant height, number of mows, mowing weight, root depth). In the present experiments, 18 different sub-surface drip irrigation treatments (100, 80, and 60% irrigations + 40, 60, and 80 cm lateral spacings + 10 and 15 cm lateral depths) and three different sprinkler irrigation treatments (100, 80, and 60% irrigations) were used. Present findings revealed that sub-surface drip irrigation systems were suitable for irrigation of green areas, and this system was more advantageous for municipalities in terms of water savings, irrigation labor, and maintenance. For sub-surface drip irrigation systems, S1 (supply 100% of evaporation from Class-A pan + 40 cm lateral spacing + 10 cm lateral depth) treatments were found to be the best system arrangement for landscape irrigations in Selçuklu district in Konya province.

In the southeastern U.S. Coastal Plains, supplemental irrigation is required to reduce the impact of short-term droughts and yield-reducing plant water stress that can occur at least biennially. Sprinkler irrigation is commonly used to water agronomic crops in the region. Microirrigation is typically used for high value fruit and vegetable crops. In recent years and at some locations, microirrigaiton combined with conservation tillage has been implemented for agronomic crop production to help conserve soil moisture. In this research, we investigated the feasibility of planting corn (Zea Mays L) in narrow rows over subsurface drip irrigation (SDI). Our specific objectives were to 1) compare narrow-row corn yields using surface and subsurface drip irrigation with laterals spaced at 1 and 2 m; 2) compare the effects of pulsed SDI applications to move irrigation water farther away from the laterals on narrow-row corn yields; and 3) evaluate the impact of corn row distance from SDI laterals on plant biomass, nitrogen, and yield components. Corn was planted in 0.38-m rows on an existing subsurface drip irrigation system with laterals installed 0.30 m below the soil surface and spaced at 1 and 2 m apart. Surface drip irrigation was installed at both lateral spacings to compare with the SDI treatments. Irrigation was applied weekly as required to meet the crop water demands. All nutrients were applied through the subsurface drip irrigation system. Corn yields for 2003 ranged from 4301 to 5420 kg/ha, while in 2004 the yields were greater and ranged from 4452 to 6329 kg/ha. No significant differences were observed between the SDI and surface drip irrigated treatments. Corn yields from the pulsed SDI treatments were not significantly different from non-pulsed treatments. Early season whole plant biomass was significantly higher for the 2-m SDI lateral spacing, but there were no significant biomass differences at later growth stages. Corresponding whole plant N concentrations were significantly higher for the 1-m SDI lateral spacing in 2004. Grain N, ear length, and ear weight were not significantly different at harvest for SDI lateral spacing. We found that the distance of the corn rows from the SDI lateral greatly influenced the crop growth and grain yield. Plant biomass, whole plant N, ear length, and grain weight all decreased significantly with distance from the SDI laterals. These results show a great deal of variability among rows when corn is grown in 0.38-m spacing over SDI laterals for wider row crops. Higher plant populations placed closer to the laterals may increase productivity.

The rapid expansion of animal production in the eastern U.S. in the 1990s resulted in large quantities of concentrated animal waste that must be utilized or disposed of in an efficient and environmentally friendly manner. To address these environmental concerns for wastewater utilization, we installed a subsurface drip irrigation system to apply treated swine wastewater effluent for bermudagrass hay production. The overall study objective was to determine the feasibility of using subsurface drip irrigation (SDI) for treated wastewater effluent applications. The specific objectives for the SDI system were to compare bermudagrass hay production using (1) commercial and wastewater effluent for nutrients, (2) two SDI lateral spacings (0.6 and 1.2 m) installed at 0.3 m below the surface, and (3) two irrigation application rates based on calculated evapotranspiration (ETc) requirements (75% or 100%). The two-year study measured hay yields, hay biomass, soil nutrients, and soil water nutrients. The SDI system was successfully operated for two years applying effluent and commercial fertilizer to supply the nutrient requirements of the bermudagrass hay. Bermudagrass hay production for 2004 and 2005 ranged from 5.65 to 14 Mg ha-1. Results from the SDI system indicated no significant differences between the SDI lateral spacings or irrigation application rates. Treatments using wastewater effluent had significantly higher hay yields and significantly higher nutrient biomass removal rates than the commercial fertilizer treatments. Nitrate-N observed in soil water lysimeters increased with depth, indicating the potential for leaching without proper management. Soil nitrogen and carbon were not significantly different for any of the treatments but did vary slightly over the life of the project.

Tomato nitrogen accumulation and fertilizer use efficiency on a sandy soil, as affected by nitrogen rate and irrigation scheduling

Subsurface drip irrigation is an advanced technique that significantly enhances agricultural water efficiency and conserves irrigation resources. The Heilonggang region is highly representative of the maize–wheat rotation system in China. This region was selected for conducting operations and maintenance experiments on subsurface drip irrigation systems. The primary objective of this study was to determine the most suitable type of drip tape for application in the North China Plain and to identify specific maintenance measures necessary to ensure the long-term functionality of subsurface drip irrigation systems. The experiment was conducted in Jing County, Hengshui City. Anti-blocking drip tape (Netafim Co., Ltd. Beijing, China) with automatic functionality was evenly laid in the test area. The experimental area was divided into six rotational irrigation groups. The key parameter examined in this single-factor experiment was the drip tape wall thickness, with values of 0.2, 0.225, 0.25, 0.28, 0.31, and 0.38 mm. Drip tape treatments were randomly sampled in rotational irrigation groups, and there were three repeat plots in each treatment. Each replicate plot contained ten drip irrigation belts spaced 60 cm apart, with an interval of more than 2 m between adjacent plots. The subsurface drip irrigation system was installed in October 2023. Prior to irrigation, drip tape troubleshooting was conducted and recorded manually on 12 March 2024 (wheat regreening stage) and 29 June 2024 (maize-sowing stage). The experimental findings indicated that the primary factor influencing the stability of the irrigation system was the wall thickness of the drip tapes, while other system components operated efficiently. A significant correlation was observed between the wall thickness of the drip tape and the number of water leakage points (p &lt; 0.05), with an absolute correlation coefficient exceeding 0.9. The number of leakage points in drip tapes with wall thicknesses of 0.2–0.28 mm (267 instances) was significantly higher than those with wall thicknesses of 0.31–0.38 mm (29 instances), primarily due to damage caused by mole crickets and wireworms. Following the injection of 40% phoxim, 2.5% lambda-cyhalothrin, and 70% imidacloprid insecticides (at a cost of 16.7 USD·ha−1) into the subsurface drip irrigation system, the insect pests were nearly eradicated within one month. A cumulative cost evaluation over a 6–10-year period recommended the use of drip tapes with a wall thickness of 0.31 mm and the application of insecticides every 1–2 months to maintain optimal system performance in this region. These measures can effectively support the stable operation of this irrigation technique at a relatively low cost.