Surface Drip Irrigation System Research Articles

Optimization of gravity-fed surface drip irrigation system for small farm under varying head and length of laterals

Optimization of gravity-fed surface drip irrigation system for small farm under varying head and length of laterals

Empirical models for calculating soil wetting patterns under surface drip irrigation systems: A comprehensive analysis

AbstractAccurate estimation of the surface wetted radius (R) and vertical wetted depth (Z) of wetting patterns in drip irrigation systems is crucial for ensuring that the designs of such systems are effective. This study compared 14 empirical models for estimating drip irrigation wetting patterns by assessing their accuracy using published measurement data and HYDRUS‐2D/3D simulations. The technique for order of preference by similarity to the ideal solution (TOPSIS) was employed to comprehensively rank the models. The results indicate that the empirical model proposed by Fan et al. (2023) (FY) exhibited the highest accuracy when the estimations of R and measured and simulated values were compared, with mean absolute error (MAE), root mean square error (RMSE), Nash–Sutcliffe modelling efficiency (NSE), and percent bias (PB) values of 2.2 cm, 3.4 cm, 0.79, and −7.1% and 5.2 cm, 7.0 cm, 0.50, and −14.1%, respectively. The empirical model proposed by Amin and Ekhmaj (2006) (AE) demonstrated the highest accuracy when the estimations of Z were compared with measured and simulated values, with MAE, RMSE, NSE and PB values of 1.7 cm, 2.0 cm, 0.95 and 4.15% and 4.4 cm, 5.9 cm, 0.82 and 4.7%, respectively. The comprehensive rankings of available models in the present study indicate that the FY model is the most universally applicable, followed by the Li et al. (2022) (LY) model, with comprehensive indices of 0.960 and 0.936, respectively. This research can aid in the selection of universally applicable, reliable and straightforward empirical models for estimating wetting patterns in drip irrigation systems.

Sustainability of Agricultural Productivity and Water Requirement of Sorghum Crop Under Deficient Irrigation

A field experiment was conducted at the Experimental Station of the College of Agricultural Engineering Sciences, University of Baghdad - Al-Jadriya (Station F), to study the effect of deficit irrigation on the water requirement of Sorghum bicolor L, using surface drip irrigation system, during the spring season 2022 in a clay loam soil, using randomized complete block design (RCBD) with three replications. The experiment included 6 irrigation treatments levels: complete irrigation treatment, 100% irrigation, (at 50% of the available water depleted), and compensated by the American evaporation basin index, Class A, and deficit irrigation applying 80, 70, 60, 50, and 40% of the 1st complete irrigation. Deficit irrigation applied at (vegetative growth, flowering and grains maturity stages for Sorghum crop. Sorghum seeds were sown on 13. Mar 2022 and harvested on 15. Jul 2022. The results indicated that water requirement for sorghum, it’s the highest value in the full irrigation treatment was 487.25 mm season-1, then it decreased to 413.87, 377.19, 340.50, 303.81, and 267.12 mm season-1 for above treatments respectively.

Response Water Productivity and Sorghum Yield to Deficit Irrigation Under Surface Drip Irrigation System

A field experiment was conducted during the spring season of 2022 in a clay loam soil at the experimental station of the College of Agricultural Engineering Sciences, University of Baghdad - Al-Jadriya, in order to study the effect of deficit irrigation on the growth and productivity of Sorghum, using the surface drip irrigation system, the experiment included irrigation treatments with six levels of full irrigation treatment FI100 When 50% of the available water is depleted, it is compensated by the American evaporation basin class A, from which the deficit irrigation treatments 80, 70, 60, 50, and 40% of the complete irrigation were applied, using the RCBD with three replications. The treatments were applied during the included plant growth stages (vegetative growth, flowering and maturity). Crop growth indicators were measured at the end of the season. Sorghum seeds were sown on 3-13-2022 and harvested on 7-15-2022. The results showed that the seasonal water consumption of corn reached its highest value when the full irrigation treatment was 487.24 mm when 50% of the available water was depleted, then it decreased to 413.59, 376.94, 340.29, 303.63, and 266.98 mm for the deficit irrigation treatments (80, 70, 60, 50, and 40%) calculated from the control treatment (FI%100). Irrigation treatment (FI 100%) gave the highest values for average plant height, leaf area, chlorophyll content, total root dry weight and yield. Water consumption amounted to 413.59 and 376.94 mm compared to the full irrigation treatment, while the treatments (60, 50 and 40) % of the full irrigation were superior in that they saved an amount of water at the expense of low crop productivity. The highest water productivity was recorded at two irrigation treatments minus 80 and 70% for the Sorghum bicolorcrop. It amounted to 13.71 and 15.13 kg m3, as the lack of 20 and 30% of the irrigation water did not affect the productivity. It is recommended to irrigate at a rate of 80 and 70% of the total ETa, which indicates the possibility of providing 20 and 30% of the full irrigation needs without affecting the grain yield.

DETERMINATION OF WATER CONSUMPTION OF POTATO UNDER IRRIGATION SYSTEMS AND IRRIGATION INTERVALS BY USING POLYMERS AND BIO-FERTILIZERS IN DESERT SOILS

Two field experiments were conducted during the spring season 2020 in Karbala governorate, to study the effect of sprinkler and surface drip irrigation systems to determine water consumption of potatoes and irrigation intervals using polymers and bio-fertilizers in desert soils. The experiment included three factors: 1-Irrigation system surface drip T1 and sprinkler T2, 2- The Irrigation interval: every 2 days I1, 4 days I2 and 6 days I3, 3- Addition of soil conditioners: control without any addition C, bio-organic fertilizers (seek) B, polymer (zeba) P, and polymer+ bio-organic fertilizers P+B. The experiment was designed according to the nested design with three replicates. Potato tuber class (Hermosa) rank E was planted. The results showed that the operating pressure of 50-150 kPa was drip and sprinkler irrigation, respectively. Irrigation interval treatment I1 also obtained the lowest added water depth of 212.64 and 486.70 mm at the drip and sprinkler irrigation systems, respectively. Moreover, the actual consumptive use ETa values ​​for irrigation interval I1, I2, and I3 at drip irrigation were 276.44, 428.31, and 593.04 mm, respectively. Though at sprinkler irrigation were 550.50, 959.46, and 1385.08 mm for irrigation intervals I1, I2, and I3, respectively. The highest values ​​of crop coefficient at tuber formation and filling stage were 0.66, 0.79, 1.06, 1.86, 3.42, and 4.73 for the irrigation interval I1, I2, and I3, respectively, at the drip and sprinkler irrigation systems.

Sustainability of Agricultural Productivity of Potato Crop in Desert Soils and Evaluation of Water Productivity Under Drip Irrigation System with Future Climate Changes

A field experiment was conducted during the spring season 2020 in Karbala proving/ Al-Sharia Distrit, located at latitude N 32° 42' 13.8" and longitude E 43° 54' 36.6" and at an altitude of 27 m above sea level. The experiment included a study of two factors: the first, Irrigation Interval, three treatments were used: irrigation treatment every 2 days, Irrigation treatment every 4 days, and Irrigation treatment every 6 days. The second factor is the addition of soil conditioners, in which four treatments were used: the control treatment without any addition, the treatment of adding bio-organic fertilizers, the treatment of adding water-conserving technology (polymer), and the treatment of adding water-conserving technology + fertilizers Organic vitality. The experiment was designed according to the randomized complete block design (RCBD) with three replicates and under the split block design (split block design).It use the results of regional climate models to highlight how climate change affects the region through the AquaCrop model and repeat the same process for another regional climate model and another scenario to assess the impact using climate projections and analyzing the impact of climate change on water resources, the results were as follows: An increase in the amount of annual rainfall and monsoon rain during the two periods (2016-2035) and (2046-2065) under the RCP4.5 scenario, amounting to 17.00, 9.42, 11.91, and 9.06 mm. respectively compared to the base period (1985-2005) and its increase during the period (2016-2035) according to the RCP8.5 scenario amounted to 3.97 and 4.51 mm, with a slight decrease during the period (2046-2065) amounting to -3.78 and -2.57 mm, respectively, compared to base period. An increase in the maximum and minimum temperatures, according to the climate change scenario RCP4.5, amounted to 0.81, 0.75, 1.65, and 1.55°C, and the RCP8.5 scenario amounted to 1.1, 0.98, 2.33, and 2.14°C, as an average of the values of climate models. (EC-Earth, CNRM-CM5, GFDL-ESM2M) for the maximum and minimum temperatures, respectively, during the period (2016-2035) and (2046-2065), compared to the base periodd. There were no significant differences between the current productivity of the potato crop and the expected productivity using the AquaCrop model, so the value of R2 was 0.85 between the expected and measured data for productivity for twelve years under the surface drip irrigation system.The correlation coefficient (r) was 0.951, the root mean square error (RMSE) was 2.426, and the efficiency coefficient was 0.659 for the surface drip irrigation system.

Effect of Surface, Subsurface Drip Irrigation and Nanotechnology Perfusion Methods on Irrigation Efficiency and Saved Water Ratio in Plowed and Unplowed Soils

A field experiment was conducted in Al-Habbaniyah district / Al- Khalidiya district / Al-Anbar governorate, western Iraq, in Silty loam soil during the fall season 2020, to study the effect of surface and subsurface drip irrigation and perfusion irrigation with nanotechnology on irrigation efficiency, the amount of added water and the percentage of water saving in plowed and non-plowed soils. Perfusion was done when 50% of the prepared water was depleted. The treatments were distributed according to the Nested-Factorial Experiments Design (NFED) with three replications. The yellow corn, cultivar Euphrates, was planted on 2020/15/7. The American evaporation basin, type A, was used in the timing of irrigation. According to the rate of water consumption in terms of the equivalent depth of the added water, the total yield and the efficiency of water use. The results of the study showed the uniqueness of the drip irrigation system by giving the highest irrigation efficiency of 100% for the two plowing modes, while the surface drip irrigation system gave an irrigation efficiency of 83% in the uncultivated soil, and the lowest amount of water was added during the season, which amounted to 5215 m3. ha-1 in the nano-technology perfusion irrigation method with a savings rate of 29.97 and 13.19% compared with the surface drip irrigation method, while it reached 15.23 and 8% compared with the subsurface drip irrigation method in the plowed and non-plowed soils sequentially, the highest average total production was 11.7 tons of grain per hectare for the tillage and no-till treatment, and it decreased significantly to 7.5 tons ha-1 in the surface drip irrigation method, while the tillage treatments did not record significant differences in the short-term grain yield.

A global synthetic analysis of the effects of reclaimed water irrigation on crop yield and water use efficiency

Abstract To quantitatively evaluate the effect of RW irrigation on yield, WUE, and IWUE, and identify aqueous, edaphic, and management factors that favor improved yield, WUE, and IWUE compared to control practices, a meta-analysis was conducted. The results indicated that RW irrigation is beneficial for improving crop yields, WUE, and IWUE (16.8, 23.8, and 18.7%, respectively). However, its effectiveness is highly dependent on the aqueous, edaphic, and management factors of the studies evaluated. Greater responses were found in practices using RW with a pH < 7 or a nitrogen content <100 mg/L. The soils with a pH ≥ 7, electrical conductivity between 2 and 4 dS/m, bulk density <1.35 g/cm3, and/or initial nitrogen content between 200 and 2,000 mg/kg produced the highest effect size. Furthermore, using a surface drip irrigation system, with a nitrogen fertilizer rate <1,000 kg/ha and irrigation level at 100% crop evapotranspiration are effective ways to use RW. Our findings highlight the potential of RW irrigation to improve crop yield, WUE, and IWUE and identify the conditions under which these results can be achieved. These results can provide a better understanding of RW irrigation and guide the practice of RW utilization in the future.

AquaCrop Model Validation for Simulating Biomass and Water Productivity Under Climate Change for Potatoes

Effective crop development modelling is essential for crop management, water resource planning, assessing climate change's influence on agricultural production, and yield prediction. Validation and simulation of the measured data indicated that AquaCrop software is an effective and reliable program for designing pressurized irrigation systems to increase water application efficiency, system performance and the future prediction. The AquaCrop model was evaluated through a solid-set sprinkler and surface drip irrigation systems at 100%, 80%, and 60% of evapotranspiration (ETo) for the potato crop. The AquaCrop model has shown better performance to simulate potato growth and predicting crop variables under various water systems. The surface drip-irrigation system's at 80% of ETo (48.00, 8.05 ton ha-1) Yield had a substantial impact on the yield of potato and water productivity (WP), matching the yield of potatoes that was irrigated with solid-set sprinklers at 100% of ETo (37.39, 7.19 ton ha-1), with 20% water savings. Attributes of potatoes (canopy cover, biomass, potato crop factor (Kc), and water productivity) were affected by increasing water deficit. The simulated of AquaCrop model was a little higher than observed at 80% of ETo treatment, but still has a similar deviation, and it was slightly lower than seen for 60% of ETo treatment at the mid-season. The AquaCrop model predicted the yield of potatoes and biomass correctly when irrigation is adequate. The results indicated that there may be some changes in AquaCrop model simulation operations over future years based on the climate and irrigation method.

Evaluation of Surface Drip Irrigation Systems Focusing on Water-use Efficiency in High-value Vegetable Production in the Semi-arid, Windy Region of the Texas High Plains

Evaluation of Surface Drip Irrigation Systems Focusing on Water-use Efficiency in High-value Vegetable Production in the Semi-arid, Windy Region of the Texas High Plains

Development of an IoT-Based Precision Irrigation System for Tomato Production from Indoor Seedling Germination to Outdoor Field Production

Proper irrigation management, especially for tomatoes that are sensitive to water, is the key to ensuring sustainable tomato production. Using a low-cost sensor coupled with IoT technology could help to achieve precise control of the moisture content in the plant root-zone soil and apply water on demand with minimum human intervention. An IoT-based precision irrigation system was developed for growing Momotaro tomato seedlings inside a dark chamber. Four irrigation thresholds, 5%, 8%, 12%, and 15%, and two irrigation systems, surface and subsurface drip irrigation, were compared to assess which threshold and irrigation system referred the ideal tomato seedling growth. As a result, the 12% soil moisture threshold applied through the subsurface drip irrigation system significantly (p < 0.05) increased tomato seedling growth in soil composed of a main blend of peat moss, vermiculite, and perlite. Furthermore, in two repeated experiments, a subsurface drip irrigation system with 0.86 distribution uniformity used 10% less water than the surface drip irrigation system. The produced tomato seedlings were transplanted to open fields for further assessment. A low-power wide area networking Long Range Wide Area Network (LoRaWAN) protocol was developed with remote monitoring and controlling capability for irrigation management. Two irrigation systems, including surface and subsurface drip irrigations, were used to compare which system resulted in higher tomato yields. The results showed that the subsurface drip irrigation system with 0.74 distribution uniformity produced 1243 g/plant, while each plant produced 1061 g in the surface drip irrigation system treatment. The results also indicated that the LoRaWAN-based subsurface drip irrigation system was suitable under outdoor conditions with easy operation and robust controlling capability for tomato production.

Effect of Irrigation Systems, Bio-Fertilizers and Polymers on some Growth Characteristics and Potato Production in Desert Soils, Karbala Governorate

Two field experiments were conducted during the spring season 2020 in Karbala governorate to study the effect of irrigation systems, irrigation intervals, biofertilizers and polymers on some characteristics of vegetative growth and potato production. The results showed that there were significant differences in the values of the average plant height due to the effect of the double interference between the irrigation system and the improvers, The height of potato plant under any irrigation system was superior when adding conditioners compared to the control treatment, as it reached 48.56, 58.00 and 64.33cm when adding polymer, biofertilizer, and polymers+ biofertilizers, respectively compared with the control treatment of 44.64cm in the surface drip irrigation system. While it was 51.74, 58.19 and 64.67cm in the treatments of adding polymer, biofertilizers and polymers+ biofertilizers, respectively, compared with the control treatment 41.51cm under the sprinkler irrigation system, Also, there were significant differences in the values of average root lengths as a result of the effect of the double interference between the irrigation system and the improvers, as the potato root lengths under any irrigation system excelled when adding the improvers compared to the control treatment, It reached 36.29, 41.94 and 49.37cm when adding polymer, biofertilizers and polymers+ biofertilizers, respectively, compared with the control treatment 31.28cm at surface drip irrigation system. While it was 35.94, 40.69 and 48.14cm when adding polymer, biofertilizer, and polymers + biofertilizer, respectively, compared with the control treatment of 30.33cm at the sprinkler irrigation system, There were significant differences in the values of the total yield as a result of the effect of the double interference between the irrigation system and the conditioners, as the total yield of potato tubers under the two irrigation systems exceeded when adding the improvers compared to the control treatment, It reached 25.31, 28.86 and 36.90 μg ha-1 when adding polymer, biofertilizers and polymers + biofertilizers, respectively, compared with the control treatment 17.21 μg ha-1 at the surface drip irrigation system.

Effect of Surface and Subsurface Drip Irrigation and Furrows Irrigation System on Water Productivity, Growth and Yield of Lettuce (Lactuca Sativa L)

A field experiment was conducted in Al-Yusufiya district - Al-Mahmoudiya district, Baghdad province during the winter season 2021, to study improving the efficiency and management of water use and the productivity of lettuce under different irrigation systems. The Nested-Factorial Experiments design was used, where the main plots include the first factor, irrigation levels (I1) 50%, (I2) 75%, (I3) 100, (I4) 125%, (I5) 150% ETpan. After depleting 35% of the available water and in terms of climatic data from the American Evaporative Basin, Class A. Then the main factor is divided into three replicates, and the coefficients of the second factor are distributed randomly within each replicate, which includes the irrigation system: surface drip irrigation, a plant line drip line (S1) and a two plant line drip line (S2), The subsurface drip irrigation system is a plant-line drip line (SS1) and a two plant drip line (SS2) and furrows irrigation system (SI.) The results show that the highest field water use efficiency is 108.2 and 104.1 kg m-3 for the subsurface drip irrigation system (SS2) and (SS1) and at irrigation level I2. While the field water use efficiency of the surface drip irrigation system was 72.07 kg m-3 at the level of irrigation I3 for treatment (S1) and for treatment (S2) it reached 68.90 kg m-3 at the level of irrigation I4. As for irrigation in-furrow (SI), it reached 33.30 kg m-1 for irrigation level I2 and the highest yield was 286.2 Mg. ha-1 for I5SS2 treatment, and the lowest yield was 62.50 Mg. ha-1 for I1S1 treatment. The highest average head length and head circumference were 46.19 and 69.20 cm at I5SS1 treatment, respectively.

Productivity and profitability of drip fertigated wheat (Triticum aestivum) – mungbean (Vigna radiata) – maize (Zea mays) cropping system

An experiment was conducted at the research farm of ICAR-Indian Agricultural Research Institute, New Delhiduring 2019–20 and 2020–21 to study the productivity and economic viability of wheat (Triticum aestivum L.)–mungbean (Vigna radiata (L.) R. Wilczek)–maize (Zea mays L.) fertigated with 0, 60, 80, 100% recommended dosesof NPK and irrigated at 0.6 and 0.8 crop evapotranspiration (ETc) through subsurface (SSDI) and surface drip irrigation (SDI). The results were compared with the conventional practice of surface irrigation and soil application of 100% recommended doses of NPK. Grain yields of wheat, mungbean, maize and system wheat equivalent yield (SWEY) improved by 22.9, 7.2, 21.9 and 19.4%, respectively with increase in NPK fertigation doses from 60 to 100% and by 15.6, 9.2, 4.9 and 9.7% with the increase in irrigation frequency from 0.6 to 0.8 ETc. However, SDI and SSDI had equal system productivity (12.48 and 12.85 Mg/ha). The SWEY at 0.8ETc fertigated either with NPK80 or NPK100was statistically at par (14.2–15.9 Mg/ha) with the conventional practice (14.3–15.2 Mg/ha). The cash inflow, netincome and benefit cost ratio (BCR) of the cropping system also increased successively with increase in fertigationdoses and irrigation frequency. The net income and BCR followed the order maize>wheat>mungbean. The net income under SSDI at 0.8 ETc with NPK80 or NPK100 in wheat, mungbean, maize and system was 11–13, 88–105, 1-9 and 8–14% higher than the conventional practice. At 0.8 ETc and NPK100, BCR in SSDI (1.86) was higher than in SDI(1.71) and conventional system (1.67).

Assessing the Effects of Treated Wastewater Irrigation on Soil Physico-Chemical Properties

For assessing the effects of wastewater on soil physical and chemical properties, manual irrigation (MI) and surface drip irrigation (SDI) systems were investigated. The experiment was conducted over 12 months. Before and after the experiment, soil samples were collected from three depths (0–20 cm, 20–40 cm and 40–60 cm) for analysis. The obtained results indicated that wastewater application probably preserves soil quality by maintaining its pH-water values whatever the irrigation system used. This study suggested that nutrient input from wastewater promotes soil microbial activity and organic matter (OM) mineralization. In fact, at the soil depths of 0–20 cm and 20–40 cm, MI using treated wastewater (TWW) leads to decrease OM content. P input may justify treated wastewater fertilizing effect in the topsoil. Moreover, TWW fertilizing effect was demonstrated by increased potassium (K) amount in the two upper soil layers (0–20 cm and 20–40 cm) following SDI system. This last system may block metals (iron (Fe), copper (Cu), cobalt (Co) and selenium (Se)) translocation to plants and their accumulation in soil. In contrast, metal translocation was maintained by the MI system. The present data is encouraging to reuse TWW for agricultural purposes, especially for orchard irrigation.

Assessment of Various Uniformity Aspects under Surface Drip Irrigation System in Tomato

Background: Water in any form is the prime constitute of plant growth and development. Right amount of water applied at right time and in right quantity to any crop will helpful to get maximum yield potential of that crop. This is possible with surface drip irrigation method. Uniform application of water through emitters is the necessary aspect to avail benefits like higher water use efficiency of surface drip irrigation. Uniformity of surface drip irrigation system can be measured by various uniformity aspects viz., coefficient of variation (CV), distribution uniformity (DU), statistical uniformity (SU) and coefficient of uniformity (CU). Factors like land levelling, maintenance of drip lines, pressure management etc. plays a vital role in conserving the uniformity of outflow of emitters.
 Methodology: In this trial, all these uniformity aspects were measured using catch cane method at initial stage of drip irrigation system installation and on the basis of these dataset several improvements were made for better uniformity of emitter outflow at later planting stage.
 Results: Coefficient of uniformity (CU) of surface drip irrigation system was recorded 96.89% at initial stage and later on it was improved to 97.02% during the first experimental year whereas in second year it was noted 95.58% at initial stage and was improved to 96.80% at later stage.

EVALUATION OF THE AQUACROP MODEL PERFORMANCE AND THE IMPACT OF FUTURE CLIMATE CHANGES ON POTATO PRODUCTION UNDER DIFFERENT SOIL MANAGEMENT SYSTEMS

This study was aimed to investigate the effect of surface sprinkler and drip irrigation systems using a model AquaCrop, irrigation intervals, bio-organic fertilizers and polymers in desert soils. Two field experiments were conducted during the spring season 2020 at Karbala governorate. The experiment included three factors: 1-Irrigation system surface drip T1 and sprinkler T2, 2- The Irrigation interval: every 2 days I1, 4 days I2 and 6 days I3, 3- Addition of soil conditioners: control without any addition C, bio-organic fertilizers (seek) B, polymer (zeba) P, and polymer+ bio-organic fertilizers P+B. The experiment was designed according to the nested design with three replicates results of regional climate models and AquaCrop model. The results showed that there was an increase in the amount of annual precipitation and seasonal during the periods (2016-2035) and (2046-2065) under RCP4.5 scenario, compared to the base period (1985-2005). With an increase in the amount of annual precipitation and seasonal during the period at scenario RCP8.5 with a slight decrease during the period (2046-2065) compared to the base period. Moreover, an increase in the maximum and minimum temperatures according to scenario RCP4.5 and RCP8.5 scenario during the period (2016-2035) and (2046-2065) compared to the base period. The expected productivity using the AquaCrop, as R2 was 0.85 and 0.81 for twelve years, under surface drip irrigation systems and sprinkler, respectively. The correlation coefficient (r) was 0.95 and 0.90, the root means square error (RMSE) 2.43 and 2.19, and the efficiency coefficient 0.66 and 0.42 for the surface drip and sprinkler systems, respectively. Finally, the increase in water productivity and productivity in the scenario RCP4.5 and RCP8.5 for the treatment of BP and the irrigation interval I1and treatment C and the irrigation interval I3 when comparing the base period with the periods (2016-2035) and (2046-2065) For surface drip irrigation systems and sprinkler.

Assessing the availability of potassium and its quantity-intensity relations under long term conservation agriculture based cereal systems in North-West India

Potassium fertilization is often neglected and /or ignored leading to imbalanced fertilization under intensive cultivation especially in the Indo Gangetic Plains (IGP) in North-West India. Recently conservation agriculture (CA) with crop residue retention has become quite popular among the farmers and land practitioners in India and globally. Crop residues are generally rich in potassium (K) content and its continuous addition under CA may impact K dynamics and supply to crops to some extent. Keeping this in view, a field experiment was conducted to assess the effect of long-term cereal-based CA on K supplying capacity in soil of North-West India. Both routine method (neutral normal ammonium acetate extractable) and quantity-intensity (Q/I) approach were adopted to predict K supply under CA vis-à-vis conventional agriculture. Available K and Q/I parameters were analyzed after 11 years of an experimental setup consisting of six scenarios i.e. Scenario 1 (Sc1): conventional till rice-wheat cropping system; Scenario 2 (Sc2): partial CA based rice-wheat-mungbean system; Scenario 3 (Sc3): full CA based rice-wheat-mungbean system; Scenario 4 (Sc4): full CA based maize-wheat-mungbean system; Scenario 5 (Sc5) and 6 (Sc6): same as Sc3 and Sc4 but with sub surface drip irrigation system. Results revealed that full CA based scenarios maintained significantly higher (p < 0.05) available K (145 mg kg−1) than Sc1 (86 mg kg−1). However, it was observed that Q/I approach helped in better understanding of K supply under long term CA soils than routine method. Regarding K availability, Sc6 was the best scenario with high values of planar K (0.147 cmol kg−1), labile K (0.325 cmol kg−1) and potential buffering capacity (PBCK) while Sc1 (without K fertilization or residue addition) presented lowest values of Q/I parameters. Partial CA (Sc2) maintained higher labile K (0.368 cmol kg−1) and equilibrium concentration ratio (CRe0K) (1.93(mol L−1) 1/2 × 10−3) but very low PBCK (36.4 cmol kg−1 (mol L−1) −1/2) suggesting that K intensity shall not be sustained for long period of time and lead to soil K depletion over time. However, on an average, all full CA based scenarios maintained higher Q/I parameters over the conventional practice (Sc1), representing better ability to supply K both immediately and over a long period of time to meet crop requirement. The impact of maize-wheat-mungbean cropping system was prominently observed with respect to CRe0Kover rice-wheat-mungbean system; whereas the effect of irrigation method was not significantly distinguishable. The study thus highlights the potential of long term crop residue retention under CA for improving and maintaining K supply to crops.

Effect of Treated Wastewater from Anaerobic Digester Coupled with Anaerobic Baffled Reactor as Fertigation on Soil Nutrient Residues, Growth and Yield of Maize Plants

Water scarcity, wastewater management and growing food demand associated with global population increase, are among the drivers cited for water reuse in agriculture. The current study intends to contribute on the influence of treated wastewater from the anaerobic digester coupled with anaerobic baffled reactor (ABR) as a fertigation on soil nutrient residues, growth and yield attributes of maize plants by using surface drip irrigation system to apply the treated wastewater. The experiment consisted of experimental plots irrigated with treated wastewater and control plots irrigated with tap water; all with three replications. The treated wastewater was lightly alkaline with pH of 7.8±0.2 and high concentration of nutrients than tap water, but were within the acceptable levels. Fertigation with treated wastewater improved soil fertility evidenced by significant improvement (P≤0.05) in plant height, leaf area Index (LAI) and maize yield. Plant height was 1.5 times taller and LAI was about 2.5 times more in treatment than in control plots. Yield attributes in experimental plots including number of grains per cob, (97±11.3); weight of grains per cob, (80.7±7.9 g); mass of 100 grains, (35.0±3.5 g), and grain yield, (745.8±62.9 Kg/ha) were significantly higher (P≤0.05) compared to their counterpart control plots. The grain yield in experimental plots was about 37% higher than the yield in control plots. Therefore, fertigation with treated wastewater from the anaerobic digester coupled with ABR improves maize yield and is advisable in areas with water scarcity.

Evaluation of nitrate redistribution in surface and subsurface drip irrigation systems

Nitrogen compounds added to the soil may convert to nitrate and cause contamination. The distribution and uniformity of soil nitrate in surface vs. subsurface drip irrigation systems were compared in a physical model consisting of a transparent glass box (1.20 x 0.5 x 1 m) and sandy loam soil, and considering emitter installation depths of 0 and 30 cm, discharge rates of Q1 = 2, Q2 = 4, Q3 = 8 L/h, and fertilizer levels of S1 = 125, S2 = 250, S3 = 375 mg/L. Irrigation continued for 6 h and nitrate and moisture sampling was performed for 68 h after the initiation of water front advance. The result showed that doubling the discharge caused the wetted area to triple in size in the subsurface drip irrigation system whereas it only doubled in size in the surface drip irrigation system. Thus in the subsurface system, when increasing the fertilizer level, the nitrate spread out extensively and therefore its concentration was greatly reduced. Also, by increasing discharge, the difference in soil nitrate concentration between the two systems increases because of increasing non-uniformity of nitrate distribution in the surface system, such that by increasing the fertilizer concentration form 125 to 375 mg/L, the difference in nitrate concentration increases from 22% to 500% (for Q1 = 2 L/h), 43% to 352% (for Q2 = 4 L/h), and 14% to 166% (for Q3 = 8 L/h). Thus the subsurface drip irrigation system has a more uniform trend of nitrate distribution than the surface drip irrigation system. Also, treatment with maximum flow and fertilizer level will create the most optimal nitrate concentration in the soil.