Irrigated Agroecosystems Research Articles

Can soluble organic fertilizers and/or manure reach the agronomic and environmental performance of synthetic fertilizers in drip‐fertigated crops?

AbstractThe substitution of synthetics by organic fertilizers, which is the current pillar of circular economy, has been broadly evaluated. However, varying results were obtained on nitrous oxide (N2O) and nitric oxide (NO) emissions as well as crop yields. Besides, in irrigated semi‐arid croplands, drip fertigation has been suggested to be an effective practice for mitigating N2O and NO emissions while maintaining or enhancing agronomic performance. However, the promising combination of drip fertigation and organic fertilization remains poorly studied. By setting up melon (Cucumis melo L.) during 2022, and maize (Zea mays L.) during 2023, we aimed to evaluate the effect of different combinations of nitrogen (N) fertilizers: control without N fertilization, 100% of the N rate as solid manure (100OrM), 50% of the N rate as solid manure and 50% as urea (50OrM–50Syn), 50% of the N rate as solid manure and 50% as soluble organic (50OrM–50OrS), 100% of the N rate as urea (100Syn) and 100% of the N rate as soluble organic (100OrS). Urea and soluble organic fertilizers were supplied via drip fertigation. N‐oxides (N2O and NO), methane (CH4) and ecosystem respiration (CO2) fluxes, mineral N (ammonium [NH4+] and nitrate [NO3−]), dissolved organic carbon (DOC) and crop parameters were analysed. As regards N2O, no differences were observed between treatments in melon crop, whereas in maize crop, the cumulative emissions were the highest in 100OrM, followed by 50OrM–50Syn. Regarding NO cumulative emissions, in the melon crop were significantly lower in 50OrM–50Syn and 50OrM–50OrS between 34%–54%, compared with 100OrM and 100Syn. In the maize crop, the highest cumulative NO emission was also detected in solid manure treatment. The agronomic response of melon to N fertilization was only detected for total soluble solids (with maximum values in the 100Syn treatment). The combination of solid manure and top‐dressing urea or soluble organic fertilizer prevented the penalties in N use efficiency, which were observed in 100Syn and 100OrS. Therefore, the combination of conventional solid manure at seeding and soluble organic fertilizer at dressing (applied by drip fertigation) was the most sustainable strategy from agronomic and environmental viewpoints in Mediterranean irrigated agroecosystems.

The ratio of transpiration to evapotranspiration and water use efficiency in an irrigated oasis agroecosystem: Different temporal-scale effects

Agroecosystems play an important role in carbon sequestration and water consumption of global terrestrial ecosystems. However, the magnitude, pattern, and regulation of the ratio of transpiration to evapotranspiration (T/ET), and also water use efficiency at ecosystem (WUEe) and canopy (WUEc) scales, remain unclear in agroecosystems in arid areas. In this study, a six-year synchronous observation of water-carbon fluxes and sap flow by the eddy covariance and sap flow techniques was conducted in an irrigated vineyard in northwest China. We found that T/ET, WUEe, and WUEc changed dynamically at the daily (1.0–98.6%, 0.3–4.9 g C kg–1 H2O, 0.4–5.9 g C kg–1 H2O) and monthly (26.0–71.0%, 0.8–1.8 g C kg–1 H2O, 2.3–3.2 g C kg–1 H2O) scales. At the annual scale, the range was relatively narrow, with mean values of 61.7% ± 3.7%, 1.5 ± 0.1 g C kg–1 H2O, and 2.4 ± 0.3 g C kg–1 H2O, respectively (mean ± standard deviation). Biological and environmental factors regulated their dynamics on different temporal scales. Specifically, leaf area index (LAI) and canopy conductance (gc) mainly determined the seasonal variation of T/ET, WUEe, and WUEc at the daily and monthly scales. However, at the annual scale, vapor pressure deficit (VPD) and air temperature (Ta) became the main influencing factors. These results highlight the complexity of water-carbon coupling in agroecosystems and the necessity of considering specific factors at different temporal scales when modeling and managing agricultural water resources. In addition, there is still great water-saving potential from the perspective of WUE in the cultivation of vines in Northwest China.

Fusarium wilt of some shallot local varieties in Yogyakarta alternating-bed (surjan) agroecosystem

Abstract Leaf twisted is one of the dominant diseases in shallot that is caused by Fusarium oxysporum f.sp. cepae. Rain intensity and air humidity due to climate change affect the severity of disease and become an essential factor for high yield loss. Alternating-bed system (surjan) is one land arrangement to cultivate multiple commodities in an irrigated rice agroecosystem. It is implemented by farmers in Yogyakarta. However, it relates to climate conditions. Research about tolerant or moderately resistant shallot varieties against leaf twisted disease in alternating-bed systems is very beneficial for farmers to increase yield. This research aims to determine the potential local shallot variety which is moderately resistant and tolerant against leaf twisted and provides high yield. The research was conducted at the alternating-bed system in Kulon Progo District, Yogyakarta Indonesia from August to September 2022. The experiment was designed in randomized blocks with five replications. Shallot varieties such as Siyem, Srikayang, Crok Kuning, and Tajuk were used in this experiment. Results showed that disease severity in Tajuk, Srikayang, Siyem, and Crok Kuning was 7.60%, 9.60%, 19.60%, and 14.00%, respectively. Disease incidence of Tajuk, Srikayang, Siyem, and Crok Kuning were 0.56%, 0.83%, 1.81%, and 1.25%, respectively. The yields of Tajuk, Srikayang, Siyem, and Crok Kuning were 7.34, 6.27, 5.31, and 7.04 tons per ha, respectively. Siyem and Crok Kuning were categorized as moderately resistant, while Srikayang and Tajuk were tolerant. All four varieties are potentially developed at alternating-bed systems in Yogyakarta.

Insect Diversity of Some Hybrid Rice Genotypes in Sleman-Yogyakarta Irrigated Agroecosystem

Diversity of insect at the rice field gives a main impact to the stability of ecosystem. Index of diversity reflects the relationship of species abundance in the community. This research was aimed to determine the diversity of insect at some hybrid rice varieties in irrigated rice agroecosystem. Research was conducted in Sleman, Yogyakarta Indonesia from April to August 2018. The experiment was conducted using purposive random sampling. Insect samples were obtained using swing net and visual observation. Diversity index was analysed using Shanon (H), while diversity and uniformity of insect was examined using Evennes index (E). Result showed pest insects found during vegetative stage of rice consist of more species, while lower numbers were found at generative stage with less species. They were belongs to 6 orders (more than 10 families) such as Diptera, Lepidoptera, Coleoptera, Orthoptera, Hemiptera and Hymenoptera. The dominant pest was Cicadellidae, followed by Delphacidae and Alydidae. Based on the diversity data analysis (H), pest insects and natural enemies were between moderate and high, with a range between 1.5 to 2.5. It indicates the rice field ecosystem planted with hybrid rice gave good impact and balance species diversity in the agroecosystem of irrigated rice area in Sleman Yogyakarta.

Measurement strategies to account for the temporal variation in soil-respired CO2 and its δ13C value in an irrigated oasis agroecosystem

Soil respiration is an important ecosystem process and fluctuates daily and seasonally with abiotic and biotic factors, inevitably leading to uncertainty in the estimation of daily, monthly or seasonal means from short-term measurements. The measurement strategies are poorly understood and are commonly analyzed using noncontinuous measurements. The objectives of this study were to evaluate the optimum measurement time and frequency of soil-respired CO2 (Rs) and its δ13C (δs) value, as well as soil temperature (ST) and soil water content (SWC) during the growing season. To provide more refined recommendations, we performed long-term continuous measurements of Rs and δs value with a multichannel and dual-cycle observation system under non-steady-state conditions in an irrigated oasis agroecosystem in Northwest China. The daily optimum measurement time of Rs was 9:00–10:00, which accounted for 89.0% of the total measurement days and was within the previously recommended time scale of 9:00–12:00. δs showed little diurnal variation, and each hourly mean approximately represented the daily mean. The Rs and δs measured at 9:00–11:00 did not significantly differ from the daily mean, yet the soil temperature (ST) and soil water content (SWC) measured at 9:00–11:00 were lower than the daily mean values. The number of days needed to obtain values ±10% for Rs, δs, ST and SWC was 101, 23, 13, and 25, respectively (95% confidence interval (CI)), which sharply decreased to 11, 3, 1, and 3 days, respectively (95% CI), when the desired accuracy expanded to ±30% for Rs, δs, ST and SWC in the growing season. That means the measurement interval of Rs and δs were about is 14 days and 53 days during the growing season in agroecosystems (95% CI, ±30% mean). Overall, this study analyzed the optimum measurement times for Rs and δs at daily, monthly and seasonal time scales and provided guidelines for improving measurement frequencies under noncontinuous measurements.

Influence of weed management practices on direct-seeded rice grown under rainfed and irrigated agroecosystems

Rice seedlings and weeds emerge concurrently in direct-seeded rice (DSR) production systems, while there is no flooding water to inhibit weed germination, emergence and development at crop emergence. Because of this, weeds are considered the biggest living barrier in DSR and significantly reduce yield. The purpose of the research was to devise an approach for management of weeds in the direct-seeded rice crop cultivated under various agroecosystems, while optimizing growth and production utilizing herbicides or herbicidal combinations. The impacts of several weed management techniques were assessed to determine the most efficient and cost-effective approach of managing weeds in DSR at the CoA, JNKVV, Jabalpur (MP) during 2019 rainy season under spilt plot design with 2 main plot treatments viz., rainfed agroecosystem, irrigated agroecosystem and 8 sub-plot treatments, i.e. different herbicide treatments with hand weeding and weedy check. Further growth parameters as well as yield attributes were documented. Conventional statistical techniques were used to evaluate the data. Bispyribac sodium at the dose of 25 g/ha efficiently controlled both narrow and broad leaved weeds under agroecosystems. Highest growth as well as yield parameters were recorded for irrigated agroecosystems compared to rainfed agroecosystems. The treatment with bispyribac sodium at the dose of 25 g/ha produced the greatest values for growth and yield indices as well as the maximum yield (3.68 t/ha), with the exception of manual weeding.

Summer Mung (Vigna radiata L.) Promotion by Cluster Front Line Demonstration in Irrigated Agro-Ecosystem: A Case Study

Background: The marginalization of pulse crops in irrigated agro-ecosystem has been among the most negative facets of green revolution technologies. Integration of summer mung in the irrigated agro-ecosystems within rice-wheat and alternate systems is feasible and remunerative. This crop facilitates the crop intensification by adding a third crop to the crop sequence and there is a large area to intervene. This crop holds the key to increase the income of the farmers and to achieve self-sufficiency in pulse production. Methods: This study was carried out at farmers’ fields under irrigated farming situations during the period from 2017 to 2022 using cluster frontline demonstration (CFLD) as farmer participatory intervention. In total 425 demonstrations were conducted within rice-wheat and alternate systems on an area of 170 ha, covering 18 villages and 425 farmers. By comparing farmers’ practices in local checks with suggested technologies in demonstrations, a gap analysis was carried out and data on various technical and economic factors were recorded. Result: The CFLD programme mitigated the gaps and increased the adoption of summer mung from 4 per cent of the farmers in 2017 to 22 per cent in 2022. The yield increase in a demonstration over local check was by 17.6 per cent with favourable economics generating net additional returns of Rs. 5488 ha-1. The extension gap, technology gap and technology index recorded in the study were 1.44 q ha-1, 5.48 q ha-1 and 36.53 per cent. The market price was less than the minimum support price (MSP) in all the years of study. The summer mung intensifies the cropping systems as a third crop and its cultivation is remunerative and climate resilient.

Increasing Legume Input through Interseeding Cover Crops: Soil and Crop Response as Affected by Tillage System

Legumes provide important benefits in rotations. Interseeding cover crops (CCs) allows an additional legume CC in case of a short window after the main crop. However, legume input level and management could modify the expected benefits. In a Mediterranean irrigated agroecosystem, we evaluated the responses of topsoil (0–10 cm) and early maize development to increasing legume CC input in a biannual maize–wheat rotation under traditional tillage (TT; CC incorporated) and minimum tillage (MT; CC rolled-crimped). In the third year, at two early maize stages, we tested three legume input levels: (i) R0, non-CC; (ii) R1, barley–vetch CC; (iii) R2, vetch interseeded into maize in addition to the CC mixture. Overall, MT enhanced soil properties, but frequently conditioned to legume input level. The tillage system affected R1 the most, with MTR1 showing the better overall soil response while TTR0 showed the poorest. MTR2 was the best combination for early maize development, but not for soil health. Moreover, a better overall soil health did not lead to a better early maize performance in the short term. In this alkaline soil, CC favored early maize growth, whereas mycorrhization, enhanced under TT, favored crop nutrition. Increased legume input under MT should be monitored to avoid negative effects in soil in the mid–long term.

Population Dynamic of Brown Plant Hopper, Predators and Neutral Insects in Irrigated Rice of Yogyakarta after Insecticides Application

Brown Plant Hopper (BPH) infestation in irrigated rice agroecosystem resulted yield loss. The application of insecticides by farmers are usually excessive, reducing pest population and negatively affecting the predators. This research aimed to define the impact of insecticides on the population dynamic of BPH, predator and neutral insects which influenced rice yield. Research was conducted at Yogyakarta, Indonesia, during May to September 2021. Randomized Block using four replications was applied. Rice varieties Inpari 32 HDB and Inpari 42 GSR were planted. Insecticide with active ingredient spinetoram 120 g/l and triflumezopyrim 106 g/l were applied to the rice plant on day 40th then pimetrozin 50% was applied at day 50th. Results showed that BPH population was reduced from 30-50 nymph per 30 plants to 10 nymph at day 12th after pimetrozin 50% application or at the day 2nd after spinetoram and triflumezopyrim insecticides application until day 50th. In contrast, BPH population in all insecticide plants was significantly lower than in all control and did not increase until harvest. On the other side, predators such as Paederus sp and Coccinelids were not affected by all insecticides, except Ophionea sp, Spiders and Cythorinus sp. However, their population recovered at day 30th after first insecticides application. Within the fluctuated population of BPH, rice productivity of Inpari 32 HDB and Inpari 42 GSR applied with insecticides were 9.52 ton ha-1 and 10.60 ton ha-1, while Inpari 32 HDB control and Inpari 42 GSR control 9.44 ton ha-1 and 10.72 ton ha-1

Effects of climate variability and aridity index on wheat yield in contrasting environments of Iran

Climate change is one of the challenges that humanity is facing and can have different effects on agricultural production. The effect of climate change is mainly related to the three factors namely increasing carbon dioxide concentration, rising temperature, and changing rainfall patterns. The present study investigated the relationship between grain yield of rainfed and irrigated wheat (Triticum aestivum L.) with climatic variables including minimum and maximum temperature and rainfall in different counties of Tehran, Alborz, Golestan, Kermanshah, and Fars provinces. The drought index (AI) was also calculated to quantify the drought phenomenon. Also, the relationship between drought index and grain yield of rainfed and irrigated wheat was calculated in annual and seasonal dimensions. The results showed that Gorgan (2306.8 kg ha−1) and Larestan (559.3 kg ha−1) have a higher and lower potential for rainfed wheat production compared with other studied areas, respectively. Also, based on the results of the drought index, the climate of Lamerd, Larestan, and Ravansar counties has become drier in the period 1995–2015 and the climate of Karaj has become wetter. The results showed that winter compared with other seasons had the highest drought trend during the studied years. The relationship between rainfed wheat yield and climatic variables in seasonal scale showed that temperature and rainfall in winter and spring had a greater effect on rainfed wheat grain yield in the study areas than other seasons. The relationship between AI and rainfed wheat grain yield showed that areas such as Gorgan, Karaj, and Larestan with increasing drought index value, rainfed wheat grain yield increased. Unlike rainfed wheat, Marvdasht county had the highest potential for irrigated wheat production compared with other areas with the averages of 4481 kg ha−1, while Lamerd had yield of less than 2.7 tons ha−1. The correlation between grain yield and climate variables on seasonal scale showed that the role of temperature was greater than rainfall in irrigated wheat agro-ecosystems. Also, significant correlations between yield and temperature were more in winter and spring seasons than in summer and fall seasons.

Assessment and mechanism analysis of plant salt tolerance regulates soil moisture dynamics and controls root zone salinity and sodicity in seasonally irrigated agroecosystems

Soil water deficit and saline-alkaline stress impose severe constrains to agriculture and vary across different salt-tolerant crops. Yet, the effects and mechanisms of plant salt tolerance on long-term soil water budget and future root zone (both primary and secondary) salinization and alkalization trends under changing environments in irrigated agroecosystems have not been fully understood, particularly driven by seasonal irrigation practices and stochastic climate conditions. Here, we introduce a robust species-dependent soil water, salinity, and sodicity coupled model that enables explicitly simulation to the feedback between evapotranspiration and salinity being shaped by plant salt tolerance and saturated hydraulic conductivity as affected by salinization and alkalization in seasonally irrigated agroecosystems. Using this model in conjunction with field comprehensive measurements from a typical arid inland river basin in Northwest China, we find that the species-dependent model performed well in simulating the root zone moisture (s), salinity (Cs) and sodicity (Ex) dynamics as driven by seasonal irrigation and random precipitation under different salt-tolerant crops, with average consistency measure (CM) reaching to 0.825 ± 0.017, 0.819 ± 0.027 and 0.728 ± 0.033, respectively. Stochastic simulations indicate that plant salt tolerance plays a predominant role in regulating the feedback of vegetation on soil water budget and root zone salinity and sodicity levels over time in seasonally irrigated agroecosystems. In contrast to salt-sensitive species, salt-tolerant plants seems to exhibit higher efficiency in water extraction from soil, with higher evapotranspiration rates, less frequent leaching events and greater capillary upflow fluxes, thereby lowering soil moisture and boosting salinization and alkalization in the root zone, particularly in arid climates. Sensitivity analysis revealed that plant salt tolerance, together with climatic forcing and anthropogenic perturbations, can significantly modulate the soil water balance and determine the possible trends of root zone salinization and alkalization in future, thus controlling potential risks of soil degradation related to reducing soil hydraulic conductivity Ks(Cs, Ex) in irrigated agroecosystems. Notably, since Ks(Cs, Ex) decreases with plant salt tolerance increases, salt-resilient species have the potential to exacerbate soil degradation. Our results emphasize the importance of comprehensively considering plant salt tolerance for assessing the sustainability of agricultural management practices and environmental protection measures, as well as proposing adaptive strategies under global changes.

Agricultural practices influence biological soil quality indicators in an irrigated semiarid agro-ecosystem

A study was conducted to investigate how soil biological measurements can be used to indicate differences in soil quality in arid and semiarid agroecosystems. The objectives were to assess soil biological quality indicators under different land management practices and at different depths and to explore the relationships between soil microbial community and organic matter fractions. Soil samples were collected from three replicates of six land management systems at 0–5 cm and 5–15 cm soil depths. Four management systems had medium to fine soil texture including a permanent grass field with tall fescue (Lolium arundinaceum [Schreb]; TFC), peach orchard with clover understory (Prunus persica with Trifolium repens L.; PCC), alfalfa field (Medicago sativa; ALF) and conventionally tilled soil with an annual crop rotation (CTC). Two management systems, including a young cottonwood tree orchard (Populus fremontii and Populus deltoides; CWS) and conventionally tilled soil in annual crop rotation (CTS), had coarse soil texture. Management systems had significant impacts on most of the soil biological indicators assessed at the two depths with both depths responding similarly to management practices. For the soil biological indicators that showed differences, the TFC generally had the most favorable indicator measurements compared to other management systems. The principal component analysis showed a clear separation between the management systems and microbial communities at both soil depths. The ordination pattern was structured by soil textural differences between medium to fine-textured soils from TFC, PCC, ALF, and CTC fields and coarse-textured soils (CWS, CTS). Spearman’s correlation coefficients (rs) showed that the soil organic matter (rs = 0.85, P = 0.001) and the permanganate oxidizable carbon (rs = 0.93, P = 0.001) were significantly correlated with the total microbial biomass at 0–5 cm soil depth. Also, the soil organic matter (rs = 0.84, P = 0.001) was significantly correlated with the total microbial biomass at 5–15 cm soil depth. This study suggests that in semiarid agroecosystems, management practices with permanent covers have the potential to improve soil quality, and soil texture may also influence the directional changes in soil quality within this region.

Fall-sown small grain cover crops for weed suppression and soil moisture management in an irrigated organic agroecosystem

Abstract Adoption of cover crops in arid agroecosystems has been slow due to concerns regarding limited water resources and possible soil moisture depletion. In irrigated organic systems, potential ecosystem services from cover crops also must be considered in light of the concerns for water conservation. A constructive balance could be achieved with fall-sown small grain cover crops; however, their impacts on irrigated organic systems are poorly understood. Our first objective was to determine the ability of fall-sown small grains [cereal rye (Secale cereale L), winter wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and oat (Avena sativa L.)] to suppress winter weeds in an irrigated, organic transition field in the southwestern USA. Small grains were planted following the legume sesbania (Sesbania exaltata (Raf.) Rydb. ex A.W. Hill) during Fall 2012 and Fall 2013. In Spring 2013 and 2014, weed densities and biomass were determined within each cover crop treatment and compared against unplanted controls. Results indicated that both barley and oat were effective in suppressing winter weeds. Our second objective was to compare weed suppression and soil moisture levels among seven barley varieties developed in the western United States. Barley varieties (‘Arivat’, ‘Hayes Beardless’, ‘P919’, ‘Robust’, ‘UC603’, ‘UC937’, ‘Washford Beardless’) were fall-sown in replicated strip plots in Fall 2016. Weed densities were measured in Spring 2017 and volumetric soil moisture near the soil surface (5.1 cm depth) was measured at time intervals beginning in December 2016 and ending in March 2017. With the exception of ‘UC937’, barley varieties caused marked reductions in weed density in comparison with the unplanted control. Soil moisture content for the unplanted control was consistently lower than soil moisture contents for barley plots. Barley variety did not influence volumetric soil moisture. During the 2017–2018 growing season, we re-examined three barley varieties considered most amenable to the cropping system requirements (‘Robust’, ‘UC603’, ‘P919’), and these varieties were again found to support few weeds (≤ 5.0 weeds m−2). We conclude that several organically certified barley varieties could fill the need for a ‘non-thirsty’ cover crop that suppresses winter weeds in irrigated organic systems in the southwestern United States.

Perspective of increasing value added of waste in integrated rice-livestock system on irrigated land agroecosystem

The farmers’ welfare has still the main milestone in agricultural development. Farmers are faced with a lack of access to productive assets that are managed as a source of income. The knowledge and technology owned by farmers in order to manage limited resources of farms and anticipate climate change are also still limited, causing a problem in increasing productivity, low efficiency, and added value of farming. Meanwhile, abundant plant and livestock waste have not been utilized optimally. This study aimed to determine the perspective of increasing the added value of plant and livestock waste as a bio-industrial farming system based on rice-livestock integration in irrigated land agroecosystems. The research was conducted in Setanggor Village, West Praya District, Central Lombok Regency, West Nusa Tenggara from 2015-2020. The results of the study indicate that the processing of livestock waste into organic fertilizer has become a new source of income for farmers and workers and contributes to increasing household income to meet the minimum necessities of life. The use of organic fertilizer from livestock waste for 1-2 t ha-1 in rice farming can increase productivity by an average of 13.11% and farm efficiency by an average of 9.25%, providing additional income to farmers cooperator compared to noncooperator farmers by about IDR.3.638.360 ha-1 (23.73%). The processing and utilization of straw waste into animal feed can overcome the scarcity of feed in the dry season and provide daily weight gain of 0.58-0.69 kg. day-1. The development of a bio-industry farming system based on rice-livestock integration in an irrigated agroecosystem can increase farmers’ income in a sustainable manner.

STUDY OF SURFACE CH4 FLUX EMISSION FROM GOSAT SATELLITE DATA OVER SELECTED AGRO-ECOSYSTEMS IN INDIA

The present study was carried out to characterize and quantify the seasonal behaviour of surface CH4 emissions from L4A product over two selected irrigated agro-ecosystems in India over sub-humid region of Indo-Gangetic Plain (IGP) and semi-arid region of Gujarat Plain and Hills Region (GPHR). Satellite data of Greenhouse Gases Observing SATllite (GOSAT) with L4A data product has been used with a cluster of contiguous grids of 3 x 3 within the Region of Interest (ROI) representing agricultural land uses spread over trans, upper, middle and lower part of IGP for analysis. The seasonal behaviour was studied for three agricultural years of June 2009 to May 2012 through time series plots of monthly means of each ROI. The annual CH4 emission from agricultural region using GOSAT data was found to be about 8-9 Mt CH4 which was about three times higher than reported over rice system in India using sparse ground samplings. The IGP showed the highest annual mean (88.11 mg CH4 d-1m-2) of surface emission in Lower Gangetic Plain Region (LGPR) and the lowest annual mean (7.01 mg CH4 d-1m-2) in Trans-Gangetic Plain Region (TGPR). These sub-humid irrigated agricultural regions with rice-wheat rotation showed substantially higher emissions than those in semi-arid irrigated agriculture (10.38 mg CH4 d-1m-2 to 11.32 mg CH4 d-1m-2) in GPHR. In IGP for an agricultural growing year (June 2009 to May 2010), the mean of CH4 emissions for kharif (June to October) season showed higher emission flux with 51.04 mg CH4 d-1m-2 than in rabi (November to April) Season (14.31 mg CH4 d-1m-2), but coefficient of variation was found to be more in rabi season (77.8%) than in kharif (39.3%) season. In GPHR region for same year, the annual mean of CH4 emissions for kharif and rabi season were 14.26 mgCH4 d-1m-2 and 7.03 mg CH4 d-1m-2, respectively but the coefficient of variation (CV) during kharif are more (30.37%) than in rabi (29.29%).

Spatiotemporal Patterns and Key Driving Factors of Soil Salinity in Dry and Wet Years in an Arid Agricultural Area with Shallow Groundwater Table

Soil salinization is a major eco-environmental problem in irrigated agro-ecosystems. Understanding regional soil salinity spatial patterns and seasonal dynamics and their driving factors under changing environments is beneficial to managing soil salinity to maintain agricultural production in arid agricultural areas. To better investigate this topic, soil salinity was measured, ranging from topsoil to the depth of 1.8 m in an irrigation district with 68 sampling sites before and after the crop growing seasons of the dry year of 2017 and wet year of 2018. Soil texture, groundwater table depth, groundwater salinity, and crop type were monitored. The results indicated that an increase in soil salinity in the root zone (0–0.6 m) was accompanied by a decrease in soil salinity in the deep soil (0.6–1.8 m) through the crop growing season due to water movement from the deep layer to shallow layer, whereas the opposite trend was observed during the fallow seasons. During the dry year, the area with soil desalted was measured to be 19.89%, 14.42%, and 2.78% lower at depths of 0–0.6 m, 0.6–1.2 m, and 1.2–1.8 m than that during the wet year. The groundwater table depth in the crop growing season had the least impact on the change in root zone soil salinity (p > 0.05). Interactions between crop types and groundwater table depth had a significant effect on the change of soil salinity in the root zone during the growing season of the dry year, but were insignificant during the wet year. Crop types, groundwater table depth, and climate conditions determined the contribution of shallow groundwater to crop water consumption and, to a greater extent, soil salinity. Regression tree analysis showed that groundwater salinity and soil texture had a greater influence on soil salinity than groundwater table depth and land elevation. The effect of groundwater on soil salinity is strongly related to soil texture, and the salinity of fine-textured soil was 36–54% greater than that of coarse-textured soil due to large capillary action. Therefore, we suggest strengthening groundwater management in areas with fine-textured soil to relieve soil salinization, particularly during dry years.

Automated real-time irrigation analytics inform diversity in regional irrigator behavior and water withdrawal and use characteristics

Effective agricultural water management requires accurate, continuous, and transparent accounting of water use in irrigated agroecosystems, especially in water-limited regions where moratoriums may be imposed. Advances in sensor technologies, networking, and data analytics can aid in fulfilling this task by automatically collecting, analyzing and reporting real-time data to infer irrigators’ practices and behaviors, crop water requirements, water applications and use. In this research, an automated irrigation water withdrawal and water use monitoring and data collection system was deployed to monitor actual irrigation dynamics for 31 commercial and large-scale agricultural production fields for three consecutive years. Production scale fields (representing a total of 1050 ha) included center pivot (P), gravity (surface/furrow) (G) and subsurface drip-irrigated (S) fields. On average, irrigation was initiated 40–70 days after planting (DAP) and terminated by 120–140 DAP. The proportion of irrigation systems operating simultaneously and peak water abstraction were highest (70–90 %) during July and August. Mean depth of water applied across all fields was 243, 264 and 284 mm in 2013, 2014 and 2015, respectively. Site-specific monitoring of precipitation, soil moisture, and evaporative demand and a soil-water balance model resulted in mean seasonal irrigation requirement estimates of 394, 242 and 184 mm, in 2013, 2014 and 2015, respectively; for maize; and 307, 163 and 219 mm in 2013, 2014 and 2015, respectively, for soybean. Despite reduction of calculated mean irrigation requirement in 2014 and 2015 by 40–50 %, actual irrigation applications by producers did not change considerably and irrigation applied exceeded irrigation water requirements in 80 % of the fields, suggesting needs for irrigation water management technology implementation and associated educational programs in the region. Some fields showed irrigation applications exceeding the mean annual allocated (moratorium) irrigation depth (305 mm), implying that irrigation decisions are still largely driven by non-scientific and/or technical methods. While substantial farm-to-farm heterogeneity makes it challenging to robustly benchmarking regional water footprint and irrigator behavior, it also creates an opportunity for developing and implementing methodologies and strategies for real-time monitoring of farm-level irrigation dynamics. New advances in technologies with telemetry capabilities as well as internet of things (IoTs) can be leveraged to effectively create databases, track and compare water usage to better plan, allocate, distribute, monitor and manage limited water resources for enhancing agricultural productivity. These processes can also be used for education and demonstration for irrigation professionals to enhance adoption of such technologies. This research has the potential for technology and strategy transfer for advanced water management to other regions in the United States and globally.

Drones for Area-Wide Larval Source Management of Malaria Mosquitoes

Given the stagnating progress in the fight against malaria, there is an urgent need for area-wide integrated vector management strategies to complement existing intra-domiciliary tools, i.e., insecticide-treated bednets and indoor residual spraying. In this study, we describe a pilot trial using drones for aerial application of Aquatain Mosquito Formulation (AMF), a monomolecular surface film with larvicidal activity, against the African malaria mosquito Anopheles arabiensis in an irrigated rice agro-ecosystem in Unguja island, Zanzibar, Tanzania. Nine rice paddies were randomly assigned to three treatments: (a) control (drone spraying with water only), (b) drone spraying with 1 mL/m2, or (c) drone spraying with 5 mL/m2 of AMF. Compared to control paddies, AMF treatments resulted in highly significant (p < 0.001) reductions in the number of larvae and pupae and >90% fewer emerging adults. The residual effect of AMF treatment lasted for a minimum of 5 weeks post-treatment, with reductions in larval densities reaching 94.7% in week 5 and 99.4% in week 4 for the 1 and 5 mL/m2 AMF treatments, respectively. These results merit a review of the WHO policy regarding larval source management (LSM), which primarily recommends its use in urban environments with ‘few, fixed, and findable’ breeding sites. Unmanned aerial vehicles (UAVs) can rapidly treat many permanent, temporary, or transient mosquito breeding sites over large areas at low cost, thereby significantly enhancing the role of LSM in contemporary malaria control and elimination efforts.

An Exploratory Study on Document the Major Income Risk Encountered by the Small and Marginal Farmers in Irrigated Agro-Ecosystem of Tamil Nadu

The study proposes to assess the major risks encountered by the small and marginal farmers in the irrigated agro-ecosystem of Tamil Nadu with help of a risk matrix. A total of 240 respondents were selected for this study which consists of 80 small and marginal farmers each from three districts representing three irrigation systems viz., tank irrigation (Sivagangai district), cannel irrigation (Thiruvarur district) and well irrigation (Namakkal district) respectively. There are 34 risks identified in these irrigation systems, out of which 20 risks were found to be plotted between catastrophic to critical categories. In that, five risks viz., delay in the release of water in cannel/tank and water scarcity, lower than the cost of production, insufficient revenues to cover farm operational expenses, less insurance claim/coverage and late disbursement of loan from cooperative society were assessed as the catastrophic risks encountered by the small and marginal farmers in the irrigated agro-ecosystem of Tamil Nadu. This research study helps the policy-makers to utilize the above said findings and to develop the risk management strategies for the major risk faced by the small and marginal farmers in irrigated agro-ecosystem of Tamil Nadu.

Carbon Storage Potential of Agroforestry System near Brick Kilns in Irrigated Agro-Ecosystem

The current study was conducted to estimate the carbon (C) storage status of agroforestry systems, via a non-destructive strategy. A total of 75 plots (0.405 ha each) were selected by adopting a lottery method of random sampling for C stock estimations for soil, trees and crops in the Mandi-Bahauddin district, Punjab, Pakistan. Results revealed that the existing number of trees in selected farm plots varied from 25 to 30 trees/ha. Total mean tree carbon stock ranged from 9.97 to 133 Mg C ha−1, between 5–10 km away from the brick kilns in the study area. The decreasing order in terms of carbon storage potential of trees was Eucalyptus camaldulensis > Syzygium cumin > Popolus ciliata > Acacia nilotica > Ziziphus manritiana > Citrus sinensis > Azadirachtta Indica > Delbergia sisso > Bambusa vulgaris > Melia azadarach > Morus alba. Average soil carbon pools ranged from 10.3–12.5 Mg C ha−1 in the study area. Meanwhile, maximum C stock for wheat (2.08 × 106 Mg C) and rice (1.97 × 106 Mg C) was recorded in the cultivated area of Tehsil Mandi-Bahauddin. The entire ecosystem of the study area had an estimated woody vegetation carbon stock of 68.5 Mg C ha−1 and a soil carbon stock of 10.7 Mg C ha−1. These results highlight that climate-smart agriculture has great potential to lock up more carbon and help in the reduction of CO2 emissions to the atmosphere, and can be further used in planning policies for executing tree planting agendas on cultivated lands and for planning future carbon sequestration ventures in Pakistan.