Water Irrigation Area Research Articles

Effects of Combined Application of Organic Fertilizer on the Growth and Yield of Pakchoi under Different Irrigation Water Types

The long-term utilization of inorganic fertilizers in pakchoi cultivation can result in increased nitrate levels, potentially posing health risks to human consumers. For this study, we investigated the efficacy of organic fertilizers as a promising alternative for enhancing soil structure, improving fertility, and increasing the yield of pakchoi. A two-year field trial was conducted from 2022 to 2023 to examine the effects of the combined application of organic fertilizer on the growth and yield of pakchoi. Three types of irrigation water, namely fresh water (F), brackish water (B), and magnetized–ionized brackish water (MIB), were used in combination with five different organic fertilizer rates (0, 20, 40, 60, and 80 kg/ha, denoted as 0, 1, 2, 3, and 4). The results revealed that treatments F2, F3, B2, B3, and MIB3 significantly improved the growth indexes of pakchoi. Notably, treatments F3, B3, and MIB3 resulted in an earlier onset of the fast growth period for leaf area index and fresh weight. During this period, we observed the highest cumulative growing degree days (ΔCGDD) values, which were 628.36 °C for plant height (MIB4), 475.01 °C for leaf area index (B3), 259.73 °C for fresh weight (B3), and 416.82 °C for dry matter accumulation (B3). The logistic model indicated an increase in eigenvalue at an organic fertilizer application rate of 60 kg/ha, while excessive fertilization had inhibitory effects. Under brackish water irrigation, both plant height and leaf area index demonstrated significant positive effects on yield, with plant height having a particularly noteworthy direct effect at a coefficient of 0.935. MIB water irrigation demonstrated superior advantages for promoting pakchoi growth, leading to significantly higher rates of fresh weight and dry matter accumulation compared to traditional brackish water irrigation. The maximum value of each growth index exerted a significant direct influence on its respective growth parameter, whereas ΔCGDD demonstrated a relatively smaller or potentially negative effect. Applying organic fertilizer appropriately can assist in the production of pakchoi and provide a scientific basis for increasing yield.

The occurrence, spatial distribution, and well-depth dependence of PFASs in groundwater from a reclaimed water irrigation area

With the growing development of modern agriculture and industry, groundwater is facing more and more complex contaminants. One such contaminant is per- and polyfluoroalkyl substances (PFASs), which pose a potential risk to human health, particularly for those who rely on groundwater as their primary source of drinking water. In this study, we conducted a comprehensive investigation on the occurrence, spatial distribution, and source apportionment of PFASs in shallow (<60 m) and deep (>80 m) groundwater samples from a reclaimed water irrigation area in Beijing's suburbs. Our results showed that the average total PFAS concentration (∑10PFAS) for all samples was 10.55 ± 7.77 ng/L, ranging from 1.05 to 34.28 ng/L. The dominant congeners were PFBA, PFOA, and PFBS. No significant linear relationship was observed between PFAS concentrations and the well depth. However, the averaged ΣPFASs in groundwater were highest in the uppermost layer and declined sharply to a few ng/L in the deep aquifer below 80 m. PFASs showed elevated concentration in shallow aquifers in 9 out of 11 paired wells, indicating an overall descending trend of PFASs with increasing aquifer depth. The spatial distribution of PFASs was highly heterogeneous and showed different patterns in shallow and deep groundwater, which may be related to the complicated attenuation behavior of PFAS compounds when they transport and diffuse through overlapping aquifer layers. The influence of the landfill on groundwater PFASs was most pronounced within a 5 km radius. Source apportionment results indicated that reclaimed water irrigation is the main non-point source of PFASs in shallow groundwater. In contrast, deep groundwater is primarily subject to point sources and lateral recharge flow. This investigation of PFASs in shallow and deep wells provides a foundation for further exploration of PFASs transportation and risk prevention in regions where groundwater is a major water resource for domestic and industrial development.

Temporal trends in agricultural water use and the relationships to hydroclimatic factors in the High Plains aquifer region

AbstractThe High Plains aquifer (HPA) is the primary water source for agricultural irrigation in the US Great Plains. The water levels in many locations of the aquifer have declined steadily over the past several decades because the rate of water withdrawals exceeds recharge, which has been a serious concern to the water resources management in the region. We evaluated temporal trends and variations in agricultural water use and hydroclimatic variables including precipitation, air temperature, reference evapotranspiration, runoff, groundwater level, and terrestrial water storage across the HPA region for different periods from 1985 to 2020 at the grid, county, or region scale. The results showed that water withdrawals decreased from 21.3 km3/year in 1985 to 18.2 km3/year in 2015, while irrigated croplands increased from 71,928 km2 in 1985 to 78,464 km2 in 2015 in the entire HPA. The hydroclimatic time‐series showed wetting trends in most of the northern HPA, but drying and warming trends in the southern region from 1985 to 2020. The groundwater level time‐series indicated flat trends in the north, but significant declining in the central and southern HPA. Trends in irrigation water withdrawals and irrigation area across the HPA were controlled by the advancement of irrigation systems and technologies and the management of sustainable water use, but also were affected by dynamical changes in the hydroclimatic conditions.

Effects of Ecological Water Conveyance on Soil Salinization in the Shiyang River Basin’s Terminal Lake—Qingtu Lake—Area

(1) Background: Recently, secondary soil salinization has frequently occurred in ecological water conveyance and irrigation areas. Therefore, monitoring the information on soil salinization in the conveyance irrigation area and analyzing the change process of soil salinization are of great significance to both environmental improvement and salinization management. (2) Methods: This study takes the Shiyang River’s terminal lake—Qingtu Lake—and its surroundings as the research area. The salinization index was extracted by remote sensing data and methods, and a comprehensive salinization model (CSI) was established. Firstly, the spatial distribution regular of soil salinization, since ecological water conveyance was explored, and the change trends in soil salinization were analyzed. Secondly, the relationship between the change characteristics of soil salinization and groundwater, water area changes and land use types were analyzed. (3) Results: The Kappa coefficient between the soil salinization extracted by CSI and the measured data reached 0.703, and CSI can accurately monitor soil salinization information. From 2011 to 2020, the non-salinized land increased by 2.1%, mild and moderate salinization decreased by 5.7% and 3.9%, respectively, and severe salinization increased by 7.5%. The salinization in the lake area showed a decreasing trend, and the periphery of the lake area showed an increasing trend. Groundwater, water area changes and land use type have certain influences on soil salinization in the study area. (4) Conclusion: Since ecological water conveyance, the total proportion of soil salinized area in Qingtu Lake and its surrounding areas has not changed much, but there are certain changes between different grades of salinized land. The areas with changes to the level of salinization are mainly shallow, unstable water areas, saline–alkali land, wetlands and sandy land, and there are secondary salinization problems in these areas.

Remote sensing of wetland evolution in predicting shallow groundwater arsenic distribution in two typical inland basins

A large number of studies have shown that the existence of wetlands may influence arsenic concentrations in adjacent shallow groundwater. However, little is known about the linkage between wetland evolution and arsenic enrichment in shallow groundwater. This study investigated wetland evolutions from 1973 to 2015 in two arid-semiarid inland basins along the Yellow River catchment (i.e., the Yinchuan Basin and the Hetao Basin) based on remote sensing data, and their association with arsenic distributions based on arsenic concentrations of 244 and 570 shallow groundwater samples, respectively. The long-term Landsat images reveal that the covering area of wetlands exhibited increasing trends in both the Yinchuan Basin and the Hetao Basin. Wetlands in the Yinchuan Basin and the Yellow River water-irrigation area in the Hetao Basin varied with precipitation before 2000, but exhibited increasing trends because of wetland restoration policies since 2000. Wetlands in groundwater-irrigation area in the Hetao Basin decreased due to increasing exploitation of shallow groundwater. Wetlands with long existence time were mainly distributed along the Yellow River and drainage channels and in large lakes in the northern Yinchuan Basin and the Hetao Basin, where high‑arsenic (>10 μg/L) groundwater occurred. The probability of high‑arsenic groundwater distribution increased with the proportion of wetland existence time to the entire studied period (42 years), which can be best explained by a BiDoseResp growth curve. Longer existence of wetlands may cause greater probability of high‑arsenic groundwater. This was likely related to long-term introduction of biodegradable organic matter into shallow aquifers and thereafter enhancement of arsenic mobility and/or arsenic being released beneath wetlands and transported into shallow aquifers under continuing wetland water recharge. We therefore suggest that mapping wetland evolutions could probably serve as a good indicator for predicting high arsenic groundwater distributions in shallow aquifers.

Path analysis of water use efficiency in water diversion and irrigation areas in the lower Yellow River

The evaluation of water use efficiency is a comprehensive and continuous evaluation of irrigation water use efficiency in an irrigation district. The relationship between the main impact factors can effectively improve the accuracy and rationality of the results. Based on the data from 2005 to 2014 in the Yellow River irrigation area of the lower reaches of the Yellow River, this paper determined the direct effect, indirect effect, determination coefficient of the eight quantitative impact factors, as well as the difference of total contribution to R2, through the mathematical method of path analysis. Through the calculation data and analysis, it is found that the completion rate of supporting facilities is the most important influencing factor for the water use efficiency of the water diversion and irrigation areas in the lower Yellow River. The completion rate of supporting facilities also plays a role in the investment of water-saving projects, channel length and channel lining rate, which plays a significant role of water diversion and irrigation areas in the lower Yellow River. and the least influential factor is precipitation. The above studies have identified the existing problems and weak links in the process of water resources management in the Yellow River Diversion Irrigation Area, providing technical support for the scientific planning and sustainable development of the Yellow River Diversion Irrigation Area in the next step.

How stable are Australian farmers’ climate change risk perceptions? New evidence of the feedback loop between risk perceptions and behaviour

The exact relationship between people’s climate change attitudes and behaviour is a topic that engages policy-makers and researchers worldwide. Do climate change attitudes influence behaviour or is it possible that behaviour can change attitudes? This study uses a unique repeated survey dataset of 275 farmers (irrigators) in the southern Murray-Darling Basin from 2010–11 to 2015–16, to explore the dynamic relationship between climate change risk perceptions and farm adaptation behaviour. Farmers who had an increased risk exposure (expressed through higher debt, larger irrigated areas, greater share of permanent crops, and located in areas with higher temperatures and less rainfall) were more likely to agree climate change posed a risk. Whilst farmers became more accepting towards climate change over the time-period, a significant percentage of these attitudes were unstable. One reason suggested for this instability is the presence of a feedback loop between risk perceptions and behaviour. Namely, new evidence was found that farmers who agreed climate change was a risk in 2010–11, were more likely to undertake farm production decisions to reduce that risk (e.g. changing crop mix, reducing irrigated area and consequently selling water entitlements) – which had the impact of negatively feeding back and reducing their stated climate change risk perceptions in 2015–16. Conversely, farmers who were originally deniers were more likely to undertake somewhat riskier farm production decisions (e.g. increasing water utilisation rates and irrigation areas) – which consequently had the impact of positively increasing their climate change risk perceptions in 2015–16.

Variation and driving mechanism analysis of water footprint efficiency in crop cultivation in China

Water footprint regulation in agricultural production is of great significance to regional food, water and ecological sustainability. The spatial-temporal characteristics and driving mechanism of water footprint efficiency (WFE) in crop cultivation in China during 1996–2015 were analysed based on the quantification of the crop-water relationship. The results showed that China's total crop water footprint (TWF) was 1125.6 G m3, and the blue, green and grey components accounted for 24.4%, 57.4% and 18.2%, respectively. The national WFE was 0.681 and increased over time due to the improvement of agricultural technology. Spatial autocorrelation analysis showed that provinces with similar WFE values were clustered geographically and have gradually weakened since 2012. Provinces with a high WFE were concentrated in the southeast and northeast, and low-value provinces were distributed in the west of China. The main anthropogenic driving factors were the preliminary fertilizer application intensity (FAI) and population density (PD); however, these factors have been replaced by the irrigation efficiency (IE), agricultural water use ratio (AWR) and irrigation area proportion (IAP) in recent years. Specific regions should formulate water resource management policies according to their WFE performance, agricultural production scale and water resource endowment. The northeast should control crop cultivation and enhance the yield to solve water shortage problems, the central provinces should improve WFE, and the southern provinces should contribute to the promotion of national water use efficiency by expanding crop sowing and irrigation areas. This study provides a reference for water resource management in the context of social and environmental change.

DETERMINANT PRODUCTIVITY OF HONORARY EMPLOYEES IN WATER IRIGATION AREA OBSERVATION OFFICES SELUMA

This study aims to analyze the determinants of the work productivity of honorary employees at the Seluma Irrigation Water Observers Regional Office. The method of collecting data is by distributing questionnaires to 42 honorary employees. Analysis of the data used is quantitative analysis, with the method of multiple linear regression, determination test, t test and F test. The results of SPSS analysis for windows version 16.0, obtained the regression equation Y = 2.239 + 0.231X1 + 0.653X2 + 0.378X3. The regression equation shows that there is a positive influence between morale, work discipline and organizational commitment to the work productivity of honorary employees at the Seluma Irrigation Water Observers Regional Office, and work discipline variables have the strongest influence on work productivity because it has the greatest regression coefficient value, namely .653. From the results of the determination test it is known that 85.3% of the work productivity of honorary employees at the Seluma Irrigation Water Irrigation Area Observers Office is influenced by morale, work discipline and organizational commitment. The t-test results showed that morale, work discipline and organizational commitment partially had a significant effect on the work productivity of honorary employees, because of the probability value of sig. 0.05. While the F (Anova) test results showed that work morale, work discipline and organizational commitment simultaneously had a significant influence on the work productivity of honorary employees at the Seluma Irrigation Water Irrigation Area Observers Office, where Fcount Ftable (80,169 2,850).

Quantitative assessment of groundwater pollution risk in reclaimed water irrigation areas of northern China

The application of reclaimed water for agricultural irrigation can effectively reduce the use of freshwater resources including groundwater, addressing the increasingly severe challenge of water shortage. However, reclaimed water irrigation will cause potential pollution risks to groundwater, which needs to be further studied to ensure the safety of reclaimed water irrigation. An integrated quantitative assessment system including the modified DRASTIC model was developed to evaluate the pollution risks caused by reclaimed water irrigation and scientific strategies were offered for the development of reclaimed water irrigation in water shortage areas to avoid groundwater pollution. The groundwater intrinsic vulnerability index, the hazards of the characteristic pollutants, and the groundwater values were quantified to obtain the pollution risks distribution map. In the Beijing plain of north China, the low groundwater pollution risk areas were located in the midstream of Chaobai river baisin, Beiyun river basin, and Yongding river basin, accounting for 48.3% of the total study area. These areas in low pollution risk can be considered as safety areas for reclaimed water irrigation. The moderate groundwater pollution risk areas accounting for 46.9% of the total study area were suggested to apply water-saving irrigation measures for preventing groundwater pollution. The reclaimed water irrigation should be prohibited in the high groundwater pollution risk areas, which accounted for 4.8% of the total study area. This study highlights the reasonable strategy for the development of reclaimed water irrigation in water shortage areas and lay a foundation for finding alternative water sources for agricultural irrigation.

Debit Air pada Saluran Sekunder Bendung Tanah Priuk Akibat Kolam Ikan Air Deras di Kabupaten Musi Rawas

The Kelingi Tugumulyo Irrigation Area is a permanent weir irrigation that runs through the building for the Satan Muara Beliti Water channel. Secondary Air Satan Muara Beliti channel has 5 buildings with the main function to flow the water through the rice fields in the Mara Beliti sub-district. Problems that arise in the distribution of water are the loss of irrigation water due to the pool of swift water and infiltration of water into the soil if the soil is saturated. These problems cause a lack of discharge for the fulfillment of irrigation water due to water loss in the secondary channel. The method used in assessing the Evaluation of Irrigation Water Provision from the Watervang Dam for Satan Water Secondary Channels was by analyzing the data of maximum discharge, minimum discharge, and average discharge of the Watervang Dam as well as calculating water demand and water availability in the Satan Muara Beliti Water Irrigation Area. There are three results about Tanah Priuk 1 weir channel (BTP1) condition. First, based on the plan discharge, according to the Kelugi Tugumulyo Irrigation network scheme, debit from BTP 1 to BTP 2 was 30.10 l/s, whereas the result from field calculation through the use of current meter was 7.89 l/sec; it means the lack of water from the plan for BTP 1 - BTP 2 which is 22.21 l/sec. Second, the debit from BTP 2 to BTP 3 was 10.80 l/sec, whereas the result from field calculation through the use of current meter was 6.20 l/s; it means the lack of water from the plan for BTP 2 - BTP 3 was 4.60 l/sec. Third, the debit from BTP 4 to BTP 5 was 11.10 l/sec, whereas the result from field calculation through the use of current meter was 6.92 l/s; it means the lack of water from the plan for BTP 4 - BTP 5 was 4.18 l/sec . It concluded that the secondary channel from BTP 5 to the village of Bali has insufficient water.

Technical efficiency of rice farm under risk of uncertainty weather in Yogyakarta, Indonesia

One of the climate change phenomenon is uncertainty weather condition. This study aims to understand the technical efficiency of rice farm in Yogyakarta included the factors that influence them in uncertainty weather condition. We survey for sampling has been done in Sleman and Bantul Regency based on about 8 of water irrigation resources and about 25 locations of water irrigation area. The sampling method is simple random sampling to take 125 samples. Cobb Douglas translog frontier production function model has been used to analyze the factors that influence rice production and technical efficiency. The result of the production function shows that the factors that influence the rice production are land, labour, organic fertilizer, N fertilizer, irrigation pollution, irrigation type, season and location. The rice farm has not efficient. The study result gives the implication that the rice farm efficiency for sustainable agriculture, it needs using optimal input, peasant skill encouragement, and infrastructure development of irrigation.

VARIATION OF POLYCYCLIC AROMATIC HYDROCARBON (PAH) CONTENTS IN THE VADOSE ZONE AND GROUNDWATER UNDER LONG‐TERM IRRIGATION USING RECLAIMED WATER

AbstractUsing reclaimed water for agricultural irrigation is one of the most important measures for alleviating the global water crisis. The polycyclic aromatic hydrocarbon (PAH) vertical distribution characteristics in the vadose zone under long‐term reclaimed water irrigation and the corresponding impact on groundwater were studied by conducting a simulation experiment in the south‐east suburb of Beijing. The simulation experiment designed two different long‐term reclaimed water irrigation years, which were 98 and 236 years, respectively. The results showed that both treatments had a total PAH contents close to the background values (245–253 μg kg‾¹) and the long‐term reclaimed water irrigation did not result in a considerable PAH accumulation in soil profiles, which was supposed to be largely associated with the low PAH content of reclaimed water. The sources of PAH contamination in the vadose zone were mainly the combustion of fossil fuels and biomass by analysis of PAH isomer ratios. The total PAH contents in groundwater after percolation through the reclaimed water irrigation area was no more than 0.16 μg l‾¹ and the PAH removal rate of the vadose zone reached 97.7%. We stated that the vadose zone in the study area has excellent pollution prevention properties for PAHs under long‐term high‐quality reclaimed water irrigation. © 2019 John Wiley &amp; Sons, Ltd.

Spatial–Temporal Matching Characteristics between Agricultural Water and Land Resources in Ningxia, Northwest China

Agricultural water and land resources are key elements of human production and their unbalanced distribution has threatened the sustainable development of agriculture and regional food security. This study is aiming to investigate the spatial–temporal changes of matching characteristics between agricultural water and land resources in Ningxia during 2007 to 2017. The agricultural irrigation water (AIW), farmland area (FA) and effective irrigated area (EIA) were selected as quantity parameters for agricultural water and land resource. Results show that the gravity centers of AIW and EIA both moved in the southeast direction, while the gravity center of FA moved northwestward, which indicated a better spatial matching degree between AIW and EIA. According to the Gini coefficient and total spatial mismatch index, the spatial mismatch between AIW and FA of Ningxia was remedied and that of AIW and EIA was worse. Counties with sufficient and insufficient AIW were distributed in the north and the south of Ningxia, respectively. The sensitivity of agricultural irrigation water to land resources remarkably increased in the study period, particularly for the counties in northern area of Ningxia. The findings may provide implications for effective management of regional agricultural water and land resources.

Hydrogeochemical Characterization and Quality Assessment of Groundwater in a Long-Term Reclaimed Water Irrigation Area, North China Plain

Water scarcity has led to wide use of reclaimed water for irrigation worldwide, which may threaten groundwater quality. To understand the status of groundwater in the reclaimed water irrigation area in Beijing, 87 samples from both shallow and deep aquifers were collected to determine the factors affecting groundwater chemistry and to assess groundwater quality for drinking and irrigation purposes. The results show that groundwater in both shallow and deep aquifers in the study area is weakly alkaline freshwater with hydrogeochemical faces dominated by HCO3-Na·Mg·Ca, HCO3-Mg·Ca·Na, HCO3-Ca·Na, and HCO3-Na. The chemical composition of groundwater in both shallow and deep aquifers is dominantly controlled by the dissolution of halite, gypsum, anhydrite, and silicates weathering, as well as ion exchange. Geogenic processes (rock weathering and ion exchange) are the only mechanisms controlling groundwater chemistry in deep aquifers. Besides geogenic processes, evaporation and anthropogenic activities also affect the chemistry of shallow groundwater. Quality assessment reveals that both shallow and deep groundwater are generally suitable for drinking and irrigation purposes. The quality of deep groundwater is more excellent for drinking than shallow groundwater. However, long-term use of deep groundwater for irrigation exhibits higher potential risks to deteriorate soil property due to the relative higher permeability indexes (PI). Therefore, it is recommended that deep groundwater is preferentially used for drinking and domestic purpose, and shallow groundwater for agricultural irrigation.

Mapping magnesium sulfate salts from saline mine discharge with airborne hyperspectral data

Managing saline water discharges from mining operations is a global environmental challenge. Measuring the location and extent of surface efflorescence can indicate solute movement before changes in electrical conductivity (EC) are detected in waterways. We hypothesised through the use of a case study that ground-based reflectance spectrometry and airborne hyperspectral (450–2500 nm) analysis of surface efflorescence could be a rapid method for monitoring large regions of the surrounding environment, including downstream of remote mines. X-ray diffraction and X-ray fluorescence were used to determine mineralogy and elemental composition of surface salts around a uranium mine. Salt samples were found to be mixtures of magnesium sulfate. The reflectance of field spectra varied depending on the hydration of the mineral, mainly hexahydrite and starkeyite. A constrained energy minimisation technique was used to match the field reflectance spectra to the airborne data. Airborne matches were confirmed at the field sampling sites and surrounds. Salts were also detected at lower matches at mine water irrigation areas where excess mine water had previously been applied. Hence, hyperspectral remote sensing is a potentially rapid and sensitive method for mapping magnesium sulfates over large areas in operating and rehabilitated mines. It was successfully demonstrated as a tool for monitoring and assessment of efflorescence as a result of saline processes.

Influences of groundwater extraction on flow dynamics and arsenic levels in the western Hetao Basin, Inner Mongolia, China

Data on spatiotemporal variations in groundwater levels are crucial for understanding arsenic (As) behavior and dynamics in groundwater systems. Little is known about the influences of groundwater extraction on the transport and mobilization of As in the Hetao Basin, Inner Mongolia (China), so groundwater levels were recorded in five monitoring wells from 2011 to 2016 and in 57 irrigation wells and two multilevel wells in 2016. Results showed that groundwater level in the groundwater irrigation area had two troughs each year, induced by extensive groundwater extraction, while groundwater levels in the river-diverted (Yellow River) water irrigation area had two peaks each year, resulting from surface-water irrigation. From 2011 to 2016, groundwater levels in the groundwater irrigation area presented a decreasing trend due to the overextraction. Groundwater samples were taken for geochemical analysis each year in July from 2011 to 2016. Increasing trends were observed in groundwater total dissolved solids (TDS) and As. Owing to the reverse groundwater flow direction, the Shahai Lake acts as a new groundwater recharge source. Lake water had flushed the near-surface sediments, which contain abundant soluble components, and increased groundwater salinity. In addition, groundwater extraction induced strong downward hydraulic gradients, which led to leakage recharge from shallow high-TDS groundwater to the deep semiconfined aquifer. The most plausible explanation for similar variations among As, Fe(II) and total organic carbon (TOC) concentrations is the expected dissimilatory reduction of Fe(III) oxyhydroxides.

Pengaruh Sistem Intercrop Padi Gogo - Rumput Terhadap Pertumbuhan Dan Hasil Padi Gogo

The objective of this study was to determine characters of several drought tolerance and high yield upland rice variety under low soil water content in intercrops rice – grass system. The study was carried out in rain water irrigation area of Banjaranyar village. Experimental design was Split Plot Design with three replicates. The Main plot was grass i.e no grass, elephant grass and lemon grass while sub plot was upland rice variety i.e. Situ Patenggang, Kalimutu, Danau Gaung, Jatiluhur dan Cisokan. Under very low soil water content (&lt;12%), there was growth and yield differenc between rice varieties grown in intercrops system with grass. Eventhough there was no effect of this intercrop system on plant growth of upland rice, elephant grass promote higher rice yield, 0.88 t/ha than that without grass (0.39 t/ha) and with lemongrass (0.60 t/ha). Kalimutu variety showed the higher yield (1.38 t/ha) with plant height up to 46.27 cm and leaf area up to 4.63 cm2.

Experimental study of the suppression of flaming combustion and thermal decomposition of model ground and crown forest fires

This paper presents an experimental study of heat and mass transfer and phase transformations in the suppression of flaming combustion and thermal decomposition of model ground, crown, and mixed forest fires due to local exposure to water. The experiments were carried out with typical combustible forest materials (mixture of leaves, needles, and twigs) and models of trunks and branches of trees. The conditions and characteristics of suppression of the flaming combustion and thermal decomposition of combustible forest materials were determined. It is shown that in the case of crown and mixed fires, local short-term (a few seconds) action of a liquid projectile does not suppress the thermal decomposition of the material (but can only lead to localization of flaming combustion). In the case of ground forest fires, this approach can be efficient with an appropriate choice of the water-irrigated area of the combustion zone and the rate and time of water spraying.

Natural and anthropogenic factors affecting the shallow groundwater quality in a typical irrigation area with reclaimed water, North China Plain

In this study, the hydrochemical characteristics of shallow groundwater were analyzed to get insight into the factors affecting groundwater quality in a typical agricultural dominated area of the North China Plain. Forty-four shallow groundwater samples were collected for chemical analysis. The water type changes from Ca·Na-HCO3 type in grass land to Ca·Na-Cl (+NO3) type and Na (Ca)-Cl (+NO3+SO4) type in construction and facility agricultural land, indicating the influence of human activities. The factor analysis and geostatistical analysis revealed that the two major factors contributing to the groundwater hydrochemical compositions were the water-rock interaction and contamination from sewage discharge and agricultural fertilizers. The major ions (F, HCO3) and trace element (As) in the shallow groundwater represented the natural origin, while the nitrate and sulfate concentrations were related to the application of fertilizer and sewage discharge in the facility agricultural area, which was mainly affected by the human activities. The values of pH, total dissolved solids, electric conductivity, and conventional component (K, Ca, Na, Mg, Cl) in shallow groundwater increased from grass land and cultivated land, to construction land and to facility agriculture which were originated from the combination sources of natural processes (e.g., water-rock interaction) and human activities (e.g., domestic effluents). The study indicated that both natural processes and human activities had influences on the groundwater hydrochemical compositions in shallow groundwater, while anthropogenic processes had more contribution, especially in the reclaimed water irrigation area.