Paddy Field Ecosystem Research Articles

Can eDNA Present in Aquatic Environments of Rural Areas Help Identify Species Diversity in the Order Anura?

Paddy fields are classified as wetland environments, and they comprise freshwater ecosystems. They are ecologically important habitats and breeding grounds for many aquatic insects, amphibians, and reptiles. However, paddy field ecosystems are constantly threatened by climate change and the indiscriminate use of pesticides. The metabarcode analysis of eDNA (environmental DNA) method is highly effective at accumulating information on many organisms that inhabit paddy field ecosystems. It can indirectly identify the existence of taxa that are no longer found in the target ecosystem due to behavioral characteristics, such as those exhibited by amphibians. In the metabarcoding results of this study, genes of five species of frogs were found, but it was impossible to confirm all of the frogs’ taxa, morphological pictures, and croak sounds. On the other hand, some frog taxa were only found in the metabarcoding analysis. The eDNA of the frogs found only in the metabarcoding analysis is estimated to have been introduced from nearby areas inhabited by frogs rather than the target region. Due to the powerful analytical resolution of eDNA metabarcoding, this eDNA-based paddy field search is expected to help investigate the biodiversity in agricultural ecosystems.

Rational Nitrogen Reduction Helps Mitigate the Nitrogen Pollution Risk While Ensuring Rice Growth in a Tropical Rice–Crayfish Coculture System

The incorporation of aquaculture feed within a rice–crayfish coculture system significantly enhances nitrogen cycling, thereby diminishing the reliance on chemical fertilizers. However, this benefit is often overlooked in practice, and farmers continue to use large quantities of chemical fertilizers to maximize production, resulting in excessive soil fertility and water nitrogen pollution. Thus, avoiding nitrogen pollution in rice–crayfish coculture systems has become a pressing issue. In this study, we conducted a two-year experiment with two rice cultivars, and a 33.3% reduction in nitrogen fertilizer in a rice–crayfish coculture system (RC), to systematically analyze the overall nitrogen balance, rice nitrogen nutrition, and soil fertility, as compared with a rice monoculture system (RM). Our findings revealed the following: (1) Under the 33.3% reduction in nitrogen fertilizer, the nitrogen surplus in the rice–crayfish coculture system was comparable to that in the rice monoculture, and was controlled at an environmental safety level. (2) Nitrogen utilization efficiency and the accumulation of nitrogen in the rice–crayfish coculture were comparable to those in the rice monoculture. The nitrogen cycle in this system was able to provide the nitrogen required for rice growth after nitrogen fertilizer reduction. (3) The rice–crayfish coculture significantly improved the overall soil fertility and the effectiveness of soil nitrogen nutrition. Furthermore, cutting off the application of nitrogen fertilizer after the mid-tillering stage effectively controlled the total nitrogen content in soil after rice maturity. In conclusion, reducing nitrogen fertilizer in a rice–crayfish coculture system is feasible and beneficial. It ensures rice production, reduces the risk of excessive nitrogen surplus and surface pollution, and promotes a greener, more environmentally friendly paddy field ecosystem.

Aggravation of Cd availability in the plastisphere of paddy soil

Soil plastisphere has attracted many concerns, however, its influence on cadmium (Cd) availability in paddy soil was still unclear. This study carried out batch microcosmic and bagging experiments to explore the influence of microplastic (MPs) on Cd availability in paddy soil under flooding conditions in the view of plastisphere. Results showed that the presence of MPs could act as plastisphere micro-environment. The bacterial community composition changed dramatically around the plastisphere compared with MPs-contaminated bulk soil and control soil. The relative abundance of Symbiobacteraceae, Rhodocyclaceae and Bryobacteraceae was improved in the plastisphere which contributed to the enhanced the reduction of Fe(III) and sulfate in flooding paddy soil. The higher content of Fe(II) and S content contributed to the enrichment of Cd in the plastisphere which aggravated Cd availability in paddy soil under flooding conditions. The partial least squares structure equation modeling results confirmed the presence of MPs in paddy soil could act as plastisphere which could change the bacterial community composition and improve the content Fe and S that was conductive to gather Cd in plastisphere. This study shed lights on the understanding of the role of plastisphere on Cd availability in paddy field ecosystem under flooding conditions.

Rice land agroecosystem in supporting the development potential of duck-rice integration

The agroecosystem of paddy fields in the Tondano Lake area was an environmental system that has been managed directly by farmers for the benefit of food production, namely rice, fiber and various other food products such as ducks. The types of commodities that can be developed in paddy field ecosystems were more limited than those in dry land ecosystems. In fact, the farmer community in paddy fields generally had weak capabilities, especially with regard to capital, there was a rice farming culture that is not aware of damaging the environment and low technology adoption. Farmers use paddy fields for the development of duck livestock. The problem was how far the paddy field agroecosystem supports the potential for the development of duck-rice integration (INTIP). The purpose of this study was to analyze the biophysical characteristics, management of land resources and duck livestock resources. The research method used was a survey method with locations around Lake of Tondano. The number of respondents was 30 farmers who developed local ducks in paddy fields. Data analysis used was descriptive analysis. The results showed that the area of rice fields in District of Remboken was 323 Ha, South Tondano was 457 Ha, West Kakas was 664 Ha, East Langowan was 663 Ha and West Tondano was 693 Ha. The population of ducks for the five districts was respectively 8177 ducks, 6525, 4311, 4277 and 9240 ducks. Paddy fields are used as duck grazing land after the rice harvest. The feed consumed was the remains of rice that has fallen out, small animals in the fields after harvest and added with “renga”. Based on the results of the study it can be concluded that duck had the potential to be developed in paddy fields with agroecosystems that were only planted with rice plants.

Water-saving irrigation mitigates methane emissions from paddy fields: The role of iron

Iron (Fe) and methane (CH4) emissions play crucial roles in the carbon cycling of paddy field ecosystems. However, little is known about the effect and mechanism of Fe transformation on the CH4 emission from paddy fields, especially with different water management methods. In this study, the dynamic changes in CH4 emissions and different forms of Fe and soil organic carbon content were observed in paddy fields under flooded irrigation (FI) and water-saving irrigation (WSI) (including intermittent irrigation (II) and controlled irrigation (CI)). In addition, the structural equation model was used to clarify the response relationship between CH4 emissions and Fe ions in paddy fields. The results indicate that the cumulative CH4 emissions under WSI were reduced by 29.03–61.29%. The reasons are as follows (i) WSI increased the oxidation ability of Fe to CH4 by increasing the soil ferric iron (Fe3+) content in paddy fields; (ii) WSI could reduce the substrate utilization by methanogens by transforming the Fe oxide forms to increase the binding capacity of Fe to dissolved organic carbon, which reduced the CH4 production. In addition, compared with II, CI had higher soil Fe3+ content, Fe-bound organic carbon content, and lower acetate content, so it had lower CH4 production capacity. In summary, WSI promotes the direct oxidation of CH4 by Fe3+ in paddy fields and indirectly reduces CH4 production by facilitating the combination of Fe oxides with the substrates. These findings deepen our understanding of the mechanisms of CH4 emission in paddy fields and provide new insights for research on carbon sequestration and emission reduction in paddy field ecosystems.

Roles of Microbial Community and Keystone Taxa in Rice Productivity under Green Manuring in South China

Green manure (GM)–rice–rice rotation is an important management practice for improving soil fertility and rice productivity. The microbiological mechanisms for the increase in grain yield in GM–rice–rice rotation remain unclear. The responses of soil biodiversity, bacterial and fungal communities, and their interactions in the GM–rice–rice rotation were investigated based on two long-term field experiments in Gaoqiao (GQ) and Nanxian (NX) in Hunan Province, south China. Results showed that rice yields were raised by 11.79% and 15.03% under GM in GQ and NX, respectively. GM promoted Shannon diversity and Pielou’s evenness and changed the community structures of bacteria and fungi. The co-occurrence network analysis found that the percentages of negative edges were higher in GM (40.79% and 44.32% in GQ and NX, respectively) than those in the corresponding winter fallow (34.86% and 29.13% in GQ and NX, respectively) in the combined bacterial–fungal networks, suggesting more stable microbial community under GM. Moreover, GM had higher percentages of bacterial–fungal and fungal–fungal edges than winter fallow, indicating that GM increased the interaction between bacteria and fungi and fungi play more essential roles in affecting soil processes under GM. The keystone taxa in GM were positively linked with C metabolism-related enzymes and soil multifunctionality, and were important in improving soil fertility and rice productivity. We concluded that the fungal community was more sensitive to GM application than the bacterial community and that keystone taxa had important influences on soil properties and rice productivity in the GM–double-rice cropping system, which can effectively support the sustainable development of the paddy field ecosystem in southern China.

Formation of reactive intermediates in paddy water from different temperature zones for the promotion of abiotic ammonification

The paddy field is a hot area of biogeochemical process. The paddy water has a large capacity in photo-generation of reactive intermediates (RIs) due to abundant photosensitive dissolved organic matter (DOM), which is influenced by the spatial heterogeneity of paddy soils but rarely been explored. Our work presents the first investigation of the role of soil properties on photochemistry in paddy water. Soil organic matter (SOM), determined by the temperature, was the dominant factor for the photo-generation of RIs in paddy water of main rice producing areas. The RI concentrations generated with abundant SOM from cool regions are 0.05–8.71 times higher than those for the warm regions in China. The humic-like substance and aromatic-like compounds of DOM plays an essential role in RIs generation, which is abundant in paddy soils rich in SOM from Chinese cool regions. In addition, RIs can efficiently accelerate the photo-ammonification of urea and free amino acids by 15.2 %–164 %, leading to 0.13–0.17 mmol/L/d photo-produced ammonium after fertilization, which is preferentially absorbed by rice. The findings of this study will extend our knowledge of the geochemistry of global paddy field ecosystem. The potential role of RIs in nitrogen cycle should be highlighted in the agroecosystem.

Variations in antibiotic resistomes associated with archaeal, bacterial, and viral communities affected by integrated rice-fish farming in the paddy field ecosystem

Antibiotic resistance genes (ARGs) serving as a newly recognized pollutant that poses potential risks to global human health, which in the paddy soil can be potentially altered by different agricultural production patterns. To elucidate the impacts and mechanisms of the widely used and sustainable agricultural production pattern, namely integrated rice-fish farming, on the antibiotic resistomes, we applied metagenomic sequencing to assess ARGs, mobile genetic elements (MGEs), bacteria, archaea, and viruses in paddy soil. There were 20 types and 359 subtypes of ARGs identified in paddy soil. The integrated rice-fish farming reduced the ARG and MGE diversities and the abundances of dominant ARGs and MGEs. Significantly decreased ARGs were mainly antibiotic deactivation and regulator types and primarily ranked level IV based on their potential threat to human health. The integrated rice-fish farming decreased the alpha diversities and altered microbial community compositions. MGEs, bacteria, archaea, and virus exhibited significant correlations with ARGs, while integrated rice-fish farming effectively changed their interrelationships. Viruses, bacteria, and MGEs played crucial roles in affecting the ARGs by the integrated rice-fish farming. The most crucial pathway by which integrated rice-fish farming affected ARGs was through the modulation of viral communities, thereby directly or indirectly influencing ARG abundance. Our research contributed to the control and restoration of ARGs pollution from a new perspective and providing theoretical support for the development of clean and sustainable agricultural production.

Survey of Medicinal and Invasive Weeds in Paddy Field – Phytochemical and GC-MS Profiling of Cyanotis axillaris R. & S.

This study aims to determine the dominant weed species associated with rice crop fields in the Eppodhumvendran region of Thoothukudi district, Tamil Nadu and to analyze the phytochemicals, identify the bioactive compounds in ethanol extract using gas chromatography–mass spectrometry (GC-MS) and find their bioactivity using prediction of activity spectra for substances (PASS) prediction in Cyanotis axillaris. The documentation of medicinal weeds was carried out with the help of traditional local healers in Eppodhumvendran region. Phytochemical screening and GC-MS analysis of C. axillaris were performed to evaluate the chemical profiling of the extract. A total of 25 plant species regarded as invasive species/weeds were identified with the help of traditional local healers. The most commonly mentioned plant family was the Poaceae with a total of five species followed by the Euphorbiaceae, Asteraceae and Commelinaceae. Among these, C. axillaris is being studied for its potentiality due to its strong therapeutic value. The aerial plant part contains phytoconstituents such as alkaloids, glycosides, quinones, phenolics, steroids and terpenoids. The GC-MS results revealed 30 bioactive compounds, which were predicted using the PASS prediction method. The study highlights the importance of weeds in the paddy field ecosystem. The results reveal that C. axillaris contains various phytocomponents and that more research into their phytopharmaceutical relevance is required in the future.

Nitrogen Loss and Migration in Rice Fields under Different Water and Fertilizer Modes.

Irrigating aquaculture wastewater in appropriate irrigation and drainage modes in paddy fields could reduce water and fertilizer loss. However, the precise mechanisms involved in the degradation and movement of nitrogen in various water and fertilizer modes are still not fully understood. This study involves conducting a controlled experiment using barrels to examine the effects of various water quality, irrigation and drainage methods, and fertilization levels. The aim is to analyze the patterns of nitrogen degradation, loss, migration, and absorption in surface water, underground drainage, and soil leakage at different depths. The results showed the following: (1) The paddy field has a significant purification effect on aquaculture wastewater after one day of irrigation, reached at 78.55-96.06%. (2) Aquaculture wastewater irrigation increased nitrogen concentration in the plough layer, which helps rice roots absorb nitrogen and boosts plant TN. (3) In special dry years, underground seepage is the predominant method of nitrogen loss, and underground drainage nitrogen concentration peaks 2-6 days after fertilization. (4) Under aquaculture wastewater irrigation, the TN loss load of II decreased by 27.65-42.45% than FSI. Compared with IA-80, the TN degradation rate of IA in surface water increased by 18.51%, TN loss load decreased by 5.48%, TN absorption rate significantly increased by 14.61%, and yield increased by 31.14% significantly. IA is recommended in special dry years, which can improve the TN absorption rate and ensure high yield while significantly reducing the loss load of nitrogen. The findings can provide a basis for the purification of aquaculture wastewater through paddy field ecosystems in response to fertilizer supply levels.

Response of stomatal conductance, transpiration, and photosynthesis to light and CO2 for rice leaves with different appearance days.

To investigate the dynamics of stomata, transpiration, and photosynthesis under varying light intensities and CO2 conditions during leaf development, the light response and CO2 response of stomatal conductance (g sw), transpiration rate (T r), and net photosynthetic rate (P n) were observed for rice leaves at different days after leaf emergence (DAE). The results showed that (1) as photosynthetically active radiation (PAR) increased, leaf g sw, T r, and P n initially increased rapidly and linearly, followed by a more gradual rise to maximum values, and then either stabilized or showed a declining trend. The maximum g sw, T r, and P n were smaller and occurred earlier for old leaves than for young leaves. The g sw, T r, and P n all exhibited a linear decreasing trend with increasing DAE, and the rate of decrease slowed down with the reduction in PAR; (2) as the CO2 concentration (C a) increased, g sw and T r decreased gradually to a stable minimum value, while P n increased linearly and slowly up to the maximum and then kept stable or decreased. The g sw, T r, and P n values initially kept high and then decreased with the increase of DAE. These results contribute to understanding the dynamics in g sw, T r, and P n during rice leaf growth and their response to varied light and CO2 concentration conditions and provide mechanistic support to estimate dynamic evapotranspiration and net ecosystem productivity at field-scale and a larger scale in paddy field ecosystems through the upscaling of leaf-level stomatal conductance, transpiration, and photosynthesis.

Desilification of phytolith exacerbates the release of arsenic from rice straw

Arsenic (As) turnover in rice paddy agro-ecosystems has received much attention because As can enter the food chain through its accumulation in rice, thereby affecting human health. Returning straw to soil is a common practice to retain nutrients for soil and crops, but it also cycles As within the rice paddy field ecosystems. However, there is still a lack of detailed understanding of the fate of As in rice straw, and how or to what extent it is recycled back into the soil environment. This study aims to elucidate the relationship between the microstructure of rice straw and the release of As during rice straw decomposition. The microstructure of rice straw was found to comprise both organic and silica (phytolith) components. These two constituents are inter-embedded to form a composite-like structure that contains up to 6.48 mg As Kg−1. The 30-day batch experiments revealed that the biochemical release of As simultaneously depends upon the decomposition of the organic component and the desilicification of the silica component. Accompanying the release of As was the release of other elements such as Fe, Al, P and S. These elements can further interact with As to form less mobile compounds. The introduction of either Trichoderma harzianum or Bacillus velezensis was expected to accelerate the decomposition of rice straw, and enhance the silica dissolution, hence contributing to an increase in the As release. Despite these expectations, our observations showed the opposite effects. Microorganisms presumably have facilitated the change in solution chemistry or the inclusion of As into the newly-formed precipitates. The biochemical decomposition process can reduce straw particle size, while the negatively-charge surface will involve microsized straw particles in the electrostatic interaction, thereby favoring the dispersibility state. Therefore, the co-transport of micro-sized straw particles with As under field conditions should not be neglected.

Ecosystem vulnerability to extreme climate in coastal areas of China

Climate change has far-reaching impacts on ecosystems and the frequency and intensity of extreme global climate events have been increasing over the past century; therefore, assessing ecosystem vulnerability to extreme climate change is critical for sustainable and adaptive ecosystem management. As a climatically sensitive region, coastal China is currently experiencing significant environmental changes. To identify how extreme climate affects ecosystem vulnerability, we calculated and analyzed the spatiotemporal variation in extreme climates, net primary productivity (NPP), and spatial characteristics of ecosystem vulnerability to extreme climate change, and discussed the response characteristics of different ecosystems to extreme climate events based on meteorological data and NPP (1986–2015). The results demonstrated that (1) coastal China has become increasingly warmer over the last thirty decades but the precipitation trend is different in the north and south: precipitation increased in the south and decreased in the north. (2) NPP is rising overall, with the forest ecosystem growing the fastest, particularly since 2010. (3) The ecosystem vulnerability of coastal areas in China is mainly classified as mild or non-vulnerable. However, there were apparent differences in the vulnerability of different ecosystems, with dry land and shrub ecosystems having the highest mean vulnerability. (4) The effects of extreme climates on the vulnerability of different ecosystems and ecosystems in different habitats vary. Overall, rising extreme temperatures can significantly increase the ecosystem vulnerability in the coastal areas of China. The paddy field ecosystem was more influenced by extreme temperatures than other ecosystems, with the southern paddy field ecosystem more influenced than the northern paddy field ecosystem. Our study advances the understanding of vegetation dynamics and their driving mechanisms and provides support for scientifically informed ecological management practices in coastal China.

Avian diversity in the paddy field ecosystem surrounding the Assam University campus in Silchar during the rainy season

Rice (Oryza sativa L.) is one of the most effective crops for absorbing carbon dioxide. Paddy is a temporary reservoir for rainwater during the rainy season, prevents soil erosion, and emits oxygen through photosynthesis. In Assam, it occupies 88.89 percent of the net cropped area. Paddy field ecosystems are also home to various cultivated and wild species of plants and animals where numerous aquatic and bird species can be found. These fields provide waste rice, a crucial food source for various bird species. The quantity of waste rice positively correlates with rice yields, and birds often feed on freshly planted rice seeds. Paddy fields constitute a semi-aquatic ecosystem that is heavily infested by insect pests. These fields also attract waterfowls, wading birds, shorebirds, and other waterbirds for migratory movements and foraging. From this pilot study conducted in the paddy field ecosystem surrounding the Assam University campus in Silchar we report 95 species of birds that belong to 37 families and 14 orders. Highly sighted avifauna included Egret, Heron, Bittern (family Ardeidae), Waterhen (family Rallidae), Kingfisher (family Alcedinidae), Drongo (family Dicruridae), and Dove (family Columbidae). Interestingly, eight 'Least Concern' bird species according to the International Union for Conservation of Nature (IUCN) – Hooded Pitta (Pitta sordida – family Pittidae), Cinnamon Bittern (Ixobrychus cinnamomeus – family Ardeidae), Watercock (Gallicrex cinerea – family Rallidae), Common Sandpiper (Actitis hypoleucos – family Scolopacidae), Emerald Dove (Chalcophaps indica – family Columbidae), White-Browed Piculet (Sasia ochracea – family Picidae), Dark-Necked Tailorbird (Orthotomus atrogularis – family Muscicapidae) and Brown Fish-Owl (Ketupa zeylonensis – family Strigidae) as well as a ‘Vulnerable’ species Lesser Adjutant Stork (Leptoptilos javanicus – family Ciconiidae) and ‘Near Threatened’ species Alexandrine Parakeet (Psittacula eupatria – family Psittacidae) were also noted. Out of a total 95 avian species, 46 species belonged to the insectivorous category, accounting for the greatest number according to the feeding guild recorded within different line transects in Visual Encounter Surveys (VES) conducted weekly from March 2023 to August 2023. Although the avifaunal studies have enormous potential in the Barak Valley, conservation measures are essential to protect the biodiversity. Public involvement in awareness campaigns and conservation activities is crucial for conserving avian diversity within the Valley. As paddy fields are used primarily by grassland and wetland bird species, there are significant information gaps in the monitoring of bird populations in paddy cultivation as well as in different stages of rice growing cycles, which makes it essential to understand the importance of paddy fields on avian populations as well as diversity.

Contrasting change trends in dry and wet nitrogen depositions during 2011 to 2020: Evidence from an agricultural catchment in subtropical Central China

Over the past decade, China has experienced a decline in atmospheric reactive nitrogen (Nr) emissions. Given that China's subtropical region is a significant nitrogen (N) deposition hotspot, it is essential to accurately quantify the ten-year variations in dry and wet N depositions in the context of reductions in atmospheric Nr emissions. Here, we evaluated the spatiotemporal variation in N deposition on forest, paddy field and tea field ecosystems in a typical subtropical agricultural catchment from 2011 to 2020. Our findings indicated a significant decrease in total N deposition in both the tea field ecosystem (41.5–30.5 kg N ha−1) and the forest ecosystem (40.8–25.7 kg N ha−1) (P < 0.05), but no significant change in the paddy field ecosystem (29.3–32.9 kg N ha−1). Specifically, dry N deposition exhibited significant declines except in the paddy field ecosystem, whereas wet N deposition had no significant change. The reduction in total oxidized and reduced N depositions in forest and tea field ecosystems is attributed to the decrease in NOx and NH3 emissions. Additionally, The ratio of NHx deposition to total N deposition all exceeded 0.5 in three ecosystems and the NHx/NOy ratio had an increasing trend (P < 0.05) in the paddy field, indicating that reactive N emissions from agricultural sources were the primary contributor to overall N deposition. Our study emphasizes that despite the decreasing trend in N deposition, it still exceeds the critical loads of natural ecosystems and requires stringent N emissions control, particularly from agricultural sources, in the future.

Transformation Characteristics and Mechanism of Blue and Green Water flows at Watershed and Typical Ecosystem Scale in China

The transformation of blue and green water is an important hydrological process at the watershed, which is an important supplement to the study of hydrological processes. The Soil and Water Assessment Tool (SWAT) was used to investigate the evolution characteristics of hydrological processes and the transformation mechanism at the watershed and ecosystem scales in the Dongjiang River. The results show that: (1) the annual average total water flows in the Dongjiang River Basin are 37.80 and 22.287 billion m³, respectively. The blue and green water flows during the wet season account for more than 75% of the total year. The blue and green flows of the grassland ecosystem increased significantly, with the most significant change in the downstream ecosystem. (2) From 1980 to 1990 and from 2010 to 2020, the Dongjiang River Basin experienced a transition from blue to green water flow. Blue water flow accounts for the majority of total water flow in the paddy field and dry cropland ecosystems, and green water flow changed to blue water flow from 1980 to 2010. (3) The correlation between blue and green flow and land use was weak throughout the year and during the wet season, but it was significant during the dry season. This study can serve as a model for the integrated management of water resources and ecosystems in the Dongjiang River Basin.

Simulated Nitrogen Deposition Decreases the Ratios of Soil C to P and N to P, Changes Soil Enzyme Activity, and Reduces Soil Microbial Biomass in Paddy Soil in Southern China

There have been few studies on the impact of nitrogen deposition on paddy field ecosystem; therefore, we evaluated the effects of different N deposition levels (0, 40, and 120 kg N·ha−1) with the conventional nitrogen rate (180 kg N·ha−1) on rice field ecosystem through two-season experiments. The results showed that 40 and 120 kg·ha−1 nitrogen deposition had no significant effect on rice yield, although the rice grains per panicle and the 1000-grain weight increased. The 40 and 120 kg·ha−1 nitrogen deposition levels had no significant effect on rice and soil total carbon/total nitrogen (TC/TN) in the two-season experiment; however, 40 and 120 kg·ha−1 nitrogen deposition significantly increased TP content of the rice root and soil in a short time, and continuous 120 kg·ha−1 nitrogen deposition significantly decreased TP content of the rice root and significantly increased TP content of the rice stem. In addition, nitrogen deposition significantly reduced total carbon/total phosphorus (TC/TP) and total nitrogen/total phosphorus (TN/TP) in the soil. The activities of soil acid phosphatase (S-ACP), β-glucosidase (S-β-GC), and N-acetyl-β-D-glucosidase (S-NAG) increased under 40 kg·ha−1 nitrogen deposition, while the activities of S-β-GC and S-NAG decreased under 120 kg·ha−1 nitrogen deposition compared with 40 kg·ha−1. The microbial carbon, microbial nitrogen, microbial phosphorus, and fungal microbial biomass reduced under 40 and 120 kg·ha−1 nitrogen deposition. These findings suggest that, under short-term N deposition, rice and soil can adjust the C, N, P, and even the nutrient balance by themselves; however, continuous nitrogen deposition may have adverse reactions to microorganisms, thereby disrupting this balance and ultimately leading to the deterioration of paddy soil environment and a reduction in rice yield in the long term.

A dataset of the observations of carbon and water fluxes in the paddy fields of Panjin (2018–2020)

Paddy fields play an important role in the study of agricultural land use and global carbon cycle. As one of the main rice producing areas in Northeast China, the Liaohe River Delta provides a good experimental platform for the study of carbon and water cycle in Paddy fields. However, due to the insufficient study of long-term carbon and water fluxes in the paddy areas of the Liaohe River Delta, there is an urgent need of long-term data monitoring and sorting. This dataset collects the observations of the flux data of the paddy field ecosystem in the Liaohe River Delta from 2018 to 2020 from the Panjin Paddy Field Research Station of the Northeast Ecological and Agrometeorological Field Experimental Base of China Meteorological Administration. Based on the data processing system of the China Flux Observation and Research Network (ChinaFLUX), we prepared standardized data files for the dataset of water fluxes of ecosystem carbon and key meteorological elements, including data files at hourly, daily, monthly and yearly scales. This dataset is of great significance for the accurate evaluation of the position and role of carbon and water fluxes of paddy field ecosystems in the regional and global carbohydrate circle in the Liaohe River Delta.

Rice developmental stages modulate rhizosphere bacteria and archaea co-occurrence and sensitivity to long-term inorganic fertilization in a West African Sahelian agro-ecosystem

BackgroundRhizosphere microbial communities are important components of the soil-plant continuum in paddy field ecosystems. These rhizosphere communities contribute to nutrient cycling and rice productivity. The use of fertilizers is a common agricultural practice in rice paddy fields. However, the long-term impact of the fertilizers usage on the rhizosphere microbial communities at different rice developmental stages remains poorly investigated. Here, we examined the effects of long-term (27 years) N and NPK-fertilization on bacterial and archaeal community inhabiting the rice rhizosphere at three developmental stages (tillering, panicle initiation and booting) in the Senegal River Delta.ResultsWe found that the effect of long-term inorganic fertilization on rhizosphere microbial communities varied with the rice developmental stage, and between microbial communities in their response to N and NPK-fertilization. The microbial communities inhabiting the rice rhizosphere at panicle initiation appear to be more sensitive to long-term inorganic fertilization than those at tillering and booting stages. However, the effect of developmental stage on microbial sensitivity to long-term inorganic fertilization was more pronounced for bacterial than archaeal community. Furthermore, our data reveal dynamics of bacteria and archaea co-occurrence patterns in the rice rhizosphere, with differentiated bacterial and archaeal pivotal roles in the microbial inter-kingdom networks across developmental stages.ConclusionsOur study brings new insights on rhizosphere bacteria and archaea co-occurrence and the long-term inorganic fertilization impact on these communities across developmental stages in field-grown rice. It would help in developing strategies for the successful manipulation of microbial communities to improve rice yields.

PERFORMANCE STUDY OF IRRIGATION NETWORK IN RENGGUNG IRRIGUNG AREA, LOMBOK CENTRAL REGENCY

The impact of the decline in irrigation performance is direct and indirect. The direct impact is a decrease in productivity, a decrease in cropping intensity and an increase in farming risk. The indirect impact is the weakening of the farmer's commitment to maintaining the paddy field ecosystem because the poor performance of irrigation makes the land less conducive for farming, especially rice crops. In order to obtain an overview of the condition of the irrigation areas being managed, it is necessary to conduct a study of the irrigation areas, to determine the conditions of irrigation performance and to determine priorities for handling the rehabilitation of irrigation networks and to make policies. DI performance appraisal evaluation results. Renggung is 75.8% where the performance condition of Irrigation Area of Renggung Irrigation is Good Performance.