Rice Cropping System Research Articles

Exploring the effect of fertilizer application on yield and decoding CO2 flux under flooded paddy conditions towards sustainable agriculture

The impact of organic and inorganic nutrient management on the emission of carbon dioxide (CO2), soil properties such as available nutrients, microbial population and soil organic carbon (SOC) were investigated in paddy (Oryza sativa L.) field (at 8o 46’ N Latitude and 77o 42?’ E Longitude) under flooded condition during late pishanam season in 2023-2024. The treatments were designed to observe the effects of applying fertilizer based on the soil test crop response (100 % STCR-based NPK) that had been modified by organic amendments, which include absolute control (unfertilized), inorganic fertilizers, sole application of organic amendments (Farm yard manure, Green leaf manure, Vermicompost and Poultry manure) and combined these organic amendments with inorganic fertilizers. The main objective of this study is to understand the intricate relationship between fertilizers and carbon flux in paddy soils, which is crucial for developing sustainable agricultural practices that minimize environmental harm while ensuring food security. The observation of the experimental field study reported that the combined application of poultry manure at the rate of 5 tonnes per hectare with 100% STCR-based inorganic fertilizer recorded maximum yield and yield attributes. The treatment combination of poultry manure + inorganic fertilizer enhanced in sequestrating the soil organic carbon (0.67%) resulted in higher grain yield (5972 kg ha-1) and also observed that this combination will limit the emission of CO2 to the atmosphere. Therefore, it could be a better choice for carbon storage and higher productivity in a sustainable rice cropping system.

High-yield rice with rich nutrition and low toxicity can be obtained under potato-rice cropping system.

Rice is often rotated with dryland crops to produce sufficient foodstuff, as rice is the main food crop of humans. In order to verify whether under the intensive rice-based cropping system, high yield and good quality of rice can be achieved simultaneously to ensure food security. Five long-term paddy-upland rotations - wheat-rice (WR), rapeseed-rice (RR), garlic-rice (GR), broad beans-rice (BR) and potato-rice (PR) - were conducted from 2014 to investigate rice yield, along with the profiling of 24 elements in rice grain. Mg, Zn, Cu, As, Mo and Sb concentrations were highest in the aleurone layer, and Ag and Cd concentrations showed little variation among different parts of the rice grain. Al, Ti, V, Si, Fe and Tl concentrations in the endosperm under GR were higher, while the Se concentration under PR was the highest. Furthermore, the yield of GR and PR were higher than the other three rotations with N supplementation, and the sustainable yield index of PR and WR were larger than 0.8. When we consider the concentration of toxic (As, Cd and Pb) and nutrient elements (Ca, Fe, Zn, Se, Cu and Mg) in the endosperm and grain yields, PR can simultaneously achieve high yield, high nutrition and low toxicity with different nitrogen treatments. Here we provide novel insights regarding the selection of rice-based cropping systems, focused on producing nutritious and safe rice with high grain yield. © 2024 Society of Chemical Industry.

Energy Consumption in Wheat-Rice Cropping System in Punjab

Energy consumption for crop production depends on the availability of energy sources and the capacity of the farmers. This study analyzed energy sources used by farmers for wheat and rice production and identified agricultural operations where energy consumption can be reduced so that operational costs in wheat-rice production system can be lowered. Data on energy use in wheat and rice cropping system was collected by interviewing the farmers using specially designed questionnaire. Relevant information pertaining to human labour use, sources of irrigation, number of irrigations to each crop, quantity of farm inputs, utilization of mechanical power sources and grain yield etc. were collected. The average output energy of grain, input energy, energy ratio and specific energy for wheat crop in the state of Punjab were 68347 MJ ha-1, 15644 MJ ha-1, 8.4 and 3.08 MJ kg-1, respectively. The average output energy of grain, input energy, energy ratio and specific energy for rice were 115888 MJ ha-1, 16438 MJ ha-1, 14.8 and 2.09 MJ kg-1, respectively. For wheat-rice cropping system, the average output energy of grain, input energy, energy ratio and specific energy were 184234.4 MJ ha-1, 32081.4 MJ ha-1, 11.7 and 2.48 MJ kg-1, respectively. Energy ratio (output energy to input energy ratio) of rice is higher than the wheat, indicating rice efficiently utilized energy resources to convert into output of the harvested crop. Similarly, lower specific energy (input energy to yield ratio) of rice as compared to wheat also indicates lower energy consumption to produce per unit of rice. This analysis clearly indicates that rice production is more energy efficient than wheat production in rice-wheat production system. Further, the energy ratio, specific energy and energy productivity of wheat-rice cropping system were estimated as 11.6 to 11.9, 2.44 to 2.51 MJ kg-1 and 0.40 to 0.41kg MJ-1, respectively. This study will be helpful to identify the agricultural operations and implementing suitable interventions for improving energy use efficiency.

Effects of tillage management on soil organic carbon mineralization under double cropping rice system of southern China

Soil organic carbon (SOC) plays a vital role in maintaining or enhancing soil fertility and quality of paddy field, but there is still limited information about how SOC mineralization responds to different tillage managements under the double-cropping rice (Oryza sativa L.) system in southern of China. Therefore, this study was designed to explore the changes in SOC content, soil enzyme activities (invertase, cellulose and urease), SOC mineralization at 0–10 cm and 10–20 cm layers and its relationship with 7-years tillage management under the double-cropping rice system of southern China. The experiment included four tillage managements: rotary tillage with all residues removed as a control (RTO), conventional tillage with residue incorporation (CT), rotary tillage with residue incorporation (RT), and no-tillage with residue retention (NT). The results indicated that SOC and soil labile organic carbon contents at 0–10 cm and 10–20 cm layers in paddy field with CT and RT treatments were significantly higher than the RTO treatment. Compared to the RTO treatment, SOC mineralization and accumulation at 0–10 cm and 10–20 cm layers in paddy field with CT, RT and NT treatments were increased. SOC accumulation and potential mineralization at 0–10 cm layer with NT treatment were significantly higher than the CT, RT and RTO treatments. Soil mineralization constant at 10–20 cm layer with CT treatment was significantly higher than those of RT, NT and RTO treatments. This result indicated SOC mineralization rate and accumulation at 10–20 cm layer of CT, RT, NT and RTO treatments were lower than those of treatments at 0–10 cm layer. Compared to RTO treatment, soil invertase, cellulose and urease activities with CT and RT treatments were significantly increased. Compared to RTO treatment, soil invertase, cellulose and urease activities at 0–20 cm layer of CT treatment increased by 22.6%, 46.2% and 89.0%, respectively. There was significantly positive correlation between SOC accumulation and SOC content, soil invertase, cellulose, urease activities, but SOC accumulation was significantly negative correlated with soil pH, bulk density. Therefore, CT and RT treatments were beneficial managements to improve SOC content and SOC mineralization in the double-cropping rice field of southern China.

Damage associated with the african rice gall midge (AFRGM), Orseolia oryzivora Harris and Gagne (Diptera : Cecidomyiidae) in an integrated cropping system at Bama, Western Burkina Faso

Orseolia oryzivora is a major insect pest of rice in Burkina Faso. This study aimed at assessing the incidence of this pest on an integrated irrigated rice cropping system in Bama, western Burkina Faso. The work was carried out during two consecutive wet cropping seasons, 2020 and 2021. The experiment was conducted using a randomized split-plot design in a latice design. The main plots (MP) were divided into secondary plots, made up of a combination of two factors: two rice varieties (FKR64 and Orylux6) and four types of crop management before rice (Mucuna, cowpea forage, organic matter and a no-crop control); the third factor, mineral fertilization (F0, F1, F2, F3) was distributed in secondary plots (SP). Weekly entomological assessments were carried out from day 28 after transplanting (DAT) to DAT 84. Symptoms of O. oryzivora damage were assessed during the vegetative and reproductive phases of rice and examined in the laboratory. Results showed that all rice varieties were infested with O. oryzivora. The higher amount of NPK, the higher the damage caused by the insect pest. The FKR64 variety recorded the highest average rate of pre-imaginal O. oryzivora populations. The results of this study could contribute effectively to the sustainable management of O. oryzivora in Bama.

Assessment of Soil Quality Parameters under Rice and Maize Cropping Systems in Hilly Region of Central Vietnam

Assessment of Soil Quality Parameters under Rice and Maize Cropping Systems in Hilly Region of Central Vietnam

Response of seed vigor to experimental warming in a double rice cropping system

Climate warming affects rice seed vigor during ripening, which plays a crucial role in seed quality. However, the actual response of rice seed vigor to warming is still unclear. In this study, seeds after warming treatment in a double rice cropping system were used to determine seed vigor and related physiological traits during germination. Warming treatment significantly improved the germination index (GI), seed vigor index (VI), and seedling dry weight (SDW) for the late-season rice seeds but had no effect on hull thickness, grain weight, and starch and protein contents for both early- and late-season rice seeds, and these parameters were highly associated with germination rate, GI, VI, and SDW. Warming treatment increased gibberellin (GA) content and α-amylase and β-amylase activities in endosperm and coleoptile in both seasons during the later stage of germination, reaching a significant level on the 7th d. Moreover, indole-3-acetic acid (IAA) content was consistently increased in the coleoptile but decreased in the endosperm in response to warming, and warming did not affect zeatin content. These results suggest that future global warming will improve rice seed vigor by regulating the synthesis of endogenous hormones and amylases, especially in the late-season rice.

Effects of Organic Farming on Soil Probiotics of Double Rice Cropping System in South China

Organic management practices of double rice cropping can contribute to soil health and crop productivity. However, the impact of organic versus conventional farming practices (CK) on the diversity and functionality of soil probiotics remains poorly understood, despite growing interest in sustainable agricultural methods. To this end, this study evaluated the effects of these farming systems in double rice production on soil microbial communities using metagenomic sequencing and the PROBIO database. Our study accessed the Shannon and Simpson diversity indices of soil probiotics between the two farming systems. Specifically, the Shannon index values were 93.82 for CK and 93.51 for organic farming, showing no statistically significant difference. Similarly, the Simpson index values were 6.18 for CK and 6.46 for organic farming, also demonstrating no significant variance. However, distinct variations in microbial community compositions were observed. Organic farming significantly increased (P < 0.05) the abundance of probiotics that benefit plant growth and nitrogen supply, but reduced those associated with plant nutrient supply and yield. The results show that while organic farming can positively influence certain microbial functions beneficial for sustainable agriculture, it also presents challenges that may affect crop productivity and ecosystem services. These findings suggest that organic farming practices need to be carefully managed to harness the benefits of enhanced microbial functions without compromising crop yields.

Rotary Tillage Plus Mechanical Transplanting Practices Increased Rice Yields with Lower CH4 Emission in a Single Cropping Rice System

As the main contributor to greenhouse gas (GHG) in paddy soil, information on methane (CH4) emission characteristics under different tillage and cultivation practices are limited. A five-year field trial was conducted from 2019 in a single-cropping rice system in Taihu Lake region, east of China. The experiment had a completely randomized block design, and the treatments included rotary tillage plus rice dry direct seeding (RD), rotary tillage plus rice mechanical transplanting (RT), and plowing tillage plus rice mechanical transplanting (PT). We determined the rice yield, GHG emission, soil traits, and methanogens and methanotrophs in 2022 and 2023. The results revealed that PT and RT significantly increased rice yield compared to RD, whereas PT simultaneously increased CH4 emissions. The year-averaged cumulative CH4 emissions in PT were increased by 38.5% and 61.4% higher than RT and RD, respectively. Meanwhile, yield-scaled global warming potentials (GWPs) in RT and RD were lower than those in PT. Tillage and cultivation practices shifted mcrA and pmoA abundances, and PT significantly decreased pmoA abundance. The community structure and diversity of the methanogens and methanotrophs were not significantly affected. Structural equation model analyses illustrated that CH4 emissions were regulated by mcrA and pmoA directly, which in turn, regulated by soil carbon and nitrogen. Overall, rotary tillage plus mechanism transplanting was a feasible agronomic technology in a single-cropping rice system in Taihu Lake region, exhibiting higher and more stable rice productivity, accompanied with lower CH4 emissions and yield-scaled GWP.

Nitrogen scavenging by winter fallow weeds and its availability to rice crops

Weedy fallow presents a promising strategy for nitrogen (N) scavenging and reducing N losses from croplands. The study aimed to (1) reassess the N scavenging potential of winter fallow weeds, specifically foxtail grasses, within rice cropping systems and (2) determine the availability of N scavenged by winter fallow weeds in rice paddies to rice crops. A two-year on-farm investigation (2022 and 2023), a one-year 15N-tracing microplot experiment (2021), and a two-year field experiment (2022 and 2023) were conducted in Hunan Province, China. The on-farm investigation revealed that winter fallow weeds scavenged on average 10.6 g N m–2 in 2022 and 10.9 g N m–2 in 2023. In the 15N-tracing microplot experiment, a 24 % average recovery efficiency of N from winter fallow weeds, applied in conjunction with two rice varieties and two urea-N application rates, was observed. The field experiment showed that total N uptake by rice plants and grain yield of rice crops were linearly and quadratically related to the total N application rate (the sum of N in applied winter fallow weeds and urea), respectively, in both 2022 and 2023. These findings highlight the potential of winter fallow weeds in rice paddies to scavenge N effectively and reveal this scavenged N to be highly available to rice crops. This study offers insights into the dual advantages of winter fallow weeds within rice cropping systems, shedding light on their environmental benefits as well as their positive agronomic outcomes.

Azospirillum brasilense Inoculation in a Maize–Urochloa–Rice Cropping System Promotes Soil Chemical and Biological Changes and Increases Productivity

Large quantities of cover crop residues in the soil, combined, or not, with the inoculation of seeds with diazotrophic bacteria, can increase organic matter (OM) and protect soil microorganisms, such as arbuscular mycorrhizal fungi (AMF) and dark septate endophytic (DSE) fungi. Thus, the use of these sustainable biotechnologies can benefit microbial interactions, soil fertility and rice production in the Brazilian Cerrado region. In this study, we evaluated the effects of maize and Urochloa ruziziensis, intercropped or individually, as cover crops and an inoculation of Azospirillum brasilense on the chemical (fertility) and biological (C–microbial biomass and C–CO2 released) attributes of soil and the effects of root colonization by AMF and DSE on the yield of rice grown in succession in highlands. The experiment was conducted under field conditions, in a typical dystrophic Red Oxisol. The experimental design consisted of randomized blocks arranged in strips, incorporating a combination of eight residual cover crops: ((1) maize, (2) maize–I (I = inoculation of seeds with A. brasilense), (3) Urochloa (U. ruziziensis), (4) Urochloa–I, (5) maize + Urochloa–I, (6) maize + Urochloa–I, (7) maize–I + Urochloa and (8) maize–I + Urochloa–I). This was accompanied by two treatments of rice as a successor crop (inoculated or not with A. brasilense), with four replicates, totaling 64 experimental units. A cover crop and rice seed inoculation prompted increases in OM and AMF relative to DSE, while the inoculation of rice, regardless of the cover crop treatment, increased the soil’s P content. The combination of maize + Urochloa–I and inoculated rice as the next crop generated increases in its sum of bases (SBs) and cation exchange capacity (CEC). There was a 19% increase in rice grain yields when the seed was inoculated.

Carbon footprint research and mitigation strategies for rice-cropping systems in China: a review

Reducing greenhouse gas (GHG) emissions and quantifying the carbon footprint (CF) of rice-cropping systems in the context of food security is an important step toward the sustainability of rice production. Exploring the key factors affecting emission reduction in rice production is important to properly evaluate the impact of China’s rice-cropping systems on global climate change. This review provides an overview of the direct and indirect CF in rice-cropping systems; analyzes the influencing factors in terms of rice-based cropping systems, varieties and agronomic practices; and proposes mitigation strategies. Different studies have shown that direct and indirect GHG emissions in rice-based cropping systems accounted for 38.3 to 95.5% and 4.5 to 61.7% of total emissions, respectively. And the CFs of ratoon rice, rice–wheat, rice–maize, rice–rapeseed, and rice–fish systems ranged from 316,9 kg CO2-eq kg−1 to 258,47 kg CO2-eq kg−1, which are lower than that in a double-rice planting system. High-yielding rice, drought-resistant rice, and other hybrids can mitigate GHG emissions from paddy fields by 3.7 ~ 21.5%. Furthermore, organic matter, water, tillage, straw incorporation, conservation tillage, reduced nitrogen fertilizer use, and added biochar and methane inhibitors could reduce emissions. Therefore, through reasonable agronomic measures, variety selection and optimal layout of rice-based rotation systems, the carbon neutral rate of rice production can be improved to help the national carbon sequestration and emission reduction target.

Effects of 3-year organic farming management on soil antibiotic resistant genes and virulence factors in a double rice cropping system

Investigating the antibiotic resistance genes (ARGs) and virulence factors (VFs) within soil microbial communities is crucial for understanding microbial ecology and the evolution of antibiotic resistance. However, the study of ARGs, VFs, and their predominant microbial hosts in soils under varying rice production management practices remains largely underexplored. To this end, a three-year field experiment was conducted under organic management within a double rice cropping system in South China. The study revealed that, in contrast to conventional management (CK), organic farming practices did not significantly alter the total reads of ARGs and VFs. However, there was a notable alteration in the ARGs abundance at the antibiotic class level, such as an increase (P < 0.05) in the abundance of Multidrug ARGs (by 1.7 %) and a decrease (P < 0.05) in Rifamycin (by 17.5 %) and Fosfomycin ARGs (by 15.3 %). Furthermore, a significant shift in VFs was observed under organic farming compared to CK, characterized by an increase (P < 0.05) in offensive VFs and a decrease (P < 0.05) in nonspecific VFs and the regulation of virulence-associated genes. Key microbial taxa identified as influencing ARGs and VFs in the tested soil samples, e.g., Proteobacteria. The findings highlight the need for more detailed attention to soil ecology within organic rice production systems in South China, particularly concerning the significant alterations observed in ARGs and VFs.

Experimental Warming Increased Cooked Rice Stickiness and Rice Thermal Stability in Three Major Chinese Rice Cropping Systems.

Climate warming is a critical environmental issue affecting rice production. However, its effects on cooked rice texture and rice thermal properties remain unstudied in China. To address this gap, we conducted a two-year multi-site field warming experiment using free-air temperature increase facilities across three major Chinese rice cropping systems. Interestingly, warming had a minimal impact on the hardness of cooked rice, while it significantly increased stickiness by an average of 16.3% under warming conditions. Moreover, compared to control treatments, rice flour exhibited a significant increase in gelatinization enthalpy, onset, peak, and conclusion temperatures under warming conditions, with average increments of 8.7%, 1.00 °C, 1.05 °C, and 1.17 °C, respectively. In addition, warming significantly declined the amylose content, remarkedly elevated the protein content and relative crystallinity, and altered the weight distribution of the debranched starch. Correlation analysis revealed significant relationships between cooked rice stickiness, rice flour thermal properties, amylose content, protein content, and partial starch structures. Therefore, warming-induced alterations in rice composition and starch structure collectively enhanced cooked rice stickiness and rice thermal stability.

Spatio-temporal changes of rice cropping system in Anhui Province from 2010 to 2020

Monitoring changes in rice production is of significant importance for addressing food security concerns in China. However, obtaining long-term, high-resolution rice planting maps is challenging due to the influence of cloud cover and temporal resolution limitations. This study, conducted on the Google Earth Engine (GEE) platform, utilizes Landsat and Sentinel data and employs the difference in normalized difference vegetation index method (dNDVI) to extract the distribution in rice cultivation systems in Anhui Province over the past decade. The results indicate that, between 2010 and 2020, the area of single cropping rice cultivation in Anhui Province increased by 12513.612 km², while the area of double cropping rice cultivation decreased by 13527.892 km². The rice replanting index declined by 31%. With a notable shift observed in 2015, where a substantial area of double cropping rice was replaced by single cropping rice cultivation. Consequently, over the past decade, there has been a gradual decrease in the rice cultivation area in Anhui Province, accompanied by a significant shift from double to single cropping cultivation, and a continuous decline in the replanting index. This research provides vital clues for a deeper understanding of the rice planting pattern, offering scientific support for the sustainability of food production.

Tillage with Crop Residue Returning Management Increases Soil Microbial Biomass Turnover in the Double-Cropping Rice Fields of Southern China

The variety of soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN) content, and the flux turnover rate of SMBC and SMBN for 0–10 cm and 10–20 cm layers in a paddy field in southern China with different tillage practices were studied. The tillage experiment included conventional tillage and crop residue returning (CT), rotary tillage and crop residue returning (RT), no–tillage and crop residue returning (NT), and rotary tillage with all crop residues removed from the paddy field as a control (RTO). The result showed that the SMBC and SMBN contents at 0–10 cm and 10–20 cm layers in the paddy field with CT, RT, and NT treatments were significantly increased. This result indicates that the flux turnover rate of SMBC and SMBN for 0–10 cm and 10–20 cm layers in the paddy field with CT treatment were increased by 65.49%, 39.61%, and 114.91%, 119.35%, compared with the RTO treatment, respectively. SMBC and SMBN contents and the flux turnover rate of SMBC and SMBN for the 0–10 cm layer were higher than that of the 10–20 cm layer in paddy fields under the same tillage condition. Therefore, applying rotary tillage or conventional tillage and crop residue returning produced beneficial management for increasing soil microbial biomass content and its turnover under a double–cropping rice system in southern China.

Long-term application of agronomic management strategies effects on soil organic carbon, energy budgeting, and carbon footprint under rice–wheat cropping system

In the plains of western North India, traditional rice and wheat cropping systems (RWCS) consume a significant amount of energy and carbon. In order to assess the long-term energy budgets, ecological footprint, and greenhouse gas (GHG) pollutants from RWCS with residual management techniques, field research was conducted which consisted of fourteen treatments that combined various tillage techniques, fertilization methods, and whether or not straw return was present in randomized block design. By altering the formation of aggregates and the distribution of carbon within them, tillage techniques can affect the dynamics of organic carbon in soil and soil microbial activity. The stability of large macro-aggregates (> 2 mm), small macro-aggregates (2.0–2.25 mm), and micro-aggregates in the topsoil were improved by 35.18%, 33.52%, and 25.10%, respectively, over conventional tillage (0–20 cm) using tillage strategies for conservation methods (no-till in conjunction with straw return and organic fertilizers). The subsoil (20–40 cm) displayed the same pattern. In contrast to conventional tilling with no straw returns, macro-aggregates of all sizes and micro-aggregates increased by 24.52%, 28.48%, and 18.12%, respectively, when conservation tillage with organic and chemical fertilizers was used. The straw return (aggregate-associated C) also resulted in a significant increase in aggregate-associated carbon. When zero tillage was paired with straw return, chemical, and organic fertilizers, the topsoil's overall aggregate-associated C across all aggregate proportions increased. Conversely, conventional tillage, in contrast to conservation tillage, included straw return as well as chemical and organic fertilizers and had high aggregate-associated C in the subsurface. This study finds that tillage techniques could change the dynamics of microbial biomass in soils and organic soil carbon by altering the aggregate and distribution of C therein.

Estimating thresholds of nitrogen, phosphorus and potassium fertilizer rates for rice cropping systems in China.

Determining the fertilization rate plays a pivotal role in agronomic practices as they directly impact yield targets, soil fertility, and environmental risks. In this study, we proposed a method that utilizes allowed ranges of partial nutrient balance and yield to estimate the threshold of nitrogen (N), phosphorus (P), and potassium (K) fertilizer applied to rice (Oryza sativa L.) fields in China. Based on a dataset of 6792 observations from rice fields, we determined the minimum and maximum rates of N, P and K suggested for single (mono-season rice), middle (summer-season rice rotated with winter-season upland crop), early and late (double-season rice cropping system) rice, ranging between 114-146 and 220-292 kg N ha-1 per season, 56-74 and 112-149 kg P2O5 ha-1 per season, and 170-230 and 329-347 kg K2O ha-1 per season, respectively. These values serve as the lower and upper fertilization thresholds, guiding yield goals and environmental protection. Furthermore, if rice straw is returned to fields, the demand for K fertilizer can theoretically decrease by 183 kg K2O ha-1, with corresponding decreases of 50 kg N ha-1 and 26 kg P2O5 ha-1, respectively. A recommended fertilization approach, excluding returned straw nutrients from the upper fertilization thresholds, suggested average application rates of 194 kg N ha-1, 105 kg P2O5 ha-1, and 157 kg K2O ha-1, which align well with the nutrient requirements of rice. Additionally, substituting organic N for chemical N is an effective approach to conserve chemical fertilizer N, potentially reducing chemical N usage by 20%-40%. Utilizing slow-release N is also a favorable option to enhance N use efficiency and optimize N balance. This study offers valuable insights into the development of fertilization restriction indicators, aiming to achieve a delicate balance between environmental impact and agricultural productivity through the adoption of balanced fertilization rates and utilization of organic residues.

Analysis of sustainability changes in the Korean rice cropping system using an emergy approach

Analysis of sustainability changes in the Korean rice cropping system using an emergy approach

Variations in Soil Organic Carbon Fractions and Microbial Community in Rice Fields under an Integrated Cropping System

Combining rice cultivation and aquaculture into an integrated cropping system is a management approach that enhances the sustainability of rice fields. However, how soil characteristics influence soil microbial community characteristics following implementation of such an integrated system, particularly in the waterlogged paddies of the Pearl River Delta, is poorly understood. An integrated cropping system (rice–fish–duck integrated cropping system, RFD) and a rice–pepper rotation system (RPS) were compared using a conventional rice cropping system (CRS) as a reference. We used phospholipid-derived fatty acid (PLFA) analysis to assess soil microbial community structure and function and measured soil nutrient content and organic carbon fractions. Our results indicated that the soil nutrient content, organic carbon fractions, and C-hydrolyzing activities differed among the cropping systems. The RFD resulted in higher microbial PLFA concentrations and a lower ratio of Gram-positive to Gram-negative bacteria than CRS. Additionally, the integrated system reduced microbial nutrient stress by increasing soil pH. Further analysis revealed that active soil organic carbon significantly affected the soil microbial community. Thus, the RFD integrated cropping systems that alter the combined actions of pH and active organic carbon fractions can be used to improve soil microbial communities.