Search Results (99)

Co-utilization of milk vetch as green manure (GM) and rice straw is an effective practice for reducing nitrogen (N) input while maintaining crop productivity in rice-based agroecosystems in southern China. The effects of soil carbon (C) and N pools and their fractions under green manuring and rice straw return, combined with reduced N fertilization remain to be clarified. A four-year field experiment was carried out to explore the effects of synergistic utilization of GM and rice straw (GMS) on rice yield, soil C and N fractions, and their contributions to rice productivity. The study demonstrated that compared with winter fallow (WF), GMS increased rice yield by 20.3% under 40% reduction in N fertilization (N60). GM application increased soil total N content by 16.5% and 18.0% significantly relative to WF under N0 and N60, respectively. GMS treatment demonstrated improvements in the soil organic C pool and enhanced soil N activity. Compared with WF, soil organic C, mineral-associated organic C and particulate organic C under GMS increased by 11.1% and 24.9%, 31.3% and 13.8%, 13.1% and 47.3% at N0 and N60 levels, respectively. Under N60, GMS increased heavy-fraction organic C content by 42.6% while reducing light-fraction organic C content by 28.0% compared to WF, thereby enhancing soil C pool stability. Regarding soil N fractions, GMS increased particulate organic N content by 60.8% and 79.3%, and mineral-associated organic N content by 89.7% and 43.4% at N0 and N60 levels, respectively. Under N60, GMS reduced heavy-fraction organic N content while increasing light-fraction organic N content, thereby enhancing soil N availability. Based on the results of Mantel tests and random forest prediction, our analysis found that N and particulate organic C served as the key factors affecting rice yield. In conclusion, GMS combined with 60% of the conventional N rate enhanced rice yield by mediating soil C sequestration and N availability, proving to be an effective strategy for improving soil fertility and ensuring food security in the rice-growing region of southern Jiangsu, China. Full article

Crop rotation plays a critical role in enhancing cropping intensity and ensuring food security. To evaluate its long-term effects on soil quality, a fixed-site field experiment established in 2014 including four cropping systems—winter fallow–rice (Oryza sativa L.) (FR), potato (Solanum tuberosum L.) –maize (Zea mays L.) (PM), potato–rice (PR), and potato–rice → rapeseed (Brassica napus L.) –rice (RRPR)—was conducted. A minimum data set (MDS) was screened from 21 soil indicators via principal component analysis (PCA), and the soil quality index (SQI) was calculated by integrating membership functions and indicator weights to comprehensively evaluate the impact of different patterns on soil quality. Results showed that paddy–upland rotations (PR and RRPR) significantly improved soil physical properties, increasing soil moisture content, porosity, and macro-aggregate proportion by 2.27–10.17%, while reducing bulk density by 10.32–13.38%, compared to FR and PM. PR and RRPR rotations also increased total nitrogen (TN), available phosphorus (AP), and available potassium contents (AK) by 5.19–114.00% (p < 0.01). PM rotation notably enhanced available nutrients, with NH₄⁺-N, AP, and AK rising by 3.65–243.50% (p < 0.05), compared to FR. The MDS-based SQI, comprising NH₄⁺-N, AP, mean weight diameter, and soil porosity, showed a highly significant positive correlation with the total data set-based SQI (p < 0.0001). PM exhibited the highest and most stable SQI, exceeding other systems by 8.15–19.30%, while PR and RRPR increased SQI by 9.04–10.30%, compared to FR. In conclusion, potato-based cropping systems enhance soil quality by improving soil structure and increasing nutrient content and availability. The results of this study provide a theoretical basis for nutrient management and sustainable production in cropping systems. Full article

Rice paddy fields (referred to below as rice fields) are important not only for food production, but also as habitats for various species. The Nagoya Daruma Pond Frog (Pelophylax porosus brevipodus) is an endangered frog species endemic to Japan, mainly living in and around rice field areas. In July 2018, heavy rainfall caused severe flooding in Mabi Town of Okayama Prefecture, western Japan, submerging numerous rice fields and affecting local frog populations, including P. porosus brevipodus. To clarify whether the population structure of P. porosus brevipodus changed following the flood disaster in the rice fields of Mabi Town, we conducted quantitative field surveys in a rice fallow field in mid-October before (2017) and after (2018, 2020–2022, excluding 2019) the flood. The number of frogs declined sharply after the 2018 flood, reaching only a few individuals by 2020, but showed a substantial recovery in 2021 following the resumption of rice cultivation, although numbers decreased again in 2022. This recovery, despite fluctuations, indicates that habitat restoration through rice farming played a key role in enabling the population to rebound. Our findings underscore the importance of maintaining and restoring rice field environments after natural disasters for the survival and long-term recovery of P. porosus brevipodus. Full article

Co-incorporating rice straw and Chinese milk vetch (CMV) residues can enhance soil organic carbon (SOC) sequestration and productivity. However, limited information exists regarding its effects on SOC and nitrogen (N) pools as well as the sustainability of rice production in the middle and lower reaches of the Yangtze River Basin. A 3-year field experiment was conducted to assess the effects of co-incorporating rice and CMV residues into paddy soils with chemical-N reduction on SOC and total N (TN) sequestration, SOC and N fractions, grain yields and the sustainable yield index (SYI) in Ma’anshan City, Anhui Province. The treatments included winter fallow–rice rotation without or with both rice straw incorporation and fertilization, as the control (CK and WF-IF, respectively), and rice-CMV rotation with the co-incorporation of rice and CMV residues under 100%, 80%, and 70% recommended N fertilization (CMV-IF, CMV-MIF and CMV-LIF, respectively). Compared with the CK, the CMV-IF significantly increased the rice grain yield and the SYI by 82.1% and 90.4%, respectively. The SOC and TN stocks under CMV-IF were significantly enhanced by 6.3% and 26.4%, respectively, relative to the CK. The CMV-IF exhibited the highest soil active organic C (AOC) and active total N (ATN) contents, followed by CMV-MIF, CMV-LIF, WF-IF, and CK. Microbial biomass C and microbial biomass N were the primary components of soil AOC and ATN, respectively, and linked more explicitly to the SYI than other soil C and N parameters. Therefore, the co-incorporation of rice and CMV residues, coupled with 70~80% recommended N fertilization, might represent an environmentally friendly field management practice for rice production in the middle and lower reaches of the Yangtze River Basin. Full article

Under global warming, the differences in yield, soil nutrients, and economic benefits between various planting patterns in double-cropping rice areas were compared, and the high-yield and high-efficiency planting patterns that can adapt to climate change were selected. Four planting patterns, namely rape–rice (RaR), fallow–rice (FR), Chinese milk vetch–early rice–late rice (CRR), and fallow–early rice–late rice (FRR), were investigated. Compared with FRR, the yield of early rice increased by 13.6% using the CRR rotation. CRR could increase the spikelet per panicle of early rice, thereby enhancing rice yield. The soil’s available nitrogen content demonstrated an increase under the CRR rotation when compared with FRR. The yield under RaR increased by 11.9% on average compared with FR. The RaR rotation enhanced panicles per ha, thereby increasing rice yield. RaR could increase the soil’s available nutrient content compared with FR. Compared with CRR, FRR, and FR, the net income of RaR was higher by 1031 CNY/ha, 2046 CNY/ha and 5762 CNY/ha, respectively. Comprehensively compared with the other three planting patterns, RaR could effectively improve the soil fertility of paddy fields, grain yield, and net income. RaR is a sustainable planting pattern with a high yield and high efficiency worth popularizing. In addition, under the warming climate, the growth period and sowing date of rice of RaR and FR should be appropriately extended and postponed to avoid encountering more frequent high-temperature weather. Full article

This study aimed to assess the effect of organic amendment-based integrated nitrogen (N) application on major soil macronutrients, carbon (C) accumulation, crop productivity and N use efficiency (NUE) of different rice-based cropping patterns. This experiment was composed of various organic amendments ((i): control (no organic amendment, application of 100% N from urea); (ii): 25% N from compost + 75% N from urea; (iii): 25% N from cowdung + 75% N from urea; iv: 25% N from vermicompost + 75% N from urea) and rice-based cropping patterns ((i) rice–rice–rice, (ii) rice–fallow–rice–mustard, and (iii) rice–vegetables–rice). Organic amendments and soils (0–20 cm) were collected from farmers’ fields and were analyzed for major nutrients: N and organic C (OC), phosphorus (P), potassium (K) and sulphur (S). Soil OC accumulation potential, system productivity and partial factor productivity of N were also calculated. The results indicate that organic amendment application significantly enhanced soil OC (0.957–1.604%) compared to control (0.916–1.292%), with vermicompost attaining the highest OC content and OC accumulation potential (up to 24.15%), especially in the rice–vegetables–rice pattern. Vermicompost also predominantly increased N (22–62%) and S (51–78%) level in soils, while cowdung significantly amended P levels (155–178%) and contributed steadily to improved K levels in soil. Overall, nutrient improvements and soil fertility were highest under the rice–vegetables–rice system, followed by rice–fallow–mustard–rice and rice–rice–rice. System productivity was maximum in the rice–vegetables–rice pattern (up to 85.7 t ha⁻¹), with remarkable enhancements in NUE when organic amendments were applied. Cowdung and vermicompost both matched or exceeded the performance of chemical fertilizer in these cases. These results demonstrate the advantages of integrated N management and diversified cropping to improve nutrient cycling, soil health and sustainable productivity in rice-based agroecosystems. Full article

This study evaluated the effects of winter green manure incorporation on grain yield, nitrogen uptake, and use efficiency in ratoon rice production. A two-year field experiment (2019–2021) was conducted using a split-plot design, with main plots comprising three cropping systems: fallow–ratoon rice (FA), rapeseed–ratoon rice (RA), and milk vetch–ratoon rice (MV). In the RA and MV systems, green manures were incorporated in situ, while subplots featured two ratoon rice varieties (Yliangyou 911, YLY911; Liangyou 6326, LY6326). Compared to FA treatment, RA and MV treatments significantly increased main crop yields by 16.37% and 9.31%, respectively, with corresponding annual total yield improvements of 11.34% and 7.78%. Under RA treatment, LY6326 achieved significantly higher yields than YLY911. Biomass accumulation analysis revealed that RA and MV treatments enhanced plant dry matter by 24.40% and 5.63% at heading stage, and 9.83% and 7.47% at maturity, respectively, relative to FA treatment. Green manure incorporation improved plant nitrogen content at maturity (9.42% and 10.29% for RA and MV, respectively) and panicle nitrogen accumulation (11.73% and 38.26%, respectively) compared to fallow treatment. Nitrogen use efficiency metrics demonstrated that RA and MV treatments enhanced nitrogen harvest index by 1.54% and 5.65%, respectively, while nitrogen partial factor productivity increased by 11.34% and 7.78%. Varietal comparison confirmed that LY6326 exhibited superior nitrogen accumulation and utilization compared to YLY911. These findings demonstrate that winter green manure incorporation significantly enhances grain yield and nitrogen use efficiency in ratoon rice systems, providing a scientific foundation for developing sustainable and productive rice cropping practices. Full article

Integrated rice–crayfish (Oryza sativa–Procambarus clarkii) co-culture (RC) systems have gained prominence due to their economic benefits and ecological sustainability; however, the interactions between soil properties and microbial communities in such systems remain poorly understood. This study evaluated the effects of the RC systems on soil physicochemical characteristics and microbial dynamics in paddy fields of southern Henan Province, China, over the 2023 growing season and subsequent fallow period. Using a randomized complete design, rice monoculture (RM, as the control) and RC treatments were compared across replicated plots. Soil and water samples were collected post-harvest and pre-transplanting to assess soil properties, extracellular enzyme activity, and microbial community structure. Results showed that RC significantly enhanced soil moisture by up to 30.2%, increased soil porosity by 9.6%, and nearly tripled soil organic carbon compared to RM. The RC system consistently elevated nitrogen (N), phosphorus (P), and potassium (K) throughout both the rice growth and fallow stages, indicating improved nutrient availability and retention. Elevated extracellular enzyme activities linked to carbon, N, and P cycling were observed under RC, with enzymatic stoichiometry revealing increased microbial nutrient limitation intensity and a shift toward P limitation. Microbial community composition was significantly altered under RC, showing increased biomass, a higher fungi-to-bacteria ratio, and greater relative abundance of Gram-positive bacteria, reflecting enhanced soil biodiversity and ecosystem resilience. Further analyses using the Mantel test and Random Forest identified extracellular enzyme activities, PLFAs, soil moisture, and bulk density as major factors shaping microbial communities. Redundancy analysis (RDA) confirmed that total potassium (TK), vector length (VL), soil pH, and total nitrogen (TN) were the strongest environmental predictors of microbial variation, jointly explaining 74.57% of the total variation. Our findings indicated that RC improves soil physicochemical conditions and microbial function, thereby supporting sustainable nutrient cycling and offering a promising, environmentally sound strategy for enhancing productivity and soil health in rice-based agro-ecosystems. Full article

The DNDC-Rice model effectively simulates yield and greenhouse gas emissions within a paddy system, while its performance under upland conditions remains unclear. Using data from a long-term cover crop experiment (fallow [FA] vs. rye [RY]) in a soybean field, this study validated the DNDC-Rice model’s performance in simulating soil dynamics, crop growth, and C-N cycling processes in upland systems through various indicators, including soil temperature, water-filled pore space (WFPS), soybean biomass and yield, CO₂ and N₂O fluxes, and soil organic carbon (SOC). Based on simulated results, the underestimation of cumulative N₂O flux (25.6% in FA and 5.1% in RY) was attributed to both underestimated WFPS and the algorithm’s limitations in simulating N₂O emission pulses. Overestimated soybean growth increased respiration, leading to the overestimation of CO₂ flux. Although the model captured trends in SOC stock, the simulated annual values differed from observations (−9.9% to +10.1%), potentially due to sampling errors. These findings indicate that the DNDC-Rice model requires improvements in its N cycling algorithm and crop growth sub-models to improve predictions for upland systems. This study provides validation evidence for applying DNDC-Rice to upland systems and offers direction for improving model simulation in paddy-upland rotation systems, thereby enhancing its applicability in such contexts. Full article

The co-incorporation of green manure and rice straw is commonly used to increase rice yield and improve soil fertility in paddy fields. However, the effects on nutrient uptake and utilization of rice under the synergistic interaction mechanism in the Taihu Plain of the Yangtze River Delta remain unclear. Based on field experiments, this study investigated the effects of green manure with rice straw return (GMS) under different nitrogen (N) fertilization rates on rice yield, nutrient use efficiency, and soil fertility. The results revealed that green manuring significantly increased rice yield while improving the uptakes and use efficiencies of N, phosphorus (P) and potassium (K). Green manure (GM) with 40% N fertilizer reduction (GM_N60) maintained the grain and straw yields and nutrient uptakes compared to winter fallow with 100% conventional N application (WF_N100). The N recovery efficiency in GM_N60 reached 45.52%, increasing by 41.26% compared to WF_N100. Rice yield and K uptake in the GMS with 40% N fertilizer reduction treatment (GMS_N60) was 10,058 and 15.41 kg/hm², increasing by 14.43% and 9.43% compared to winter fallow with rice straw return and 100% conventional N (WFS_N100). The N, P and K agronomic efficiencies in GMS_N60 increased by 77.04%, 50.22%, and 50.22% compared to WFS_N100, respectively. These findings indicate that rice straw return enhances the fertilizer-saving and yield-increasing effects of GM, promotes rice K uptake and improves P and K use efficiencies. The GM treatment increased the soil organic matter (SOM), total potassium (TK), ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃⁻-N) contents. Among the soil fertility indicators, TK and SOM were the most important factors influencing rice yield and N uptake. In conclusion, GMS can maintain or increase rice yield with 40% N fertilizer reduction, improve nutrient use efficiencies, and increase the reuse of rice straw, thereby supporting green and efficient rice production in the southern Jiangsu paddy area. Full article

Increased saltwater intrusion likely causes a significant reduction in food production in alluvial river deltas worldwide. One of the mitigation measures for saltwater intrusion is to increase natural flow through irrigation water conservation and land-fallowing policies to prevent the saltwater from moving further inland. However, economic estimates of the costs of such measures under uncertainty are scant. Herein, we develop an integrated modeling framework for estimating the costs of saltwater intrusion mitigation policies by 2050 in the Mekong Delta. The integrated model combines hydrodynamic, advection-dispersion, statistical, crop yield, and economic models, thus allowing us to account for the risk and uncertainty of saltwater intrusion and the costs of mitigation policies. We found that a 95% confidence interval of the saltwater intrusion-impacted area is estimated to be 186,000–201,000 hectares for the baseline, 193,000–209,000 hectares for a sea level rise of 22 cm, and 204,000–219,000 hectares for a sea level rise of 53 cm scenarios, respectively. To bring the saltwater intrusion under the sea level rise of 22 cm back to the baseline level, 100,000–150,000 hectares of currently cultivated rice would need to be fallowed at least once a year. This is equivalent to annual economic losses, with a 50% chance, ranging from $100.03–$176.67 million, implying a substantial economic cost of sea level rise-induced saltwater intrusion even under a modest sea level rise scenario. Under the sea level rise of 53 cm scenario, the results show that widespread adoption of alternate wetting and drying and approximately 300,000 ha of land-fallowing would be needed to push saltwater intrusion back to the baseline level. The findings indicate that saltwater intrusion in the Mekong Delta is more likely than not to intensify considerably and is much less predictable, posing a greater risk to one of the most important rice-producing regions in the world. Full article

The cultivation of Chinese milk vetch (CMV) during the winter fallow season and the return of rice straw are important practices for increasing the soil fertility of paddy fields in southern China. In order to provide data-based evidence for the scientific strategy of nitrogen (N) fertilizer reduction through the incorporation of rice straw and CMV, a three-year field trial was conducted. The treatments included the three N application rates of 0%, 60%, and 100% of the local conventional rate (165 kg ha⁻¹), with the incorporation of CMV alone (MN0, MN60, and MN100) or with both CMV and rice straw (SMN60 and SMN100). The rice grain yield, N uptake, and dynamic changes in inorganic N in the soil and surface water were determined for the period from 2019 to 2021. The results show that both the rice grain yield and plant N uptake of the MN60 and SMN60 treatments were not significantly different from those of the treatment with only conventional N application (N100). Although the SMN100 treatment significantly increased the uptakes of N in the aboveground part in the tillering and shooting stages compared with SMN60, no significant differences were found between the grain yields in 2021. Meanwhile, the SMN60 treatment significantly increased the soil microbial biomass N and NH₄⁺-N contents during the maturity stage in 2020 and 2021, respectively, compared with MN60. Furthermore, the SMN100 treatment resulted in higher NO₃⁻-N concentrations in the surface water at days 3 and 6 after transplantation in 2020 than those under SMN60. In conclusion, the incorporation of CMV and rice straw with an application rate of 60% of conventional N fertilizer is an essential approach to reducing the risk of N loss while maintaining rice grain yields in the Jianghan Plain of China. Full article

Agriculture in the Indian Sundarbans deltaic region primarily depends on a rice-based monocropping system during the rainy season, with the subsequent season often remaining fallow. To mitigate this issue, a series of experiments using zero tillage and straw mulching (ZTSM) potato cultivation were conducted over eight consecutive years (2017–2024) across various islands in the Sundarbans Delta, West Bengal, aimed to intensify the cropping system and ensure the betterment of the land use pattern using climate-smart agricultural practices. In the initial two years, the experiments concentrated on assessing different potato cultivars and nutrient dosages under zero tillage and paddy straw mulching conditions. During the subsequent years, the focus shifted to field demonstrations under diverse climatic conditions. The research included the application of different macronutrients and growth regulators, in combination with different depths of straw mulching. In the final years of the study, the intervention was dedicated solely to the horizontal expansion of cultivated land. These initiatives aimed to enhance agricultural productivity and sustainable land use in the polders, promoting climate-resilient farming practices. From the sets of experiments, we standardized the sustainable nutrient management strategies and selection of appropriate potato cultivars vis-à-vis depth of straw mulching and, finally, the overall best agronomic practices for the region. The adoption of the ZTSM potato cultivation system demonstrated considerable success, as evidenced by the remarkable increase in the number of farmers employing this sustainable agricultural practice. The number of farmers practicing zero tillage potato cultivation surged from 23 in the initial year to over 1100, covering an area of more than 15 ha, highlighting the effectiveness of the technology. The analysis of the estimated adoption also showed that more than 90% adoption is likely to be achieved within a decade. This potential expansion underscores the benefits of the ZTSM potato cultivation system in improving soil health, conserving water, and reducing labour and costs. As more farmers recognize the advantages of zero tillage potato mulching, this approach is poised to play a pivotal role in sustainable agriculture, enhancing productivity while promoting environmental stewardship. Full article

Spiders are among the predominant predatory arthropods in rice field ecosystems. Although the potential of spiders for controlling pests during the growth stages of rice is well known, few studies have focused on the overwintering habits of spiders after rice harvesting. In the present study, we aimed to evaluate the potential of rice stubble as an overwintering microhabitat for spiders in winter-fallowed rice fields. To this end, we investigated the arthropod community composition and analyzed the prey spectra of common predators in rice stubble in winter-fallowed rice fields in Nanchong City, Sichuan Province, China. The results showed that abundant predatory arthropods, particularly spiders, were present in the rice stubble, followed by other arthropods and pests. Dietary analysis via DNA metabarcoding revealed the prey availability and/or predation frequency of spiders is low in winter rice fields. Nevertheless, pests and other arthropods (particularly collembolans) within rice stubble serve as food resources for predators, particularly spiders, in winter-fallowed rice fields. Our results confirm that rice stubble provides overwintering microhabitats for spiders in winter-fallowed fields. Therefore, it is particularly important to properly manage rice stubble in winter-fallowed rice fields to enhance the biological pest control services of predators (including spiders). In addition, our findings highlight the potential of rice stubble as a habitat for the artificial reproduction of spiders for pest control in rice fields. Full article

From May 2019 to May 2022, a field experiment was conducted to clarify the effects of paddy–upland rotations on rice yield and greenhouse gas emissions in winter paddy fields. Four types of rotation pattern, rice–oilseed rape, rice–radish, rice–faba bean, and rice–fallow (flooded), were investigated and the N₂O, CH₄, and CO₂ emissions in situ and rice yield were determined. The results showed that the paddy–upland rotation mode required fertilization during the winter cropping season. Compared with the rice–fallow (flooded) mode, the flux rate and annual cumulative emissions of N₂O were significantly higher in the paddy–upland rotation modes. The rice–radish mode had the highest flux rate and annual cumulative emissions of N₂O. When the soil in each paddy–upland rotation mode was exposed to air in winter, the soil redox potential increased and reducing substances were oxidized. Compared with the rice–fallow (flooded) mode, the flux rate and annual cumulative emissions of CH₄ significantly decreased in the paddy–upland rotation modes, with the rice–radish mode producing the lowest flux rate and annual cumulative emissions of CH₄. Fertilization and crop planting were conducted in winter, and the soil moisture was low. Compared with the rice–fallow (flooded) mode, the flux rate of CO₂ of the paddy–upland rotation modes increased significantly. The flux rate of CO₂ in the rice–oilseed rape mode was the highest. Furthermore, the N₂O and CH₄ emissions produced during the rice season and annually were significantly positively correlated with those in the winter season, indicating that the winter season had a significant effect on greenhouse gas emissions from winter paddy fields. Because of the significantly higher annual cumulative emissions of CH₄ and the significantly lower rice yield in the rice–fallow (flooded) mode than in the paddy–upland rotation modes, this mode’s global warming potential (GWP) and greenhouse gas intensity (GHGI) during the rice season are significantly higher than those of the paddy–upland rotation modes. Full article